Why do pilots normally fly by CAS rather than TAS?

The reason is somewhat deeper than just the indication. Up until Mach-related effects come into play, CAS is what the airplane 'feels' as speed, and consequently, is all the pilot needs to know. The TAS, or even better, ground speed, is needed primarily for navigation, but not for flying per se.

All the most important aerodynamic quantities (lift, drag, moments, etc.) are proportional to dynamic pressure:

$$q = \frac{\rho V^2}{2}$$

where V is TAS. So apart from TAS, they all depend on the ambient air density $\rho$. CAS is, essentially, TAS 'corrected' for the factor $\sqrt {\rho / 2}$, i.e. the effect of density. Instead of two parameters now you need one. But it doesn't mean CAS is calculated from TAS; rather the opposite: it is easier to naturally measure CAS (or q), and hence it is displayed (becoming IAS). To get TAS, you need to measure $\rho$, which is normally done via known pressure altitude (i.e. static pressure) and temperature.

If you climb at a constant CAS, your TAS will increase as the air becomes thinner ($\rho$ falls), but most importantly, the airplane handling qualities remain largely the same. But at some point, you'll hit the Mach limit and will have to obey it. Technically, the transition is governed by Mach itself rather than the altitude.


How is engine management being done without auto throttle during a VNAV approach?

Is the pilot continuously adjusting thrust levers (or power levers in the case of turbo prop) to maintain appropriate angle of attack, as the speed, decent rate and heading is controlled by the auto-pilot...?!!

In 747-100/200 operations at the two 747 carriers I flew for, if you chose to have the autopilot fly a coupled ILS approach and didn't have auto-throttle capability, the autopilot tracked the glideslope by changing the pitch of the aircraft.

Personally, I never did this because I preferred to hand fly all approaches, but I watched others do it when I was the non-flying pilot, and they did indeed continually adjust the thrust levers as necessary to get the desired speed, just as we did when hand flying the approach.

In the 747 classics this wasn't hard. Initially you set the thrust levers to a fuel flow of 5,000 lbs/hr per engine, maybe a little less if very light, maybe a little more if heavy. Often that initial setting would give you the speed you wanted within a few knots and no further adjustment of the thrust levers would be necessary until starting into the flare. If it didn't, you adjusted as necessary, and with experience it took very little jockeying of the thrust levers.


How is the load & trimsheet form sent to ACARS?

When the loadsheet arrives to the aircraft via ACARS it has to be acknowledged and printed. This is accomplished by the flight crew by selecting the proper screen and pressing the respective button or LSK on the MFD (Multi-Function Display for latest Boeing models) or in the MCDU (Multi-Function Control Display Unit for Airbus).

Along with the acknowledgement sent back to the system, goes the timestamp. Legally, this action is considered the wet signature. Then the sent ACARS form is printed in the aircraft printer, so the crew has a backup copy of the loadsheet containing in the header the "ACK" confirmation and the same timestamp sent to the system.

Every airline has different policies regarding the format of the loadsheet and even the procedure to accept and correct the values. that sometimes change in the last minute again, but this can give you a generic idea of the procedure.


Can I use the private pilot written exam for sport pilot?

No.  You will have to take both written and practical exams for sport and private pilot, if you go that route.  I’d recommend that, if you do ultimately want to obtain a PPL, that you not pursue an SPL as part of your training and solely concentrate on obtaining your private only.  You can exercise all the privelages of an SPL with a PPL, and it cuts out the excess costs and time with the SPL testing and checkride prep.


Why does an airplane captain sit in the left seat?

There are several reasons, mostly historical, or theories behind this:

After World War I, most airplanes had rotary engines with left turning tendencies because it followed the torque of the engine. Therefore, turning left was easier than turning right. Because of this, pilots considered left turns as more convenient maneuver, and thus more experienced pilot started sitting on the left.
Since the early days of aviation, the fact that pilot was sitting on the left, they keep the airplane on the right side along the airway. At that time, pilots often navigate visually following roads and railways. Opposite traffic following the same path then pass each other on the left.
Because captain sits on the left, left-hand traffic patterns are more common.
In order to avoid a head-on collision, each airplane must turn right. Since the captain sits on the left, they will have an unrestricted view of the other airplane, and therefore can assess the situation easily.

In modern times, almost all airplanes (other than single-pilot airplanes or where one pilot sits behind the other), both seats have full controls to fly the airplane.

Regulations do not specify which seat should be occupied by the pilot-in-command (PIC) or the Pilot Flying (PF).

Please note that on many helicopters, captains sit on the right side.

Bibliography:

Why a Captain sits on the left side of a plane?
Why Does The Captain Sit On The Left?
Why Captain sits on the Left?


Why might a passenger jet fly at altitudes in a strong headwind when the winds are more favorable at a different altitude?

You assessment is flawed in that it does not take different air density in account.  You state the following conditions:

FL320
80 kt headwind
355 kt groundspeed
1000 nm distance

and you are proposing descending to the following conditions:

FL220
40 kt headwind

At 32,000 ft, standard conditions are around 275 hPa, 225 K and density of 0.43 kg m$^{-3}$.  If your 80 kt wind is a pure headwind, a 355 kt groundspeed translates into a 435 kt TAS. If we correct this TAS for the ambient conditions we get an indicated airspeed of about 255 KIAS.  This is the airspeed that really matters because it is what the airplane experiences as it interacts with the atmosphere.

If we descend to FL220, where standard conditions are 430 hPa, 244 K and 0.61 m$^{-3}$, an airspeed of 255 KIAS yields a TAS of 363 kt TAS.  If we have a headwind of 40 its, this yields a groundspeed of 323 kt.  This is about 30 kt slower than you were flying at FL320.  A flight of 1000 nm will take about 15 minutes longer to complete.

However, it is most likely possible that the airplane you were in is capable of flying faster than 255 KIAS at FL220 and in fact is probably capable of somewhere around 310 KIAS.  Flying at 310 KIAS at FL220 will have true airspeed or 440 KTAS and with the 40 kt headwind a ground speed of 400 kt. This will get you to your destination faster, but at the expense of a much higher fuel burn.

It is also likely that you could have been flying faster at FL320 (not sure what max mach number would have been for you), but also at the expense of burning more fuel.  If the airplane wasn't dispatched for the additional fuel burn to go faster at FL220, then after descending you would probably not have enough fuel to go fast enough to make up the difference in true airspeeds.


What is the expected range of handheld radio?

This ICOM hand held has a max output of 5W compared with their panel mount radio which outputs at 8W. Unfortunately they don't quote effective ranges on their website (and its highly dependent on many factors anyway). In any case you are limited by line of sight which depending on the plane you are flying (and how high up you are) may be more of an issue. There is some discussion here on the matter and generally people say the work pretty well. Keep in mind also that the aircrafts installed radios have their antenna that are mounted on the exterior of the plane which has an effect on the reception and transmission ability. Using a hand held inside a plane may in practice yield different results even if it has the same transmission specs as an installed radio.


Biggest things here are going to be the availability of training courses as well as full motion simulators to do the training in. There are a lot of FMS systems for 737 aircraft operated by multiple companies offering type ratings in that airplane.  Conversely I only know of a few companies that offer initial and recurrent type rating work in a 787.   Boeing offers a type rating course in this aircraft, and as well as the individual 787 operators have their own initial and recurrent type rating training.

Your ease of obtaining a type rating is largely going to be a function of how big your bank account is.  You will also have to select whether you want to receive an initial type rating as a first officer on 787 or as a captain of the 787.  The training will probably take 3-4 weeks and approximately 20 to 30 hours of sim time (you will never fly the real thing for a type rating) to complete in a full motion simulator, and those are costing roughly 1000 dollars an hour to operate.   So at that time requirement plus say 2000 dollars for the course cost of materials,  you're probably looking at around 22,000-32,000 USD, provided of course you pass the check ride at the end.   If you were new to jets or other fast movers, this would probably be a monumental task for you.  If you have been type rated already in another airplane like the 737 or similar, the process should not be very difficult.

On top of that, unless you're going to go immediately fly for a 787 operator somewhere, that type rating is pretty much useless. (If you don't already have 4000 hours TT plus at least 1500 PIC Jet time, don't even bother applying; no airline would hire you for that role, type rated on the jet or not).  And it's only good for 12 months; you'll then be required to undergo a recurrent type rating as either a first officer captain on the 787 and will cost about 60% what the initial type rating did.


Is it possible to power a B-52 bomber with four bypass turbofan engines?

A four-engine configuration has been proposed at least two times but would require expensive modifications to the wings.

A 2017 Flight global report, Rolls Royce offers BR725 for B-52 re-engine effort, said

  So far, the USAF has foregone plans to reconfigure the B-52s with four engines, which would have required expensive modifications to the wings, R-R says. R-R previously considered a higher thrust variant of the RB211 turbofan engine as a four-engine option on the B-52, but the service does not appear to be moving in that direction, according to R-R.

A 2014 Aviation Week report, B-52 Re-engine Resurfaces As USAF Reviews Studies, said

  Pratt & Whitney studied the idea in 1982, with four PW2000-series engines. In 1996 Boeing and Rolls-Royce jointly proposed to fit B-52s with four RB211-535s, with the government leasing the engines. The first plan was not taken up because all B-52s were to be replaced by B-1s and B-2s by the late 1990s, and the second failed because of resistance to leasing combat assets and a flawed economic assessment by the Air Force.


Do fan blades use bell shaped lift distribution curves?

The bell shaped lift distribution has been used on the Horten flying wings in order to reduce lift at the outer, rearward parts of the wing for stability and better controllability.

The fan blade of a jet engine has no need for a tailored reduction in lift towards the tips; instead it tries to maximize the thrust from the available area. The wavy shape is the result of a compromise which tries to sweep the outer, supersonic part of the blade aft and at the same time to minimize the torsion resulting from that sweep. Therefore, the blade is first swept forward and then aft.

RR Trent fan (picture source)


What is the relation between velocity and rate of pitch?

