What is the moderate dihedral angle for a low wing airplane?

Please do not worry about the loss in lift. It is real, but so small that it can be neglected. A poor flap or aileron seal will cost you more in L/D than the dihedral ever will.

The loss is proportional to the difference of the cosine of the dihedral angle to unity. With 5° (which is on the upper end of typical values for low wing aircraft) this is just 0.38%.

The exact amount of dihedral depends a lot on details of the configuration:

Aspect ratio of the wing
Fuselage size relative to wing root chord
Wing sweep
Directional stability

In general, you need a good balance between $c_{l\beta}$ (dihedral effect) and $c_{n\beta}$ (weathervane effect).


How able were pilots of three-person cockpits at running the normal FE work?

First, these answers insofar as the licenses and airline operations apply to the U.S. system since that is all I am familiar with.

You must have a Flight Engineer license to operate as an FE. Just as a pilot's license has ratings on it, so does an FE license, and you have to have a rating that matches what you're flying. My FE license has a single rating, TURBOJET POWERED, so I could not sit as an FE in other than a jet aircraft.

In the days when 3-man cockpits were the norm, the usual career course at large carriers was to start out as an FE (second officer), progress to being an FO (first officer), and then a captain. In that system, if the FE was incapacitated, it was likely that one if not both of the pilots had actually been an FE.

The U.S military continued with FEs well after the 3rd seat came out of civilian aircraft (I think they still do, but am not sure). Military FEs were typically never intended to become pilots. When all new civilian aircraft being manufactured were 2-man cockpits, but lesser airlines were still flying the old 3-man cockpits (think freight carriers in particular), former military FEs became the source for their FEs and were considered professional FEs, in other words they would not be progressing to a pilot seat. A few did, but they were definitely the exception.

The two 747 carriers I worked for hired pilots into the FO seat. The FEs they hired had to have A&P licenses as well as an FE license, the reason being that the company wanted them to be able to perform and sign off minor maintenance problems that occurred in remote places (think Africa especially) where maintenance wasn't locally available. With only a couple of exceptions, every FE I ever flew with was ex-military with an A&P, and they knew the airplane mechanically better than I.

In the airline ground schools, especially the initial groundschool, the FE panel and its operation were thoroughly covered in the material presented and in the testing. The oral exam for the aircraft type rating thoroughly covered that FE panel. As I remember my 747 type rating oral was 3 to 4 hours long. Fortunately I got through that and the sim ride on the first try. Not all do.

So, in the case of an incapacitated FE in the 10 years I was on the 747, it was likely that neither pilot had actually operated as an FE. However, he would have studied it in ground school and had demonstrated an understanding in an oral exam. There is, though, nothing like experience and currency.

Every once in awhile I would get out to a cold airplane before the FE had arrived and would want to start the APU. This was usually at a remote station without local maintenance. There was, of course, a procedure for doing this, and I had a copy. But even with that check list and doing everything very carefully, I always breathed a sigh of relief when the APU started and there were no problems. If the APU failed to start on the first try, I usually waited for the FE to arrive. I might try a second time if I knew he was going to be awhile, but never a third.

The old 747-100/200 had a lot of switches, and interesting things could happen if the APU was started and the switches were not properly set. I always did an outside check to make sure all gear doors were closed and that nobody was around the bottom of the airplane. If a gear door was down, and switches were not set right, when the APU started, the doors would immediately close when the hydraulics were pressurized. Anyone in the way would certain get hurt.

Individual pilots on the line varied greatly in their knowledge of the FE panel. FOs were at a disadvantage insofar as watching it be operated. They can't see it well. Captains can see it. However, some FEs resented captains looking at it too much, feeling that was their turf. What I often did during cruise, as much to pass the time as learn, was to let the FE be my tutor.


How possible is a successful landing just with 1 wing?

This would be possible with other fighter jets that are of similar design to the F-15, i.e. have a low aspect ratio, much of their lift produced close to the centerline, and a lot of control authority. They would also need the other two key ingredients for a landing of this kind: a strong aviator at the controls and a bit of luck.

