Does altitude affect how you interpret the attitude of the aircraft?

Yes, due to the curvature of the earth.  But you'd have just as much variation with a small change in pilot eye position within the aircraft.  The exact "sight picture" of the top of the nose (or the top of the instrument panel) relative to the horizon is not really something that you memorize and use as an absolute reference point with the expectation that it will be exactly the same every time you fly a given airplane.  It's more just something that you keep an eye on to watch for changes.  By the time you've climbed to altitude, you've had plenty of time to (perhaps unconsciously) get used to the resulting slight change in the sight picture between the nose and the horizon line.  All the while, other instruments such as the altimeter or airspeed indicator or vertical speed indicator help tell you whether the place you are putting the nose relative to the horizon, is really the correct place to make the airplane do what you want it to do.  Of course, there many instances where the horizon is not clearly discernible anyway.


Is the "PROB" in a TAF only applying to the next group or all following ones?

PROB40 is targeted only on the immediate TEMPO group. If there are several PROB/TEMPOs both keywords must be repeated every time. Also, PROB is never associated with BECMG or FM groups, which indicate permanent change.


Is there a formula to calculate ground distance traveled given rate of climb and true airspeed?

You need ground speed not TAS. GS is affected by the head- or tail-wind components.

Assuming in your example GS is 75 knots, then just check how long it takes to change altitude.

11,200 ft at 1,250 ft/min takes 8.96 minutes, or 0.1493 hours.

At a speed of 75 knots, that's 11.2 NM.

$$\frac{\text{altitude change (ft)}}{\text{rate of climb (ft/min)}\cdot60}\cdot\text{ground speed (knots)}$$

Since the density of air changes during a climb/descent, it affects the rate of climb/descent. Fancy planes have green bananas or similar indications on the navigation display to show where you'll reach the target altitude (it updates in real-time).

The green arc is that green banana (altitude range arc).


HSI KG 525 PNI non slaved or only slaved?

The G5/430 combination was approved by EASA back in February! No reason why you can't use it. Some advice for you, learning how to use Google search is an invaluable skill for any aircraft engineer. :)


The downwash is about as high as wide, and angled only by a few degrees (more at slow speed). So the longitudinal distance needs to be many times longer than the wing span to make the wings independent.
And it would still be less efficient than increasing the span:

If you double the span, you will decrease induced drag four times.
If you half the lift, you also decrease the induced drag four times, but then you add the second wing to get your lift back and that also doubles the induced drag, so you have half the induced drag, not quarter.


Do FDRs & CVRs (black boxes) have an in-service life span?

The FAA is making an effort to phase out magnetic tape style recorders as noted in the this AC

  1.7 Obsolete Technology. We are phasing out magnetic tapes through
  mandates and voluntary efforts and replacing them with modern
  solid-state recorders. These new recorders not only enhance safety but
  also benefit you directly, as they avoid the high costs and technical
  problems of maintaining outdated recorders. Modern recorders do not
  require the hourly replacement of tapes and calendar weighing of
  thermal capsules. Also, existing tape recorders no longer meet the
  most recent FAA TSO minimum performance standards.

However they clearly state the replacement is voluntary. The wording here also implies that the tapes are replaced on an hourly cycle and the thermal capsules are checked.

This AC covers quite a bit about the design and function of the FDR and CVR. I would take a look at CHAPTER 3. CONTINUED AIRWORTHINESS REQUIREMENTS starting on page 12. It outlines some of the things old FDR/CVR's may need to comply with to remain airworthy.

Im sure there are also specific limitations on specific units out there like any other component in aviation that may have caused them to be removed from service or lose their certification somehow.


What are the differences between the two main brace positions?

One is for when the seat in front of you is in the way of using the other.

The other is for when you can't reach a seat in front of you.

They won't both be relevant for the same person in a given seat. If you can assume the second position, the first one probably won't provide meaningful support for your head anyway.


What is the maximum altitude ATC would deal with?

There are many examples of aircraft with high service ceilings. While most commercial aircraft have service ceilings of FL410 and rarely fly even that high, many business jets have a service ceiling of FL510, such as the Dassault Falcon 7X, Gulfstream G650, and Bombardier Global Express.

That being said, military jets can fly higher and will be talking to ATC while in their airspace. Fighter jets are capable of high altitude flight, and planes like the U-2 and Global Hawk still fly up there as well.

In the US, all aircraft from FL180 to FL600 must be in contact with ATC, but above this they are not required to. ATC will still provide services when able though.


What is the quickest way to get an airship rating?

Since you didn't specify the type of Airship you're looking to get a rating in, I found a Flight Standardization Board (FSB) Report for a Zeppelin, that discusses the training required for that specific Airship.

Here is the relevant time requirements for this particular airship from the document:

5.2 Commercial Airship Pilot
(a) Ab Initio:
Standard duration of training: Approximately 20 months
Maximum duration of training: 24 months
Theoretical training: 300 hours
Practical training: Three months on a ground crew
Minimum of 50 training flight hours
Minimum of 150 supervised flight hours

(b) Students holding a CPL:
Standard duration of training: Approximately 15 months
Maximum duration of training: N/A
Theoretical training: Minimum of 93 hours
Practical training: Three months on a ground crew
Minimum of 40 training flight hours
Minimum of 130 supervised flight hours

(c) Type Rating:
Standard duration of training: Approximately four months
Maximum duration of training: N/A
Theoretical training: Minimum of 49 hours
Practical training: Minimum of 25 training flight hours
Minimum of 100 supervised flight hours

The Commercial Practical Test Standards for Lighter-than-Air can be found on the FAA Website, and you would need to make sure that you had satisfied the following conditions:

  An applicant already holding a commercial pilot certificate who
  applies for an additional category and/or class rating on that
  certificate must:

  hold a commercial pilot certificate;
  have the prescribed aeronautical experience and training required for the category and class rating sought;
  pass an additional knowledge test for the rating sought (unless already rated in airplane, rotorcraft, or airship) since the beginning
  of the 24th month before the month in which he/she takes the practical
  test; and
  obtain an endorsement from an authorized instructor certifying that the applicant has been given flight instruction in the applicable
  AREAS OF OPERATION listed in 14 CFR part 61, section 61.127, for the
  commercial pilot rating sought in preparation for the practical test
  within 60 days preceding the date of application. The statement shall
  also state that the instructor finds the applicant competent to pass
  the practical test, and that the applicant has satisfactory knowledge
  of the subject area(s) in which a deficiency was indicated on the
  knowledge test report.

So you can see the standard duration of training is approximately 15 months. There are some interesting anecdotes in this article from AOPA:

  Pilots interested in getting their pilot certificate with an airship
  rating will have to train while on the job, since there are no schools
  that teach this particular skill, according to Bret Viets, chief pilot
  on the MetLife Snoopy Two blimp.

Veits goes on to say that it took him 66 days. (He started Dec 4, 2007 and took his checkride on Feb 8, 2008). And he thought he did in a pretty short time period. It sounds like he got lucky and ended up having the airship to himself for training for a couple weeks!

Looks like you're on your way with a commercial rating, too:

  The company prefers that applicants have a commercial rating, whether
  it’s on airplanes, helicopters, gliders, or hot air balloons, said
  Viets. “It just makes the transition to airship hourly requirements
  less if someone already has a commercial rating,” he said. “To
  transition to airships is a minimum of 50 hours, but it usually takes
  a little longer than that, like any aircraft rating.”

  If an applicant does not have a commercial rating, he or she will need
  250 hours in airships before getting that commercial airship rating,
  said Viets. “They prefer pilots with 1,200 hours and a CFI
  certificate,” he said.


Does the APU consume a lot of fuel compared to a jet engine?

To give a comparison with an engine at idle:

On the 737 NG, the APU can use 240 lb/hr when under load. It is rated at 90 kVA, same as the generator on each engine.

The engines can use about 850 lb/hr at idle, which from those figures is about 1/10 of fuel flow at full (takeoff) power. So the engines use about 4 times as much fuel (each) as the APU does to just provide power. Of course these values will vary based on ambient conditions and the load placed on the systems (like the bleed air system).

This is why if a plane has to stop away from the gate for a while, they will shut down the engines and run on the APU.


Why haven't the remaining TRSAs been converted to Class C airspace?

Class C airspace is established by a rulemaking procedure (i.e., Notice of Proposed Rulemaking, comments, publication, etc.).  TRSAs are not established by rulemaking action.

From FAA JO 7210.3Z- Facility Operations and Administration -para. 11-1-3 & 4

Class C:

  Class  C  airspace  must  be  officially  designated  by
  airspace action in 14 CFR Part 71 and is established
  solely to define the airspace in which all aircraft are
  subject  to  operating  rules  and  equipment  requirements specified in 14 CFR Part 91.[emphasis is mine]

TRSA:

  TRSAs
  are not officially designated
  by airspace
  action and were established solely to define an area
  within which a separation service will be provided.
  [empasis is mine]

Within a TRSA the (vfr) pilot is not required to participate.  However, within Class C airspace a (vfr) pilot is required to participate.

It is not as simple as a charting issue:

If a Radar Facility Manager wants to change a TRSA and make it Class C airspace a staff study must be done and proper justification has to be documented and approved. See Class C Airspace Processing (staff study protocol) FAA Order 7400.2L - Procedures for Handling Airspace Matters - para: 16-3-1

Since the implementation of Regulatory Class C airspace requires more ATC involvement to provide the service (Class C service) and requires mandatory participation on the part of vfr pilots, the process can be a significant challenge that has to be clearly needed for the area in question and fully justified with consideration of public comments, etc., and a variety of other procedural steps to comply with rulemaking procedures.

In short, unless the Facility Manager (for that area) has determined that a higher level of air traffic control  is necessary for safety/service, etc., and then provides justification and considers comments from the public (who may not want the additional restrictions of Class C), changing a TRSA into Class C airspace won't happen.


Under what conditions can a flight continue beyond the point of in-flight re-planning?

it’s just a complicated way of saying: you are not allowed to begin an IFR flight either from the ground (“shall not take off”) nor can you file a new one in the air (“continue beyond the point of in-flight re-planning”) unless some weather conditions are met at the destination and nominated alternate(s).

I other words the “point of in-flight re-planning” is not a decision point, it’s just: the point where we would like to file (re-plan) a new flight plan (in-flight).

And the conditions are the same wether you are on the ground or already flying: either (destination WX > operational minima) or (ALL nominated and required alternates > planning minima)

note that (depending on jurisdiction) most of the times a minimum 2 alternates are required if destination WX < operational minima.