A constant speed pull-up is basically a circular motion, albeit in vertical plane:

$$q=\frac{(n_z-1)g}{V}$$

where $q$ is pitch rate, $V$ is true airspeed assuming no wind, $n_z$ is the load factor (lift to weight) and $g$ is gravitational acceleration.

The amount of load factor is limited by the airplane and its flight condition. As you can see, the faster the speed, the smaller is the obtainable pitch rate for a constant load factor.

Note: a constant speed pull-up is a theoretical idea that only approximates a pull-up at the very beginning, before the airspeed begins to decay. But the conclusion is valid.


How does ATC handle different kinds of emergencies?

FAA Order JO 7110.65W - ATC Procedures, Chapter 10 outlines how ATC should handle procedures for emergency situations.

In the very first section though, it says:

  10-1-1(d)
  Because of the infinite variety of possible emergency situations, specific procedures cannot be prescribed. However, when you believe an emergency
  exists or is imminent, select and pursue a course of action which appears to be most appropriate under the circumstances and which most nearly conforms to the instructions in this manual.

So, for Mayday and Pan-Pan, it says in 10-1-1(a):

  A pilot who encounters a Distress condition should declare an emergency by beginning the initial communication with the word “Mayday,” preferably
  repeated three times. For an Urgency condition, the word “Pan-Pan” should be used in the same manner.

The use of Mayday and Pan-Pan declares an emergency, but doesn't tell ATC about the nature of that emergency. Therefore just saying those words doesn't trigger any particular method for handling the emergency other than probably the controller offloading other traffic and giving you priority handling. It'll probably also trigger a clearing of the airspace around you, and if you are on final or near an airport, a ground hold.

For Medevac:

2-1-4(b) outlines:

  Provide priority to civilian air ambulance flights (call sign “MEDEVAC”). Use of the MEDEVAC call sign indicates that operational
  priority is requested. When verbally requested, provide priority to AIR EVAC, HOSP, and scheduled air carrier/air taxi flights. Assist the pilots of
  MEDEVAC, AIR EVAC, and HOSP aircraft to avoid areas of significant weather and turbulent conditions. When requested by a pilot, provide notifications to
  expedite ground handling of patients, vital organs, or urgently needed medical materials.
  NOTE−
  It is recognized that heavy traffic flow may affect the controller’s ability to provide priority handling. However, without compromising safety, good judgment must be used in each situation to facilitate the most expeditious
  movement of a MEDEVAC aircraft.

For Minimum Fuel

2-1-8 Outlines:

  If an aircraft declares a state of “minimum fuel,” inform any facility to whom control jurisdiction is transferred of the minimum fuel problem and be alert
  for any occurrence which might delay the aircraft en route.
  NOTE−
  Use of the term “minimum fuel” indicates recognition by a pilot that his/her fuel supply has reached a state where, upon reaching destination, he/she cannot accept any undue delay. This is not an emergency situation but merely an
  advisory that indicates an emergency situation is possible should any undue delay occur. A minimum fuel advisory does not imply a need for traffic priority. Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations. If, at any time, the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, the pilot should declare an emergency and report fuel remaining in minutes.

(Emphasis mine)

Really you should read through the entire (long) document to see how ATC is supposed to behave for certain situations. Chapter 2, Section 1 has a lot of "emergency" situations, but most of it boils down to giving priority and assistance that the pilot asks for.


Do services still apply foam carpet on belly landings?

Firefighting services still apply foam path, atleast outside US, though the practice is no longer encouraged.

FAA, in its 2002 CertAlert 02-04 actively discourages it:

  The FAA does not recommend the foaming of runways for emergency landings and warns against the practice with any foam other than “Protein” foam....  It is recommended that ARFF personnel decline to foam a runway when requested by a pilot because they do not have the specialized equipment and protein foam

FAA lists a number of reasons for this decision (It had actually recommended foam paths for emergency landings in 1966, before withdrawing it in 1987), including,

Time may not be always available for foaming
The use of foam in foam path should not affect the subsequent firefighting abilities.
Foaming the runway should not affect the movement and safety of other aircraft.

ICAO too, does not recommend for foaming the runway in its Airport Services Manual, stating,

  15.1.2 The effectiveness of runway foaming is not fully substantiated by the real evidence of operational incident studies.

ICAO also considers the various reasons for foaming the runway and analyses them:

  a) Reduction in aircraft damage. ... The data available from a study of emergency landings made with, and without, the application of foam show
  that no significant reduction is achieved in the risk of fire or in the extent of damage by the foaming of runways.

  Reduction in deceleration forces. ... It is to be noted that from what is
  known to date, the braking action of an aircraft on a foamed runway will only be slightly worse than that on a wet runway, assuming non-freezing weather.

  Reduction in friction spark hazard. ... tests have shown that aluminium alloy metals produce no friction sparks capable of igniting aircraft fuel vapours ... on either dry or foam-covered concrete or asphalt runway surfaces. ... Titanium friction sparks, capable of igniting aircraft fuel vapours, could not be effectively suppressed by runway foaming in any of the scale research tests ...

  Reduction in fuel spill fire hazard. From all that is known of the fire suppression qualities of foam and the scale research tests, it is clear that a foamed runway would have no appreciable effect on the fire hazard of fuel vapours in the atmosphere over the foam.

ICAO also points out that the primary firefighting vehicles should not be used for foam laying operations; Also, the time taken for the operations and replenishment is a concern.

It is to be noted that, though the practice is no longer recommended, fire services are not barred from using it if the pilot asks for it and facilities are available.

In a related note, US armed forces seem to use it.


Why do tapered wings not stall at the root first?

I will try to make it simple without going into mathematical details.

Source
Here, λ = ctip/croot
The important factors controlling the lift in the Tapered wing.

The ctip being too small affects the Reynolds Number (as the distance travelled is very small). Assuming the constant speed, density and viscosity, Reynolds number only varies with the distance travelled (x) directly. As the tip distance is too small, Reynolds number is not much increased for the boundary  layer and therefore transition from laminar flow to turbulent can not happen. Also due to skin friction, the flow gets slow and becomes separated. The separation causes loss of Lift and thus Wing Tips stall first.

The sweepback effect makes the boundary layer tends to flow spanwise toward the tips and becomes separated near the leading edges of tip.

Increasing Span Efficiency Factor,e as it is higher for tapered wings, it produces more Cl.

There may be other factors too, that I might have missed. But these are the most prominent. You can refer to below image. The Red Line shows seperated flows.

Yes, wingroot has a higher effective AoA. It is easier to understand this way. For a given AoA, the wingtips suffer from downwash and vortices which decreases AoAeff and increases Induced AoA (AoAi). As the wingroots do not suffer from the vortices, their AoAeff is higher.

Figure 2 & 3: FAA Pilot's Handbook of Aeronautical Knowledge
Figure 4: Introduction to Flight, Anderson


Do aircraft fitted with both a trimmable horizontal stabilizer and a trim tab exist?

Trimmable horizontal stabilizer (THS) and trim tab serve the similar purpose for two entirely different control architectures:

Trim tab neutralizes the force on the pitch control for a reversible control system.
THS neutralizes the pitch position (and, in the process, the force) for an irreversible control system (e.g. hydraulically/electromechanically actuated, analog or digitally commanded).

In the presence of an irreversible actuator, the actual hinge moment on the elevator no longer matters since the elevator position is being closed-loop controlled by the actuator (provided the actuator is sized correctly, of course); but more importantly, it is no longer felt directly by the pilot. Without this direct feel, a trim tab would be more than useless.

On the other hand, in the case of reversible control with direct elevator-to-stick linkage, deflecting the stabilizer would not allow the dual objective of maintaining trim and neutralizing hinge moment to be accomplished, since a TE up stabilizer would impart even more nose down stick force to the stick. The THS is equally useless for a reversible control for this purpose.

For this reason, I would be very surprised to see an aircraft fitted with both. But maybe there are oddballs?


Did airlines fly their aircraft slower in response to oil prices in the 1970s?

As a French who grew up in the Caribbean, I can tell that flights are getting longer. A flight between France and my island that took 7.5 hours 15 years ago is almost 9 hours long today.

This post published by the MIT’s School of Engineering says (emphasis mine):

  Specified cruising speeds for commercial airliners today range between about 480 and 510 knots, compared to 525 knots for the Boeing 707, a mainstay of 1960s jet travel. Why? “The main issue is fuel economy,” says Aeronautics and Astronautics professor Mark Drela. “Going faster eats more fuel per passenger-mile. This is especially true with the newer ‘high-bypass’ jet engines with their large-diameter front fans.”

Today's high bypass engines are more efficient at low speed:

  Observant fliers can easily spot these engines, with air intakes nearly 10 feet across, especially on newer long-range two-engine jetliners. Older engines had intakes that were less than half as wide and moved less air at higher speeds; high-bypass engines achieve the same thrust with more air at lower speed by routing most of the air (up to 93 percent in the newest designs) around the engine’s turbine instead of through it. “Their efficiency peaks are at lower speeds, which causes airplane builders to favor a somewhat slower aircraft”

This article also states that slower aircraft's structures are cheaper to build:

  “A slower airplane can also have less wing sweep, which makes it smaller, lighter and hence less expensive.” The 707’s wing sweep was 35 degrees, while the current 777’s is 31.6 degrees.


Measurement discrepancy on vfrmap dot com sectional -- is the grid wrong?

All the clues were there; another member figured it out (see comments).  My computer screen was stretching out the image in the left-right sense, so when I took my nautical miles scale off the tick marks on the north-south line of longitude, and then made an east-west measurement, the measurement ran significantly high.  The question noted I had seen this elsewhere and the fact that that was also on an east-west measurement, but at much lower latitude than Alaska (neither of which were noted in the question), should have been a clue to me as to what was going on.  Nothing to do with high latitudes and nothing to do with errors in the way the airspace or the map grid were charted.

I looked at the same url on a different computer screen and the measurement came out fine.


How often do V1 cuts come up in airline sim training?

During initial and upgrade training you will fly many V1 cuts. At every recurrent check ride you'll experience V1 cuts both as pilot flying and non flying pilot.