Specific contributing features of the F-15 were its fuselage's lifting design, side-of-fuselage engine placement, blended wing with strakes, and large control surfaces, common to fighters.

If you look at the planform, it wasn't missing a full 50% of its wing, but only about 20% of its lift-contributing planform area (lift distribution isn't equal across it of course), with the body, the intakes and wing root strakes continuing to provide lift. As a result, the center of lift didn't move as far away from center as it would have for a tube-with-wings design.

In principle this is a more violent version of a runaway aileron scenario, and one has to compensate for roll from the lost wing area. The F-15, being a fighter, has large control surfaces for combat maneuvering, and they proved sufficient for stopping the roll in this case. The loss of lift was not so much of an issue.

The red box is the lost area, the green box the remaining planform, and the dashed line its very approximate center.

It's possible that other fighter aircraft could do something similar. Commercial aircraft, however, almost universally feature high aspect ratios, and with such a wing, the center of lift will move too far away from the design centerline in a similar scenario. Partial wing loss, however, can be compensated for, and there's a lot of incidents where planes landed having lost some part of their wing.


What is the altitude record for the F/A-18 Hornet?

I can tell you my experience during my stay in Zaragoza Air Base in northeastern Spain, in 1998. After heavy maintenance work, the twin-seater was ready to fly. In order to check all work done, we did a parabolic flight in clean configuration (no loads under wings or fuselage). It was a flight test so we decided to push the limits a little and see the real capability of the General Electric F404 engine. After acceleration and trying to maintain the best angle, we were able to climb up to 63,000 ft.
It was quite difficult to fly the plane when crossing 45 or 48 thousands (I don't remember well), so we decided to connect the auto-pilot. The auto-pilot can handle the plane easily at those altitudes with such low air density.
I recall the last portion of the climb was a nice parabolic trajectory in zero-g (you cannot imagine how dirty the cockpit was, I could see a pencil and some screws from maintenance floating in front of me, among some other things) until we regained positive g's in the descent. It was an interesting flight, but as stated by others, not practical at all from the combat viewpoint.


Problem with right crosswind landing but not left

In my opinion it's because of your left of centerline vantage point and the sight picture burned into your brain by the always left side crosswind aspect, and in your particular case the transition to an opposite aspect is confusing your eye/brain/hands-feet processing more than other people. Everybody has their learning quirks.

The sight picture you are used to from your seating position, which includes the azimuth aspect (heading relative to center line) and bank angle from side slip, is a much bigger deal than a lot of people think.  When pilots start flight instructor training, one of the first airborne activities is learning to fly a trainer from the right side.  Some adjust right away, and for some it's like learning to land all over again.  In your case it seems you are having a similar problem with the left crab/right crab change in sight picture from the left side.

You just need to practice right side crosswind landings until that sight picture starts to sink in and responses become automated, and then you will wonder what all the fuss is about.

I second Carlo's suggestion to use a home computer flight sim for this sort of thing, which are perfect for this sort of "sight picture" learning (use Track-IR as well because this provides much more realistic sight picture movement).  Should help a lot.  But, be careful that when you practice things at home you are practicing correct procedures, not reinforcing wrong ones; that's the one big pitfall of using home sims for practice/proficiency.


Why simple paper planes fly better than most "realistic" paper plane models?

The reason is really the size! Air molecules have the same size if they flow around a small paper airplane or a big real airplane, but since their relative size is so much smaller when they flow around the real airplane, friction effects are much smaller for the big airplane. When comparing airplanes of different sizes, a dimensionless number first formulated by Osborne Reynolds is most helpful. It is basically the ratio of inertial to viscous forces in the airflow, and the formula is
$$Re = \frac{l \cdot v}{\nu}$$
Nomenclature:
$Re\:\:\:$ Reynolds number
$l\:\:\:\:\:\:$ characteristic length, for example wing chord
$v\:\:\:\:\:$ airspeed
$\nu\:\:\:\:\:$ kinematic viscosity of air

Flows with the same Reynolds number behave identically, but your scaled-down aircraft flies at a very different Reynolds number than the original (both speed and characteristic length are a lot lower), so the airflow around it will be very different. For it, the air looks more like a syrup when that around the original is like flowing water! Therefore, lift creation needs different means at this scale (wings with more chord, for example), and the paper airplane is better suited to cope with this particular flow condition.

