There is no distance to the touchdown point because there isn't a set touchdown point. there's no runway start distance because that's not what you are aiming for. The purpose of the ILS is to get you close enough to the runway to complete a landing visually. If the visibility is so bad you cannot see the runway even when you are right on top of it then you need an airplane with a completely automated landing system to legally shoot the approach.

What you do have a DIS (Distance) reading in nautical miles to the ILS at the top of the screen, which usually tells you all you need to know. This distance is what you use in the approach procedure which you get from the approach plate for the runway and category of approach you are doing. If you get to the missed approach point, which is a set distance from the ILS, without seeing the runway lights then you must go around.

I'm going to assume you are working with a simulator like x-plane or MFS, in which case you aren't bound by procedure, and you can give it a try without endangering anyone. The ILS in most airports is placed right next to the runway, about where you'd want to aim a touchdown, so in a white out condition you would follow it down as far as you can until you contact the ground. It's been successfully done in emergencies, there's a good deal of pucker factor involved.


Is fuel moved around during flight on a passenger or cargo plane? If so why?

Maybe

This is dependent on the air frame and varies from plane to plane and not all planes have capability of moving fuel although most large planes do. The Concorde moved fuel all over the place from its 13 tanks to cool the nose cone as well as trim the aircraft. It was perhaps one of the most complex implementations of such a system and kept the flight engineer quite busy.

(source)

Here is a layout of how it was used to control trim.

(source)

For any of this to be possible the aircraft must be equipped with cross-feed abilities. On larger planes this is fairly common, in case of a single side leak the cross feed valve is usually kept shut but since engines can have slight variances in fuel burn the pilots may need to cross feed every so often to balance the plane out. There is a nice overview on 737 fuel systems here.

(source)

In small, often single engine aircraft fuel management is generally left up to the pilot. There are often multiple tanks which can be individually selected and must be rotated in flight every so often (30 min usually). Since some planes are prevented from drawing from "both" tanks, the switch has a lot to do with not running a tank dry in flight.

This article overviews weight and balance fairly well. Often times quantity of fuel is more important than location. Most modern airliners store the fuel fairly close to the CG (in the wings or belly for that matter). The Concorde's unique delta wing design led to a fairly different use case than your run of the mill jet.

Some of the balance issue is solved within the tank using baffles which keep the fuel from sloshing around too much but allow it to flow freely around a fairly large tank when need be.

You can find the full text of the FAA's book on fuel systems here.

Here is a neat video of how to actually cross feed fuel.


Why is the Su-27 so much larger than the MiG-29?

The Su-27 and Mig-29 were the result of high-low concept subscribed by both the USAF and Soviet Air Force (VVS) in the 1970s. Basically, this involved the development of two different fighters, a high performance medium weight fighter crammed with every advanced technology (which made it expensive) and a low cost light weight fighter to make up the numbers.

In this direction, the USAF announced the FX (Fighter eXperimental) program, which resulted in the McDonnell Douglas F-15 Eagle (designed to counter the misunderstood Mig-25), followed by the LWF (Light Weight Fighter) competition, that gave birth to the General Dynamics F-16 Fighting Falcon.

The Soviet equivalent of these programs was the PFI( Perspektivnyi Frontovoy Istrebitel, Perspective Frontline Fighter), which called for a high performance multirole aircraft to counter the new generation US aircraft and the LFI (Lyogkiy Frontovoy Istrebitel, Light Frontline Fighter), which called for a low cost fighter with respectable ground attack capabilities.

The PFI was required to operate 250-300 km beyond the frontline, with sizeable internal fuel and a comprehensive Communications, navigation, avionics and weapons suite. The LFI, on the other hand was required to operate 100-150 km beyound the frontline, while being easy (read cheap) to build and maintain and capable of using semi-prepared strips while carrying limited armament (initially limited to a couple of medium range AAMs and gun).

In 1972, the VVS tasked the Sukhoi bureau to build the PFI, resulting in the Sukhoi Su-27, while the Mikoyan bureau got the LFI, resulting in Mikoyan MiG-29.

F-15 and F-16; image from sunketh.wordpress.com

Basically, Su-27 is to Mig-29 what F-15 is to F-16; hence the size difference.


On coaxial helicopters, how exactly does the yaw mechanism work?

Mechanically it's simple, and ingenious.
The following is from a 1966 patent titled: Coaxial rigid rotor helicopter and method of flying same (US3409249A) by United Technologies Corp. (Of course this is not the only way, but it's one way as invented by a major aerospace company over 50 years ago.)
I've done the laborious reading referencing numbers and text, and I'll summarize it here.
Swash control

(Don't mind the steering wheel, it's the inventor's idea of pushing the cyclic left/right.) I've added an arrow pointing to 274 in the illustration, it's a wheel, and it's the key.
Using the collective (254) translates that wheel forward and aft, which moves the rigging of both swash plates up/down collectively.
But using the anti-torque (yaw) pedals, rotates that same wheel by way of cable 328. The wheel rotation would move the rigging for each rotor opposite each other.
Below is a simplified elevation view for the effects of translation and rotation of the wheel on both swash plates:

Swash mounting
For yawing, the summary is that the up/down translating parts do not rotate. It is the attachments from plates to rotors that do rotate and are on bearings. Basically two of the same but in a concentric manner.

The two main element per rotor are bearings that permit the vertical translation of the fixed portion, and the rotation of the attachments to the rotor. Focus on labels 136 and 140 (added arrows for easier finding) for the upper rotor, and here's the quotation:

(...) Bearing 136 is positioned between ring member 132 and fixed housing 52 so as to prevent rotation of ring member 132 about the axis of rotation 28 but to permit translation of ring member 132 along axis 28. Swash plate mechanism 130 also includes inner gimbal ring 133 which is pivotable about axis 134, outer gimbal ring 135 which is pivotable about axis 137, and ring member 138, which is supported from ring member 135 by bearing 140 for rotation with blades 96 about axis 28.

(Emphasis mine.)


How can an international MRO apply for FAA approval?

These 14 CFR Part 145 Forms might be the forms you are looking for however there may be other forms for applying from overseas.

This site (FAA Aircraft Repair Stations Homepage) has some good links and here are the pre application regulations you need to comply with.

Here is the letter of the law of the FAA regulations (Starts at Title 14 Section 145.1).

I am no lawyer and cant really comment on this but I have no idea how FAA regulations work outside of the country and how/what foreign entities must comply with. I would advise contacting a local lawyer as well as a US lawyer about this.


What is the effect of opening airplane bay doors on the radar cross section of the airplane?

Radar waves are sent back to the radar by two mechanisms, reflection and diffraction.  Opening a bay door may present a surface that is angled such that waves will be reflected to the radar.  As for diffraction, low observable (stealth) aircraft are designed so that a radar wave encountering the aircraft's skin will travel along the skin and be gradually absorbed.  Opening the bay doors creates a break in the skin, causing waves on the skin to diffract.  Some of the radar energy is returned to the sender.

For an amateur looking at "stealth" diffraction is often not accounted for.


Actually, the CF34-3B1 engines are certified to use wide-cut fuels, JetB/JP4. This comes straight out of the AOM for the CRJ200. I would venture to guess that all variants from CF34-1A to 3B would have the same certifications.

The CF34-8C5 engines on the other hand are not, again straight from the AOM for the CRJ 705/900. CF34-8C1 to 10E also likely have similar certifications for fuel certifications.

The difference is likely more to do with cost to certification. Seeing as wide-cut fuels aren’t overly common, except in the most remote locations north of 60 degrees of latitude, GE probably said why bother spending the extra money. JetA1 is good to -47*C/-53*F so for most commercial aviation, it’s more than sufficient. Every aircraft I’ve flown to date had an on-ground operating limitation of -40*C anyway.


Why are Gatwick's runways too close together?

Historically, Gatwick had only one runway (08R/26L) with a taxiway to the north, but this obviously would cause problems if that runway was out of use for any reason - emergency, scheduled maintenance, etc.

In 1979, the taxiway was upgraded so that it could be used as a runway when the main runway was out of use. Since this used existing infrastructure, the locations were obviously fixed.

However, at that time the then owners of the airport (BAA) agreed with West Sussex County council that the second runway would only be used when the main runway was unavailable. This was to protect the interests of the airport's neighbours. With this agreement in place there was no incentive to address the issue of separation. The agreement was set to run for forty years, and expired recently on 13th August 2019.

With the imminent expiry of that agreement, the airport is now exploring ways to  bring that second runway into use. One suggestion is to widen the existing main runway southwards, allowing the centerline to be moved south and increase the separation.

Source: The Independent, 15 October 2018


Aerodynamics and fuel consumption of a powered glider

I can talk about a couple of these...

  3) Optimum long distance cruising speed is at max lift/drag ratio, and when the lift is equal to the aircraft weight, given that the engine and propeller are also optimized for it. In other words, the speed where it sits stable in the air without any control.

Well, there are two speeds you're talking about:

The most efficient cruising speed, which is also the speed that maximizes L/D, which is also the best glide speed.
The "trim speed", which is the speed where the aircraft tends to maintain a constant pitch ("sit stable in the air") when the pilot is not applying any forces to the control.

For full-scale aircraft, the trim speed can generally be altered by the pilot in flight, using the trim wheel (or whatever trim control that aircraft has). So, the trim speed is usually not equal to the best glide speed.

That said, you certainly can (and it's probably a good idea to) design your powered glider so that its trim speed is constant, and equal to the best glide speed.

  I can find this speed for my model glider by flying it at zero attack angle and with neutral control surfaces, and then increase the throttle gradually until the plane stops sinking.

Yes, you can find the trim speed (but not the best glide speed) of your model glider by controlling the throttle so that the height remains constant. If the controls are neutral and your aircraft is not pitching, then it is flying at trim speed.

(I'm not sure what you mean by "flying it at zero attack angle", since you can't explicitly control the angle of attack without moving the control surfaces. For steady flight, the angle of attack is determined by the speed and the bank angle.)