In our sim events the V1 cut would generally be a 600 RVR takeoff with 10 kt direct crosswind from the side that would fail. Not always though -- you expected the V1 cut on every takeoff.


For FAA currency purposes, must flight time be in an N-registered aircraft?

14 CFR 61.57(a)(ii) details "category, class, and type" but does not mention registration of the aircraft.


Why aren't cell phones allowed to be used in aircraft?

Why aren't cell phones allowed?/ What problems to cell phones cause?

Most of these cases apparently originate from a series of unexplained events in the 90s which were believe to be caused by electronic gadgets, hence the ban. This was when cell phones appeared, and there was an aggressive ban as a result. NASA has a list which includes some of these and makes for an interesting read.

Now however an increasing list of airlines is allowing them again, depending on jurisdiction. FAA is working on allowing it from a regulatory standpoint. Bear in mind that phones were probably much more powerful back when these rules were introduced.

Mythbuster (episode 6, 2006) did a test on this by sticking in a powerful transmitter into a business jet. Their website gives a slightly different version: It was the FCC, not the FAA, who led the way for this regulation:

  Explanation: Never mind what the chatterbox in the seat next to you
  says about cell phones messing with plane navigation — those metallic
  birds are built airtight against foreign signals and operate on
  entirely different frequencies than cell phones.

  So why all the fuss about phones? When you make a call at 10,000 feet,
  the signal bounces off multiple available cell towers, rather than one
  at a time. That means too many phone-happy jetsetters might clog up
  the networks on the ground, which is why the Federal Communications
  Commission (FCC) — not the Federal Aviation Administration (FAA) — banned
  cell use on planes.

How is using a cell phone in the air different than using it from the ground?

Is it sensible to allow them on aircraft? To quote one of the above sources:

  although the FAA recommends that you still switch to airplane mode
  because you’re not going to get a signal 30,000 feet in the air — the
  only hit you’ll take is a dead battery when you land.

So it's probably not a huge loss if you're flying commercial aircraft at 10,000 meters. In any case, you can't expect a service like you do on the ground, unless like Lnafziger says that the aircraft is equipped with a cellular basestation called a Picocell, illustrated below:

(source: wordpress.com)


Why is tape being applied to this jet engine?

It's not duct tape. It's speed tape.

  Speed tape is an aluminum pressure-sensitive tape used to do minor repairs on aircraft and racing cars. It is used as a temporary repair material until a more permanent repair can be carried out.

Probably just got a bit of a gap around the cowling or perhaps a loose fastener or two. It's common practice for sealing minor gaps and things until it's next in the hangar for work.

Whilst I was Googling for speed tape, I also found these:

http://www.askthepilot.com/duct-tape/

This is how the wonderful British "tabloid" press deal with aviation stories.  Top marks for getting the "shocked passenger" phrase in.


Do pilots switch their cell phones into airplane mode?

Almost always.

If they don't, you often end up with this annoying sound on the radio:


Is it possible to integrate an AI CoPilot on existing planes?

If an "AI Co-pilot" existed, it could likely be integrated on existing airplanes with an auto-pilot system.

Since your question is a little vague, I'm going to take a stab at some your hidden assumptions and go from there. I'm also making the assumption that you're talking about the enroute phase of flight, and leaving the taxiing, take-off and landing in the hands of the human pilot.

At the risk of (extreme) oversimplifying, an AI system is essentially something that takes in a lot of data, analyzes it (through different algorithms) and outputs data that can then be used to do something.

I'm going to assume that the AI algorithm is supervised and has been trained on a bunch of existing data, and it has been figured out what data is important to make high-probability inferences.

In-flight, there are multiple sources of data that could be fed to the AI algorithm for it to make probabilistic inferences on what it should do.  These data sources are things like:

Engine monitors (my EDM 700 I think logs 60 data points/second on things such as cylinder head temperature, exhaust gas temperature, RPM, location, power setting, etc.)
GPS Receivers (3D position)
AHRS (attitude information)
ADS-B (Traffic and Weather)
On-board Weather Radar
XM Satellite Weather

(As an aside, SavvyAnalysis already does a bit of this type of analysis using the data from your engine monitor).

So, provided that your "AI Co-pilot" has been properly trained in advance on the same type of data that you are able get from your airplane while in-flight, your AI Co-pilot could ingest the data, and output signals to the auto-pilot which would then fly the airplane. The autopilot controller is simply sending information to a particular servo for a particular control surface (aileron, elevator, etc.) and if your AI Co-pilot can output the same signal, then it could control the servos the same as the autopilot.

One of the (many) difficulties lies in designing the system to safely handle things that it hasn't seen in the training data.

But to answer your question, it wouldn't require the design of a new aircraft, but rather a new autopilot control system.

EDIT: Extra thoughts

After thinking about your question some more, I was thinking why you might want an AI Co-pilot? I'm thinking the answer to that might would be for it to either make decisions for you that you are unaware you should be making or to help you make better decisions.  There is existing software that does something like this, called Xavion, which continually figures out where you should land if your engine quits based on the current location and performance of your airplane. It's not hooked up to an autopilot, but it wouldn't be too far of a stretch to think that sometime in the future, something like this could be a part of the autopilot controller.

  Furthermore, Xavion is constantly running engine-out flight
  simulations behind-the-scenes as you fly. The app imagines an engine
  failure every single second, and it checks how your plane would do in
  a power-off glides to every runway at every airport in gliding range.

  For each of these simulated engine failures, Xavion estimates the
  likelihood of a successful landing based on the runway’s length,
  width, proximity to the aircraft, and glide path from your current
  location down to the threshold of that runway. When Xavion has found
  the runway that it believes is most likely to result in a safe
  engine-out landing, it builds a series of hoops from your current
  location to that runway—spiraling, circling, or extending as needed in
  order for the hoops to follow a constant descent angle that your
  airplane should be able to sustain without power.

When you start to think of something like this, you can start to imagine analyzing real-time weather data and having the system make (or help make) a decision to divert or land based on your performance and experience. However, this is all something that would happen in the auto-pilot controller, so retrofitting it to an airplane with an existing autopilot would be more of a software upgrade than a hardware redesign.

UPDATE:

Wired had a good article on this on 3/28/2017. It talks about all the different sources of data that could be used to make an AI learn about the airplane, figure out where the holes are in the data and who could fill them.  An interesting place for data that I didn't think about (because it's not data generated in flight), is maintenance and service logs.

Particularly relevant to the intent (I think) of your question might be this passage:

  Elsewhere, researchers are working to ensure AI can help pilots manage
  crises as they arise. At University College London, a team led by
  Haitham Baomar and Peter Bentley is developing a new autopilot system
  that learns how to manage emergencies by watching how well-trained
  pilots do so, and then behaving as they do in similar circumstances.

  “We want to increase safety by trying to tackle the human-error factor
  that might be caused by stress, information overload, and sometimes a
  lack of sufficient and up-to-date training,” Baomar says. “Modern
  autopilots, unfortunately, can’t handle challenging flight conditions
  such as severe weather conditions or system failures.”


Is it "cutting off" in the pattern when I go before a plane that is going faster than I am but let me in first?

The Cheyenne would have been "cutting you off", if he hadn't worked it out with the aircraft in the pattern and maintained visual separation.

According to the AIM, 4-3-3, standard pattern entry at an uncontrolled airport is abeam the midpoint in the downwind.

  Enter pattern in level flight, abeam the midpoint of the runway, at pattern altitude. (1,000’ AGL is recommended pattern altitude unless established otherwise. . .)

http://www.faraim.org/aim/aim-4-03-14-189.html


Why are speed restrictions imposed for flights flying below 10,000 ft?

The speed limits were set by FAA in the early days of jet age for better control of the aircraft and safety where the air traffic (in VFR) is the densest and have little to do with noise.

FAR § 91.117 states

  Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).

TWA Flight 553, a DC 9 collided with a Beechcraft Baron, killing 26 people on March 9, 1967. NTSB investigation determined that due to the high rate of descent of the DC-9, its pilots were not able to see the other plane in time to avoid a collision.

Following this accident the FAA issued Advisory Circular 90-32 titled 'Air traffic control and general operations, radar capabilities and limitations' in Aug 1967.

According to NTSB report on the accident,

  The FAA has adopted a rule establishing that all aircraft flying below 10,000ft m.s.l will be limited to a maximum speed of 250kts effective December 15, 1967... (to) provide a more realistic 'see and avoid' environment in the airspace below 10,000 feet mean sea level (MSL) where the traffic congestion is greatest ....


Which is longest Oceanic crossing for any commercial flight route?

For the longest  Oceanic Crossing, the following are the top three contenders:

Sydney to Vancouver
Melbourne to Los Angeles
Auckland to Vancouver

Out of this, 1 and 2 pass over a few islands on their way, 3 does not pass over any landmass.

Have a look at this : www.gcmap.com

Image :

(Image Source: www.gcmap.com)


How much does it cost to give an airliner a fresh coat of paint?

According to WallStreetJournal article, Tom Horton stated in an interview that :

  A 777 paint job can cost  \$100,000 to  \$200,000, depending on the number of colors involved, and a smaller Airbus A320 can cost $50,000 or more.


What is in 'stealth paint' to reflect radar, and how does it work?

Stealth paint doesn't reflect radar, it absorbs it by converting it to heat which is absorbed and dissipated by the airplane's structure. Paint is only one of several Radar Absorbing Materials available.

The paints known have suspended balls of ferrous material which absorb radar energy at certain frequencies and convert the radio energy into mechanical vibration, which causes friction and in turn heat.


Can a tiltrotor fly safely with one engine?

Short Answer: yes. If they could not, they'd likely not get certified
One engine can drive both prop rotors.