The next difference is wing loading: The paper airplane is very light; its mass per area is low. Therefore, it can fly at a slower speed than your scaled-down real airplane, and it will be easier for you to launch the paper airplane properly into the air. The scaled-down airplane needs to be thrown harder, but still straight, and this might be another reason for it falling down quickly.


How do I locate a list of restrictions that would prevent a pilot from flying in the US?

The list is exactly one item long:
Any condition which would impair your ability to conduct the flight safely, and in accordance with FAA Regulations.

Any more specific list will miss things and be riddled with loopholes - at some point we have to trust that pilots are sane and responsible individuals, just like we do when we let people get in a car.

From a medical perspective the general medical certification information page at faa.gov is a good starting point, and the FAA's guidance for Aviation Medical Examiners has lots of details.

There are also some disqualifying conditions which are explicitly listed in the regulations, and a list of (some of the) medications which will prevent the FAA from issuing a medical certificate.

The things I noted above will prevent you from getting a medical certificate.  Once you HAVE that certificate the "I'M SAFE" checklist or something equivalent expands upon that and tries to help pilots determine whether they're fit to fly right at this moment. There are various ways of interpreting the acronym, but a common one is:

I for Illness
Do I have an illness or any symptoms of an illness?

M for Medication
Have I been taking prescription or over-the-counter drugs?
If so, do they have a negative affect on my ability to perform this flight?
Are any of them disallowed by the FAA?

S for Stress
Am I under psychological pressure from the job or personal issues?

A for Alcohol
Have I been drinking within eight hours? Within 24 hours?

F for Fatigue
Am I tired and not adequately rested?

E for Eating
Am I adequately nourished, or at least "not hungry"?


Will an aircraft always crash on take-off if de-icing is not performed correctly?

The claim that de-icing must have been done perfectly in Brussels or the plane would have crashed on take-off is patent nonsense. Ice on the aircraft degrades performance. A little bit of ice degrades performance a little bit; a lot of ice degrades performance a lot. It's perfectly possible that they took off from Brussels with slightly degraded performance, realised that there was still some ice on the plane and decided they needed to get rid of it.

There's no reason to suspect a cover-up. If there was even a hint of terrorism, the plane would have diverted to Stansted, not Heathrow. If the plane had some mechanical problem, they'd have made a vague statement about the plane having mechanical problems, landed, fixed the problem (which requires maintenance technicians, not a de-icing crew), and then said something much less vague to reassure the 227 passengers that the plane was safe. If there was a problem with the passengers, luggage or cargo, the plane would have gone to a terminal. If a vice-president of the company had been served macadamia nuts in the wrong way, they'd have dealt with that in Brussels.


Where does the "APU Auto Shutdown" message appear?

Both the "APU AUTO SHUT DOWN" and "APU EMER SHUT DOWN" appear on the lower-left section of the E/WD (the upper display of the ECAM) as amber messages.

In the procedures section of the FCOM, the title is on a white background. The introduction of that section, "FCOM Procedure Layout", explains how the title formatting corresponds to how the actual message appears.

The APU SD display will also be called. And the word "APU" will appear under "INOP SYS" once the procedure is completed.

From a CBT video on YouTube, here's what it looks like:


Why are the tails always painted, but not the fuselage, in test and delivery flights?

Excerpt from McDonnell Douglas MD-11 by Arthur A C Steffen:

  The remaining eight aircraft were delivered bare-metal with a corrosion protection coating, except for the rudder which has to be painted prior to being installed and balanced, and was completed in the full livery in the carrier's modern paint facilities.