  7) The speed has doubled, which means the drag has approximately quadrupled, so a new engine and propeller with four times the power and optimized for twice the speed must be installed.

That's almost right. If the speed doubles, then the drag quadruples. But power equals force times speed, so if the speed doubles, and the drag quadruples, then the needed power increases eightfold, not fourfold.

Responses to your comments:

  However, as I understand it the "trim" is just a minor adjustment to the elevator, correct? So in effect we are nudging at the angle of attack so the lift perfectly matches the weight and the plane can sit stable, but we aren't really flying at the optimum L/D?

I wouldn't call it "just a minor adjustment". In a Cessna 172, trim is what determines whether the aircraft flies at 55 knots or 155 knots. Other airplanes and gliders work the same way: there is one particular speed at which the aircraft will fly steadily without any force on the control stick, and trim is used to determine what that speed is.

Trim isn't used for making the lift match the weight. If the lift is too high, then the aircraft will begin climbing (or stop descending), and if the lift is too low, then the aircraft will begin descending (or stop climbing). You control this by using the stick and the throttle.

The aircraft can "sit stable" with the trim in any position, but for each trim position, there is only one corresponding speed at which the aircraft will fly steadily without force on the stick.

(There's an exception to the above: with some aircraft in some circumstances, if the trim is too far back, then constant forward pressure on the stick or yoke is required in order to prevent the aircraft from stalling.)

If you're sitting in an aircraft and you want to fly at optimum L/D, you'll usually do that by knowing what airspeed corresponds to optimum L/D, and setting the trim for this airspeed. (The process for setting the trim appropriately is: use the stick to fly at that airspeed, hold the stick in place, and then use the trim control to relieve the force the stick is exerting on your hand.)

  I'm just assuming that airfoils are designed to be at their best L/D at zero angle of attack, is that really the case?

I doubt it. In particular, some aircraft have symmetric airfoils, which have an L/D of zero at zero angle of attack.

  When I said "flying at zero attack angle", I mean that the plane sits completely horizontal in the air, and it does so without any compensation from control surfaces.

If the plane is completely horizontal, that's zero pitch, not zero angle of attack. Zero angle of attack is when the nose is pointed exactly into the oncoming air, rather than higher or lower.

The pitch that an airplane settles at depends on both the trim and the power setting.

  Last part doesn't seem right to me. If you look at it from the perspective of the engine, it creates a forward force. This force is constant, no matter the aircraft speed (taking aside the fact that a propeller cant be equally effective at all speeds). However the drag is related to the speed, and the drag is four times stronger. So it feels to me like the needed power is only four times more, not eight.

Well, the thing there is, an engine doesn't really create a constant force. In particular, you need to produce enough force to counteract drag. If your aircraft experiences four times as much drag, then your engine also needs to produce four times as much thrust in order to fly the same way.

So in order to fly twice as fast, you need to make the engine produce four times as much force (either by opening the throttle more, or by using a more powerful engine). The engine also needs to operate at twice the airspeed. Power is force times speed, so together, these two facts mean that the engine needs to produce eight times as much power.

Further responses to your comments:

  Re angle of attack and pitch, I might have just confused the terms. As I understand the terms, "angle of attack" refers to the angle of incoming air relative to the chord of the airfoil, so it relates to the wings only. Pitch is the angle of incoming air relative to the aircraft itself. So if the wing chord is mounted exactly horizontal, angle of attack and pitch are identical.

Pitch doesn't have anything to do with the angle of the oncoming air; it's exclusively defined by the way that the aircraft is oriented in space, relative to the horizon. Specifically, pitch is the angle by which the nose is pointing above or below the horizon. If it's pointing 10 degrees above the horizon, the pitch is 10 degrees; if it's pointing 20 degrees below the horizon, the pitch is -20 degrees. This is regardless of how the aircraft and the air are moving.

  It makes more sense to me when I imagine putting a piston engine with a propeller in a wind tunnel. Would the thrust force of that engine/propeller vary greatly with incoming airspeed when running the engine at constant power? I can't imagine why it would. As the air speed increases, the engine would increase its RPM to exert the same power on the air, and the propeller efficiency would vary slightly, but the engine power would still be the same. And overall the thrust force would be approx the same. Or am I thinking the wrong way here?

Well, the best way I know how to put it is "that's physics". If you want to push something in the same direction that it's already going (as an airplane propeller does—it pushes the air aft, even though the air is already moving aft), and you want to push it with a constant force, then the faster that thing is going, the more power is required in order to push it. I don't think it's easy to see why this is the case, but this is, in fact, the case.

Maybe it would be helpful to imagine an airplane flying straight up. Imagine that this airplane is heavy but sleek, so that the drag is very small compared to the weight. Then, in order for this airplane to fly straight up at any speed, its engine will simply have to generate thrust equal to the airplane's weight. (The only time the engine would need to generate more thrust than the airplane's weight, is when it's making the airplane accelerate.) And yet, if this airplane were to fly twice as fast, surely the engine would need to generate more power, right?

The moral of the story is that power depends on both force and speed. That's physics; there's no way around it. If you had an engine that generated a constant amount of thrust, using a constant amount of power, regardless of speed, then you'd be able to make a perpetual motion machine out of it.


How can a SID's MEA be above its top altitude?

Top Altitude is the initial climb altitude for a 'climb via SID' instruction, unless otherwise is stated.

  TOP ALTITUDE– In reference to SID published altitude restrictions the charted "maintain" altitude contained in the procedure description or assigned by ATC.

Initial climb altitude/level is not directly related to the MEA. It has more to do with radar acquisition, noise abatement, and clearing obstacles.

  MINIMUM EN ROUTE IFR ALTITUDE (MEA)− The lowest published altitude between radio fixes which assures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes. The MEA prescribed for a Federal airway or segment thereof, area navigation low or high route, or other direct route applies to the entire width of the airway, segment, or route between the radio fixes defining the airway, segment, or route.

Source: FAA AIM


What are the advantages of twin-fuselage aircraft?

Depending on the design, one of three advantages made designers choose a twin-boom layout:

No structure directly aft of the fuselage, which helped to integrate the propulsion, or improved access to the cargo area, or improved pilot vision,
Smaller overall surface area for two-engine aircraft, or
Shorter development time for high-performance aircraft.

There are two groups of twin boom designs: Those which were designed that way from the outset, and those which were later derived from single-fuselage designs. You could add a third group, those with two distinct fuselages and an offset pilot position, but an offset cockpit could also be a result of other design considerations. Examples are the Junkers 322 or the Blohm&Voss BV 141, both single-fuselage designs with an offset cockpit.

The first group comprises aircraft like the D.H. 2, the Saab 21 (picture below, source) or the Gotha Go-242. Here the designers wanted to create space for the propeller or a loading ramp. Also, some early jet aircraft used a two-boom layout to keep the tail structure free of the jet blast. The advantage is obvious: No structure at the rear fuselage.

The second group arose due to the performance requirements of modern, all-metal, stressed-skin designs with cantilevered wings. Remember that at the beginning of the 1930s fighters were still biplanes (Hawker Fury, Heinkel He-51), and new designs like the Caudron 460 or the Messerschmitt Bf-108 showed that sleek aerodynamics and high wing loading were the way ahead. However, unlocking the performance potential possible with these designs required much more powerful engines. The engine manufacturers could increase power output only slowly, so a number of designs (Lockheed P-38, Messerschmitt Me-110, Bristol Beaufighter, Northrop P-61) tried to use two engines. Since there were two engines already with a big space requirement for the turbocharger, Lockheed decided to use a two-tailboom design. Here the advantage was a smaller overall surface area to house two engines, their coolers and turbochargers, and the pilot (picture below, source).

During the war, again the requirement for more powerful aircraft arose, and to avoid the delay of a fully new design, existing aircraft were combined, shortening the development time greatly. The first of those was the Heinkel He-111 Z (for Zwilling = Twin), which added a fifth engine to be able to pull the giant Me-321 transport glider. Joining two powerful aircraft was proposed for the Messerschmitt Bf-109 (Bf-109 Z), the Messerschmitt  Me-309 (Me 609), the Dornier Do 335 (Do 635), the Savoia-Marchetti SM.92 and the North American P-51, the only one of those to result in an operational aircraft, the F-82. This resulted in an agile aircraft with high speed and high range, which was very useful for escort or reconnaissance tasks. However, only few of those were used operationally, because soon jet aircraft filled that need in a better way.

The main disadvantages of the twin fuselage designs with their offset pilot position is the high radius of roll inertia and the vertical acceleration suffered by the pilot during rolling maneuvers. Especially for a fighter, a fast roll response is the key to success in aerial combat, and a twin fuselage will impose a penalty not suffered by a two-engined aircraft with a central fuselage. This is compounded by the pilot suffering additional vertical acceleration when rolling, which again will reduce the likely roll agility of the twin-fuselage aircraft.

Might we see more twin-boom or twin-fuselage designs in the future? Probably only for special purposes, like the example you have given yourself. Another might be the Kensgaila VK-7, a Lithuanian airfoil testbed which combines two Blanik gliders with a special, exchangeable center section for testing new airfoils under realistic conditions. This one is not even on Wikipedia's list of twin-fuselage aircraft!

Earlier twin-boom transport aircraft like the Fairchild C-119 or the Nord Noratlas have given way to conventional layouts with a raised tail to accommodate the rear ramp. Twin-boom and twin-fuselage designs are less stiff and more prone to flutter than conventional configurations, so the conventional design prevailed and will do so in future as well.


Would better location tracking for airliners improve safety?

Very simply, no.... us knowing where AF447 was would have made exactly zero difference to the fact that it crashed into the ocean at 400+ knots.

Would we have had a better idea of where to find it? Most probably. Would it have saved any lives? Absolutely not.

As always, these things come down to cost-benefit, and the simple fact is that GPS tracking would prevent very, very few accidents. The only possible benefit would be that it may help us find the black box or wreckage, assisting in the investigation which may just possibly reduce the chances of a similar accident occuring in future. Note that of the two examples you gave, though, only MH370's black box hasn't been found (yet)... so even this benefit is tentative.