After digging into an old version of the V-22 flight manual, I find a whole pile of tables in the chapter that cover single engine flight.   Gross weight and DA and flight configuration informs what the "best" airspeed is for single engine flight.
The general approach for single engine flight to a safe landing is to fly at a particular configuration and airspeed, and then to set up the aircraft for an approach to a run-on-landing "between 55 and 65 knots."  As I understand the procedures, that final approach will have the nacelles tilted up far enough to prevent the tips of the prop-rotors from striking the ground once the aircraft is on the ground.
Flight Safety Note: I am not going to replicate (cut and paste) these procedures here for a number of reasons, one of which is that I am referring to an out-of-date manual, and some of the details may have changed.  I suspect that the current procedures are similar.
Note on the source:
An old version in the A1-V22-NFM-000 series; Part V/Chapter 12; Emergency Procedures. (There will be a similar section in the Dash Ten for USAF CV-22's).
Where a run-on-landing is not achievable, the manual calls for an approach to ...

... maintain the highest suitable air speed until deceleration is required for a no-hover touch down.

This general method is very similar to the single engine procedures that we had in the SH-2F and the SH-60B helicopters that I flew from ships in the Navy.  The aircraft's Gross Weight and the Density Altitude of the day will lead to some variations in the "best" airspeed for this; there are tables in the manual (and usually in the pocket checklist) to determine the best airspeed to fly.
Then ...

A shallow approach into the wind maintaining 30 KCAS until right before landing is recommended.

This is a little bit different from how we did this, and taught this, in those two helicopter models; we would try for a constant angle of descent approach (not a shallow approach) to a spot if we, as was usually the case, did not have single engine hover capability.  The resulting landing would be fairly firm, but that was by design.
Bottom Line
Not only is single engine flight possible, as well as single engine approach and landing in a tilt rotor, it's a well known flight characteristic that has well established procedures to accomplish.  (At least for the V-22.  The AW-609 doubtless has similar procedures in its flight manual).


Why don't plane wings start at the front of a plane and end at the back?

You are right, a short wing span is a blessing for the structural design and the wing will be nice and light. But since you need a certain wing area to keep the aircraft in the air, the wing will have a long chord as well, and that won't be good for aerodynamic resistance.

For subsonic aircraft, you want the longest, narrowest wing possible: the lift create by the wing is caused by air accelerating downwards. The amount of air streaming in is a function of the span, so a long span accelerates a lot of air downwards only a little bit; a short span wing has to accelerate much less air much more. That creates induced drag: the horizontal component of the backwards tilted lift vector.

Another source of drag is the tip vortex, where air 'flips over' from high pressure below to low pressure on top of the wing. So for subsonic aircraft, the longest, narrowest wing is the most beneficial from an aerodynamics standpoint. It will add constructional weight and therefore increase weight induced drag, but will compensate for it by a reduction in aerodynamic induced drag.

Supersonic aircraft have an additional source of drag: shock waves. The air gets no warning that an aircraft appraches. The nose arrives first, and a shock wave streams off of the nose in the form of a cone. Inside the cone, the air has lower velocity - if the wing can stay within the cone, it creates much less supersonic drag.

Image source

The higher the supersonic speed, the more the shock cone bends backwards, and the widest bit of the wing needs to be more towards aft to remain within it. So for supersonic aircraft, the delta wings that you draw are in use. They create a relatively huge drag when flying subsonic though.


Why are SBAS-equipped planes exempt from the preflight prediction check?

The slide refers to ADS-B integrity, which requires a different integrity level than RNP. The ADS-B preflight check they refer to is a different than the check for RNP.
The FAA requires an integrity bound of 0.2 NM or less for ADS-B. For RNP2 (en-route) and integrity bound of 4 NM is sufficient. RNP-approach requires and integrity bound of 0.6 NM.
The probability of not achieving the integrity level required for ADS-B is significant for TSO C129 (SA ON) installations, much lower for TSO C196 (SA Aware) installations and insignificant for TSO C145/146 (SBAS) installations.
The better performance of thw SBAS installations is because SBAS does a few things to improve integrity:

it is an extra GPS satellite at a fixed (geostationary) position.
it supplies parameters for an error correction model that improve the accuracy of GPS signals received by the GPS receiver
it does its own integrity monitoring of the whole GPS system and reports any issues with GPS within 6 seconds to the WAAS receivers.


Are there benefits in training instrument students how to fly a DME arc?

Apart from the fact that it is required to learn, the obvious "benefit" is that you know what to do when flying to an airport that uses a DME Arc approach. RNAV/GPS approaches are becoming more common, but have far from taken over from conventional approaches. Even if an airport has radar, it does not necessarily mean that radar vectoring for final approach course is available - consider, for example, uncontrolled airports. Here is an example of a DME Arc approach still in use today, at an uncontrolled airport in Denmark that does have radar, but no radar vectors are provided (since it is uncontrolled):

And an example from Norway:

(images from AIP Denmark and AIP Norway respectively)


Accelerated Stall, what is it, how do you prevent it?

Short Version

An accelerated stall is a stall that occurs at an airspeed higher than normal due to a higher load factor (g loading).

Longer Version

When an aircraft is in a bank or when pulling back on the yoke quickly, the wing has to create additional lift to support the aircraft since the load factor has increased.  This increases the angle of attack beyond the critical angle of attack (the point where the wings can no longer produce enough lift to support the airplane) and the airplane will stall even though it is above the normal stall speed for the airplane.

Example

Let's say that we are flying an airplane that has a "normal" stall speed of 60 KIAS.  If we start a 60 degree banked turn, this will increase the load factor on the airplane by two (2g) and will increase our stall speed by 41% to 85 KIAS.

A fairly common cause of this type of accident is when a pilot overshoots the runway centerline during the turn from base to final and steepens the bank angle in order to "turn faster" to get back on final.  Because the stall speed goes up, they can stall the airplane even though they normally never even come close at their current airspeed.

Instead, they should have just maintained the current bank angle that they had (instead of steepening it) and continued the turn back to re-intercept final using normal maneuvers.  If that couldn't be done in the amount of altitude/distance available, then simply go around and come back to try again (while making the proper wind correction in the turns this time).


How can one determine if a Service Bulletin is still applicable?

This FAA AC outlines how SB's should be drafted. It also says that the Design Approval Holder should make available an easy way to search the SB's

A DAH should develop a robust SB/AD tracking and management system
using the following process to ensure overlaps and conflicts between
new and existing SB actions are identified and addressed: a. Search
capabilities should include the following primary areas:
(1)
Make/model or part number of affected product(s),
(2) Major aircraft
elements (e.g., engine, strut, wing, etc.),
(3) ATA code,
(4)
Maintenance zones,
(5) Service information (e.g., service bulletin
number),
(6) Airworthiness limitation sections,
(7) Previously issued
ADs, and
(8) Planned ADs (i.e., action(s) that the FAA proposes to
mandate in an AD).

This puts the ownership on the company a bit.
The FAA makes all current bulletins available here so you can check if they still list it as current.
There is also a bit of duality between service bulletins and Air worthiness directives. SB's are issued by the company if they feel there is a safety hazard to the aircraft. Most importantly, unless they are issued alongside an AD they may not be mandatory. You can check out this blog post that goes into it a bit more.


Why does airport security use numbered baskets for my carry-on stuff to be x-rayed?

It makes it easier to pull a basket from the line. Its likely that those numbers show up on the X-Ray screen so that if the person watching sees something that needs inspection they can say

  pull basket number 18

instead of,

  i think thats the one to pull, it was 4 baskets after the one with the shoes and the laptop.

There are also ones are available now with RFID tags inside for a similar reason.


What happens if an aircraft goes above maximum altitude?

There is a variety of reasons for a maximum altitude:

Most common is insufficient engine performance to climb any higher. Then your question never arises. The aircraft simply cannot go higher.
For more powerful aircraft the partial pressure of the oxygen supply in an unpressurized cabin would drop below the value to keep the pilot(s) alert. For GA aircraft without supplemental oxygen this would be 15,000 ft (short term) or 12,500 ft (long term).
For many airliners it is the pressure limit of the cabin which is certified for a maximum differential to outside pressure. If the airplane climbs higher, the internal pressure must be reduced to less than what is deemed the acceptable minimum for the passengers.
For special subsonic high altitude aircraft with sufficient engine power the limit is the coffin corner when minimum speed and maximum Mach fall together. When that height is exceeded, the aircraft stalls and exceeds its Mach limit at the same time. The result is a shallow dive which can only be recovered a few thousand feet lower.
In some cases the limit is given by minimum combustion chamber pressure inside the engine to keep the flame burning. There are cases when aircraft climbed too high, suffered a flame-out and could not restart.
With supersonic aircraft the limit might be set by maximum flight Mach number, when higher speed means stagnation heat exceeds structural limits. The high Mach number is needed to sustain minimum dynamic pressure to produce enough lift.


What qualifies as "open water" with respect to FAR 91.119?

Most probably the same definition as a dictionary's:

open-water. An expanse of an ocean, sea, or large lake which is distant from shore and devoid of nearby islands or other obstructions.

I searched for a legal definition but I can't find one. It's like defining a sparsely populated area, it's hard to draw a line. So sticking to charts is best I guess.

You might want to search for maritime laws that define such boundaries, which are borrowed by aeronautical charts.

On an FAA chart it's depicted like this:

Source: FAA


Why did Boeing not create a new 737 instead of just upgrading the old model?

Other sources confirm the statement from your documentary that James "Jim" McNerney made the decision to build the 737 MAX rather than a new model:

When Airbus was about to land American Airlines with a huge order for the A320 family, both the ceo and neo, Boeing’s hand was forced. Within 48 hours, Jim McNerney, Albaugh’s boss, made the decision to go forward with what would become the MAX.

(Leeham News, emphasis mine)
The 737 MAX program was eventually launched as a response to the Airbus A320neo, the new engine option. If Boeing had started development of a new model immediately when Airbus announced the A320neo in 2010, they might have been able to come up with a competitive product in a similar time frame. But Jim Albaugh, who was head of the 737 program at the time, underestimated the A320neo and said:

I think Airbus will find re-engining the A320 more challenging than they think it will be. [...] When they get done, they will have an airplane that might be as good as the Next Generation 737. We think we can continue to make incremental improvements to the 737 to make sure that it is a more capable airplane than even the re-engined A320.

(Leeham News)
Boeing wasted valuable time here while Airbus was working on the A320neo. Boeing also struggled with the 787 at the same time:

Boeing was indecisive about which direction to choose.
The ambiguity was driven in no small part during this era by the continued 787 debacle, which at the time of this interview, had not entered service.