  Can I continue flight at the point of in-flight re-planning if:
  "destination APO WX > minima" & "alternate APO WX < minima"

if destination > minima, under specific circumstances you might not require an alternate. if still required, it must be nominated and above the planning minima. So answer : probably no.

  Can I continue flight at the point of in-flight re-planning if:
  "destination APO WX < minima" & "alternate APO WX > minima"

if destination < minima, you will most likely require 2 nominated alternates and the must BOTH be above planning minima. Shory answer: yes


How close are we to replacing pilots with computers?

As a person that "tries to replace pilots with computers" I personally say: not even close.

The processing power (certified for flight, not the latest pentium sitting under your desk) is too behind, in particular concerning the point here below.
Synthetic vision is still extremely lacking. This is currently the biggest hurdle to overcome. While pilots can look out of the windows and assess the situation (with some limits, admittedly), computers still have several problems with it, starting from a general lack of cameras and going all the way to the daunting level of processing power required.
Ability to adapt is still a long way to come. Computers are "fundamentally stupid", they do what they are told (programmed) to do, they are not capable of adapting to an unforeseen (and never experienced before) emergency. There are several people working in machine learning and the field has advanced significantly in the latest years, but good luck certifying those programs.


Why is the A330/A340's angle-of-attack protection disabled in alternate law, even if the AoA vanes are operating normally?

1. AoA vanes are speed sensitive

An AoA vane is in essence a weather vane, but due to various aerodynamic interactions it's not perfect. From flight testing they would have worked out how speed affects the position, and based on that the sensed position is corrected by speed input.

From the A330/A340 FCTM (Flight Crew Training Manual) section 8.110.4:

  The ADRs provide a number of outputs to many systems and a blockage of the pitot and/or static systems may also lead to the following:

  (...)
  Alpha floor activation (because AOA outputs from the sensors are corrected by speed inputs)
  (...)

2. Alpha floor inhibition

The above suggests alpha floor could have been activated due to the blockage, but unlike the A320, alpha floor is inhibited on the A340 above Mach 0.53 (no reason is given). (Source: A340 FCOM 1.22.30)

3. Crickets + stall

That stall warning in alternate law is based on a computed VSW (V Stall Wanring), and not the AoA. (A340 FCOM 1.27.30)

The A340 FCOM and FCTM are obscure as to what goes into the VSW calculation, but one of the inputs for that speed for the A320 is the calculated gross weight.


I don't know about the situation specifically in the US, but in my - mostly European - experience crew are happy to welcome you to their office after flight.

When I feel the need to see the cockpit or discuss things with the pilots I try to ask the flightcrew before take-off if I can meet them after the flight. Sometimes I explain my interests to the cabin crew and often they will arrange the visit. In a few cases I just asked while deboarding.

Depending on the aircraft type and airport situation you have to think about the logistics a bit. In single aisle aircraft, if you start a discussion with crew while deboarding, you are blocking the queue. This gives the feeling that it is an inconvenient moment and reduces your chances. So if you ask at the last possible moment, make sure most people already exited before you.

However, if passengers are transported to the terminal by bus, you will be holding the bus since you are the last to get off. This reduces the time you can spend in cockpit drastically. If you expect to be bussed to the terminal, ask cabin crew before the descent and don't wait until everybody has exited.


Does NASA use T-38's to train all crew members of a space flight as pilots?

Non-pilot astronauts are not required to become pilots. They fly in the backseat of T-38's partially for transportation purposes, and partially for flight regime training. They are called "mission specialists" and since their job does not require piloting skills, there is no reason to train them as such.

NASA literature says "The T38 is used for
flight readiness training to help the astronauts become adjusted to
the flight environment, including the g-forces experienced on launch" and that non-pilots fly at least four hours per month in a T-38. Pilot astronauts fly at least 15 hours per month to maintain proficiency.

You can look up whether someone has a US Pilot's license using the FAA's Airmen Inquiry Page. A quick search turns up several astronauts who have never been licensed. For example, the mission specialists on the final shuttle mission, Sandra Magnus and Rex Walheim, are not pilots. That being said, I wouldn't be surprised if most, if not all, of the non-pilot astronauts got some stick time in a T-38 since it is a trainer with dual controls.

  Obviously the pilot and I'm guessing the commander would be airforce pilots

In the NASA vocabulary, commander is equivalent to what you would think of as pilot or captain, whereas pilot is equivalent to what you would think of as co-pilot. In the Apollo program, the commander landed the lunar module on the moon, not the "Lunar Module Pilot," and in the shuttle program, the commander landed the shuttle, not the pilot.

So, you are correct that both the commander and pilot must be pilots, and some of them did come from the Air Force, although US Navy was more common, and a few came from the Marine Corps. Almost all of them were test pilots.

A few astronauts joined NASA with the qualifications to be pilot-astronauts, but only flew as mission specialists (for example, James Voss and Carl J. Meade). I am honestly not sure whether or not NASA allowed them to fly the T-38's; however, the only photo evidence I can find shows them in the rear seat, which leads me to believe they were not allowed to fly solo.

  I have no idea if NASA still uses T-38's

NASA does still use T-38's because NASA still sees a need for pilot astronauts in the future, and the pilots need a way to maintain flying proficiency. In the 2013 Astronaut Candidate Class, four out of the eight were test pilots of some sort, although it's unclear how many will be considered pilot-astronauts.

There is anecdotal evidence that the number of T-38's which NASA operates does appear to be shrinking, which is likely a reflection of a reduced astronaut corps size, budget constraints, and the fact that the aircraft fleet is about 50 years old. According to unconfirmed sources (wikipedia), the number of NASA T-38's is expected to be reduced from 32 to 16 by 2015.

Other Space Shuttle-specific aircraft have been retired entirely, such as the Gulfstream II Shuttle Training Aircraft and the Shuttle Carrier Aircraft (the latter wasn't flown by astronauts).


What is the difference between Fly-By and Short-Turn?

The context of your question is a bit unclear, but assuming that you're asking about navigation waypoints in the US then you're probably referring to these terms as defined in the FAA's Pilot/Controller Glossary:

  FLY-BY WAYPOINT- A fly-by waypoint requires the use of turn
  anticipation to avoid overshoot of the next flight segment.

  FLY-OVER WAYPOINT- A fly-over waypoint precludes any turn until the
  waypoint is overflown and is followed by an intercept maneuver of the
  next flight segment.

As per the comments, I have never heard of a "short turn" waypoint and it isn't in the P/CG.


Why are the Phugoid and Short period approximated instead of calculated exactly?

By approximations, I believe you mean the following (found in any major stability & control textbook and this MIT course note), where the $_0$ notation stands for undisturbed trim condition:

Short-Period damping:

$$\zeta_{sp}\approx-\frac{M_q}{2}\sqrt{-\frac{1}{V_0M_wI_{yy}}}$$

Short-Period frequency:

$$\omega_{sp}\approx\sqrt{-\frac{V_0M_w}{I_{yy}}}$$

Phugoid damping:

$$\zeta_{p}\approx\frac{1}{\sqrt{2}}\frac{C_{D_0}}{C_{L_0}}$$

Phugoid frequency:

$$\omega_{p}\approx\sqrt{2}\frac{g}{V_0}$$

They are useful because:

They are computationally easy, and offer first approximation during early conceptual design and rapid iterations. However, in the 21st century, that's not saying too much.
They offer important design insight to engineers. It's not enough to calculate the modes; more important is to understand how to change the aircraft design such that the modes are adequate. With the full linearized matrix, it's hard to appreciate how derivatives influence these results (certainly for me). Now when you look at these simpler equations, the effects are almost intuitive! For this reason, these approximations (especially the lateral/directional approximations) will never go out of fashion.

On another note, since aerodynamics, especially transonic aerodynamics, propulsion and the equations of motions are inherently nonlinear, the linearized matrix (and the concept of eigenmodes) is itself an approximation.


What aircraft can make these sharp 90-degree turns?

It looks like a 90 degree turn, but it isn't. You're not looking vertically up at it; you're looking at a fairly shallow inclination, maybe only 20 degrees elevation at the corner of the turn. It means that the actual course change is probably only about 20 or 30 degrees, and just looks like more because of the optical effect of foreshortening. As for the aircraft, pretty much anything capable of flight at high altitude - probably 30,000 to 40,000 feet - any jet airliner or many business jets.


Was the F-4 Phantom the only fighter to be in service for the US Navy, Air Force and Marines?

The statement is accurate.

Here is a list of all U.S. Fighter Aircraft, in service and retired on Wikipedia. The following is an excerpt from that list for relevant aircraft.

F-4 Phantom (Air Force/Navy/Marines)
F-5 Freedom Fighter (Navy)
F-6 Skyray (Navy/Marines)
F-7 Sea Dart (Navy)
F-8 Crusader (Navy)
F-9 Cougar (Navy)
F-10 Skynight (Navy/Marines)
F-11 Tiger (Navy)
F-12 Lockheed (Air Force, A12 Variant)
F-14 Tomcat (Navy)
F-15 Eagle/Strike Eagle (Air Force)
F-16 Fighting Falcon (Air Force)
F-17 Cobra (Air Force)
F-117 Nighthawk (Air Force)
F-18 Hornet/Super Hornet (Navy/Marines)
F-20 Tigershark (Prototype, cancelled)
F-21 Kfir C-2 (Navy)
F-22 Raptor (Air Force)
F-23 Black Widow II (Air Force, cancelled)
F-35 Lightning II (Navy/Marine Corps/Air Force)
F/P-80 Shooting Star (Air Force/Navy)
FH-1 Phantom (Navy/Marines)
F2H Banshee (Navy/Marines)
FJ-1 Fury (Navy/Marines)
F-86 Sabre/Super Sabre (Air Force)
F-82 Twin Mustang (USAF)
F7U Cutlass (Navy)
F-102 Delta Dagger (Air Force)
F-106 Delta Dart (Air Force)
F-104 Starfighter (Air Force)
F-101 Voodoo (Air Force)
F3H Demon (Navy)
FJ-2/FJ-3 Fury (Navy/Marines)
F-89 Scorpion (Air Force)
F-84 Thunderstreak (Air Force)

This list includes fighter aircraft introduced or in service after 1949, when the US Air Force was created until the end of 1960 when the F-4 Phantom came into service.

Table image was removed because the data is out-of-date. You can view the original image here.


Are there laws about how close military aircraft can fly to passenger jets, and are they enforced?