The above text is in reference to KLM's first batch of MD-11's.

The paint has to be applied so the manufacturer can balance the rudder after the added weight of the paint.

That extends to other control surfaces and engine cowls.

For the vertical stabilizer, the minimum requirement is the rudder, but if the airline's logo extends to the rudder, then for colors and shapes alignment the whole tail is painted by the manufacturer.

If the fin was repainted and the operator couldn't afford or didn't have time for the re-balancing, we end up with Frankenstein tails:

(Source)


Why do certain aircraft's landing gear tilt up?

Pulling mostly from the answers provided here it seems that

The torque produced by the straightening gear helps to flatten the plane out.
The main gear tilt on the B747 also provides air/ground sensing. All four main gear bogeys tilt when the aircraft is airborne, so on touchdown any systems relying on air/ground logic can activate
The gear is tilted to fit into the wheel well

You can check the link for the rest of the explanations.


What is the difference between "Standard Metric Level" and "Altitude" in ICAO flight plans?

Standard Metric Level is the metric equivalent of the foot-based Flight Level. It is what you get when the altimeter is set to QNE, i.e. above the Transition Level, and read in meters.

Metric Altitude is the metric equivalent to the foot-based Altitude. It is what you get when the altimeter is set to QNH, i.e. below the Transition Altitude, and read in meters.

These are actually the official ICAO systems, with the foot-based systems declared a "temporary" alternative.


Why didn't Boeing make the Sky Interior for the Boeing 777?

I don't know if it is an exception, but Ukraine International Airlines seems to claim that they have a Sky Interior in their 777. User gparyani comments that this claim may be mistaken. I'll leave this answer here in case somebody else independently comes up with the same thing.

  Welcome on board modern Boeing 777-200ER airliner! The aircraft’s quiet and cosy cabins are equipped with comfortable reclining seats, contemporary Sky Interior [...]

https://www.flyuia.com/ua/en/services/long-haul-b777


At what point of the design process the manufactures build their first prototype?

There is no definite answer that will fit all manufacturers and projects for the question you're asking.

Simply put, the decision to create a scale model or a first prototype depends on what the goal of the creation is, the underlying technology, cost and market interest. A lot of aircraft, either new models or improved variants of already existing models never make it past the design stage. Other results in scale models to verify aspects of the underlying design or technology, while some may even skip this and go directly to a full-size prototype to be used for testing.

In some cases, a manufacturer will build a prototype regardless of market interest, because it allows them to showcase the technology and show that it actually works, while other manufacturers might not continue to that stage unless they have generated actual orders for the aircraft.

Needless to say these decisions will be based on different input from project to project, but generally speaking the end goal is to lower the risk if you decide to continue a project. If you are designing a very new aircraft, it makes sense to validate aspects of it before committing to production unless you can demonstrate that the risk is already low enough not to matter greatly.


Why does the DC-9 have engines that are angled slightly upwards?

I believe there this could be traced back to the so-called downwash angle of the air coming off the wing.

Looking at the picture below (and put on some imaginary engines on the back like the DC9/MD80), it becomes clear that by mounting it upwards by a few degrees would make it meet the airstream at the streamline angle:

You would want to that streamline to interact with the aircraft fan blades with the wind at the same angles. I would imagine that if you did not do this, it would result in an uneven force on the fan blades, which would probably be highly undesirable.

Looking at the drawings of the DC9, it might appear that the shorter version has a higher angle, and that the longer version has a smaller angle, as further from the wing the downwash angle is less, as could also be seen above.

For a little further analysis, the following is apparently off the DC-9 Manual, and might shed a little more light on the design, in particular in the last paragraph:

  "The nacelles have been designed to enclose the JT8D engine with a
  shape that will allow the highest installed performance ( thrust minus
  drag ) possible at all flight conditions. The nacelle nose cowling is
  nonsymmetrical to keep the drag to a minimum at the high mach number
  cruising conditions.