(Leeham News)
The final decision to re-engine the 737 instead of developing a new aircraft, came when American Airlines decided to purchase a large number of Airbus aircraft. Boeing realized they had to act quickly at this point:

Boeing faced an unthinkable defection in the spring of 2011. American Airlines, an exclusive Boeing customer for more than a
decade, was ready to place an order for hundreds of new,
fuel-efficient jets from the world’s other major aircraft
manufacturer, Airbus.
The chief executive of American called Boeing’s leader, W. James
McNerney Jr., to say a deal was close. If Boeing wanted the business,
it would need to move aggressively, the airline executive, Gerard
Arpey, told Mr. McNerney.
To win over American, Boeing ditched the idea of developing a new
passenger plane, which would take a decade. Instead, it decided to
update its workhorse 737, promising the plane would be done in six
years.

(New York Times, emphasis mine)


Is there a comprehensive list of IFR terms with definitions?

The FAA's Instrument Flying Handbook would be a good start, in particular the glossary.


Do commercial flights continue with an engine out?

The image looks like four engines running at the same cruise thrust. The wake vortex is blowing the exhaust of the inboard engines down and the exhaust of the outboard engines out and in the perspective of this image this makes the lower two streams look merged while the upper ones further apart. Close behind the engines it is clear there is four of them and all have similar strength.

That said, a four-engine aircraft may continue on three engines as far as it has enough fuel and there is no other damage (so not if the engine flamed out after a big bang). With one engine out it can't maintain as high altitude, so it has to drift down to lower altitude where it flies slower and thus has shorter range. However if they have enough contingency fuel, they can continue to destination. Or return back to departure point, or proceed towards the destination, but land somewhere short. The dispatcher will consider the repairs, taking care of the passengers, rebooking them, the next flight the plane was scheduled for and other things and tell the pilots which is the preferred option.

In contrast a two-engine aircraft shall land as soon as possible. One engine out of two means there is no redundancy left and that is an emergency and shall be handled as such. Note that as soon as possible does not necessarily mean closest airport—the aircraft will cover over 100 NM during normal descent from cruise altitude, so if there are more options in about 150 NM, the pilots and dispatcher still get to choose.


METAR wind is expressed like this:

04011KT indicates the wind is from 040° true (north east) at 11 knots (20 km/h; 13 mph). In the United States, the wind direction must have a 60° or greater variance for variable wind direction to be reported and the wind speed must be greater than 3 knots (5.6 km/h; 3.5 mph).

04011G20KT indicates wind gusts reaching 20 knots.

090V150 indicates the wind direction is varying from 90° true (east) to 150° true (south-southeast).


What radio frequencies are used for intercom in formation flying?

For the US, according to section 4-1-11 of the AIM (Designated UNICOM/MULTICOM Frequencies) for private fixed-wing flights you should use 122.75:

  Air-to-air communication (private fixed wing aircraft): 122.750

  Air-to-air communications (general aviation helicopters): 123.025

  Aviation instruction, Glider, Hot Air Balloon (not to be used for
  advisory service): 123.300, 123.500

I have no idea what the military does and their tactical comms might even be encrypted anyway, but they frequently use UHF instead of VHF, at least in the US.

Nor do I know what to do if you have two formation flights at the same time, but I guess that in reality it's either an air show with some form of semi-official control and perhaps even NOTAMs, or it's something private and in that case people make their own arrangements, e.g. picking some frequency that doesn't overlap with any nearby assigned frequencies. Using 123.45 is apparently common, but definitely not official.

Non-VHF communications for private flights would be regulated by the FCC, not the FAA, and personally I'm not sure if the benefits would be worth the extra equipment and the risk of confusion, but then again I know nothing about formation flying.

There's some useful information from the FAA in this policy order clarifying the use of 121.5 and 123.45. It says that 123.45 is for operational use in oceanic regions, and within the US it's reserved for "non-government flight test operations". There's also an FAA document on requesting temporary frequencies for airshows etc. but it's air to ground only.


In an aircraft with tab-flown control surfaces, how can a jammed surface be detected during preflight examinations or flight control checks?

The system you describe was used on large aircraft before hydraulic actuation became standard. The proper name is servo or Flettner tab.

The preflight check would ideally have one mechanic move the cockpit controls and a second mechanic walk around the aircraft and command control movements. While the actual control surface would not move, the servo tab would, and the second mechanic would hold on to the tab to check if it does so against moderate resistance. Then he would manually move the control surface to check if it moves freely through the full deflection range. This might require climbing on a ladder for the second mechanic, but would be the only way to ensure proper function of the control system.

One pilot by himself would not be able to properly check the airplane.


Where are the locations of the elevators or horizontal stabilizers in a Concorde?

There is no "horizontal stabilizer" on the Concorde like other commercial aircraft, the wing performs that duty because it is a delta-wing. The elevators for the Concorde are combined with the ailerons into something called "elevons" which perform both functions (Think stereotype paper airplane).

Note: Elevators and Horizontal stabilizers are not the same thing. Most aircraft have their elevators located on their horizontal stabilizers, only a few have the whole stabilizer as an elevator.

Source here


At least in the United States the FAA recently (I think in 2012?) changed the recommendation for transponder operation in the AIM.  It now reads:

  Civil and military transponders should be turned to the “on" or normal altitude reporting position prior to moving on the airport surface to ensure the aircraft is visible to ATC surveillance systems. IN ALL CASES, WHILE IN CONTROLLED AIRSPACE EACH PILOT OPERATING AN AIRCRAFT EQUIPPED WITH AN OPERABLE ATC TRANSPONDER MAINTAINED IN ACCORDANCE WITH 14 CFR SECTION 91.413 MUST OPERATE THE TRANSPONDER, INCLUDING MODE C IF INSTALLED, ON THE APPROPRIATE CODE OR AS ASSIGNED BY ATC. IN CLASS G AIRSPACE, THE TRANSPONDER SHOULD BE OPERATING WHILE AIRBORNE UNLESS OTHERWISE REQUESTED BY ATC.

(Cribbed from Chapter 4-1 of the AIM)

So, basically "Turn it on before you taxi, and turn it off right before you shut down the engine. Always use the Altitude mode (Mode C) unless ATC tells you otherwise."

In practice having the transponder on while on the airport surface doesn't do much unless your field has something like ASDE-X which plots aircraft transponders on a screen in the tower, but it generally doesn't hurt anything and it ensures you don't forget to turn the transponder on when you take off.

Operating your transponder while on the ground may cause "ground clutter" on nearby radar station's displays (possibly setting off the conflict-alert system) - this is why many of us were taught to set our transponders to standby mode while on the ground. In practice this usually isn't an issue, and if it is a problem local ATC will ask you to "squawk standby while taxiing" to resolve the issue.
If anyone gives you a hard time about it copy the number and politely quote the AIM.


How is the terrain displayed on the ND in a A320?

The terrain data is contained in a database within the EGPWS (Honeywell TM) or the Terrain Awareness and Warning System (TAWS) as defined in the regulations -- can't use a trademark in the regs.
The discussion in your link about "blockiness" when zooming in is a result of the database grid references.  To save memory space, the resolution of the world-wide terrain data varies based on terrain variation and it's relative hazard to flight operation.  There's greater resolution (smaller grid) near airports and in mountainous areas.
The A320 does have airborne radar that is capable of displaying "weather" which really means precipitation.  It can't be displayed at the same time as the terrain to avoid confusion.
Neither the EGPWS or the radar data are in the FMGS.  Their data is just underlayed on the navigation display.  (EGPWS does receive data from the FMGS to support it's warning functions.)
TAWS/EGPWS function is described in TSO-C151c


Are fighter jets designed to be so inherently unstable that a human can't fly one unassisted?

My short answer:

Stability is reduced by shifting the center of gravity aft.
Shifting it past the neutral point makes the airplane unstable, so movements away from the trimmed state are accelerated. This increases maneuverability.
Flight computers are multiple redundant, if one dies the others take over.
Slow unstable airplanes can be flown by a human pilot, but not fast unstable airplanes.

For the long answer, let me first clarify terms:

Static stability is the tendency of a system to return to it's old state after being disturbed. Take a pendulum: If you pull it to one side, it will return to the middle. Eventually.

Dynamic stability is the tendency of an oscillating system for the oscillations to die down over time. Take the same pendulum: It will swing from side to side, and  friction will ensure this happens with ever smaller amplitude.

Now we need to add dimensions, all three of them: Pitch, roll and yaw. An airplane can be stable in one dimension and unstable in a different one. I understand your question such that you ask about the static pitch stability (or longitudinal stability) of fighter aircraft.

The Wright Flyer was longitudinally unstable (see here for more). Once aircraft designers learned that aircraft can be made to fly stable, and learned that this is of immense benefit in pilot training, static stability became a requirement for new aircraft. When war in Europe broke out, the British forces were equipped with a superb training aircraft, but it was so stable that it took effort and time to convince it to change course. They were shot down in droves.

From now on, low stability was a prime requirement for fighters and aerobatic aircraft. Static stability is proportional to the control forces (more precisely: To the hinge moment of the respective control surface), so reducing stability gave pilots more response for the same effort. Longitudinal static stability is measured as the relative distance between neutral point (NP) and the center of gravity (CG). See here for more. Longitudinal static stability is achieved by placing the CG ahead of the NP. Shifting the CG back gives you a more responsive airplane, but also one which is more easily disturbed by gusts.

This is the design technique you asked about. Pretty simple, right?

Once you shift the CG aft of the NP, stability is lost and the airplane will increase deviations from the trimmed state. This can be helpful if you want large angle changes, and quickly. An unstable aircraft only needs a small kick and will do the rest of the maneuver all by itself.

This is how it helps in maneuverability. But it is even more helpful to reduce the inertias, especially around the roll axis, for a faster response. That is why all combat aircraft have their engines close to the center.

Of course, negative stability is not acceptable when you need to take your hands off the stick to get a map out or to pee on a long flight. So without computer control, the limit was a CG position near, but not aft of the NP.