Could a FOSS autopilot system ever pass FAA regulations?

Short answer: technically and legally yes, a free open source autopilot could be certified.  But I think it is unlikely to happen anytime soon.

Long answer: Aircraft software certification is governed by DO-178C. There is nothing in there that says anything about whether the source is open vs closed, or free vs non-free.  What it does lay down is a lot of very rigorous requirements for proving that the software does what it says it is going to do.

For example, for something like an autopilot, an independent testing/validation would typically be required.  That means the person who writes/codes the software and the person who tests the software have to be different people. i.e. you must have a fresh set of eyes looking at it. Further that testing will have be very extensive, covering every possible scenario your autopilot could encounter.  You might have to mock up an entire fake airplane, with simulated sensors and simulated actuators, and feed the autopilot simulated data and see if the actuators move like they are supposed to.

You also need to provide a massive amount of very careful documentation about all parts of your software process.  E.g. the software requirements need to documented, and then you need to be able to show every step of the way on how each specific requirement gets translated into the final machine code.

An free open source project certainly could meet all of these requirements. However, they end up being very time consuming and expensive. You need an army of software engineers working all day every day for years to meet some of these requirements.  FOSS project typically do not have the level of manpower that is required to meet these requirements.


Dead reckoning navigation: gyromagnetic compass, how it is stabilized?

Gyromagnetic compasses do indeed exist even in smaller aircraft, and need not be overly complex. The basic principle for an analog system is as follows:

Heading is measured against a gyro rotating in the vertical plane (just like a normal heading indicator). The gyro may be in the instrument case, or electronically repeated from elsewhere in the aircraft.

The earth's magnetic field is sensed by a sensing unit, a "Flux valve" usually located in the wing, or otherwise in a good position to minimize electromagnetic interference from the aircraft.

The gyro position and the magnetic reference are compared electronically and the resulting difference becomes an error signal. This error signal is sent to electric motors on the gyro frame, which will move to very slowly (a few degrees per minute) correct the gyro to align with the magnetic reference, combining the short term accuracy of the gyro with the long term accuracy of the earth magnetic field. To further enhance accuracy, cut-out switches cuts the error signal out when the aircraft is banking/accelerating, as this tends to give a less precise magnetic signal from the flux valve, while a gyro is unaffected by it. See the Bendix King KCS55A for a real life example.

On older, larger aircraft, you'll find similar installations. On modern aircraft, with inertial navigation platforms (IRS) heading is often taken from the inertial platform as true heading, with magnetic variation applied from a database to provide magnetic heading.

The IRU will in that case (among other things) act as a kind of gyrocompass, finding true north by leveling and rotating 3 nowadays usually mathematically modelled gyro planes (solid state Ring Laser Gyros, no moving parts), to align with true north, by sensing gravitation and angular movement around gyro axes from the rotation of the earth. The planes are then kept level by integrating gyro data, and filtering/fusing it with accelerometer data, movement over earth curvature, Schuler tuning, other sensor data etc.)


The short answer is, when the surrounding environment requires it. The procedure here is perhaps most akin to a short field take off over a 50 ft obstacle but a few things are going on. The aircraft, as soon as it leaves the ground is climbing at Vx which allows for the maximum angle of climb.

  Vx is the speed for best angle of climb while Vy is the speed for best
  rate of climb.

In your linked video its mostly for show. In practice short field over a 50ft obstacle takeoffs are used for, well, short fields... or when you need to get off the ground fast so as to get over some obstacle at the end of the runway. Generally speaking most commercial airports have long runways that are more or less obstacle free (with some notable exceptions) so short field maneuvers are not what they are in general aviation. There are lots of small fields all over the country that have trees (also known as 50 foot obstacles) power lines, buildings, church steeples or any manner of obstacle at the end of the runway. On top of that many of these strips are on the shorter side (under 3000 ft.) so you simply have less runway to work with and your margins can be far smaller. In this case you want to get off the ground as soon as possibly and climb as fast as possible.

It is the pilots responsibility to operate the aircraft safely and these kinds of maneuvers are well within operating limitations. In small planes they happen more often than you would think, especially if operating out of a short strip. and even us lowly private pilots are trained in short field 50ft obstacle clearance maneuvers. As for the big guys if the airport environment calls for it, it may be performed but I would think it is less common as most commercial airliners can pitch up far more than people in the back would be happy with. Someone with more commercial experience may be able to elaborate on how often they happen in practice there.

There are a few things to keep in mind as well, military planes simply have a much higher thrust to weight ratio than commercial airliners and can in some cases sustain vertical climb outs. Military jets also often have afterburners for an added boost. The commercial planes you see in the linked video are more than likely lightly loaded carrying only a partial fuel load. Camera angles can also make it look as though the plane is climbing much steeper than it really is.


What is a G-Check and what are the differences relative to other checks?

It's tough to tell based on your question, but I think you are talking about an inspection due to an over-G reported on a flight either by the pilot or the flight control system post-flight report.

Maintainers will do inspections of known stress points on the aircraft to look for breaks, cracking or loosened parts and then declare it safe for flight or fix anything out of tolerance.  For a low level over-G, this could be pulling a few panels.  For higher level over-Gs it could be 8 hours worth of work


Can TCAS cope with situations involving more than two aircraft?

TCAS can deal with conflicts with multiple aircraft, a so called Multiple Threat Encounter. It will attempt to resolve the conflict but it will be limited in its options.

Examples of a MTE are rare, one case I can point to is this incident involving an aircraft turning into the approach stream between two aircraft instead of following the last in line.

MIT Lincoln lab has reported on MTEs and the TCAS algorithm performance in 2009. They report the majority of MTEs involved three aircraft, but mention one TCAS MTE involving seven aircraft.


How much actual difference does fixed pitch propeller make in takeoff distance?

With my old VariEze (not a training aircraft; in the same power class as the Cessna 152 but lighter and with much higher wing loading) I had a cruise propeller and a climb propeller that I could exchange on the ground with about 30 mins of work. I measured ground roll at max gross weight and calm wind to be around 1500' with the cruise prop and 1100' with the climb prop. I could usually get around 1500 fpm climb with the climb prop and 1000 fpm with the cruise. Cruise speed was 10 to 15 kts slower with the climb prop depending on altitude; you'd usually have to throttle back quite a lot to avoid exceeding redline RPM.

The difference in takeoff performance is more dramatic when a constant-speed (variable pitch) prop is compared to a fixed-pitch prop. I'm presently in the process of upgrading my Lancair 360 from a cruise/climb compromise fixed-pitch prop to a constant speed and I expect that to decrease the ground roll to less than half the current 1500'. I'll report back with data once it's flying.


A route is how you go from place to place.  A segment is a portion of your route which is characterized by a consistent course/altitude.

A route may have one segment, or many.  An MTR is a Military Training Route.  If no portions of the route exceed 1,500 AGL, then it is given a four-digit identifier.

I'm pretty sure that the three-digit / four-digit decision was arbitrary, but I'm ready to be educated.


Basically, neutral mid-toned greys or tans are considered to be the best color to use, because they aren't any other color:

The base color shouldn't be confused for anything in an instrument display. This precludes using red, yellow, green, bright blues or brown, but also black and white as black is used to represent empty space in instrument displays while white is commonly text and also used for other display elements.
The color shouldn't cause glare. Too light a hue will increase sunlight scattering in the cockpit, reducing pilot visibility in high-sunlight situations.
The color shouldn't be too dark, as in those same situations a dark color will absorb the sunlight and become hot, increasing ambient temperature of the flight deck, requiring additional cooling system capacity for both pilots and instruments (many civvie aircraft have black instrument panels, but other elements of the design typically prevent the panel catching too much sunlight).
The color has to be relatively easy to find or make, allowing touch-ups. Brighter colors are harder to match exactly; neutral tones blend easier and aren't as distracting even if they are slightly mismatched. This is mainly a military concern, where crew chiefs do what they can with what's on hand; commercial airliners will have hundreds of gallons of their livery colors and other standard touch-ups including cockpit-approved colors available at maintenance hubs.
Western thought says the color should be visually uninteresting in order to provide the minimum distraction to the pilot from more important colors in the cockpit. This is where Western and Russian thought primarily differs; Russian designers favored a "mood color" over being completely nondescript, while Western designers favor the background color "disappearing" even if the net effect is depressing to a pilot sitting in it for several hours a day.

To be fair, Western cockpits are not always grey or tan, but really there are only a couple more common options. European Mirage, Rafale and Gripen fighters are commonly seen with a sky-ish blue interior, providing some of that mood color benefit while remaining nondescript. Aircraft cockpits in WWII, on all sides, were painted in whatever the crew chief had available, which usually amounted to land-based planes getting the same olive drab that coated every piece of metal the Army owned, while naval variants got one of the various blue-grays used on the ship itself.


How do airplane "life jackets" compare to marine life jackets?

Source - Been a pilot for years. Sailboat liveaboard for 1 year.

Aviation life jackets are reliable, but the overall intent is for a rescue operation to occur within hours.  One piece of advice is to stay away from debris.

Marine life jackets are designed to provide flotation for a longer amount of time.  They are also more durable due to the material in which they are constructed from.  Marine life jackets are also designed for multiple uses.


Why were the first airplanes "backwards"?

"Backwards" is relative, there are modern aircraft that have forward placed elevator i.e. canard designs that fly quite successfully

(source)

As for why its not more popular you can read up more on that in why are there no production canard GA aircraft? and Why is the Tu-144 the only commercial airplane with canard configuration? as well as in the answers to lots of 'canard' questions on this site.

As for why the Wrights did it this way, NASA offers an explanation

  The placement of the elevators at the front of aircraft is rather
  unique for the Wright flyer. Modern aircraft typically have the
  elevator at the rear, attached to the horizontal stabilizer. The
  Wright's placed their elevator at the front to provide protection to
  the pilot in the event of a crash. (The pilot of this aircraft lies
  next to the engine on the lower wing.) But there is also a static
  performance advantage when the elevator is placed forward. Lifting
  wings have a natural tendency to flip tail over nose because of the
  way the pressure is distributed.