  The nonsymmetry is required to maintain an extremely flat nacelle line
  adjacent to the fuselage, such that the nacelle supervelocity
  increments, when added to those from the pylon and fuselage, do not
  lead to super-critical velocities with resultant shockwave losses.

  The nacelle axis and pylon have been set at 3 degrees angle of attack
  relative to the fuselage to align them with the local flow conditions
  prevalent at cruising conditions. This is necessary to eliminate the
  interference and high induced drag that they would otherwise be
  subjected to. The nozzle is then canted upward relative to the engine
  axis, thus eliminating the pitching effects due to thrust."

Following picture appears to show the nozzle angle is in fact more horizontal than the entry angle, with the underside longer than the upper side:

Thus, while it might not aesthetically pleasing maybe to have it off by a few degrees from the fuselage body, but it does bring advantages when seen with the airflow, and resulting concerns about that the thrust is not being vectored along the body axis is corrected by the nozzle.


Why is the DC-9-80 ("MD-80") prohibited from taking off with a flap setting between 13 and 15 degrees?

When the FLAP/SLAT handle is in the 0° to 13° range, the slats are in the mid-sealed position. The slats will be in the extended position whenever the FLAP/SLAT is in the 15° to 40° range. The range between 13° and 15° is the DO NOT USE range.[1]

Given the above and the analogue nature of the input (dial-a-flap), between 13 and 15° the slats are very likely not to settle on a position.

(...) with the flaps flap/slat control lever in the cockpit below flaps 14°, the slats extend to their intermediate position (MID); and with flap/slat control lever positions above flaps 14°, the slats are fully extended (EXT).[2]

In other words:
$$0° \le \text{slat}_1 \lt 14°$$
$$14° \lt \text{slat}_2$$
What happens at 14°? Simply "Do Not Use". The slat is both alive and dead.
Chronology of Douglas / McDonnell Douglas flaps/slats for context:

EIS Year
Plane
T.O. Flaps
Slats

1959
DC-8
fixed detents
slots (with an O);[a] doors opened when flaps extended

1965
DC-9-10
fixed detents
no slats

1967
Rest of the Original DC-9 Family
fixed detents
manual slats; separate lever

1971
DC-10
dial-a-flap (patent)
manual slats; separate lever

1980
MD-80
dial-a-flap
automatic flap-based three-position[b] slats (leading to the switch point at 14°)

1990
MD-11
dial-a-flap
automatic slats having only one extension position; slats stow button

1995
MD-90
dial-a-flap
same as MD-80

1999
717 (MD-95)
dial-a-flap
automatic slats having only one extension position

a: the DC-8 slots failed to produce the desired pitch-down on the DC-9 during development; tests revealed it was due to the lack of engine pylons; further experiments led to the invention of mini-pylons – the vortilons[4]
b: counting the retracted position
How can the narrow-body MD-80 be compared to the much larger tri-jet MD-11? The underlying high-lift system is practically unchanged since the 60s:

The DC-10 models utilize the DC-9 high-lift technology, and the MD-11, being a derivative of the DC-10, is very similar to it. (...) All its airplanes today, the MD-80s, MD-90s, and MD-11s are derivatives of the DC-9 and DC-10 airplanes, and they use their almost-30-year-old high-lift system technology with few changes.[3]

1: MD-80 FCOM
2: Report A-032/2008 – Accident involving a McDonnell Douglas DC-9-82 (MD-82) aircraft
3: Peter, K. C. "High-Lift systems on commercial subsonic airliners." NASA Contractor Rept 4746 (1996).
4: Shevell, Richard S. "Aerodynamic anomalies-Can CFD prevent or correct them?." Journal of Aircraft 23.8 (1986): 641-649.


We can count more than 15 blade-images in that short arc of revolution of the propeller, so there's no way that each one corresponds to an individual firing of a cylinder.  Perhaps there is a resonant vibration involving a slight twisting of the blade, and the sun angle is such that this produces a strobing effect.
The suggestion of a 300 rpm variation between each individual firing of a piston is completely implausible.
Some sort of camera artifact seems a possibility.