This is somewhat speculation, but here's what I think happened:

You were flying at around 35,000 feet, in RSVSM airspace. The fighter jet was correctly on track 1000 feet below you. Without any other guides of distance, you tried to judge its distance by apparent size compared to real size. You might have underestimated the size of a fighter jet; they're typically about 50 feet long. I know I, for one, always thought they were much smaller. Thus what looked like "slightly below" was actually 1000 feet below you.

As for the more general question you posted: the military can get as close to other aircraft as they damn well please, through a procedure called Military Assumes Responsibility for Seperation of Aircraft, or MARSA (thanks to fooot for pointing this out!). Generally this only happens with a civilian aircraft during an interception. I don't know the specific procedures that are followed, but I know that in the past intercepting pilots have gotten close enough to pick out individuals in the cockpit.

As for enforcement, the question is kind of null. Generally, if civilian pilots violate separation without putting anyone in danger, the air traffic controller will just yell at them for a bit, but it does depend on the case. The FAA doesn't have much authority over the military, however. If the air traffic controller passed the information on to the military, perhaps there could be some sort of corrective action, but at this point I'm just guessing.


In an engine failure, should I expect less range than with the engine in idle?

Yes to some degree.  It depends on the idle rpm, prop pitch, engine compression and your gliding speed, but if the engine is off but windmilling, there is substantial drag from the energy needed to windmill the prop without any help from the engine and it will knock some measurable amount off the glide ratio.

When it's idling, it might still be windmilling a bit if there is still a negative angle of attack on the blades.  At some rpm just above idle, the prop's rotation speed will be at the zero thrust point (blade AOA at zero) and the glide will be like there is no prop there at all. To know where that is, you'd have to be able to measure the thrust load directly somehow.  So it's quite a moving target, trying to come up with a gliding value with different conditions with a running engine.

With the engine off completely, the windmilling drag drag case is at its worst, and the best glide is achieved if the propeller can be stopped completely so that the blade is fully stalled with a near 90 deg AOA, but this is not something advocated in training.

A stationary fixed pitch propeller makes way less drag that one being driven around by airflow, which is effectively in an "autorotation" making substantial lift aft. You an visualize this by imagining an autogyro, which can descend vertically with the airflow going straight up through its rotor to drive it - it's windmilling - and the rotor creates enough lift to limit the gyro's descent rate to about 500 fpm. Make the rotor stop completely and the autogyro becomes a falling anvil.   Turn the gyro 90 degrees, make the rotor really small, like propeller size, and there's your gliding 172.

Problem is, while it's theoretically beneficial to get the prop to stop, you usually have to slow down quite a lot, maybe close to stall speed, not a good idea at low altitude. And a tired engine with low compression might keep windmilling right down to the stall speed (and an engine with tight cylinders may stop windmilling right at glide speed - a nice bonus).  Under a few thousand feet, there are too many risks and other priorities to bother with this just for the L/D improvement.

If the engine quit at a substantial altitude and glide distance was absolutely critical (like over the water and trying to make it back to shore), I might try slowing it down to get the prop to stop windmilling. How slow I have to go to get it to stop, and how fast I can go before it starts windmilling again depends on the cylinder compression in the engine, so it may work well or it may not, and I may have used up most of the benefit trying to get the thing to stop.

As a student pilot, don't go there on your own (thinking about slowing down to stop the prop) but it wouldn't hurt at all to ask for a demonstration at altitude to observe the glide performance with the prop windmilling vs stopped vs idling.  You'd get some sense of the drag differences by noting the descent rate at the same airspeed for each case.

The above applies to fixed pitch propellers.  If you have a constant speed prop (variable pitch, non feathering, and if it's feathering, like on a turboprop, well it's not an issue at all), it gets more nuanced.  Normally if the engine quits the prop goes to full fine pitch with the blades nearly flat and it likely will stop windmilling at gliding speed.  Some people argue that moving the prop control to full coarse (low RPM) before the oil pressure decays can get the blades to kind of "part way to feather" and this will reduce the drag of the prop to less than a stationary prop at full fine with the blades nearly flat.  On the other hand, the coarse pitch might just get it windmilling... Hard to say without some testing.


Is repeatedly pitching an aircraft up and down to help it lose its energy quicker a viable landing technique?

No, that kind of landing technique is too risky and dangerous.

You’re most likely to just exchange kinetic energy for potential energy, gain altitude, then slam into the ground with the aircraft exhausted of airspeed.

Also it’s superfluous, considering that a properly managed approach on glide path and airspeed will accomplish pretty much what you intended to do with your proposed landing technique.  A stabilized approach and entry into the roundout will result in the aircraft exhausted of energy and settling onto the runway once the power is pulled to idle, with little float.


Are GPS airspeed meter and altimeter going to replace traditional measurements?

In general, even very low cost GPS units can provide very very accurate velocity vectors.

Altimetry is not quite as good, and is different in that it is referenced to a geoid, rather than a barometric pressure.

Similarly, airspeed is referenced to the ambient air, and while a GPS is a very accurate velocity vector source, there is no easy way to know the ambient air velocity.

So in short, by necessity to maintain safe flight, airspeed utilizes relative wind on an aircraft, and there is not an easy way to determine that with GPS alone.  And altimeter settings by convention, are based upon ambient air.  However, by utilizing a geoid model reasonably accurate absolute altitudes or MSL altitudes could be determined. Cost? As much as an old cellphone and some software.  Pretty cheap.


Is there an order for the instructions of a go-around?

Standard ICAO phraseology for ATC commanded go around for callsign XYZ would be:
"XYZ go around (possible reason for go-around)"

XYZ would then acknowledge this:
"Going around, XYZ"

ATC may then give additional instructions in the order it sees fit. If turning is first priority:

"XYZ turn left heading 360, climb and maintain 3000"

In any case the plane would of course be climbing, so if there is a heading to give, it would be logical to command it first.

If for some reason it is imperative to turn the plane away from something as quickly as possible, ATC can command "XYZ turn IMMEDIATELY left heading 360"

Why like this? Because it is imperative that that ATC can be assured as fast as possible that the aircraft will be initiating the go around. Anything other is secondary. The pilot will be preoccupied with the go around procedure for a couple of seconds, and should not worry about heading untill safe climb speed has been established. It is also good practise to keep messages short when something out of the ordinary is happening. Not that go arounds would be that rare, but the pilot might be wet behind the ears, and too many instructions might overwhelm him/her.

In any case ATC must assume there will be some delay in anything an airliner does. There's all kinds of CRM going on in the cockpit to verify everything happens safely.

As to why Canadian phraseology would use the non-standard "pull up" seems strange, but from what I hear Canadians are very nice people so I'll let it slide :)


Where can I find detailed information about ground lighting systems exist in aviation?

I know you said you didn't want to just be told what they meant, however in completeness of answering the question here are some abbreviations:

MALSR: Medium-intensity Approach Lighting System with Runway Alignment Indicator Lights
MALSF: Medium-intensity Approach Lighting System with Sequenced Flashing lights
SALS: Short Approach Lighting System
SSALS: Simplified Short Approach Lighting System
SSALR: Simplified Short Approach Lighting System with Runway Alignment Indicator Lights
SSALF: Simplified Short Approach Lighting System with Sequenced Flashing Lights
ODALS: Omnidirectional Approach Lighting System
ALSF-1: Approach Lighting System with Sequenced Flashing Lights configuration 1
ALSF-2: Approach Lighting System with Sequenced Flashing Lights configuration 2
CALVERT I/ICAO-1 HIALS: ICAO-compliant configuration 1 High Intensity Approach Lighting System
CALVERT II/ICAO-2 HIALS: ICAO-compliant configuration 2 High Intensity Approach Lighting System
LDIN: Lead-in lighting
REIL: Runway End Identification Lights
RAIL: Runway Alignment Indicator Lights

I found them here on wikipedia which has a nice entry on the subject


These are gas balloons. Instead of heating the air to reduce its density and providing the buoyancy, these balloons use helium or hydrogen which is lighter than air. Before lifting off, the balloons are kept on the ground by extra weight hanging on the basket. Usually these bags, clearly visible on the picture, are filled with sand.
During the flights, the gas will slowly dissipate through the fabric of the balloon reducing the buoyancy of the balloon. By throwing more weight overboard, again sand, the balloon can maintain in the air.
Gas balloons have less control in height than hot air balloons. The balloons are more expensive to operate because of the price of helium and to a lesser extent hydrogen.
Although gas ballooning is less popular then hot air ballooning, there are a number of gas balloons operating in Europe and the USA.

Once a year the Gordon Bennett race  is held in which teams compete to fly the longest distance in their gas balloon.

After some more research into the Trophee du ballon libre I found this Polygoon Journaal item of 1976 (in Dutch). It mentions that the balloon is kept afloat by 630 cubic meters hydrogen gas.


On the 737 MAX, can the pilots switch to the backup MCAS, or switch active MCAS input to another AoA probe during flight?

As far as I understand from reading the B737 Operations Manual and the Lion Air Accident Investigation report,

Each Flight Control Computer (FCC) receives AOA input only from the onside ADIRU and vane.

  The AOA and Mach inputs are provided to each FCC by the associated Air Data Inertial Reference Unit (ADIRU). Each ADIRU receives AOA information from one of the two resolvers contained within the associated AOA sensor (i.e. the Left ADIRU uses left AOA vane and the Right ADIRU uses the right AOA vane).

  Source: FINAL KNKT.18.10.35.04 Aircraft Accident Investigation Report

The Maneuvering Characteristics Augmentation System (MCAS) and the Speed Trim System are controlled by the master FCC, which alternates between A and B per flight.

  Similar to the Speed Trim Function, the MCAS function is also a flight control law contained within each of the two FCCs. MCAS is only active in the master FCC for that flight. At aircraft power-up, the master FCC defaults to the left side FCC; and will then alternate between the left and right FCC by flight.  The master FCC is not affected by the position of the Flight Director switches.

  Source: FINAL KNKT.18.10.35.04 Aircraft Accident Investigation Report

This master FCC is different from the master FCC used to compute for the Flight Director (F/D) and the autopilot (A/P). For the purpose of AFCS, the master FCC can be cycled via the F/D switches on the Mode Control Panel (MCP), and the master FCC is illuminated.

  The master FCC is indicated by illumination of the respective master (MA) F/D
  indicator light. The master FCC is determined as follows:

  with neither A/P engaged in CMD, the FCC for the first F/D turned on is
  the master
  with one or both A/Ps engaged in CMD, the FCC for the first A/P in CMD
  is the master FCC, regardless of which F/D is turned on first.

  Source: Boeing 737-600/-700/-800/-900 Operations Manual

There does not appear to be a way for the crew to know which FCC is actively controlling the MCAS, nor a switch out the controlling computer, apart from pulling the circuit breakers.