With supersonic aircraft, things got more complicated. Now the aircraft operates in two flight regimes, one where lift acts at the quarter chord of the wing and one where it acts at mid-chord. Aircraft with low static stability become very stable in supersonic flight, and the tail surface has to create a high down-force so that the sum of all lift stays where the CG is. Creating lift always incurs a drag penalty, and in supersonic flight it has to be payed twice: One for the excess lift on the wing (which is needed to compensate for the tail's down-force) and one for the down-force on the tail.

Using a flight control computer offers the possibility to allow the pilot to let go of the stick without the aircraft going off course. Now the stick does not command elevator deflection, but pitch rate, and the CG can be moved back from maybe 12% of MAC (mean aerodynamic chord) to -2%. If you compare the wing areas of stable and unstable jets (Jaguar and Mirage F-1 are prime examples), you will see how much is achieved just by going back with the CG by a few percent of wing chord.

Conventional SEPECAT Jaguar and CCV version (picture from Ray Whitford's Fundamentals of Fighter Design). Both configurations have the same airfield and combat performance!

Can a human still fly such an aircraft? In glider competitions, the more daring pilots fly with relaxed static stability and have no problem to keep the aircraft under control. Even the Wright brothers could handle their unstable airplane, and handling improved when they moved the CG further back (If you want to know why, please post a new question. This answer is getting too long already!). However, the speed of an aircraft's pitch response is proportional to flight speed (and inverse to the pitch moment of inertia), so faster aircraft are harder to control. You can compare dynamic pressure with the stiffness of a spring: A stiffer spring moves the eigenfrequency of a spring-mass system up, and the same is true for the eigenvalues of the equations of motion of an aircraft. Given that the reaction time of a good pilot is at least 0.1 s (and more if he/she is tired), it is impossible to counteract motions with frequencies of more than a few Hertz. The lag means that the reaction comes too late and will support the motion. See this YouTube clip how that works out in practice. This crash was due to wrong signal gains, not a classic instability (after all, the flight computer was still working, but produced too strong elevator deflections).

I would venture to say that a human can still barely fly an unstable jet at low speed (after all, Tom Morgenfeld almost got the YF-22 under control), but once he firewalls the throttle, he will be always behind the plane, and will crash it soon.

Size helps: Bigger planes have lower eigenfrequencies, and light, big vehicles are easy to control, regardless of stability. All Zeppelins were completely unstable in yaw and above the critical airspeed of an airship (again, please ask for a more detailed answer on this aspect) also in pitch, but with one person each for the vertical and the horizontal control surfaces, and enough people on board to rotate them after 2 - 4 hours, nobody felt the need to make Zeppelins naturally stable.

If one computer dies, the others take over. Most unstable configurations have four parallel computers which cross-check their result to catch any malfunction. The Dassault Rafale uses only three, but adds safety by clever algorithms for checking the results.


Is it usual for a first officer not to know how to taxi?

After reading that article carefully, here's what appeared to have happened:

Pilot collapses
Passenger-with-pilots-license comes to flight deck (with both elitist and sexist chip on his shoulder)
First officer moves to left seat, PwPL takes right seat, runs the radios and checklists, maybe drops the gear.

First Officer is a right-seat qualification, on 737s (and many others) the steering handle is on the left side.

So it's quite possible that the FO has never steered a 737 on the ground. It's quite IMpossible that the FO has never taxied an aircraft of any kind before. And there's a huge difference between driving a Gulfstream around and driving a 130-passenger jet around.

If you don't take a corner just right, the main gear ends up in the ditch, the wing hits the ground, the engine inhales grass, gravel and maybe the taxiway sign and a couple of gophers. Trashing a Ferrari is cheaper.

The FO moving to the left seat and flying the plane was the correct action - the B-1 pilot was no more qualified to fly a 737 than I am. But radios are radios, and even the greenest flight attendant can read a checklist.


Are flame holders made of a special material other than that used in combustion chamber?

In The Jet Engine, there is no mention of a two-material setup for the flame-holder/combustor. It's all about the design of the diffuser and combustor shape / holes.

One of the fancy things they mention (p. 122, image below) is the lining of the walls in elevated ceramic-coated tiles for internal cooling.

Having to deal with two materials would decrease the structural integrity of the combuster. And to my knowledge, the flame-holder and combustor are one and the same, a single unit.


Why do many commercial aircraft have a red circle on the wing?

That would be the Japanese sun symbol which also appears on that nation's flag. You can also see that symbol on the tail of that JAL 777 on top.

Same as the Japanese Flag:


Where to find Tach hour and clock hour equivalence rpm?

As far as I know the only place to get this information is the tachometer specifications (or at least I know Mitchell provides it for their tachometers).
As you noted, it's not on the TCDS, nor have I ever seen it in the (Piper or Lycoming) maintenance manuals. (It is of course possible I've missed it in the maintenance manuals - they're pretty thick books.)

If you are flying around in a plane with a working tachometer and don't know the hour-meter's equivalence speed you can always determine it with a watch: every 6 minutes is 0.1 hours, and when the tach is recording at that rate you've found the equivalence RPM.
(For the Archer I assume it's the same as my Cherokee 180 - around 2300 RPM.)

  It's worth noting that while you would think the tach's hour meter would be "accurate" (1:1 correspondence) at typical cruise powers that is often not the case!
  Using the Archer as an example, 65% power cruise at 7,000 feet is around 2500 RPM, so the tach hour meter will be running slightly faster than 1:1 in a 65% power cruise at 7,000 feet.

The watch-check I described above doesn't help you if the reason you need to know this information is your tach has died and you need a replacement - fortunately tachometer manufacturers all know this and publish recommended applications for their tachometers.
Mitchell lists their D1-112-5023 (2300RPM) tach as the appropriate replacement for the PA28 family, which matches up with the watch-test on my Cherokee.


Can winglets be used to compensate the high induced drag created by a low aspect ratio wing?

In the lens of potential theory, we can explain and predict the efficacy of winglet through how much it dilutes the trailing vortices strength. Just like we can show that the Elliptical lift distribution produces the least induced drag for a given span length on a flat planform, we can equally derive the optimal lift distribution for any wing+winglet combination of arbitrary winglet height and cant angle.
The graph below, collected from Drela, Flight Vehicle Aerodynamics, shows parametrically how the most optimal induced drag of various winglet extensions and cant angles compare against the flat Elliptical drag, if the total lift on the wing is fixed. $h_{winglet}$ is the vertical height of the winglet above the planform plane, and $\theta_{winglet}$ is the cant angle measured from the planform plane (0 means a simple span extension, while 90 means a perpendicular winglet).

Image from Drela, Flight Vehicle Aerodynamics
As you can see, a simple span extension ($\theta_{winglet}=0$) is always better. For example, to achieve the same induced drag reduction as a span extension of 20%, we must have a vertical winglet whose combined height is 40% span (assuming we don't allow span extension whatsoever).
I must stress that the results above are a comparison between the most optimal planform + winglet combinations. Optimality means that when the winglets are attached, the wing itself is modified to achieve optimality. In practice, with the wing itself fixed, you could only do worse.


What is the range of an air traffic control tower's radio transmission?

VHF transmissions are limited by line of sight. So, assuming the transmitter is at the tower location, and assuming the aircraft is at cruise altitude (say F300, or 30,000 feet or more), the maximum range is perhaps 200 to 300 km before the curvature of the earth eliminates the line of sight. This also depends on weather conditions and the transmitter power.

In practice, VHF coverage may be extended using additional transceiver sites on the same (or different) frequency. This is particularly important in mountainous terrain.

For oceanic flights where there is no place to put additional transceiver sites, HF (shortwave) radio can be used which has a much greater range (thousands of km), especially at night. Some aircraft are also equipped with satellite phones so controllers can simply call them. However, this wouldn't be the tower controllers talking to the pilots over the ocean, as tower controllers aren't responsible for en route control.


Why are RVR values reported in good visibility?

It looks like that METAR was corrected to

  KLAX 281553Z COR 00000KT 9SM FEW012 FEW045 18/08 A3000 RMK AO2 SLP157
  FU FEW012 FU FEW045 T01780083 $

Note the COR for corrected. The corrected METAR does not include RVR.

Including a screen grab of aviationweather.gov in case they dont keep the info up for a long time.


What is the worlds shortest runway for FAR 23 commuter type aircraft?

That would be Out Skerries (IATA: OUK) in Shetland with a 1,195 ft / 364 m runway (source).

60°25'30.08" N   0°44'55.93" W

(Source)

(Source)

Above plane is a Britten-Norman BN-2 Islander, with a stall speed of 35 knots.

  The Britten-Norman BN-2 Islander is a 1960s British light utility aircraft, regional airliner and cargo aircraft. Still in production, the Islander is one of the best-selling commercial aircraft types produced in Europe.


In the compressor characteristic, what does this value represent?

In German it is called "Ähnlichkeitsparameter", a comparison parameter for the compressor state. This one in particular is a non-dimensional mass flow comparison parameter. To be more correct your equation is actually missing the gas constant "R" under the square root (together with temperature) to make it non-dimensional. This non-dimensional mass flow factor makes it possible to compare different scenarios like high altitude and high speed at low temperatures as well as low speed, sea level conditions. Just like we do with the lift coefficient on wings.

It's not a material property of any particular engine or compressor, just an operating point with a dimensional mass flow m (kg/s), T3 being the total pressure (K) at station 3, P3 being the total pressure at station 3 (Pa) at that time. Station 3 is entry into combustion chamber.

This factor usually comes up in compressor maps (in German "Verdichterkennfeld"), where you plot the compression ratio (pi) on the y-axis over this mass flow parameter on the x-axis. These maps can tell you how much the compressor can compress the air without stalling.

https://en.wikipedia.org/wiki/Compressor_map


Why wasn't a scramjet used for the Concorde?

A supersonic ram jet (scramjet) requires a fuel with a very high flame speed, so the combustion doesn't take place after the fuel-air mixture has left the engine. Aviation fuel would be completely unsuitable, and only hydrogen gives acceptable results. The low density of gaseous hydrogen, the storage problems associated with cryogenic hydrogen and the creation of a hydrogen infrastructure would had created tremendous problems for the Concorde development.