Is there anything in any airport called a "warm apron"?

A warm up apron is a portion of the airfield close to the runway entry, where the engine can be warmed up before taking off. It seems to be more frequently used in military documentation.

There are such aprons at Cairns Army Airfield:

Source

Found in FAA regulations, e.g. AC 150/5340-30:

  PAPI LHAs must not be located closer than 50 ft from a crossing
  runway, taxiway, or warm-up apron or within the ILS critical area.

But also in other not regulatory documents, here for synonymous of hardstand:

  ... construction of the RMP test section and warm-up apron (hardstand)
  at the east end of Runway 04-22. The RMP warm-up apron was
  successfully constructed and has been opened for traffic since October
  1992.

Source: Design, Construction and Performance of Resin Modified Pavement at Fort Campbell Army Airfield, Kentucky

A vintage post-card:

Source: eBay


How do exhaust cones affect the performance of turbine engines?

(Source)
This is looking into the tail-pipe of a Rolls-Royce Trent 772B.
The purple circles mark the shape of the exhaust, it's ring shaped, also called annular.
If there was no cone, the exhaust will want to fill the gap, creating drag, the cone helps a smooth transition from annular to circular without this drag. As far as I know, every jet engine has one, it's a cheap solution.
Regarding the speed of the exhaust, if the cone is housed in a converging shape, then from start to finish it will be an equal area transition with no loss in velocity. If it is exposed, then some loss in velocity will happen. But more thrust loss would happen if there was no cone.
And as this excerpt below shows, a small reduction in velocity is beneficial:

EXHAUST GAS FLOW
Gas from the engine turbine enters the exhaust system at velocities from 750 to 1,200 feet per second, but, because velocities of this order produce high friction losses, the speed of flow is decreased by diffusion. This is accomplished by having an increasing passage area between the exhaust cone and the outer wall.
The cone also prevents the exhaust gases from flowing across the rear face of the turbine disc. It is usual to hold the velocity at the exhaust unit outlet to a Mach number of about 0.5, i.e. approximately 950 feet per second. Additional losses occur due to the residual whirl velocity in the gas stream from the turbine. To reduce these losses, the turbine rear struts in the exhaust unit are designed to straighten out the flow before the gases pass into the jet pipe.

AgentJayZ on YouTube explains it here (starts from 3:30).
Thanks to @mins for finding the linked exhaust system page.


What are the pros/cons of low/forward powerplants on helicopters?

The radial was put down there to keep the center of gravity low with a heavy piston engine while leaving a decent size space for payload on the center of gravity below the rotor head.

The compactness and lighter weight of turbines made it possible to mount them up at the rotor head, resulting in a cascade of benefits, and as usually happens, the configuration hits a sweet spot where all the competing compromises are in the best possible balance, so the turbine engine/transmission behind the rotor head becomes almost universal.

In the case of the Wessex, the turbine engines' location is an artifact of its radial powered ancestor and it likely would never have been designed that way if it had a turbine at the start.


Forces that wing attach fittings must transfer to fuselage?

For your first question, it depends on the way they are attached, as is often the case in structures. I haven't seen this model up close to know their fitting type, but:

If they are fixed by a joint that allows them to rotate (the easiest and cheapest solution) then they can only carry one kind of load, that being tensile (or compressive) stresses. this would mean they can only transmit force along their own axis.
If they are rigidly jointed (cannot rotate at the joint) then they also carry some torque, although how much is a matter for the structural engineers. My guess is not much as the attachment points already offer a large moment arm.

For your second question, I believe you mean to ask for what part of the overall lift are the lift struts responsible for. That I cannot readily answer without some calculations I don't have time for right now, but it is not as straightforward as you imply. The Wing-Fuselage-Strut structure is hyperstatic (statically indeterminate or over-constrained) so it is a bit too long to napkin-math.


Can you identify this old cockpit canopy?

Looks like a B-47 Stratojet to me.