How does change in airspeed affect pitching moment?

How exactly do you plan to increase speed? You can add thrust. The aircraft is trimmed for a specific airspeed (normal flight assumed) so the added thrust will introduce a climb.

If you want to increase speed in level flight, you trim down (the engine power force vector rotating down, shrinking the vertical component and increasing the horizontal, so converting more engine power to forward movement and losing a little lift) AND add power to compensate for the lift loss.

It follows that there is an optimum: when there is no more vertical component, you cannot increase forward component of the engine force vector. But by that time the aircraft is already converted into a rock (no vertical force = only gravity = fall).


Are HUD systems available for light GA aircraft?

It looks like there have been several attempts at coming up with viable HUDs for light singles but none have, well, taken off (business jets are a different story):

The VirtualHUD company mentioned in this article doesn't exist any more
The G-HULP exists and you can buy it but I couldn't find any useful information about it or even the manufacturer's website

Since there's really nothing much out there, it suggests that HUDs for light singles are too expensive for typical pilots and/or just not useful.

Cost is always relative, but the standalone G-HULP costs USD 6,000 and that has to be compared to other, potentially more useful things like avgas (i.e. flying time!), avionics upgrades, ADS-B or just general maintenance.

But even if a GA pilot has nothing better to spend his money on, it isn't clear that HUDs are actually as useful as you might think. This article looks at a new Honeywell system for business jets that overlays a HUD view on the PFD, and they compared the landing precision of 'heads-up' (traditional HUD) vs. 'heads-down' (HUD on the PFD) pilots:

  A chart that showed landing points at the end of approaches flown by
  pilots using the two systems showed scattershot points with no
  apparent bias toward either system. Both systems allowed their pilots
  to fly very accurate approaches.

  This result, Ververs says, surprised the pilots in the study who had a
  lot of HUD time going into the testing. They had all assumed, she
  says, that the HUD would be the better technology. As far as the
  testing experience could show, it wasn’t better [...]

Of course that's only one specific testing scenario, but it's a very critical one because landings are when you really need to see and react quickly. Personally, I'm not convinced that focusing my eyes on the HUD for airspeed and then through the HUD to the runway would be any quicker or easier than just flicking my eyes between the airspeed indicator and the runway centerline. (Jan Hudec made the comment that focusing shouldn't be an issue with a "good" HUD, so this may not be an issue at all, at least in theory.)

And there are probably other issues with a HUD too, like making an instrument scan more complex; making the pilot focus his vision on the HUD rather than into the distance; or just being a general distraction.

There is an interesting alternative concept to a fixed HUD, by the way: wearable tech. Whether it's any more successful remains to be seen.


Why is alcoholic gasoline such a showstopper for aviation?

The modifications required are just not economically viable.

The main issue is vapor lock, because ethanol has a lower vapor pressure (i.e. more likely to vaporize) than gasoline.  Worse, mogas ethanol levels are varied to achieve ideal vapor pressure for different temperatures.  This is fine for cars that go through a tank of gas every week or two, over a relatively small temperature range, but a serious problem for planes where the gas may sit for months and then experience a wide temperature range at different altitudes in a single flight.

Vapor pressure matters because engine-driven fuel pumps, which are the norm on planes, pull fuel through the fuel lines.  Especially when combined with low wing tanks, ethanol may vaporize in the lines and block any further fuel flow, which is a far more serious problem for a plane than for a car.  Pure gasoline has a high enough vapor pressure that doesn't happen.  When ethanol was first added to mogas, carmakers solved this by moving the fuel pumps to the tank so the fuel is instead pushed through the fuel lines and therefore won't vaporize regardless of its vapor pressure, and given normal fleet turnover, that was the norm within a few years.  Some planes do have tank boost pumps like cars, but they are usually not intended to be run full-time; ethanol would require tank boost pumps that can run full time, which means either replacing the existing ones or adding new ones.

Ethanol is also more corrosive than gasoline.  Using ethanol regularly may mean replacing fuel pumps (both engine and, if applicable, tank), fuel lines, seals, injectors or carbs, etc.  To make such modifications, you'll need an STC for each.  Developing an STC is expensive and the market is quite limited, so the companies selling them need to charge a lot to recover their costs--on top of the high cost of the parts themselves, which have the same issues.  Also, while many engines were retroactively rated for mogas (even with ethanol in some cases), you still need an expensive STC to change the old placards that require avgas.

Also, while not directly related to ethanol, mogas doesn't contain lead.  Older airplane engines still require a tank of leaded avgas occasionally to lubricate valve seats and guides.  That can usually be fixed by replacing certain parts with newer ones made from newer materials, but that's not cheap either and usually best delayed until the next overhaul.  Until then, you can't run mogas full-time, regardless of the ethanol content.

Once you add up all these costs, retrofitting most GA aircraft for ethanol could easily end up being more than the planes are worth.


How would a low-airspeed fixed-wing drone be designed to reduce effects from gusts and wind shear?

First, kudos for the well-researched question! You certainly did your homework before coming here.

As you realized yourself, your requirement is quite contradictory. I also wonder what blimp would be flown into hurricanes, but I leave that aside for the moment.

In order to reduce gust susceptibility, a variable configuration would be one option. However, just when you want steady flight in gusty conditions, you also will fly slowly, so variable wing sweep or elaborate wing flaps will not help. The next option which combines low flight speed and high wing loading would be some direct lift, like in the VTOL-designs of the 1960s. Since the direct lift is needed for a short time and when propulsive demands are low, an engine like the Rolls-Royce Pegasus would allow to add lift that is less affected by gusts than the wing.

Make sure your design will draw ample bleed air in order to feed the reaction control system, and maybe a gyro platform to control this system, and the contradiction can be resolved.

Stalls should now be less of a concern, too. Much of how much lift is lost in a stall depends on the choice of airfoils, and if you use one with benign stall characteristics, stalls can be tolerated.

Anhedral is a poor idea, however, especially if you use unswept wings. Only if you have a high wing on a large fuselage can anhedral be justified. Examples are the Harrier jump jet and the F-104 Starfighter, where the large T-tail made wing anhedral necessary. You want moderate dihedral in order to make the aircraft roll in a sideslip. This rolling motion will tilt the lift vector sideways and pull the aircraft away from the sideslip condition.

Also, please reconsider whether there really is such a thing as a pendulum effect.

Regarding the tail: The best one is as symmetrical as practical.


Which GPU (Graphics Processing Unit) is used to generate the graphics for avionics?

Real Aircraft displays do not use 'off-the-shelf' display adaptors. They will have some graphics processor (often developed by one of the major companies ATI/Nvidia) but this will often be an older/mature chipset. Each display also might have multiple graphic processors. The cost of an aircraft display is more closely related to the cost of developing/certifying the hardware/software than the physical cost of the components. You can't realistically compare an Aircraft display to your desktop PC.

Aircraft displays aren't just dumb monitors, each is a computing device in their own right that processes the data from the aircraft's systems. Each display will continue to work if another fails. Modern standards such as ARINC661 moves some of the processing/behaviour to other computing units, but the display unit itself is still responsible for drawing the graphics.


What noises are considered worrying on a passenger flight?

The only noise (other than a clear and obvious explosion) that gets my complete and immediate attention is "This is the captain..."


What criteria do FAA VFR Charts use for High-Intensity Obstruction lights?

The DOF_README.PDF includes the following field description:

  Type of Lighting

  "R": Red
  "D": Medium intensity White Strobe & Red
  "H": High Intensity White Strobe & Red
  "M”: Medium Intensity White Strobe
  "S" : High Intensity White Strobe
  "F" : Flood
  "C" : Dual Medium Catenary
  "W": Synchronized Red Lighting
  "L" : Lighted (Type Unknown)
  "N": None
  "U": Unknown

Since the charting would only use the "High Intensity" label if it was known, it would map to types H and S.

It's also useful to note that the Aeronautical Chart User's Guide adds the following note:

  High-intensity lights may operate parttime or by proximity activation.


Hub-and-spoke networks: fixed and variable costs

The fixed cost problem with the hub and spoke model is mainly due to the need for banked flights to minimize average connection times.
Ideally, every plane starts the morning at a spoke and arrives at the hub at roughly the same time. Then passengers have an hour or two to change planes, and all the planes fly back to their spokes. This cycle is repeated again in the afternoon, and then the planes spend the night at their spoke to start the cycle again the next morning.
The problem is that this requires duplicate gate space at the hub and spokes, even though planes will only use one or the other at any given time (or neither, while flying). It also requires sufficient planes to serve every spoke in every bank even if there’s not enough demand to fill them. And it requires much larger airports and terminals at the hubs to serve massive numbers of passengers and flights during the banks, which goes unused the rest of the day.
Of course, nobody operates quite this stupidly in practice, but every flight that deviates from the model means longer connection times for its passengers because if it arrives at the hub between banks, passengers have to sit in the terminal and wait for the next bank to connect, which makes your flights less desirable than a competitor’s.
The upside is that you can (in theory) size the aircraft serving each spoke to its average demand, and likely use fewer, larger aircraft since one plane can serve every passenger connecting to every destination, which reduces variable costs.


Which airport is the busiest general aviation airport in the world?

US
According to General Aviation News in Feb 2020 that would be Van Nuys in California.

Van Nuys Airport (KVNY), Van Nuys, California: 155,420 local GA operations + 332,117 itinerant GA operations = 487,537.
Phoenix Deer Valley (DVT), Phoenix, Arizona: 130,886 local operations + 243,075 itinerant = 373,961.
Centennial Airport (KAPA), Denver, Colorado: 153,744 local operations + 133,098 itinerant = 286,842.
Ernest A. Love Field (KPRC), Prescott, Arizona: 177,233 local operations + 85,290 itinerant = 262,523.
Long Beach Airport-Daugherty Field (KLGB), Long Beach, California: 151,912 local operations + 101,734 itinerant = 253,646.
Portland-Hillsboro Airport (KHIO), Portland, Oregon: 160,261 local GA operations + 83,381 itinerant = 243,642.
Phoenix-Mesa Gateway Airport (KIWA), Phoenix, Arizona: 166,519 local operations + 66,727 itinerant = 233,246.
Falcon Field (KFFZ), Mesa, Arizona: 175,051 local + 53,307 itinerant = 228,358.
Grand Forks International Airport (KGFK), Grand Forks, N.D.: 212,325 local + 12,634 itinerant = 224,959.
Gillespie Field (KSEE), San Diego/El Cajon, California: 140,189 local + 68,061 itinerant = 208,250.