So they were not necessarily backwards so much as different considerations were taken under advisement during the design.


How is/was RFID bag handling introduced in a baggage handling system tailored to barcodes?

By printing them along with bar codes. RFID mode became operational in HK in 2005. Basically, the airport replaced the barcode only baggage tags with RFID embedded tags:

  Hong Kong International Airport (HKIA) today announced that all of its check-in counters can now print integrated radio frequency identification (RFID) baggage tags. The new tags, which combine an embedded RFID chip with a barcode, are replacing barcode-only baggage tags on an airline-by-airline basis.

Basically, the system reads both the RFID tags and barcodes.


Why don't short runways use ramps for takeoff?

V1.

There are other valid reasons, as have been listed - cost, bidirectional runway use, etc. These would still not completely disqualify ramps, just limit them to very special circumstances. But the one disqualifying factor is that a ski jump takeoff removes the necessary element of safety airliners depend on during takeoff.

Up to a certain airspeed, called V1, an aircraft on a sufficiently sized flat runway can decide to abort. Using all available means, mostly brakes, an aircraft can halt its takeoff run and stop by the end of the runway. With a ski jump takeoff, you don't get that luxury - go off the ramp too slow and you fall off the end, nose first into the ground.

This is not a concern for carrier takeoffs. Every takeoff or landing on a carrier is a close call as it is. There's no spare runway for second thoughts. If things go wrong enough, the pilot has to pull the eject handle before he plunges into the water. In that situation, a ramp adds safety, giving a few more seconds on that ballistic trajectory.

So ski jump ramps are used on carriers that don't have much more expensive and complicated catapults. They are extremely effective there; just a 3 meter tall ramp can cut the takeoff roll in half for a fighter. But this comes at the cost of committing to it completely, do or die (which is the case on carriers anyway).

Since there's no eject handle on airliners, every takeoff has to be a safe one. This means being able to abort the takeoff if you develop a problem on the runway, such as your engines not spinning up to takeoff thrust.

The only way you could get a safe enough V1 with a ski jump is by having a runway of normal length, and then some, before the ramp, which removes the whole point of installing a ramp. You'd never reach it except on aborted takeoffs.


Does an instrument exist to measure the different types of drag?

Yes, partially.  A wind tunnel's wake rake (an array of pitot tubes) can be adapted to measure in-flight profile drag (form drag plus skin friction).
Measuring Wing Profile Drag using an Integrating Wake Rake, by Pifer and Bramesfeld, in Technical Soaring 36(3):74-82, 2012.
The article doesn't have any in-flight photos, so it may not have actually been flown at time of publication.

@quietflyer mentioned Richard Johnson, who indeed has flown an airplane with a drag rake.

The wing drag rake was installed on N3176T’s left wing trailing edge, 1.0 meters outboard from the wing root joint. ...

R. Johnson, "A flight test evaluation of the SZD-55-1," Soaring, March 1992.
The drag rake itself is described and shown in another article:
R. Johnson, "At last: an instrument that reads drag!," Soaring, October 1983.


My 1973 Cessna Cardinal has a key to unlock the doors and another to start the engine.  Just like a car.

I could use a horn to scare deer & geese off the runway.


What does the instruction "Climb heading [BEARING] to [NAVAID] 2.5 DME" mean?

DME is "Distance Measuring Equipment". It tells you how far you are from the equipment transmitting the signal. This is often co-located with a VOR, or at an airport.

  turn heading 180 degrees to LGA 2.5 DME

So, this means turn due south and continue until you are 2.5 nautical miles from LGA. At this point you're instructed to turn left on to a heading of 040.


Can I land on an abandoned runway in California?

As noted in the comments it depends on who owns the land and what the local regulations are. With permission and proper operations it may be ok.

However if the runway was formerly active and is now no longer maintained its likely a bad idea to try and land on it. The FAA can even get you under their catch all 91.13 Careless or reckless operation.

There are procedures for closing a runway and marking it as such (you can find the AC here). Some times the "x" used to mark the closure is a physical structure that can make it dangerous to land on the runway. In other cases the runway may no longer be suitable for use or there may be active construction going on. While the runway may appear to be ok on the surface that does not mean it is safe to land.


Why is London City getting a virtual tower?

London City is severely space-constrained, being on an island in the Thames. Moving the tower means more space for functions that cannot be moved.

  ... will also include an extended terminal building, enabling it to serve two million more passengers a year by 2025.

A high tower means substantial foundations, so you can't just stick the tower on top of another building. You have to build around it.


What is the optimum separation between contra-rotating propellers?

Here is a paper that partially addresses your question; however, they discuss a ducted-propeller system.

  The effect of axial gaps showed that at the design speed combination best performance was observed at an axial gap of 50% of the 1st [fan's] chord.

A lot of research on contra-rotating props has been done for ships, it seems. This thesis indicates that, for ships,

  the effects of the spacing between the propellers is almost negligible with respect to the CRP efficiency.

This paper has an extensive review of rotor spacing for helicopters (it's also a good read for answering your second question). The author notes for one configuration that

  the effect of separation distance on the optimal performance of the system is not very noticeable for practical operation,

but for another that

  the separation distance significantly reduced the influence of the mutually induced velocities.

What all this tells me is that the optimum separation distance is likely highly dependent on the specifics of the propeller design and the aircraft's overall design. Various airflows from the aircraft structures (fuselage, wings, etc.) would affect the interference between propellors. The propellors' rotation speed, size, number of blades, and chord would all come into play. Furthermore, "optimum" could be a balance of any number of things, but most likely efficiency, thrust, and noise. Any commercial or military design would need to undergo extensive trade studies and CFD and wind-tunnel testing for the specific model, not rely on a general rule.


What is special about the ICAO Caribbean region for VFR climb/descent?

It looks like by default, night VFR isn't allowed in oceanic airspace. The 8-8-5 text you quoted appears to be an exception that does allow night VFR in certain specific Control Areas (CTAs) that are in US airspace.

This is from the US AIP 7.1:

  1. IFR/VFR Operations
  1.1 Flights in oceanic airspace must be conducted under Instrument Flight Rule (IFR) procedures when operating:
  1.1.1 Between sunset and sunrise.
  1.1.2 At or above Flight Level (FL) 055 when operating within the New York, Oakland, and Anchorage Oceanic Flight Information Regions
  (FIRs).
  1.1.3 Above FL180 when operating within the Miami and Houston FIRs and in the San Juan Control Area. Flights between the east coast of
  the U.S., and Bermuda or Caribbean terminals, and traversing the New
  York FIR at or above 5,500 feel MSL should be especially aware of this
  requirement.

1.1.1 essentially says "no night VFR"; 1.1.2 and 1.1.3 say "except in US airspace".

As to why, many countries don't allow night VFR at all and I suspect that it's generally not allowed in oceanic regions to simplify international operations and/or comply with ICAO requirements. Trying to remember which countries allow night VFR as you fly along an international route is probably impractical, especially in the Caribbean. But, since the US does allow night VFR, a VFR climb/descent is possible if the specific airspace in question is US airspace.

(I couldn't find any source on why these rules exist so this is all just my own explanation based on what I could piece together. Someone else may come up with something better.)


Why do aircraft on a junk yard have blind windows (e.g. German "Landshut")?

taken from Business jet news

  For outside storage, cover windows and recognition/strobe lights with barrier material and pay attention to atmospheric conditions, as humidity will accelerate corrosion. Make sure all control locks or control column gust locks are installed to prevent movement of flight control surfaces.
  (emphasis mine)

One reason to protect the inside fabrics, plastics etc from the effects of discolouration from sunlight, as well as inhibit biological growth. Also without the coverings the temperature inside the aircraft will be significantly higher on sunny days see Desert Usa

  [without protection] the interior could quickly heat up to 200 degrees Fahrenheit during hot summer days


Does a "take-off" assist make sense for electric aircraft?

Yes it would, for fuel based aircraft and for electrical ones. The higher the MTOW, the larger the benefit.
This article makes a case for installing catapults on runways for commercial aircraft: the engines are dimensioned for the take-off, and an assisted takeoff means lighter engines with the associated fuel burn savings. Take-off is particularly demanding on the power installation because it needs to acquire a lifting velocity from standstill.
Other power-hungry flight stages:

TOGA for go-arounds is applied when the aircraft is at approach speed. The more the better of course - but why should GA power be max TO power for the highest payload ever, on the hottest day ever, on the shortest runway ever. This is what the engines are dimensioned for. From the wikipedia article:

..the engines then increase to their computed take off power. Modern aircraft flight management computers will determine the power needed by the engines to take off, based on a number of factors such as runway length, wind speed, temperature, and most importantly the weight of the aircraft.

Climb power is set after TO: a lower thrust/power setting is selected after the TO. When reaching cruise altitude the thrust/power setting is reduced further. So the engines would be dimensioned for the climb stage.

Aeroplanes certified under 14CFR part 25 must be able to climb after a single engine failure after $V_1$: twin engined aircraft will be dimensioned for this case, if the launching device accelerates the aircraft to a high velocity such as $V_4$ there will still be an engine size saving.
A steam catapult will do the trick, or any of the options that OP states. Of course, the take-off run should not be the couple of metres that an aircraft carrier allows, but should be longer to limit the accelerations that the structure is subjected to.


What were the procedures to follow in US Airways Flight 1549 during descent?

17 seconds after bird impact, they used the "QRH Engine Dual Failure checklist" as per the NTSB report at:

https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf

  Even though the engines did not experience a total loss of thrust, the
  Engine Dual Failure checklist was the most applicable checklist contained in the US Airways QRH, which was developed in accordance with the Airbus QRH, to address the accident event because it was the only checklist that contained guidance to follow if an engine restart was not possible and if a forced landing or ditching was anticipated (starting from 3,000 feet). However, according to postaccident interviews and CVR data, the flight crew did not complete the Engine Dual Failure checklist, which had 3 parts and was 3 pages long. Although the flight crewmembers were able to complete most of part 1 of the checklist, they were not able to start parts 2 and 3 of the checklist because of the airplane’s low altitude and the limited time available.