A scramjet is like wing sweep: It is best avoided if possible, but necessary if you want to go really fast. For the scramjet the speed above which it makes sense is Mach 4 or 5, and Concorde was designed for Mach 2.


What is the proper technique for using rudder pedals with toe brakes?

Unless you have extra long feet, keeping your heels on the floor of the plane is usually sufficient to keep them off the toe brakes.  Or pull your legs back a little and press with the balls of your feet near the middle of the pedal and not the top.  You'll get the hang of it pretty quick.

Learning to relax helps also, otherwise you'll fly with your legs all tensed up and just have the rudder pedals all mashed down all the time.  Very tiring.


How to best navigate around and land at KPAO (Palo Alto, CA)?

If you’re coming in VFR from the south, I’d recommend skirting around the San Jose Class C and Moffet’s Class D by flying over the Lexington Reservoir, over Los Gatos and Saratoga and staying just north of the foothills of Palo Alto.  Flown at lower altitudes, you’ll avoid KSFO’s Class B airspace.  Just be aware there’s a lot of GA VFR traffic down in the weeds in that area.  Also be aware of TFRs over Stanford, should they be hosting football games at their stadium.   Typically arrivals and departures from the west are given the Stadium visual arrivals, routing them to Stanford Stadium, thence to a downwind or base entry at KPAO.  Arrivals and departures to the north are given the Bridge visual arrival and departure to the Dumbarton Bridge then entry into KPAO pattern.  Remember as well that “Kung Pao” only has a 2400 ft runway, so be on the ball with you short field ops.  There is extensive flight training going on at that airport and the pattern can be extremely busy on good weather days.  Have a taxi diagram ready to go and be aware of taxi routing via the east loop Taxiway Golf - terminal side - or the west loop taxiway Golf - hanger side.


What is a "flare-out" and why does auto-thrust reduce thrust during flare-out?

The proper term is "flare" not "flare-out".

"Flare" is a term used to describe the act of raising the nose of an aircraft in order to increase lift and stop descending in order to land on a runway smoothly.

Whether the pilot, or Auto Thrust does it, a reduction of power to idle is needed in order to bleed off the excess speed that is used during the approach phase.  If the thrust is not reduced to idle, the aircraft will take longer to land, and use up more runway.

If you don't flare enough, the rate of descent will be too high and the aircraft will land hard.

Too much flare will make the aircraft climb back up.


What kind of warranty comes with a commercial aircraft?

I have had direct experience with this and yes new aircraft are sold with a warranty like a car, say for 3 years or 5 years and x hours.  The OEM may maintain local service centers, and a/c under warranty may be sent there for moderate fixes, although most of the time the airline fixes the problem itself and charges back the OEM for labour and gets parts provided by Spares free of charge (to the extent it's worth their while to do so for labour chargebacks; sometimes the administrative hassle to recover, say, 5 manhours at an overhead allowance of 50 or 60 bucks an hour isn't worth the trouble).

In extreme cases problem aircraft have been known to have been taken back by the OEM to prevent an angry operator from canceling a large ongoing order, or some such situation where it's important to mollify the customer.

Sometimes the OEM will use in-house product support teams to go out and do more significant work on aircraft under warranty, especially if the airline doesn't have the resources in-house, for free.

The OEM's program office will have a warranty administration group that manages all this.  A significant sum of money is budgeted by the OEM to cover warranty reimbursements and you could say this is built into the price (I dimly recall that on the Regional Jet program there was a budgeted warranty allowance of about a quarter or half a million $ per aircraft, but it may have been more than that).

Once it's out of warranty, well, you're on you own buddy.  You'll pay for spares, and for support from the OEM beyond basic help desk advice.  Major mods may or may not be provided free of charge to out of warranty a/c, depending on how nearly broke the OEM is budget-wise, or how much the bad publicity will hurt.  An airline may get satisfaction, on old out-of-warranty costs it was unhappy about, as part of a package negotiated on a new aircraft sale.  This is common on re-orders where airlines add more aircraft to an existing fleet.

Airlines may also negotiate (if they're smart) "AD clauses" where the OEM agrees to pay parts and labour for work required under a mandatory AD, with it's own, later, expiry date.


How was flutter mitigated in jets such as the F-15 and F-16?

Short answer: By not  flying faster than the 104 did and adhering to the lessons learned.

Flutter first started to cause crashes in WW I when improved engine power and aerodynamics made a substantial rise in flight speed possible. Every time technological advance allowed higher speeds, flutter became an issue which was then solved both by trial and error and by analytics.

From NASA TM 4720:

  The first recorded flutter incident was on a Handley Page O/400 twin
  engine biplane bomber in 1916. The flutter mechanism consisted of a
  coupling of the fuselage torsion mode with an antisymmetric elevator
  rotation mode.

This was easily fixed by removing one degree of freedom for the elevator: Initially, both sides could be moved independently, and by connecting them with a torsion tube the flutter mode could be avoided.

From control surface flutter in WW I, which was generally solved by the practice of balancing all control surfaces (something the early aircraft designers were oblivious of), flutter problems moved to primary surfaces from 1925 on. Again NACA TM 4720:

  Air racers experienced many incidents of flutter from the mid-1920's
  until the mid-1930's as attempts were made to break speed records

The first analytical testing was performed by von Schlippe in 1935 in Germany. He vibrated the aircraft at increasing speeds and measured the resulting amplitude. An increase in amplitude indicated a reduction in damping and imminent danger of flutter.

Typical amplitude over speed plot (from NACA TM 806, which is a direct translation of von Schlippe's work which was first published in Luftfahrtforschung Vol. 13 No. 2, February 1936)

With jets and their higher speeds, new types of flutter occurred. Again NACA TM 4720:

  Supersonic speeds also produced a new type of flutter known as panel
  flutter. Panel flutter involves constant amplitude standing or
  traveling waves in aircraft skin coverings. This type of instability
  could lead to abrupt fatigue failure, so the avoidance of panel
  flutter is important.

Since maybe fifty years every new design must go through a static vibration test to check which elastic eigenfrequencies exist. Analytical methods are used to predict the (speed dependent) aerodynamic frequencies and the structure must be modified to remove any possibility of resonance. Next, the airframe is tested in flight at ever increasing speeds and with exciters at the tips of all surfaces (those can be like the vibration motor in your smartphone, only bigger, or, in the simplest of cases, the pilot moves the control surfaces). At increasing speeds, the exciters are run through a frequency sweep (typically from 5 to 60 Hz) and the resulting amplitude is measured by strain gages or accelerometers.

Below is a diagram (taken from NACA TM 4720) depicting the flutter test of the F-14. The F-14 and F-16 went through the same procedure to make sure flutter is no issue in operation. Modern fly-by-wire designs can even use their control surfaces for active flutter suppression.


What, if any, are the rules on ATC politeness?

I worked as a controller in the U.S. for many years in the 1970's and 1980's at 3 different busy facilities (twr/artcc/tracon).  There was never a written policy regarding politeness on the radio.  It was, at least for me, common sense to not engage in any extraneous conversation.  Controllers are keenly aware everything that is said on the radio and landlines is being taped.

The few times I was aware that a pilot made a complaint regarding a particular controller, the controller's supervisor would get the tapes, listen to the pertinent section, and then if warranted counsel the controller.

Generally, it was my experience, that when working traffic in a busy facility you would just want to get the job done as professionally as possible and avoid any extra conversation.


TL;DR : according to the most usual meanings of these acronyms :

ACARS and CPDLC are applications
VDL is a point-to-point communication technology

To give an everyday-world analogy, the relationship between VDL and CPDLC/ACARS is the same as the relationship between 3G/4G and the web browser/facewhatstime app of your smartphone.

More detailed answer

From a telecommunication point of view, we represent the different functions of a network by different layers. Ideally, one can replace the technology used to implement a given layer by any equivalent technology without impacting the other layers.

The VHF Data Link (VDL) is a technology used to implement the functions of the physical and datalink layers. It means that it is a technology designed to carry any digital data directly from one "device" (aircraft or ground station) to another (resp. ground station or aircraft), independently of its actual content. There are different versions of VDL, namely modes 1 to 4. The current deployments of VDL in europe by ANSPs use VDL mode 2.

CPDLC is an application (application layer). It is directly facing the user, and can use any layer below it (in particular, it can use VDL, HFDL or satcom as layers 1/2)

ACARS is ... a more ambiguous word. It predates the OSI model, and at first it described both the application (text-oriented transmission) and the point-to-point communication technology. Nowadays, pilots use the word ACARS to talk about the application (the printer in the cockpit), and that particular application can, as any application, use any underlying link layer (VDL, HFDL, satcom...). But the old meaning of "ACARS" to describe the original blob of "point-to-point  technology + network + application" can still be found today, for example in the acronym POA (plain old ACARS). By the way, the  point-to-point technology originally used by ACARS is also called VDL mode 1.


Can you fly a glider in a cloud on primary instruments?

With basic instruments (altimeter, speed and climb indicator and compass): Forget it!

A glider can enter a cloud when thermalling into it from below. Below the cloud the rising air was governed by dry adiabatic laws. Once it crosses into the cloud, the air is fully saturated and humidity starts to condense - after all, this is how clouds form. Now the rising air gets additional energy from condensation (its lapse rate goes down from the usual degree per 100 m of the dry adiabatic lapse rate to half a degree per 100 m) and the thermals inside the cloud become stronger. This is to say that turbulence will be more violent and the airplane will be tossed around. It will bank and pitch, and there is little chance that it will stay level for long. Since the spiral dive motion has very little damping, the glider will soon enter a spiral dive and overspeed.

The advice I got for the case that you are "sucked" into the cloud always was: Let go of the stick and open the speed brakes. Then wait until it gets light again.

In the 1930's some competition pilots tried to gain additional altitude by entering clouds. The results were catastrophic. In some cases the cover of the wings was torn to shreds by hail, and even bailing out would not be safe: One pilot froze to death when strong thermals inside the cloud lifted him to more than 8000m while he hung on his parachute.