Source: https://generalaviationnews.com/2020/02/03/top-10-busiest-general-aviation-airports/
Anecdotally; although not American, I just realised I learned to fly at the 5th busiest GA airfield in the US. Mind blown!
UK
Contrast this to the UK, which has a fairly busy GA scene:

Official Civil Aviation Authority statistics have revealed that Gloucestershire Airport at Staverton was amongst the busiest in the UK during 2011, with the majority of the traffic being GA aircraft  [...] Gloucestershire appears at number 13 in the list of 64 UK commercial airports, handling 66,715 flights during the year -- just pipping Bristol and beating other major regional airports such as Newcastle and Belfast.

As you can see the UK's busiest GA airfield doesn't even come close to the US' 10th busiest.
Australia
Not so easy to find a list, and there is more than one contender for busiest
Jandakot deems itself to be busiest by movements:

Jandakot Airport is "the busiest general aviation airport in Australia in terms of aircraft movements". The airport recorded 208,778 aircraft movements in the fiscal year ending 30 June 2018

Moorabbin seems to be the busier by aircraft movements, and is clearly a strong contender.

With over 295,000 aircraft movements each year, Moorabbin Airport is the second busiest airport in Australia. [...] Moorabbin Airport is Australia’s leading general aviation flight training airport located in the south-east of Melbourne.


Why are so many ATR involved in accidents in the past years`?

ATR-72, 16 October 2013, Lao Airlines Flight 301

  The probable cause of this accident were the sudden change of weather
  condition and the flight crew's failure to properly execute the
  published instrument approach, including the published missed approach
  procedure, which resulted in the aircraft impacting the terrain.

ATR-42, 19 October 2013, P2-PXY, Air Niugini

According to released information this cargo aircraft overran the runway after the crew aborted the take-off above Vr after experiencing pitch control problems. The final report of this accident is not yet published but a preliminary report is available.  The investigation focusses on the payload distribution which may have caused imbalance leading to the perceived control problems.

ATR-72, 23 July 2014, TransAsia Airways Flight 222

The aircraft crashed on final approach in low visibility conditions (800 meters). During the initial approach the crew had requested and ILS approach (precision approach) to runway 02 but then changed their minds and asked for a VOR approach (non-precision approach) to runway 20. During the approach, after deactivation of the autopilot, the aircraft deviated 340 meters to the left and the crew subsequently announced they were going around. Shortly afterwards the aircraft hit tree tops and impacted residential buildings.

The final report is expected in October 2015.

To me it seems the probable cause is the failure of the flight crew to properly execute the published instrument approach including the published missed approach procedure which resulted in the aircraft impacting the trees and buildings.

ATR-72, 02 February 2015, TransAsia Airways Flight 235

The investigation into this accident is still running, only some preliminary information has been published. Preliminary data indicates that about 36 seconds after takeoff the engine no.2 auto-feathered, about 46 seconds subsequent to auto-feather the engine no.1 was shut off by the crew, resulting in loss of all thrust. The aircraft subsequently descended, stalled and crashed into a river.

ATR-42, 16 August 2015, Trigana Air Service Flight 257

This accident occurred just a couple of days ago so there are few facts known yet and no preliminary findings are published. I will not speculate about the probable cause of this accident.

The common thread in the first four accidents seems to be the failure to comply with established procedures resulting in the loss of the aircraft.

In two cases (Lao Airlines Flight 301 and TransAsia Airways Flight 222) the flight crew flew a controllable aircraft into the ground.

In the case of the Air Niugini crash improper loading of the aircraft is likely to be the cause, resulting in the aircraft being not trimmed correctly for take-off.

The crash of TransAsia Airways Flight 235 is the only crash that involved an aircraft system malfunction (engine 2 failure). However, the ATR-72 can fly on a single engine so the failure itself should not have been fatal. The crew then shut down the other engine (number 1) which sealed the aircraft's fate. It is too early to conclude that the crew didn't follow the correct procedures here; for example there may have been ambiguous indications from the engine instruments that led them to believe that engine no. 1 had failed. However with the information currently available it seems that the crew did not follow the correct procedures for shutting down a failed engine.

The high number of crashes involving an ATR aircraft seems not to be related to the model itself, but to the safety culture and lack of training within a number of airlines operating the aircraft.


Has a commercial airliner ever crash-landed in an ocean?

Yes, commercial airplanes have landed or crash landed in water many times.

If I am not mistaken, you are asking about scenarios when the on-board life jackets and life raft are used.

Here is a list of water landings. Examples when a life raft was used are (in addition to ratchet freak's mentions):

  On 22 October 1962, a Northwest Airlines DC-7C with 7 crew and 95
  passengers made a successful water landing in Sitka Sound. ... The
  plane stayed afloat for 24 minutes after coming to rest in the water,
  giving the occupants ample time to evacuate into life-rafts.

  In 1993, China Airlines Flight 605, a Boeing 747–409, ended up in
  water after it overran runway 13 ... All of the 396 occupants donned
  life-vests, boarded the eight slide/rafts and no fatalities resulted.


What are the differences between the proportional flow control FCU and pressure control FCU?

The pressure control system is a typical system as fitted to a turbo-propeller engine where the rate of engine acceleration is restricted by a propeller speed controller

The proportional flow control is a typical system where H.P. compressor shaft r.p.m. is governed by a hydro-mechanical governor which uses hydraulic pressure proportional to engine speed as its controlling parameter

Therefore the pressure control system is one step ahead as it looks at the tendance of speed, of course the pressure control system alone is not sufficient because even if the rate of speed increase is not excessive, the final speed could become excessive, that’s why also a speed limiter is included in the system

Today’s FADECs directly protect the engines for excessive speed and for excessive speed rate

Please refer to to the following Website

http://aeromodelbasic.blogspot.com/2012/01/fuel-control-system.html

Also please refer to the following website

http://aeromodelbasic.blogspot.com/2012/02/proportional-flow-control-system.html


The Australian Transport Safety Bureau recently published a comprehensive research paper on reported stall warnings in high capacity aircraft - http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx

The report says that 30% of all stall warnings were false. Note that stall warnings aren't limited to the stick shaker.

The report says that of all reported stick shaker events, 16% were false warnings. Have a read of it, you'll find lots of interesting bits of information.


How can I create a map of all paths of flights incoming to an airport in a given day?

Well you didn't state which airport you are interested in but obviously you only want data for a single airport.

You might want to look into a noise abatement reporting system. For instance, London Heathrow maintains the great website Webtrak (https://webtrak52.bksv.com/lhr4) to communicate with the pubic about changing SIDs, STARs and noise levels. (They already have much of the TMA over the heavily populated area, and they want to add another runway)


What is propeller / engine sync and how does it work?

I don't know how it is achieved, but here is the reason:

If you have two sources of the same noise, with nearly the same frequency, the sum of both noises will be a noise of slowly increasing and decreasing volume. It's called beat and can become very annoying.

The math says

$$\sin(2\pi f_1t)+\sin(2\pi f_2t)=2\cdot\sin\left(2\pi \frac{f_1+f_2}{2}t\right)\cdot\cos\left(2\pi \frac{f_1-f_2}{2}t\right)$$

To demonstrate this, there you see two sinus-tones of almost same frequency, and what happens if you mix them:

The blue curve is of frequency $(f_1-f_2)/2$.

As example, one machine running at 3000rpm and one at 3030rpm results in a noise which increases for one seconds before it decreases within one second again.

As said, I don't know how it is done, but synchronization must be done very precisely to avoid this beat.

Edit:

Here is what happens if the two noises do not have the same volume. One of the curves has three times the amplitude of the other. The envelope is not a pure sin function, but the blue function fits it quite well.


Is the autorotation in San Andreas movie realistic?

Let's see how many things we can find wrong.

There's a bang, smoke starts coming from the exhaust.  Master caution comes on and his first response is to tap and check the 115v AC gauge!  The pilot takes his hand off the collective!
You hear the engine wind down and the rotor RPM drop.  He announces a gearbox failure.  So why did the engine wind down?  His passenger even asks if he switched the engine off.  If the gearbox had seized, the engine would have been destroyed or, the input shaft would shear and the engine RPM would increase leading to a very rapid overspeed.  There is no gearbox failure mode that results in the engine winding down.
He had a long think and a bit of a chat after the engine and RRPM wind down.  In a Bell 412, with the speed of that wind down, the blades would have stalled after 2 or 3 seconds if he hadn't dropped the collective.
He announces that he is going to autorotate.  His passenger asks "auto what?"  He says we're going to crash.  The whole point of autorotation is that you don't crash.
With the RPM already low (let's forget that he would have stalled by now), his first action is to dive and you hear the RRPM increase.  In reality, they would go even lower.  If he wasn't already stalled (which of course he would have been) he would now.
He was straight and level, with significant airspeed over level open ground.  At the first bang and sound of the engine winding down, he would have lowered the collective and flared to preserve RRPM. He would then look for a good place to land, not a shopping centre car park, and fly towards it.
Each time he flares, he pitches forward again and the RRPM drop rapidly.  Flaring like that in auto would cause a large increase in RRPM, possibly overspeeding and lowering the nose to the level would cause a small drop in RRPM.  Diving again would reduce the RRPM.  So why would you flare to increase, then dive to decrease?

In short, the sequence is complete nonsense.


Why do some aircraft have multiple switches for the landing lights?

On a dark morning preflight check, I can verify that the lights all work by turning each one on, one at a time, without leaving the flight deck. Less lifespan on the bulbs & less disruption to the ramp to have several quick flashes of light within a few seconds, than turning everything on, walking outside to observe everything, and then going back inside.
Plus, it's probably a hold-over from days of minimal automation (think, 727 Flight Engineer panel - now entirely replaced by automation & a few switches on the overhead panel) when each {whatever} had its own switch.
I could get creative & invent another scenario or two when I want "this" but not "that" light on, but the preflight is probably the best example of that.


Aircraft towbars are almost exclusively aircraft-grade aluminum or
  steel in construction  to meet or exceed the working load. Not only
  must the towbar be able to safely pull/push the vehicle, it must also
  be able to withstand the towed vehicle's inertia.

Source

Although there are several components that make up the tow bar they all must be strong enough to withstand the forces exerted on them. That's what the label on your picture is for, it dictates what aircraft you can use the tow bar on. Larger aircraft = Larger more robust tow bar.


How can I deal with insurance requirements for flight hours and training in order to carry passengers?