The "procedure" that the captain followed was the mantra taught to student pilots very early in their training: aviate, navigate, communicate. The ultimate priority in all flight circumstances is to first fly the aircraft. By realizing that 1) continued flight was impossible, 2) attempting to restart the engines was futile, and 3) deviating to the softest and least congested improvised landing site was necessary, in fact in these circumstances the best possible option, the captain saved his own life and the lives of his crew and passengers.

The captain was almost a 20,000 hour pilot at the time of that accident and the first officer had accumulated over 15,000 hours of pilot time. This cannot be understated. This was an extremely experienced flight crew.

In many years of dealing with imminently life-or-death circumstances, I have seen two categories of people: those who act and those who freeze. Obviously, the crew in this situation was composed of people in the former category. That is the category in which I place myself, but thus far almost all of the life-or-death circumstances I have faced have been ones I have trained heavily to mitigate. My actions have been almost reflexive based upon that training, but in my craft I am also well over the 10,000 hour mark.

The ultimate answer to your underlying question of how did this flight end successfully is the right kind of experience of the flight crew, and this cannot be summarized in a checklist or procedure. They knew how to fly. They intimately knew the systems of their aircraft. Most importantly, they worked together as a team to accomplish the mission even though that mission had changed significantly since the time when they were cleared for takeoff.


Controlling jet engine thrust on airliners

Are there any attempts to allow faster thrust response than this? Are any in current or planned use?

First, for turbine engines, the more often used term is thrust lever or power lever rather than throttle. You can Google "throttle vs thrust lever" for that discussion.

I'll use the 727 and the 747 to illustrate what was done prior to when I retired in 1999.

In initial 727-100 sim training, the instructor had us bring the power levers all the way back and allow the descent to stabilize in landing configuration at full flaps. Then, at a given altitude the instructor would tell us to start climbing, at which time we would advance the thrust levers to max power and clean up. From that moment, we would lose hundreds of feet before the aircraft started to climb. The primary reason for the delay was that the engines took 7 seconds to go from flight idle to full power.

In initial 747-100 sim training, we did the same thing. The result was a loss of less than 100 feet, the difference being that engine response was almost immediate, and we also could pitch up immediately without noticeable loss of airspeed.

As I remember being told, the big difference in engine response was because the idle position still had a relatively spooled up engine.

The engines running at that relatively high power output even at idle had the drawback that while taxiing the aircraft would accelerate to a higher than permitted taxi speed, which then required braking.


Can you obtain a pilot license with impaired vision / being blind in one eye?

It's possible to get a special issuance medical certificate in this case:

  An applicant will be considered monocular when there is only one eye
  or when the best corrected distant visual acuity in the poorer eye is
  no better than 20/200. An individual with one eye, or effective visual
  acuity equivalent to monocular, may be considered for medical
  certification, any class, through the special issuance section of part
  67 (14 CFR 67.401).


Does a prone position for the pilot minimize g-force effects?

It is true that the body can withstand higher g-forces in the prone position. The reason is that in the prone position, g-forces don't pull blood down to the lower body and away from the brain, as happens in the seated position.

The concept was explored for combat aircraft with the Italian Savoia-Marchetti SM.93 and the British Gloster Meteor F8. These aircraft revealed some practical issues with the prone position:

It is much less comfortable for the pilot than a seated position, especially during long flights.
It is much more difficult to design an ejection/escape system. The Meteor F8 required the pilot to jettison the rudder pedals and crawl backwards to an escape hatch.
It affords much less visibility to the pilot.

In light of these issues, it was found more practical to stick with seated pilots. In modern times, g-suits and advanced training techniques like the "hook" maneuver have allowed fighter pilots to withstand higher g-forces than in the past. Both involve reducing blood pooling in the lower body by squeezing or flexing leg and abdomen muscles to restrict unwanted blood flow and pooling.


Why do police helicopters always fly in circles?

Police helicopters don't always fly in circles. I've often seen my local police helicopter hovering. There are a few reasons you might have seen police helicopters flying in circles:-

Not all types of helicopter can hover out of ground effect. It might be that the police helicopters in your area can't hover at the heights they work at, with the weight of their usual equipment.
Helicopters are safer if they're moving forwards than hovering. In the event of an engine failure, they can autorotate to land safely, but they need to have some airspeed to be able to do this. The required airspeed depends on height (see the chart in the linked question), so if your news helicopters are usually operated higher up than police helicopters, they may be able to hover safely. (This is quite likely, as police aircraft are exempt from the 500 ft rule and the 1000 ft rule, while news helicopters are not.)
Police helicopters often circle to search an area for a fugitive or casualty using thermal imaging cameras. News helicopters tend to either follow a vehicle or hover to get a steady camera shot of a news event.


When aircraft is flying, there will be air flowing outside of static port.

No, that is not true if the aircraft flies without sideslip and at constant altitude (which it should do most of the time). Instead, there will be a pressure equilibrium between the air in the lines leading to the static port and the static pressure outside. The position of static ports is carefully chosen so the airflow around them is neither accelerated (which would lower local static pressure) nor retarded (which would increase local static pressure). Also, static ports are on both sides of the fuselage so the ram effect of the windward static port in a sideslip is equalised by the suction on the leeward static port. Note that in this case there is indeed some air flowing from the windward to the leeward side through the static line connecting both.

Now to the Bernoulli effect. It says in essence that the sum of static and dynamic pressure is constant (if we disregard the height term, which is not needed in this context). Since you want to measure the same pressure that a stationary observer would measure, you need to pick a place along the airframe where the dynamic part of the pressure is zero because all flow is tangential to the port opening. Small errors can be corrected by calibrating measurements in flight test.


How is the mass flow between 2 streamlines derived?

Short answer: Because that's how we've defined $c_1$ and $c_2$.

Long answer: Read 2.14 carefully. As you've said, we have $f(x,y)=c$ via integration. Anderson then chooses $\bar{\psi}$ as $f$ (a convention) to get $\bar{\psi}=c_1$ and $\bar{\psi}=c_2$ for the two streamlines. However, we know that $c_1$ and $c_2$ are just arbitrary constants of integration that we can set to whatever we want. Anderson just happens to know that later down the road it will be helpful to

  define the numerical value of $\bar{\psi}$ such that the difference $\Delta\bar{\psi}$ [between the two streamlines] is equal to the mass flow between the two streamlines.

Furthermore,

  $\Delta\bar{\psi}$ equaling mass flow (per unit depth) between streamlines is natural. For a steady flow, the mass flow inside a given streamtube is constant along the tube; the mass flow across any cross section of the tube is the same. Since $\Delta\bar{\psi}$ is equal to this mass flow, then $\Delta\bar{\psi}$ itself is constant for a given streamtube.


Can a contra-rotating helicopter simply tilt its entire rotor set instead of using a cyclic?

Juan de la Cierva, inventor of the autogyro, on the C.30 went to a tilting rotor. Most autogyros tilt the entire rotor for cyclic control. Some autogyros apply engine torque to the main rotor to assist in achieving short takeoffs. Now for this brief time, the autogyro is functioning like a helicopter, and the main rotor is driven by the engine prior to takeoff. There is now a torque from the engine acting on the airframe, that requires more pilot hand force to control the rotor while the engine is driving the rotor. Counter-rotating rotors on a helicopter would neutralize the reaction torque into the airframe. So yes for a very small helicopter, it should be possible to tilt the main rotor for cyclic control, without hydraulic power assist. If one is going to use a swashplate for collective control, it is easier to just control cyclic conventionally.
Here is one example of a helicopter that tilted the rotor for the cyclic:
http://www.aviastar.org/helicopters_eng/bensen_zipster.php


Which one needs longer runway of an airplane between take off and landing for a constant weight?

Generally, aircraft require longer distance for taking off than landing roll.

The standard definition for take-off phase is from the start of acceleration (stopped aircraft) to the point where aircraft reaches 35 ft above ground. Similarly, the landing phase is from 35 ft to the final stop. What you mentioned is a sub-phase, which is called "ground roll".

When the aircraft is accelerating for the take-off, the engins' thrust must overcome the aerodynamic drag and the ground friction, and the resultant will contribute to the acceleration. But when the aircraft is landing the reversed thrust in addition to an increased aerodynamic drag (due to spoilers and increased flap deflection) and increases ground friction (due to application of brakes) are decelerating the aircraft. This is physical reason.

While there are some engineering methods (such as equations or charts, usually presented in aircraft design books i.e. Roskam or in aircraft performance books), the most accurate method is to writing the force balance acting on the aircraft and computing the acceleration at any time step, and solving the position differential equation for the distance. But this method requires details about aerodynamic and thrust characteristics. This method somewhere was called time marching.


What is the role of an intermediate fix?

The Pilot/Controller Glossary can shed some light on your question.

The GPS approach is the clearest example of an Intermediate Approach Fix.

  IF/IAWP− Intermediate Fix/Initial Approach Way- point. The waypoint
  where the final approach course of a T approach meets the crossbar of
  the T. When designated (in conjunction with a TAA) this waypoint will
  be used as an IAWP when approaching the airport from certain
  directions, and as an IFWP when beginning the approach from another
  IAWP.

  INTERMEDIATE APPROACH SEGMENT [ICAO]− That segment of an instrument
  approach procedure between either the intermediate approach fix and
  the final approach fix or point, or between the end of a reversal,
  race track or dead reckoning track procedure and the final approach
  fix or point, as appropriate.

The Instrument Flying Handbook warns that, “Randomly joining an approach at an intermediate fix does not ensure terrain clearance."

On other approaches, there may not be an intermediate fix, but the segment is defined as follows:

  INTERMEDIATE FIX− The fix that identifies the beginning of the
  intermediate approach segment of an instrument approach procedure. The
  fix is not normally identified on the instrument approach chart as an
  intermediate fix (IF).