I have done it once on a calm day when returning from the Alps. In the mountains the cloud base is higher, so it is entirely possible to arrive at the clouds over the alpine upland above their base height. I had a GPS on board that told me that I would reach the glider port safely when flying a straight line. It was late in the day, the thermals had died down and the clouds were fuzzy already, so little turbulence could be expected. One was in my way, and I went into it and flew out less than a minute later. The whole thing was completely uneventful, but I would not had done it with active thermals.


Does the velocity of air in an engine increase in the compressor section or turbine section?

Air velocity increases in the turbine section.

In order to compress air, we need to apply work on it, like running a car engine harder to drive it up the hill. Part of the work required comes from decelerating the air that flows into the engine.

The work done can be released by accelerating the gas and letting it escape, creating thrust. The expanding gas also applies work on the turbine blades, which absorb part of the accumulated energy. Each turbine stage slows down the gas, but from a higher velocity base due to the expansion. In the turbine section as a whole, gas velocity is increased.

The faster the gas flows out of the engine, the higher the thrust that is created.


What factors besides tail/headwinds cause the time taken to fly some routes to be different from the time it takes to return?

Sometimes, prevailing winds will account for the difference -- flights going west to east in the US will generally be scheduled for less time than flights going the opposite direction.

The other major factor that can play is in taxi times.  If the delays waiting to get in to a gate matched the times waiting to depart at each airport, these delays would affect both legs equally, but that's not generally the case.  Most of the time, at a congested airport like Atlanta, you can generally get into the gate fairly quickly, but the delays getting airborne can be far longer.

Thus, a flight scheduled from Podunk into ATL might be scheduled for 10 minutes taxi from the gate to departure at Podunk, the flight time, and another 10 or 15 minutes to taxi in, but in the other direction they might build in 30-45 minutes of taxi time departing ATL, plus the flight time, plus 5 minutes landing until blocking in at Podunk.  Thus the leg into ATL is scheduled for flight time plus 25 minutes, while the leg from ATL is scheduled for flight time plus 35-50 minutes.

If it's winter time and your flight was going from BOS or PHL to MCO, another factor in addition to the potential for massive departure delays would be the need to build in time for deicing -- done before departure in PHL or BOS, but not so much leaving Orlando.

Of course, if you didn't need to deice "today," then you'd probably beat the scheduled time by a good bit.  Likewise if the weather was clear and the airport had no delays.  But the mega-hub airports run so close to capacity that any little hiccup in the weather or otherwise causes delays to start building, and then you're using all of your scheduled time, and sometimes more.


In short, it is the vacuum gauge. It measures the vacuum pressure in Inches of Mercury. It runs/powers your non-electrical gyroscopic instruments. Those are your Attitude Indicator, your Directional Gyroscope, and sometimes your Turn Coordinator. These are all necessary to fly by Instrument Flight Rules.

Read these:

PHAK

Airplane Flying Handbook


How ribs angle change wing overall shape?

It depends on the rigidity of the upper and lower skins.
As far as large jets go, you see different variations; ribs parallel to the airflow, ribs perpendicular to one of the spars, ribs perpendicular to mean chord.  In the 737 cutaway below, they appear to be more or less perpendicular to the rear spar.
Aerodynamically it's not important on large swept wing aircraft, since the ribs' orientation doesn't impact the outer contour of the airfoil, because the upper and lower skins are very heavy and stiff and are effectively the spar caps (the primary tension and compression members of a box beam), and the "spars" are really just bulkheads closing the box at the front and back, with the ribs supporting the box. So whether you angle the rib this way or that doesn't make much difference and it comes mostly down to ease of manufacture.
On the other hand, if you have a swept fabric covered wing, or a metal wing with thin skins that can bulge between the ribs, then it could be an issue and ideally you'd want the ribs to be parallel to the local air stream (which may vary a bit from the free stream) as much as possible to minimize air flow "across the bulges" so to speak.  But if the upper and lower skins are stiff enough to retain their contour between the ribs, it makes no difference and you can orient the ribs in a way that makes it easiest to build the wing, with the rib contour shaped to accommodate the orientation in achieving the overall airfoil shape.


How does take off mass impact induced drag?

Induced drag is caused by lift. (historically, Induced Drag was named "lift induced drag").

If weight(mass) of the aircraft decreases, the lift required to fly the aircraft decreases. And the drag associated to that lift also decreases.

The quoted statement is true, but "slightly" can be discussed. Because the increase in range depends a lot on how much payload the aircraft could carry. (If it's %50 of the max takeoff weight, the range could increase a lot).


What are the regulations for non-aircraft targets in airport movement area?

Ground vehicles are really problematic at an airport. The problem is not so much a matter of regulation as a problem that the people driving the vehicles sometimes are unfamiliar with flight processes so they create hazards without really understanding the danger they are creating. The "regulations" are that nobody is supposed to be on taxiways or runways without approval whatever that means, but since the FAA cannot revoke the license of somebody that does not have a license, it's a toothless rule. Also, the typical runway intruder does not even have a radio, so getting approval is problematic for them. Cops are the worst offenders. I have seen some very dangerous situations evolve from ignorant cops with no idea what they are doing just driving onto runways acting like they are god or something.

The main way the FAA interfaces to the ground control problem is to publish a lot of safety guidelines hoping that somebody will read them. Some airports have elaborate safety training for ground personnel, but the main risks usually come from untrained personnel at smaller airports where there is little or no training.

This is one of the main reasons why most airports work hard to get good fencing set up, so some bozo does not drive onto the runway.

In general, ground control takes care of authorizing vehicle movement and utility trucks are supposed to coordinate their actions with ground control. In untowered airports, utility trucks are supposed to call on CTAF to notify nearby pilots what they are doing, but unfortunately most do not have radios. Once I was landing and there was some truck on the side of the runway because the guy was removing a turtle or something. The truck had flashing lights so it was easy to see luckily.


Why are downward pointing winglets more efficient?

For efficiency the orientation of winglets is not important. Best would be to stretch them out horizontally, but on a canard they do double duty as vertical tails.

Things look different when maneuvering is added: Now the downward-pointing winglet is superior especially if it carries a rudder. When roll is commanded by deflecting the ailerons, the lift change on the outer wing will carry over to the winglet. On upward-facing winglets this creates an opposite yawing moment while on downward-facing winglets this yawing moment supports the intended turning maneuver.

Also, they look cooler.


How much do aileron on a commercial airliner move for manoeuvring and trim?

I have never flown an aircraft, only flew in them, but I am studying aerospace engineering. If ailerons were deflected the whole time, I would say that it was a trim issue. Note that the MD-88 are old aircraft (introduced at 1980 and production stopped at 1999, source: Wiki page on MD80 series), so having some idiosyncrasies such as some roll instability or drift is to be expected. I have not studied the degradation of aircraft over time, but it makes sense. I had to mention that since stackexchange does not like people sharing opinions.
This question is more interesting for me since we can do some back of the envelope calculations to establish some simple facts. Lets approximate how much force would be required to get an angular acceleration of say 5 degrees per second squared, a very extreme case. Gradual turns are initiated with angular accelerations of about 2 degree per second squared; that way a 30 degree bank takes about 15 seconds to enter.

The most relevant thing that would be required is an estimate of the mass moment of inertia (MMOI) of the aircraft along its X axis (which is an axis pointing in the flight direction).

First the Maximum takeoff weight (MTOW) is taken from data (MD88 mass data) and the dimensions are approximated from drawings and data (MD88 dimension data)

Than the aircraft is modeled as a filled cylinder with the wings as two cuboid. The mass of these 3 sections are approximated from the mass fraction as found in this article. Crunching up all the numbers leads to an approximate $I_x$ for the MD-88 as $3350 \times 10^3$ $kg$ $m^2$.

We know that $M = I \alpha$, where $M$ is the rolling moment, $I$ is the MMOI and $\alpha$ is the angular acceleration. 5 degrees per seconds squared is about 0.09 radians per seconds squared. And $M = Fl$, where $F$ is the force from the aileron and $l$ is the moment arm. The moment arm is about 16 $m$ since the half wing span is about 17.9 $m$. So we have $F = \frac{I \alpha}{l}$. This leads to a requirement of 19000 N of force from both ailerons, and about 9500 N from each aileron.

In normal flight (at approximately MTOW) the wings are producing about 600 $kN$ of force to keep the aircraft in air. For this rather extreme banking maneuver the ailerons need to create a 10 $kN$ difference in lift (which is about 2% of the total lift).

Lets estimate the required change in lift coefficient for this change in lift. Assuming one aileron influences 15% of the wing surface, a flight at an altitude of 10 km, and a airspeed of 230 m/s, we find that each aileron should cause a 0.05 change in the lift coefficient of the wing segment. Have a look at the image below for an idea of about how much the lift coefficient changes with flap deflection. It seems evident that about a 5 degree deflection is required to get to the required order of magnitude of change in the lift coefficient.

(source: stanford.edu)

Now that we have some idea about the order of magnitudes, we can talk about the aileron deflection question. Using information from the aileron sizing documentation, we can think about the moment caused by your specific question. If we imagine a deflection of 5 mm (seems ok for stabilization but a little too low for control), we can approximate a aileron deflection of about 0.7 degree (assuming a $c_a/c$ of 0.25 and chord length of 1.5 $m$). Hence, I do not think deflections of a few mm are enough to roll the aircraft as would be required during landing maneuvers around an airport. Thus I think the aileron you saw that was trimmed is doing the heavy lifting for the rolling.

There are further subtleties introduced into the required magnitude of deflection of the ailerons due to other design parameters such as the incidence angle of the wing and the specific nature of the airfoil in the wing extremities. The former introduces a differential in how much the left and right ailerons need deflecting and the latter may cause the sections with the ailerons to have inherently higher lift in order to get a better lift distribution over the wing. These two are just to mention two of many things that interact to determine the rolling dynamics of the aircraft.

I wanted to include more sources for my work, but apparently I can only include two links; so I removed all of my supporting material and left only the image for consideration. If you want sources for my analysis, send me a message.