The flight school might issue a waiver of that policy but it’s going to be based on a number of factors, including instructor opinion of your pilot proficiency on rotorcraft, time in the particular type you want to rent, and whether the insurance company can do this for you.  I’ve had to do that during my flight training when renting high performance and complex airplanes which had certain minimums set for their solo operation under the terms of the school’s insurance policy.  Ask to speak with the chief flight instructor for the school and see if they are flexible with a similar arrangement.  If they feel comfortable with your skill and proficiency in operating the R22 and R22 and you have at least a few hours in each type, they might just approve this.  Again, this is largely their insurance company’s call and not the flight school’s.  I’d guess the school gets discounted rates for insuring their rental aircraft by requiring pilots to undergo factory authorized training programs.


What is the meaning of HOT-1, HOT-2, CAM, etc., in cockpit voice recorder transcripts?

They may vary from report to report, and the abbreviations used will be laid out in the report before the transcript, for flight 1549 (NTSB, .pdf) they are as follows:

  ATIS Radio transmission from the Automated Terminal Information System
  RDO Radio transmission from accident aircraft, US Airways 1549
  CAM Cockpit area microphone voice or sound source
  PA Voice or sound heard on the public address system channel
  HOT Hot microphone voice or sound source
  INTR Interphone communication to or from ground crew

  For RDO, CAM, PA, HOT and INTR comments:

  -1 Voice identified as the Captain
  -2 Voice identified as the First Officer
  -3 Voice identified as cabin crewmember
  -4 Voice identified as groundcrew
  -? Voice unidentified

  FWC Automated callout or sound from the Flight Warning Computer
  TCAS Automated callout or sound from the Traffic Collision Avoidance System
  PWS Automated callout or sound from the Predictive Windshear System
  GPWS Automated callout or sound from the Ground Proximity Warning System
  EGPWS Automated callout or sound from the Enhanced Ground Proximity Warning system
  RMP Radio transmission from ramp control at LaGuardia
  GND Radio transmission from ground control at LaGuardia
  CLC Radio transmission from clearance delivery at LaGuardia
  TWR Radio transmission from the Air Traffic Control Tower at LaGuardia
  DEP Radio transmission from LaGuardia departure control
  4718 Radio transmission from another airplane (Eagle flight 4718)
  CH[1234] CVR Channel identifier 1=Captain 2= First Officer 3= PA 4= Cockpit Area Microphone
  * Unintelligible word
  @ Non-Pertinent word
  & Third party personal name (see note 5 below)
  # Expletive
  -, - - - Break in continuity or interruption in comment
  ( ) Questionable insertion
  [ ] Editorial insertion

HOT vs. CAM:

  This recording contained audio from Hot microphones used by the flightcrew. The voices or sounds on these channels were also, at times, heard by the CVR group on the CAM channel and vice versa. In these cases, comments are generally annotated as coming from the source (either HOT or CAM) from which the comment was easiest to hear and discern.


Even after years of research, why are planes unable to keep passengers alive in case of a fiery crash?

Short answer

The kinetic energy involved in a plane crash is inhumanely high.

Slightly longer answer

We can built bombs which will go through concrete roofs and ceilings of a bunker, counting the number of floors they crash through while descending so they can explode at the level where the bad guys sit and not where the widows and orphans are kept. We could equally well build a plane with this kind of strength, so the fuselage stays intact even when it crashes into a mountainside. That's not the problem.

Limits of the human body

The problem will be that rescuers will only find dead bodies inside. The human body was "designed" to endure things like running into a tree, but not being hurled around at Mach 0.85 and then being stopped almost instantly. Thanks to years of research we now have quite a good idea where the limits are. Martin Eiband collected a lot of data on this, if you want to know more, google for "Eiband diagrams". If you want the full picture, read the Army Aircraft Crash Survival Guide. It comes in five volumes, and volume 1 covers the design criteria. The Eiband diagram below is lifted from this source.

Note the time scale: A deceleration with 40 g can only be tolerated for a duration of 0.1 seconds; if the deceleration takes more than 1 second, the limit is only 10 g. Now let's see what deceleration distance is required to stop a human with an average deceleration of 10 g. The energy $E$ of a body of the mass $m$ increases with the square of speed $v$:
$$E = m\cdot\frac{v^2}{2} = m\cdot a\cdot s$$
At $a = 98.0665$ m/s², the stopping distance $s$ from an initial speed $v$ is $\frac{v^2}{2\cdot a}$:

Car crash at 30 m/s: This needs 4.6 m and good restraints, but is generally survivable.
Free fall at 60 m/s terminal velocity: 18.4 m. A few humans have indeed survived this by falling into soft ground like a snow-covered conifer forest. This is also the typical approach speed of airliners, and the 18.4 m is the fuselage ahead of you. That is the reason why a crash is more survivable for the occupants in the rear seat rows.
Propeller airplane flies into mountain (120 m/s): 73.42 m. This kind of crumple zone is simply not available, and nobody has survived such an impact.
Airliner flies into a mountain (240 m/s): 293.7 m. To make such a crash survivable, every airliner would need to carry a 300 m boom of stiff material around which would be needed as a crumple zone in an accident. Just think what kind of aft fuselage and tail this would require.
And to top it: Astronaut on a space walk collides with a satellite in an opposing orbit (16,000 m/s): 1305.23 km. Note that I had to switch units to keep the number manageable.

Please consider lower deceleration limits for elderly and untrained persons; the limit in the Eiband diagram was established using healthy young pilots (and hogs, chimps and corpses for the higher limits. A lot of blood was spilled to arrive at these numbers).

The problem is not the aircraft structure, it is the fact that humans like to go fast but are not built to stop quickly.


What was the first fighter jet that utilised thrust vectoring nozzles?

Hawker harrier... (actual plane that got used)
https://en.wikipedia.org/wiki/Hawker_Siddeley_Harrier


Why is Reverse thrust more effective at higher airspeeds?

From "handling The Big Jets" by D.P.Davies.

Reverse thrust is much more effective at high aircraft speeds than low speeds for two reasons. Firstly, the net amount of reverse thrust increases with speed because the acceleration imposed on the (constant) mass flow is greater. This is because the aircraft forward speed is additional when in reverse thrust as opposed to subtractional when in forward thrust. Secondly the power produced is higher at higher speeds because of the increased rate of doing work. In this context it means that the kinetic energy of the aeroplane is being destroyed at a higher rate at higher airspeeds.


Why does the co-pilot sometimes keep a hand on the throttle as well as the pilot?

The pilots were probably executing a Cat II coupled or monitored approach. The PF is flying the plane (via autopilot, usually), while the PNF had his hands at the base of the throttle ready to take over to initiate a manual go around (or land in some cases, this varies from airline to airline).

There is a thread regarding this on this on airliners.net. It gives one version of the procedure:

  At my airline we use this procedure for Cat II approaches. The FO always flies the approach... well the autopilot flies it and the FO monitors the instruments, ready to perform a missed approach if the approach becomes unstable. The Captain at the 500 to minimums call places their hand near the base of the thrust levers, under the FOs arm, and focuses outside looking for the runway. If at any point prior to minimums the captain gets the runway in sight, they call "landing, my controls" and move their hand up to the thrust levers, bumping the FOs arm and hand up and off of the thrust levers. If at minimums and the runway is not in sight the FO performs the missed approach.


Contribution of wing vertical location to roll stability

An aeroplane in a pure co-ordinated turn has a deflection of both the ailerons and the rudder. This is cumbersome however, much easier to only deflect the wheel, tilt the lift vector, and let the aircraft sway into the turn. The vertical tail will then experience a slip angle, which will point the nose into the direction of the turn at the expense of a small sway velocity: sideways.

So now the question is: how does the aeroplane react to a sideways incoming airstream. What we want is that if the pilot deflected the wheel to the right, he has to keep the wheel to the right to maintain the right hand turn. So upon an un-coordinated turn, without touching the pedals, we want the aircraft to try to level itself again upon an incoming sideways velocity.

If we look at what happens to a low wing aircraft first, we see that the incoming sideways stream sees little resistance when streaming over the fuselage top, but gets caught in the wing/fuselage intersection and builds up pressure there. So the sideways velocity introduces a rolling moment in the direction of the turn, which the pilot has to compensate for by turning the wheel the other way. This is not the behaviour that we want.

In order to correct for that, we can introduce wing dihedral: now the incoming sideways air stream wants to level the aeroplane again, and the pilot needs to keep the wheel deflected into the turn, which is what we want.

And of course, with a high-wing aeroplane the above is valid vice-versa: the sideways stream wants to level the aircraft, so the roll behaviour is naturally how we want it to be already. Depending on the wing/fusleage shape and many other factors, the aeroplane can be too stable and we'll need to implement anhedral, wings pointing down.


The relation between Euler-angle rate and body-axis rates?

Let me use the following graph to try to clarify your confusion, which is excerpted from Etkins, Dynamics of Flight:

The body axis is rotated from the [flat] Earth axis via a series of Euler angle rotations, $\psi$ (heading), $\theta$ (pitch), $\phi$ (roll), in this sequence. In the nomenclature of the graph, we've rotated from $(x_E, y_E, z_E)$ (Earth axis) to $(x_3, y_3, z_3)$ (body axis).
Now angular velocity is always expressed in the body axis, so the roll rate $p$ is about $x_3$, the pitch rate $q$ is about $y_3$ and yaw rate $r$ is about $z_3$. Our goal is to relate an instantaneous change in Euler angles ($\dot{\phi}$, $\dot{\theta}$, $\dot{\psi}$) to the angular velocity ($p$, $q$, $r$). Since the rotation is instantaneous, it does not add to the existing Euler angles.
We start off backwards, with the last rotation, $\dot{\phi}$. This rotation is about $x_3$, which is the same unit vector as $p$. Therefore, no frame transformation is required. i.e. $\dot{\phi} = r$. That's why your rotation matrix, $R_{v2}^b$, is identity.
Next, let's look at $\dot{\theta}$. This rotation is about the $y_2$ axis, which lags behind the body axis by a roll rotation ($\phi$). So to bring it to the body axis, we need to pre-multiply by $R_{v1}^{v2}=\begin{bmatrix} 1 & 0 & 0 \\ 0 & \cos{\phi} & \sin{\phi} \\ 0 & -\sin{\phi} & \cos{\phi} \end{bmatrix}$.
Last, $\dot{\psi}$ is about $y_1$, which lags behind by two rotations: $R_{v1}^{v2}R_v^{v1}=\begin{bmatrix} 1 & 0 & 0 \\ 0 & \cos{\phi} & \sin{\phi} \\ 0 & -\sin{\phi} & \cos{\phi} \end{bmatrix}\begin{bmatrix} \cos{\theta} & 0 & -\sin{\theta} \\ 0 & 1 & 0 \\ \sin{\theta} & 0 & \cos{\theta} \end{bmatrix}$.
When you add everything together, we have the kinematic relation:
$$\begin{bmatrix}\dot{\phi} \\ \dot{\theta} \\ \dot{\psi}\end{bmatrix} = \begin{bmatrix}1 & 0 & -\sin{\theta} \\ 0 & \cos{\phi} & \sin{\phi}\cos{\theta} \\ 0 & -\sin{\phi} & \cos{\phi}\cos{\theta}\end{bmatrix} \begin{bmatrix}p \\ q \\ r\end{bmatrix}$$
To answer your second question, no, this is not an approximation because the angular velocity is, by definition, an instantaneous change. Magic of calculus. The paper is incorrect to say that the rates are small; the magnitudes of the rates have no bearing on the derivation of the kinematic relation.