  INITIAL APPROACH SEGMENT [ICAO]− That segment of an instrument
  approach procedure between the initial approach fix and the
  intermediate approach fix or, where applicable, the final approach fix
  or point.

The Instrument Flying Handbook also talks about intermediate fixes where there is sometimes a charted Intermediate Fix:

Teardrop Procedure

  When a teardrop procedure turn is depicted and a course reversal is
  required, unless otherwise authorized by ATC, this type of procedure
  must be executed. [Figure 1-15] The teardrop procedure consists of
  departure from an IAF on the published outbound course followed by a
  turn toward and intercepting the inbound course at or prior to the
  intermediate fix or point. Its purpose is to permit an aircraft to
  reverse direction and lose considerable altitude within reasonably
  limited airspace. Where no fix is available to mark the beginning of
  the intermediate segment, it shall be assumed to commence at a point
  10 NM prior to the FAF. When the facility is located on the airport,
  an aircraft is considered to be on final approach upon completion of
  the penetration turn. However, the final approach segment begins on
  the final approach course 10 NM from the facility.

Holding in Lieu of Procedure Turn

  A holding pattern in lieu of a procedure turn may be specified for
  course reversal in some procedures.  In such cases, the holding
  pattern is established over an intermediate fix (IF) or a FAF.


Would a flight consisting of solely first-class passengers be cancelled due to center-of-gravity issues?

It is much more difficult to load a plane so that the center of gravity ends up being too far forward than too far aft.
Excessive weight forward can almost always be counteracted by increased trim on the stabilizer.

When small GA planes crash due to Balance, its almost always too much rear-weight, not too much forward-weight.

Especially in the case you describe, the pax probably have luggage, and the luggage can be loaded in the rear of the plane for balance.


How should the maximum output force of the actuator be chosen?

If the largest hinge moment is known for the entire flight envelope, including that required for continued safe flight and landing after failure(s), then the actuator can be readily sized. Of course, some engineering judgement is needed to compromise between:

Buffering for additional unforeseen loading (i.e. factor of safety) for later stages of the design and flight test, during which swapping the actuators can be costly, and
Sizing down the actuators to save weight and costs.

Therefore, the more scenarios you have considered for obtaining this maximum hinge moment and the more confidence you have in your model, the better off you are. For example, for elevator, consider the following (but not limited to):

Achieve -1g to 2.5g at Vmo/Mmo with 3 sec out-of-trim in the opposite direction (14 CFR 25.255(a) and (c))
Achieve 1.5g at Vdf/Mdf with 3 sec out-of-trim in the opposite direction (14 CFR 25.255(a) and (f))
Takeoff rotation with dual hydraulic failure
Achieve 0.8g and 1.3g at Vmo/Mmo with dual hydraulic failure (or single elevator surface jam)


What's the point of intercepting an aircraft?

Military interception usually happens after failure to make the aircraft comply by other means (such as radio, light signals, flares). So, first and foremost it is one way to do visual communications, which is usually hard for the pilot to miss. The messages for follow (wide level turn), land (low pass, landing gear extended), and continue on course (climbing turn) are well established (possibly even internationally?) and all pilots should know them, and are probably enough to defuse most situations. Not to mention that you should try to establish radio communications on 121.5 if you're being intercepted.

I'd wager a guess that the most common cause for interception is that a pilot has strayed into restricted airspace without talking to anyone on the radio, without any malicious intent.

If the pilot ignores the messages, there's always the option of using force, if the risk to occupants and collateral on the ground is acceptable.


Which type of jet leaves black trail at cruising altitude?

That could easily be a military jet, or it could be an older type passenger jet. The old jet engines had inefficient fuel injectors and simply used a lot of them, creating a higher fuel-to-air ratio which results in black smoke from carbonised fuel. There is only a short time to mix the fuel with the air under pressure in the combustion chamber, and modern day engines pre-mix the fuel with air before injecting.

Olden days jet engines also used water injection in times of high demanded thrust, creating more black smoke due to a cooler combustion chamber, but since the aircraft you saw was in cruise it would not be in a water injection flight phase.

So any older type of jet engine could have caused the black smoke you saw. Could have been an old DC-9 or even a B-52 :)


Why is there a difference between military parachutes and those used for skydiving?

From what I learned, different types of parachutes don't make them 'old' or 'new'. They are used for different purposes.

For example the dome shape parachute is usually used for static line jump where no maneuverability is really required. They drop vertically relatively to the plane path when air friction is negligible.

The other kinds are usually used for special forces because they always do jumps like HAHO (High Altitude [Jump] High [Altitude] Open) when the location they jump is outside their country's territory, and infiltrate by air so the plane is out of the radar/SA missile range. They have to have the ability to glide on a long distance.

Another case is they have to have the ability to change the trajectory or precisely land in the drop zone. So maneuverability is a must.

Size differs for different manufacturer and different specs. Even though the dome type parachute is relatively larger, the chance of getting hit is similar with other types as you don't have much speed and you can't do crazy high G turns. You really can't avoid any attack towards you unless you have superhuman reactions and the sixth sense.

To conclude, different types of parachutes are used for different purposes in different scenarios.


How does gross weight affect the Minimum Controllable Airspeed (Vmc)?

I think your objection to #2 is exactly correct, and your #1 is where the misunderstanding may lie.

The point of VMCA is essentially to maintain a constant heading, and when you have no more rudder authority to make that happen, you're there -- and any slower, with slightly less rudder authority, your heading starts to change in the direction of the dead engine.  With no bank, it's all rudder; the lift from the wings doesn't tend to move the nose in any direction.  With bank, there is now a component of the lift from the wings that does tend to affect heading (which is the dynamic of banking when you turn -- the heading change comes from the lift created by the wings, not from the lift generated by the rudder).

If you are banking into the good engine, that component of lift tends to change your heading toward the good engine and away from the failed engine.  Since the asymmetric thrust is working to change your heading toward the failed engine while you hold rudder to oppose that change, you now have the component of lift from the wings that is assisting your rudder.

If you consider a case of symmetric thrust, you can hold a heading with right wing down and left rudder or vice versa; the lift from the wings is working to change your heading to the right, and your rudder is counteracting that drift. At some point, with enough bank, you run out of rudder authority & the airplane will turn, although pretty badly uncoordinated.  With an engine out, you CAN fly straight ahead holding bank into the dead engine, you just need a lot of rudder authority (i.e. lots of speed above VMCA) to hold your heading -- the rudder is fighting both the asymmetric thrust and the component of the wings' lift. And doing that, you'll run out of rudder authority a lot sooner (i.e. at a higher airspeed).  If you switch to bank into the good engine, the component of lift from the wings is now working with you, and that's the usual case for computing and demonstrating VMCA.

I suspect that the confusion on your point #1 comes by conflating horizontal (earth reference) with horizontal (aircraft reference). Hopefully the explanation above separates things out?

And, to bring things back to gross weight, the higher the weight, the greater the lift from the wings, so a Sin(5 degrees) (I think that's right -- LONG time since I took Trig!) component of "more lift" is a greater force to resist heading change than that same component of "less lift" with a lighter aircraft.  The other forces involved in the balance, the asymmetric thrust and the rudder force, are independent of aircraft weight.

Best wishes for your MEL checkride!


What does it take to maintain a private pilot certificate?

A license, once granted, is good forever (barring some enforcement action).

But, you need more than just a license to fly.  To use your license, while flying solo, you also need a Medical Certificate (if required for the aircraft or flight rules) and a Current BFR (Biennial Flight Review).

Medical Certificates are good for 5 years until you're 40, then good for 2 years.
Its a quick trip to an FAA approved doctor to examine you for any obvious medical conditions.

A BFR is a review with an instructor every two years to make sure you're still proficient and safe.  If all goes well, it takes about 90 minutes.

However, if you want to fly passengers, you also need 3 landings within the previous 90 days.

If you want to fly passengers at night, you need 3 landings to a full stop, at night, within the previous 90 days.

If your 90-day landings have lapsed, you can quickly fix it with 3 trips around the pattern, taking off and landing each time (touch-n-go during the day, or full-stop at night).  Then taxi back to the ramp, pick up your passengers, and go on your way.


Why is the tail group of virtually every airplane swept instead of straight?

There is more to it than just looks.

One immediate benefit is a more backward location of the center of pressure on the backwards swept surface. But that effect is small and has to be bought with a lower lift curve slope, i.e. lower effectivity at low angles of attack rsp. sideslip.

But once sweep is big enough, it will extend the useable range of sideslip angles at which the tail is effective. Sweep reduces the lift curve slope but extends its linear range to higher angles, so the maximum lift per area of a swept surface is about as high as that of an unswept surface. This is especially true for low aspect ratio wings where the outward movement of the boundary layer is not a big factor. Therefore, the aerodynamics of a vertical tail suffer much less from the usual sweep effects we know from swept wings.

Adding a fillet ahead of the root of the vertical tail increases this effect further and has been instrumental in making designs like the Boeing 307 spin proof. Before that change the Boeing 307 prototype suffered separated flow on the vertical in a spin and crashed when the aircraft oversped in an attempt by the pilot to end the spin by applying differential thrust.

While the wing operates in a narrow range of angle of attacks and straightens the airflow for the tail, so the horizontal tail is able to work within an even narrower range, the fuselage creates an unstable yawing moment over a much larger range of angles of sideslip. In order to have enough directional stability even at high angles of sideslip, a swept vertical tail is very helpful. Yes, this swept tail needs to be larger than an equivalent vertical tail which is designed for single-digit angles of sideslip, but this straight tail will render the aircraft unstable once it ventures into higher sideslip angles.

Reference: NLR Report A-1582. Sorry, I found no online source. It is discussed in Ed Obert's "Aerodynamic design of Transport Aircraft" on page 418.

Horizontal tails do not need the extended working range - here, it is enough to add stabilizer trim in order to adjust tail lift for different wing flap settings. Besides, building a horizontal tail with a swept hinge line is much more complicated than building a straight hinge line, so most horizontal surfaces have just a little sweep such that taper and sweep together result in a straight hinge line.

But there is one exception: In the early 70s many glider designs used a full-flying, swept horizontal tail, like this Standard Cirrus below (picture source):

This is obviously not for compressibility. By sweeping the tail its center of gravity can be moved close to its center of pressure, so this tail needs no mass balance and has low actuation forces. The downside is the rigid, symmetrical airfoil: At low speed and higher angle of attack it has very little effectivity because the flow stays separated while a conventional tail with a fixed stabilizer will already show attached flow. This led to a number of fatal crashes in winch launches when the aircraft would pitch up into a stall and could not be controlled.


Can foreign pilots get an FAA ATPL and work for a US-based commercial airline?

At the most basic level, the DHS/Dept.Of State regulations regarding work authorization have to be followed. There are essentially three categories you can be in, as far as employment is concerned:

A naturalized or natural-born U.S. Citizen. You're allowed to work for any U.S. employer.
An (in-status) permanent resident (green card holder). You're allowed to work for any U.S. employer.
A non-resident. You're allowed to work only with DHS authorization.

The first two are somewhat self-explanatory. Some positions may have special requirements - for example, you can't be a U.S. President without being natural-born. Some employers place limits on non-citizen employment due to various U.S. laws usually related to access to information of military nature or applicable to military needs. Thus, a lot of aerospace manufacturing is off-limits to non-U.S. citizens, simply because the company might also handle aerospace jobs and doesn't wish to sufficiently compartmentalize access. For example, most if not all SpaceX jobs are for U.S. citizens only. No such limitations apply to normal commercial transport pilots.

Permanent Resident Workers

Unless you're already a permanent resident, you may wonder how to become one. In most cases, someone else - a family member or an employer - must petition on your behalf, you can't apply yourself. There are also strict yearly numerical limits for most permanent resident visa categories. Citizen or permanent resident family members 21 years of age and older can apply for you, but unless you're petitioned for by a spouse, the waiting times are measured in years.

We can review the directory of Visa categories, immigrant, with an eye for transport crew employment. I will elaborate only on the categories that apply to a pilot who isn't eligible for another category (say you're not an Iraqi who has worked for U.S. Govt, etc.).

DV category - Diversity Visa - if you seriously think of working in the U.S., you should be applying every year. It's a lottery. Make sure you apply at the official .gov website; the entry is free.
E Category - Employer-Sponsored. The first and most obvious requirement is that the potential employer must be willing to spend the money (on the order of $10k) to petition on your behalf. If they can find employees already authorized to work, there's very little incentive to petition.

Assuming that your employer is willing to sponsor an E immigrant visa on your behalf, the next step is to obtain a labor certification from the Dept. of Labor. A Pilot would most likely fall under the third preference, assuming that a labor certification can be obtained. And here's the real clincher: given the never-ending supply of commercial transport pilots in the U.S., and a lack of any particular special requirement for the job (we aren't talking about test pilots!), there's a nil chance of the DOL certifying the position. The DOL certification process requires the employer to prove that there is an insufficient supply of qualified workers who are already authorized and qualified for the job. So that is, essentially, where it ends.

Non-Resident Workers

The third category is the most complex one. There are various kinds of work authorization available, under various programs. All of them have special requirements, thus a non-resident is by default ineligible for any work authorization, unless he/she fulfills the requirements. For example, students on F-1 status are authorized to perform on-campus work, and for certain off-campus jobs iff they amount to practical training.

The non-immigrant category (usually Letter-Number, with an optional Letter suffix, e.g. F-1) is indicated on the Visa, but remember that the Visa is merely a document that is necessary (but not sufficient) to enter the U.S. After you're in the U.S., you or your employer can adjust your immigration status, as long as you fulfill the requirements to do so.

Thus, we can review the directory of Visa categories, non-immigrant, with an eye for transport crew employment. I will elaborate only on the categories that apply to a pilot who isn't eligible for another category (say you don't work for NATO or UN, you're not a NAFTA signatory citizen, etc.).

D category - allows you to work as a pilot, but you must be employed by an international airline, and you can't stay over 29 days. Your employment must be bona-fide; it can't be a sham set up just so that you can mostly work as a domestic pilot.

And that is, unfortunately, "it". You may be eligible for work if you're a citizen of one of the countries that U.S. has special agreements with, usually based on humanitarian and similar reasons, but those are few.

As you can see, FAA regulations don't even enter anywhere in the picture yet. The DHS regulations are a primary concern here.


Will flying cars fall under aviation regulations?

Flying cars will need to be regulated by both the FAA and the DOT as per current laws here in the US. For what its worth flying cars are really more like road capable airplanes. When the car is airborne it will be subject to the regulations set fourth by the FAA for the airspaces it passes through and maneuvers it makes. When the car is on the road it will be subject to vehicular laws that any other car would see. That being said there is room for change here and who knows what rules may be passed in the future. There is also some grey area around things like landing in a parking lot, folding up your wings and driving away as well as the reverse case.

The rules that currently govern aviation are more than capable of handling flying cars, even if they start taking off from peoples driveways. The larger issue is licensing the pilots. A drivers license is pretty easy to come by here in the states while a PPL or sport pilots license takes quite a bit of time. Everyone that currently would want a flying car would need both a drivers license and a pilots license of some form.

As far as I know the FAA makes the rules for any and all altitudes. While some airspaces (class G) may be unregulated they are still considered from the ground up. There is no minimum altitude at which FAA regulations don't apply and its far from a free for all in the skys the way it is on the roads in a manner of speaking.

Flying cars could potentially cause an increase in air traffic however the advantage of a plane (over driving) is generally speed. Until someone can build a car that can do 80MPH consistently on the road and a formidable 130Kts (and thats the slow end of planes) through the air the use case is pretty small.

One of the biggest preventers in the whole flying car situation is the engine its self. Car engines fit quite a different role than aircraft engines. The similarities end basically at the fact they are both piston engines. Some car engines have been put in planes (Mooney/Porsche PFM 3200) and in the end they are generally not great planes. You can find a full discussion on this here. You also need to keep in mind that anyone who will be fixing these vehicles will need to be an A&P licensed mechanic.

There are a few companies with some cool animations of future products and even a few test rigs that have been built but to date the engineering is just not really there. Chances are it will be some time before flying cars are even on the road let alone creating major air traffic issues. For the 279,000 a Terrafugia will cost you, you could buy a Used Piper Arrow (in great shape) and a Porsche and still have 79,000 left over for a hanger to keep them in...


The technical report NACA-TR-824 has been digitized.  The digitized version includes Cl and Cd for 118 airfoils at 3 Reynolds numbers.  To get it, create an account on x-plane.org.  (It's been online sporadically elsewhere over the decades, e.g. here.  People associated with the digitizing include Gregory Peter, Gregory Siemens, and James Sonnenmeier.)

Convert plots to tables of numbers with Data Thief or WebPlotDigitizer.

At lower Reynolds numbers, http://airfoiltools.com/polar/index lists XFOIL-calculated polars for many of those airfoils, as text as well as plots, e.g. http://airfoiltools.com/polar/details?polar=xf-n0009sm-il-500000:

alpha    CL        CD       CDp       CM     Top_Xtr  Bot_Xtr

-13.500  -0.9606   0.06449   0.06155  -0.0264   1.0000   0.0073
-13.250  -0.9745   0.05737   0.05426  -0.0319   1.0000   0.0074
-13.000  -1.0011   0.04929   0.04597  -0.0377   1.0000   0.0072
-12.750  -1.0177   0.04406   0.04052  -0.0404   1.0000   0.0073
...

You may need some clever webscraping script to collect them all in a NN-friendly format.  Or you could run XFOIL yourself:  they describe exactly how they generated these tables.


Lift isn't at 25% of chord, the aerodynamic center is. Lift acts at the center of pressure, which depends on the wing's camber and angle of attack.

Broadly speaking, you can split lift into two constituents, one from camber and one from angle of attack. Deploying the flaps on the Dash-7 changes both camber and wing chord, and of course shifts the center of pressure back.

Changing the angle of attack will add a pressure change over chord which has its center at the quarter chord. The reason has to do with the strong local curvature near the leading edge which causes strong suction peaks. For a more mathematical explanation see the work of Birnbaum. Or read this answer.


Can a F-4 Phantom II pilot control weapons?

Can the pilot in the front seat control the weaponry as well, or do they only fly the aircraft?

Yes, the pilot in the front could control all weapons.

  And can the weapons officer in the back fly in emergencies, like, pilot is unconscious or something?

This is more complicated. The USAF F-4's did not have controls for the RIO's (now called WSO's), but the Navy/Marine F-4's did.


Imagine a wing that is infinitely long, and stretches from east to west. It is moving north at 400 mph. Obiously, it does not produce a shockwave, as it is moving subsonically.
Now, imagine a copy of this wing  that is moving to the east at 800 mph (along its length) while still moving north at 400 mph. Other than skin effects, this wing is aerodynamically identical to the first, so it does not have shockwaves, yet it is very supersonic.
Of course, a real swept wing is not infintely long, and so there are shockwaves at nose and tip of the wing, but mid span it really does behave similarly to a wing moving much more slowly perpendicular to its leading edge.


What are the types of NOTAMs and how do USA NOTAMs differ from the ICAO definitions?