Does a Stalled Wing Exhibit No Circulation

If there is no circulation, there would be no lift. In reality, circulation stops to increase linearly when the angle of attack nears the stall range and drops beyond stall. However, there is plenty of lift left beyond stall.

180° polar for several NACA 4-digit airfoils, from Hoerners Fluid Dynamic Lift.

  how would this affect the pressure distribution […]?

Think of the stalled airfoil as of an entity which comprises the airfoil itself, the boundary layer around it and the separated flow in its wake. This will still have nearly-inviscid flow around it, and the wake will make it "look" to the outer flow like an airfoil with a lower angle of attack and a really drawn-out pressure recovery. There is still a suction peak at the nose, albeit much weaker than for the clean airfoil in attached flow, and constant suction past the separation point. On the bottom, however, flow is almost unchanged except for a region near the trailing edge where the low pressure in the wake speeds up the local flow.

  Would the top portion of the wing (low pressure) carry most of the lift?

The answer to the question on which side more lift is created depends a lot on how lift is interpreted. In the end, lift is the difference between the pressures on the bottom and the top sides, and cannot meaningfully be split into a top or bottom contribution. What can be done is to compare the pressure on one side with static pressure, which will yield a side-specific lift fraction. But then you can arbitrarily compare surface pressures with any pressure level found inside the wing box - it will cancel out once you calculate total lift.


What is this closed cabin / open cockpit biplane from the 1910s?

I submit the Sopwith Type D "3-Seater".

No.104 appears to be one of the first Sopwith aircraft produced for the Royal Navel Air Service (RNAS). The RNAS received at least three examples (No.33, No.103, No.104) one of them being the original prototype, known as the Hybrid that was later rebuilt and delivered to the RNAS. The Hybrid was made from combining the fuselage and tail of a Coventry Ordnance Works biplane and the wings of a Wright Biplane, the Type D retained the wing warping method of lateral control used in the Wright biplane until fitted ailerons after entry into service.  Wikipedia

Comments about No.104 found in the Kingstone Aviation page for 1914: (All bold formatting added by me)

  The Daily Telegraph leader sums it all up. “These aircraft represent an extension of our sea power; they are the scouts of the future.  A fleet of battleships unattended by aerial craft will be blind.  Cruisers even if able to steam at 30 knots will be inadequate.  Their range of vision is limited; their rate of steaming is insufficient.  The seaplane on the other hand is the fastest and handiest ship ever contrived by the ingenuity of man – with a speed of 70 miles an hour and a capacity for manoeuvring which defies competition.  In two years the rate of flight has doubled and no one can say that the limit has been reached.  A fleet without aerial squadrons will be robbed of the essential intelligence which is the talisman of victory – the foundation of successful naval tactics.  As we are forced to develop our sea fleet, no effort must be spared to build up the complementary air service.”

  It is no surprise then that the RNAS are upgrading their older wing-warping landplanes by placing orders with Sopwith for sets of ailerons for “Type D” biplanes No.33 and No.104 at a cost of £198.10.0d a set.

  On 25th July 1914 Sopwith get an order from the Admiralty to repair “Type D” No.103 and retro-fit with the ailerons recently ordered for No.104.

  On 2nd August 1914, reflecting the deteriorating situation in Europe,
  the Order of Battle is issued by the Royal Naval Air Service.  The
  RNAS now owns 95 aircraft:- “57 seaplanes, 34 aeroplanes and 4
  monoplanes”.  Only 46 of these are considered operational and assigned
  to the nine Naval Air Stations. Only 3 of the 15 aircraft supplied to
  the Admiralty by Sopwith over the last 19 months appear amongst those
  46 - “Type D” No.104 at Eastchurch, “Anzani Pusher Floatplane” No.123
  at Grain Island and their original Bat Boat No.38 at Felixstowe.

Comments about No.104 found in the Kingstone Aviation page for 1915:

  On 11th January the Sopwith “Type D” No.104 which has been at Eastchurch since early September suffers a failure of its 80hp Gnome engine.  Flt. Lt. I.G.V.Fowler manages a forced landing on mud flats by the River Blackwater but this ends the 17 month career of one of the earliest Sopwith machines still in naval service.

  There is news that on 20th January long-serving Sopwith “D1 Three-Seater” No.103 crashed on landing at Eastbourne but is probably repairable, unlike sister-ship No.104 nine days before.

Images found here: kingstonaviation.org


It can be done. Some bushplane action...


Why can’t level D simulators produce a G-force effect?

They can produce sustained G-forces, by tilting the sim without the occupants noticing. Of course, this tilting of the 1G gravity vector is limited to practical angles of about 45°, producing 0.7G of simulated sustained horizontal acceleration.

Vertical sustained acceleration is a different matter altogether: the 1G is always already there and can only be reduced by tilting the sim, while in manoeuvres with increased load factor we're looking to increase beyond 1G.

Fortunately the inner ear sensors can be tricked to an extent: they are very good at detecting acceleration onsets but get flooded by sustained acceleration inputs. Our brain seems to rely on the inner ear for detecting the first onset of acceleration, then on our peripheral vision to read the motion velocity. So if we heave the sim rapidly and show the movement on the visual, we cannot detect very readily if we're not pressed down by g-forces anymore after some time.

Image source

Level D simulators are for civil aviation training, which teaches how to limit load factor. Military sims are a different kettle of fish, as mentioned in this answer. G-seats like depicted above provide cues to our body skin sensors, as do G-suits.

Centrifuges can of course produce sustained g-forces, and they do exist, used by the military to train sustained g flying and by medical facilities to check how long a person can remain conscious. A combination of a centrifuge with a civil 6-DoF system is not really possible for realistic acceleration simulation.


It seems to be a C-12 or C-13 sensitive altimeter (SA) from Kollsman Instrument Division / Square D Company, manufactured circa 1940:

(Source)

The only difference seems to be the marking "ALTITUDE" replaced by "SA-91". As this is the 39th in the series, this could be the initial marking, later replaced by the more standard one. I don't see what could be "91" for.

The Kollsman window is black (as commented) because the setting dial has been turned past maximum pressure reference, as indicated by the bug between 7 and 8. The window value and this bug are linked.

The brown color seem to be related to phosphorescent markings and needles.

The C-12 has apparently many variants, likely designed on demand, especially for the USAF, like this one with alternate colors for the marks:

C-12 manufactured by C.G. Conn Ltd., (source)

C.G. Conn Ltd. is a music instruments company (saxophones), but at war time they provided aircraft instruments to the USAF (flying on instruments finally explained!).

Kollsman published handbooks about their instruments. Here is one from 1938. It doesn't cover this model of altimeter, but can be helpful though:

(Source)


What is the absolute ceiling of a 737-200?

Find the pertinent  performance charts for Vx (Max climb angle)and Vy (Max climb rate). You may have to extrapolate, but the altitude where Vx and Vy converge is the Absolute ceiling.


Can the Airbus A380 safely fly with two engines out on the same wing?

Proving that a multi-engine aircraft is flyable with one or more engines inoperative is part of the certification programme. The Airbus A380 is certified under FAR (Federal Aviation Regulations, USA) part 25 and JAR (Joint Aviation Regulations, Europe) part 25. One of the requirements of FAR/JAR 25 is that the directional control can be maintained when two critical engines (that means under the same wing) fail.

The following is selectively extracted from FAR part 25 (JAR is similar, there are some differences). Emphasis added by me.

  Controllability and Maneuverability

  §25.143   General.

  ....

  b) It must be possible to make a smooth transition from one flight
  condition to any other flight condition without exceptional piloting
  skill, alertness, or strength, and without danger of exceeding the
  airplane limit-load factor under any probable operating conditions,
  including—

  The sudden failure of the critical engine;
  For airplanes with three or more engines, the sudden failure of
  the second critical engine when the airplane is in the en route,
  approach, or landing configuration and is trimmed with the critical
  engine inoperative;

  ...

$ $

  §25.147   Directional and lateral control.

  a)  Directional control; general. It must be possible, with the wings
  level, to yaw into the operative engine and to safely make a
  reasonably sudden change in heading of up to 15 degrees in the
  direction of the critical inoperative engine. This must be shown at
  1.3 VSR1 for heading changes up to 15 degrees (except that the heading change at which the rudder pedal force is 150 pounds need not be
  exceeded), and with—

  The critical engine inoperative and its propeller in the minimum
  drag position;
  The power required for level flight at 1.3 VSR1, but not more than
  maximum continuous power;
  The most unfavorable center of gravity;
  Landing gear retracted;
  Flaps in the approach position; and
  Maximum landing weight.

  b) Directional control; airplanes with four or more engines.
  Airplanes with four or more engines must meet the requirements of
  paragraph (a) of this section except that—

  The two critical engines must be inoperative with their propellers
  (if applicable) in the minimum drag position;
  [Reserved]
  The flaps must be in the most favorable climb position.

  c) ...

  ...

  d) ...

  e) Lateral control; airplanes with four or more engines. Airplanes
  with four or more engines must be able to make 20° banked turns, with
  and against the inoperative engines, from steady flight at a speed
  equal to 1.3 VSR1, with maximum continuous power, and with the
  airplane in the configuration prescribed by paragraph (b) of this
  section.

  f) ...

$ $

  §25.149   Minimum control speed.

  ...

  g) For airplanes with three or more engines, VMCL-2, the minimum control speed during approach and landing with one critical engine
  inoperative, is the calibrated airspeed at which, when a second
  critical engine is suddenly made inoperative, it is possible to
  maintain control of the airplane with both engines still inoperative,
  and maintain straight flight with an angle of bank of not more than 5
  degrees. VMCL-2 must be established with—

  ...

  ...

$ $

  §25.161   Trim.

  ...

  e) Airplanes with four or more engines. Each airplane with four or
  more engines must also maintain trim in rectilinear flight with the
  most unfavorable center of gravity and at the climb speed,
  configuration, and power required by §25.123(a) for the purpose of
  establishing the en route flight paths with two engines inoperative.


Are there ILS approaches where a non-precision procedure isn't allowed?

Yes, there are.

Note: This is as opposed to those ILS approaches listed as ILS or LOC in the title—such as KGEG ILS or LOC RWY 3—which do have an authorized LOC approach.

Special Authorization Cat I ILS, and Cat II & III ILS approaches do not have authorized LOC procedures. These are precision only approaches.

See KGEG approaches, for example. Specifically, the ILS RWY 3 (SA CAT I), and the ILS RWY 3 (CAT II & III) approaches do not have authorized LOC procedures.

See also this screen cap of the KGEG ILS RWY 21 (SA CAT I) approach:

[][6]


Flex temperature isn't actually "fooling" the FADEC, right?

There are at least two misconceptions in your question:

The way I understand flex temperature is: It's a user interface for pilots to request a derating of engine power to reduce wear on the engine.

This is not quite correct. A derating would imply that the engine thrust needs to remain at the derated level after an engine failure. A FLEX or assumed temperature method takeoff allows setting higher thrust in case of an engine failure, so it's not a derating. See also What is the difference between Assumed Temperature and Derate takeoff thrust?

If the FADEC actually thought the air was less dense, then if anything it would increase engine power, not derate it.

This is not correct when the engine is temperature limited. The hotter the air, the hotter the EGT at the same fuel flow. Therefore, the FADEC has to reduce fuel flow to the engine for higher air temperatures, which reduces thrust.

Consider the following slide from this Airbus presentation:

You can see that the engine is flat rated (see What is a flat rated engine?) below a temperature Tref, which means the engine is not limited by EGT and can provide the same thrust regardless of temperature (see e.g. this answer for other limitations). If the temperature is higher than Tref, the FADEC has to reduce fuel flow to keep the EGT below the limit. This results in less maximum available thrust.
By entering a FLEX temperature, the FADEC will reduce fuel flow to the engine as if the actual temperature would be that high. We can argue about the semantics of whether or not this is actually fooling the FADEC, but the fact is that the FADEC will reduce the fuel flow accordingly. This will then actually give you a lower EGT than the maximum because the actual air temperature is colder and therefore reduces engine wear and tear.
The FCOM contains some additional information about what the FADEC does:

The FADEC system performs the following functions:
Control of gas generator

control of fuel flow
acceleration and deceleration schedules
variable bleed valve and variable stator vane schedules
control of turbine clearance
idle setting

[...]
Power management

automatic control of engine thrust rating
computation of thrust parameter limits
[...]

(Airbus A320 FCOM - Power Plant - FADEC)

When the thrust lever is in the FLX/MCT detent:

On the ground
The engine runs at the flex takeoff thrust rating if the crew has selected a flex takeoff temperature on the MCDU that is higher than the current Total Air Temperature (TAT). Otherwise the engine produces Maximum Continuous Thrust (MCT).

(Airbus A320 FCOM - Power Plant - Thrust Control System)


How can I find telephone numbers for FAA ATC facilities?

You would think the control tower phone numbers would be listed prominently and conveniently on the FAA website.
You would however be wrong1.

Your best bet would be to contact the Flight Standards District Office that covers your area - they can get you in touch with whatever other branches of the FAA you might need to talk to. You can also get tower phone numbers from Flight Service (1-800-WX-BRIEF).

AC-U-KWIK also has tower phone numbers in a conveniently searchable system (punch in the airport identifier and it will be in the results you get), and the printed edition of the AOPA airport directory used to have tower numbers as an appendix (I'm pretty sure it still does).

1 – Actually that's not strictly correct: some regions publish tower numbers prominently. Most don't, or my search skills aren't good enough to find them.


Why do fighter pilots use night vision goggles rather than normal light inside the cockpit?

former F-18 pilot here, it's my first post here so be kind :)

NVG's are not for domestic use, they are entirely tactical. Here are some uses;

Night formation (Defensive/Offensive counter air missions), such that formation members can fly lights off or in night mode (which we did all the time). Most fighters have external NVG lighting that can't be seen with the naked eye.
Target acquisition (Offensive Strike/CAS etc) in low/no light environments (permits visual rules of engagement upgrades etc
Laser ID. Laser range finders and target acquisition pod lasers can be seen through NVG's, we can conduct visual 'hand-over' procedures using lasers to talk on a wingman to a target. Lasers are weapons and have their own master arm switch, just like the gun, bombs and missiles.

With NVG's, I can see formation members with low/no light dozens of miles away, which can't even be done during the day. This brings enormous tactical advantage in air-air scenarios.

NVG's are not used to see inside the cockpit.

Hope that answers your question!


Could an airliner be as efficient lower and slower?

It's important to note that an airliner cruising at 50000 ft (I assume that's what you meant, and that's actually business aircraft territory; airliners are generally below the low 40s).  Is going pretty slow from an indicated airspeed perspective.  At 50000 ft an airplane is going roughly twice its indicated airspeed (it's actual speed through 3D space is twice the dynamic air pressure acting on it - if you stick your hand out, you'll feel the force of a 200 kts acting on your hand, even though you're actually going 400 kt).  So, such an airplane is actually optimized to only fly at 240 kts anyway, if it's cruising at a true airspeed of 480 kts.

What it means is, however you want to optimize for sea level flight, the higher you go the faster you can go in reality for a given fuel burn, whatever the configuration, burning far less fuel per unit of distance in the process.


What is the official unit of airplane/aviation speed?

Knot. Pilots think and communicate with ground personnel in knots. HUD tells you knots. Textbook tells you to increase speed to 500 knots after takeoff, and land at 150 knots.


When will I hear the sonic boom from a plane flying towards me?

In case a supersonic aircraft (flying faster than the speed of sound) flies directly over a person, that person (the observer) will not hear anything.

The (supersonic) aircraft produces sound throughout its flight (i.e. while flying towards as well as away from you).

The sonic boom you hear is the sound produced by the aircraft when it was coming towards you.

For how this works, see this question and the Wikipedia page.


Fuel doesn't have the same density as water. We're not planning a real flight, so a quick and dirty fuel density figure from Wikipedia tells us:

  In performance calculations, airliner manufacturers use a density of jet fuel around 6.7 lb/USgal or 0.8 kg/l.

So if we take your figure of 320,000 litres (it's a bit unclear quite how much of that is actually usable for flight, but that's a subject for another question), that's about 560,000lbs of fuel or around 254,000kgs.

Which, indeed, is a lot. The fuel is spread throughout the wings (and the trim tank in the tail), which are designed to carry the weight. If you look at What is the weight budget of a fully loaded A380?, you'll see how the fuel capacity interacts with the other weight specifications for the aircraft:

  The maximum fuel weight is the difference between maximum ramp weight and zero fuel weight (which is 562,000−361,000=201,000kg)

Max take-off weight is a bit less than maximum ramp weight, but we'll handwave over taxi fuel for simplicity. The point here is that if you can fill the aircraft with cargo, it would be too heavy if you also filled it with fuel. If you want to take a full load of fuel, you'd have to reduce your payload to keep the total weight low enough. Working out the weight/fuel/range trade-offs for a given flight is what dispatchers and load planners do, using specialized software.


Why did early 747s have only two or three windows on the upper deck on each side?

Early on in the design and development of the aircraft the function of the upper deck changed throughout the early life. Windows are high stress areas and if they can be avoided they typically are. Juan Trippe was a major figure in pushing the 747 into production but during the SST race it was his view that the 747 would largely be a freighter holding the crew on the upper deck. Generally freight aircraft do carry small crews and were likely the original reason for the windows.

  Boeing was competing for a supersonic transport contract in 1965, at
  about the same time the 747 was conceived, and Pan Am founder and
  chairman Juan Trippe believed that the big subsonic jets would end up
  as freighters and that the SST would replace the 747 on passenger
  routes. Trippe was one of Boeing’s best customers and usually the
  first to order new models, so Boeing put the flight deck of the 747
  above the passenger cabin to give the aircraft a hinged nose for a
  front-loading cargo door.

The original bubble deck was much smaller but created too much drag and was ultimately elongated. This left dead space that Trippe and his team drove Boeing to turn into a lounge/bar akin to the 377 Stratocruiser's area. Bar's rarely have windows on the ground so why have them in the air...

  The first design for the cockpit enclosure was a hemispherical hump
  atop the fuselage. This produced too much drag, so Boeing extended the
  aft portion of the hump to form a teardrop. Then, in a deliberate echo
  of the below-deck lounge on the model 377 Stratocruiser, Boeing’s
  1940s flagship, Trippe and his colleagues persuaded Boeing to turn the
  extra space behind the cockpit into a bar and lounge.

It was not until almost a decade after its introduction during the '73 fuel crisis that airliners started using the upper deck for full passenger seating. This likely lead to the later models having full window treatment of the upper level.

  The party days ended with the 1973 fuel crisis, when virtually every
  747 operator got rid of the lounge and replaced it with more seats for
  paying passengers. In announcing the change, a British Airways press
  release noted that the upstairs area was “currently used for a
  first-class lunge”—the spelling was probably appropriate more often
  than not


Does EASA require airliners to be fitted with autopilots?

Indeed EASA requires "autopilot" but they don't state it directly like "every airliner flying in the European airspace must be autopilot equipped". They require it indirectly.
When I first read your post I immediately thought of RVSM. I recall talking to an ATCO (retired now) about automation on board, and he told me that without autopilot you cannot fly in RVSM airspace.
So I had a look in skybrary concerning RVSM and they did the dirty job for us. They mention all 3 EASA regulations  IR-OPS SPA.RVSM.100 and SPA.RVSM.110, EU-OPS 1.241, EU-OPS 1.872 and they have quoted the interesting parts:

Regulatory Requirements[...]
An operator shall ensure that aeroplanes operated in RVSM airspace are equipped with:[...]
An automatic altitude control system

Emphasis is mine.
There might be other regulations requiring other automatic flight components but I am not aware of them although a quick look in the documents reveals references to auto-land systems as well so these documents cover more than RVSM.
The summary is that EASA does not simply specify "you need autopilot if you fly an airliner" but they go into detail, of what they require and for what reason.

Acronyms
RVSM Reduced Vertical Separation Minima
ATCO Air Traffic Control Officer