There are significant differences between US domestic NOTAMs and international NOTAMs, please note that US NOTAM Office issues NOTAMs in both formats (NOTAMs susceptible to affect international flights being issued in international format). Canada is also issuing domestic NOTAMs in the same format than US.

encoding is different, US domestic encoding is described in FAA order 7930.2R (https://www.faa.gov/documentLibrary/media/Order/7930.2R_basic_dtd_1_5_17_(2).pdf), international NOTAM encoding is defined by ICAO doc 84000
Domestic NOTAMs are mainly split between D NOTAMs (about airports and navigation facilities) and FDC NOTAMs (about airspace, procedures or regulations), there are also military NOTAMs with more subtypes.
there is to my knowledge no document describing in detail all differences between both encodings, although the FAA order 7930.2R is quite detailed and provide information on both types and some list of differences.
other documents are useful, for example https://www.faa.gov/documentLibrary/media/Advisory_Circular/150-5200-28F.pdf that provides guidance on using the NOTAM system for reporting airport facilities changes or outages and for
utilizing the Runway Condition Assessment Matrix for airport condition reporting

There are many differences between both formats, for example:

domestic NOTAMs are easily recognized as they start with an exclamation point !
the international NOTAM encoding is more structured. For example, a Q field will summarize essential NOTAM information, including affected FIR, vertical boundaries, geographic coordinates. In US NOTAM, geographic coordinates is described in the text of the NOTAM and then less easily decoded automatically.
the Q code also store the type of affected facility and the state of the facility. US encoding for facility types is different.
domestic NOTAMs are using standardized phrases defined in FAA document but not recognized by ICAO standard, the FAA order 7930.2R list them.


Gyroplanes have quite a few applications, but the problem is that anything they can do, others (helicopters/fixed wing aircraft) can do better.

The main advantage of a rotorcraft is that they can hover at a location; the gyroplanes are unable to do this, which is kind of a deal breaker.
The main advantage of the gyroplane is that they cost less and are easier to maintain, compared to other type of aircraft. However, most of the autogyros available in market are small ones and as the size scales up, this may vanish.
The gyroplanes are used mainly for low speed surveillance operations due to their low stall speed. Of course, helicopters can be used to do this, albeit at a higher cost
So basically, the autogyro can do most of the things the helicopters/small GA aircraft can do at a lower cost. This low operational cost may be its main advantage.

I'm not aware of anything the autogyro can do which the others cannot do though.


Are there any negative health indications from getting sea legs?

Key point --

  The sensation only occurred once on the ground and after completion of
  the XC.

  until I went to sleep (~11pm)

If you have no further symptoms or at least no more severe symptoms, then I see no reason to be too concerned about this, and certainly no reason to bring it up with an AME.  (But see added comment below re long-term career plans.)  Interestingly, after hours spent feeling certain repetitive sensations, whether due to to thermalling flight in a hang glider or sailplane, or bobbing up in down in a kayak, I have sometimes noticed a sense of the motion continuing later, but ONLY while laying down prior to falling asleep in the evening. These sensations may have been more related to the repetitive forces felt by the skeletal-musculature system (increased G-load, rhythmic variation in G-load), than to the vestibular-occular system, so perhaps they were fundamentally different from what you are describing.

Comment incorporated into answer--

  this is a medical condition called mal de debarquement syndrome or
  MdDS. Do a search on line, you will find literature on it. I developed
  a severe case after flying from Denmark to Los Angeles in a DC-7C in
  1960 which would flare up anytime I was in an enclosed space, like a
  clothes closet or stairwell. it did not subside until 10 years after
  that flight. – niels nielsen

A google search on that term produced other similar results of symptoms lasting many years-- remarkable.  Some rather interesting ideas may be found about just what is going on here, and how to treat it.  See for example https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5418223/

  We reasoned that if the notion of MdDS caused by maladaptation of the
  VOR holds true, a reversed VOR stimulus should mitigate or even cure
  the MdDS symptoms. Based on these findings, a treatment for MdDS was
  devised that consisted of rolling the head at the frequency of body
  rocking, while the subjects viewed a slowly moving visual surround.
  This postulate was tested in 24 MdDS patients employing cross-axis
  visual coupling (1). The results were promising: 75% of the MdDS
  patients had significant improvement in a 12-month observation, which
  was the first successful treatment of this debilitating illness.

(Front Neurol. 2017; 8: 175.
Published online 2017 May 5. doi: 10.3389/fneur.2017.00175
PMCID: PMC5418223
PMID: 28529496
Treatment of the Mal de Debarquement Syndrome: A 1-Year Follow-up
Mingjia Dai,1 Bernard Cohen,1 Catherine Cho,2,3 Susan Shin,1 and Sergei B. Yakushin1,*)

It would appear that there are enormous gradations in how severe this sort of thing can be.  If you are simply feeling some sensations on the ground, after a flight, and they are gone the next morning, it would seem both un-necessary and unwise to mention them to an AME.

I would say that occasionally-recurring symptoms at the level you've reported might be reason to think twice about a career as a professional pilot-- lest the symptoms get worse-- but still not something that would suddenly and significantly compromise your ability to fly safely on any given instance, and therefore not something that you should feel compelled to report to an AME.

Obviously I am speaking from the viewpoint of what is in your best interest as long as  it does not significantly conflict with safety.  An AME might well give a different opinion.


Why does fuel vaporization in a carburetor cause a temperature decrease rather than a rise?

Good question! There's two parts to the answer.

The first part is the ideal gas law.
The formula of the ideal gas law is $PV = nRT$, where

P = Pressure
V = Volume
n = amount of substance
R = the ideal gas constant, which can be ignored for our purposes
T = Temperature

Since we're ignoring $R$, we're left with $PV = nT$.
Now, say that you send some air through the throat of a venturi. Pressure decreases greatly (that's the point), volume stays close enough that we can leave it alone, the amount of molecules remain unchanged, so to keep the equation in balance, the temperature drops.

The second part is the latent heat of vaporization
In order for a liquid to change state and become a gas, a certain amount of heat is required. Consider a firefighter spraying water on a fire. The liquid water is heated by the fire and evaporates into steam. The energy of the fire is decreased by the amount of energy that went into the steam and which is now floating away into the atmosphere.
Now, replace the fire with your carburetor, and replace the water with fuel. The heat energy in your carburetor is transferred to the fuel in order to cause it to vaporize. The fuel gets hotter (but who cares, it's about to get burned in the cylinders anyway) and the carburetor gets cooler.


What you could do right now is train to be a glider pilot. You probably already have the right age. It is a wonderful experience, and it will be a good basis for a power license.


How will the lack of ground stations affect navigation?

GPS/WAAS will replace all but ILS in the end. Even now, with graphic displays, smart-lookup from databases, and a line to follow presented to the pilot, VOR use is rapidly falling by the wayside, and point to point navigation will become the norm (and that was occurring in 1996 even, I recall getting cleared direct to a waypoint that was off my paper chart and having to ask for a heading to put in the autopilot to fly the plane while I found it on the chart).  In my airplane, my AVIDYNE IFD-540 does all the work, and I have ILS for precision landings and VOR if needed. Nearby VORs are going away.  DME and ADF were pulled out of my plane years ago.


How do large drones communicate with ATC?

They have an onboard VHF radio that can be used to receive and transmit on local frequencies.

For example, on the MQ-1B Predator you will see a small fin on the back of the aircraft behind the GPS dome. That is an omni-directional antenna which can transmit VHF. The Global Hawk has a similar capability.


Do fuel reserves take into account the possibility of a constant headwind?

The fuel "to reach the destination" is computed using winds, head- or tail-wind as appropriate. For "30 minutes of reserve" that is 30 minutes, and it is the same 30 minutes regardless of flying into or with the wind. In 30 minutes of flying with a tailwind you'll fly FARTHER than 30 minutes with a headwind, but 30 minutes is 30 minutes.

-- Edit to answer the question as expanded in a comment:

Wind predictions are actually pretty good now, and "30 minutes" isn't really all that the pilot has to work with.

For FAR Part 91, essentially general aviation (think taking a Cessna on a flight of a few hundred miles as an easy picture), the legal minimum in good weather is 30 minutes.  For FAR Part 121, which governs airline flying, it's 45 minutes (plus other categories as explained in the other answers for things like a destination alternate).  Beyond that, the plan for the flight will almost always include additional fuel above that to account for the routine things that happen to burn more gas: delays waiting to take off, small changes in routing that add a few miles to the planned path, and so on.  That way, even with the routine "stuff" that happens, you don't plan to eat into the 45 minutes reserve.  If the wind forecast is off, then that tends to be another of "those things" that changes the plan.

Realistically, how much are the winds off of the forecasts?  Typically, the forecasts are pretty close.  The computer models that are used now are very detailed, which is possible with all the computing power that's available now as compared to a decade or two ago.  Also, these models are constantly updated by data coming in from aircraft that are airborne.  Various datalinks can transmit the winds and temperature in real time, and ATC will also sometimes ask for current winds at a particular altitude.  All of this combines to give a picture that isn't simply a wind forecast issued in isolation, but a combination of forecast + recent data.

The issue that would arise if an airline were required to plan on the worst-case wind that might be encountered as if it would be present for the entire flight, is that in some cases the flight would significantly under-burn: it would arrive with more fuel than planned.  Why is that an issue?  Maximum Landing Weight.  If your airliner is fully loaded with passengers & cargo, there is a limit to how much fuel it can have on board at landing, driven by the maximum certified landing weight.  On my airplane, that tends to be enough fuel for a bit over two hours of flying.  (Obviously a LOT of factors influence this on each flight -- this is a ballpark number.)  So if I have a full airplane and I want to plan on having as much fuel as possible upon arrival (so that we can hold if necessary, fly the approach, and still have adequate fuel for a missed approach and then a divert, arriving at the alternate with adequate margins), there is a limit to how much I can take off with.  And that limit is driven by how much fuel we're expected to burn enroute.  If my enroute burn is lower than planned and I do NOT have to hold or take a longer route than planned, I can show up too heavy to legally land.

There are two options when that happens: land anyway (safe, but requires an inspection of the aircraft, and it's generally frowned upon to do this without good reason), or fly circles to burn off the gas.  The latter is what is generally done, and is obviously wasteful.  So it's preferred that the enroute burn calculations be as accurate as possible, rather than including unrealistic headwind values.


How many of this aircraft were manufactured?

The aircraft looks like the Convair CV 440 Metropolitan (maybe CV 340) a variant of the CV 240, in operation with the KLM. According to Wikipedia, a total of 1181 of all the variants were built.