Image from wattflyer.com

I'm not sure about this particular model. But usually the canopy will have part number markings on it, which can be correlated to the program.

Also, see the B-47 Stratojet association's page.


What privileges do off-duty pilots have in their own airline?

This is airline specific, so there's no single true answer: but I'll give an overview of what's "normal practice" for many airlines:

Airline staff will typically be bumped to First/Business class when there are available seats, although they're not usually top of the list.

In a typical airline, frequent flyers will be bumped first (particularly those with a lot of business class miles but who happen to be travelling economy right now): it's a way of rewarding loyal/frequent customers.

Once the frequent flyers are all moved up, though, the seats will often be filled with staff or contractors. Typically deadheading/on duty staff first (ie those who are flying home from a previous flight that they were working on), followed by off duty staff and their families.

This is airline specific, however - some airlines will bump everyone on the frequent flyer program  until Business is full, leaving no space for staff. Others will not move any passengers up (to discourage business class flyers deliberately trying to "game" the system by booking economy on quiet flights knowing that they'll likely be moved up), leaving more space for staff. Some airlines will not bump staff at all, or will only do so for deadheading staff (those who are flying because of work, not for their own holiday etc).

There's a lot of variation on things like whether your family will be bumped with you, or whether only higher-level contractors will be moved up. I used to work for a company which worked with airlines, and typically our directors would be moved up to Business while the lackeys were left in Economy


Does a turbojet aircraft restriction on a SID or STAR also apply to turbofan aircraft?

The term "turbojet" in this context is used a bit more loosely. The pilot-controller glossary document from the FAA defines it as follows:

  TURBOJET AIRCRAFT− An aircraft having a jet engine in which the energy
  of the jet operates a turbine which in turn operates the air
  compressor.

You can see this is general enough to include turbofan aircraft as well. The main distinction is vs. a turboprop, where the turbine drives the propeller.


Who defines the callsign for radio communication?

The proper procedures for use of aircraft call signs with ATC in the U.S. are spelled out in the FAA Aeronautical Information Manual (AIM).

For Commercial flights the call sign is usually preceded by the company name (e.g., "United two-seventy five").  The last digits (e.g., "two seventy five" [275]) are associated with the city pairs/route that the aircraft is flying.  Flight numbers are internally derived by the carrier based on its needs for publishing/tracking/scheduling.  So, for example, a particular company's flight from SFO to DFW that operates 7 days a week at the same time normally would always carry the same flight number (such as UAL 527 [ I just made up this number for illustration purposes]).

With respect to proper radio communication techniques:

Under normal circumstances (for non-commerical civil aircraft in USA), on initial contact with ATC pilots should state the aircraft's full call sign.  For example - "November 12345" or "Cessna 12345." After initially establishing communication with that ATC facility, during subsequent transmissions, the pilot may abbreviate the call sign by using the "prefix" (i.e., "Cessna") and the last 3 digits or letters (i.e., "345") such as "Cessna 345."

It is never appropriate to not include the "prefix" (i.e., "Cessna" or "November") and only use the last 3 digits/letters (i.e., "345").

From the AIM:


7700 is a "general emergency" squawk. It tells ATC that there is "a problem" of some sort with a particular plane. And I agree that this "general umbrella" type of squawk is a good idea. I have several disagreements with the FAA, but this is a good one. Several thoughts:

the specific nature of the emergency is only for the PIC and ATC. Nobody else needs to be informed, they can't help anyway.
oftentimes lost comm is part of the problem. So they can't talk, but you still want to show ATC that you have an emergency. You could squawk 7600 for lost comm, but if you have some truly serious, like an engine failure (I personally don't consider lost comm anything even remotely near "truly serious"), you can inform ATC with 7700 that you have a more serious problem than just lost comm. They'll notice the "lost comm" aspect of this situation on their own, by not being able to talk to you. Now they know you have something more serious, because you don't show 7600.
If you really want to use different squawk codes for different types of emergencies, it would merely add to the already large amount of numbers and codes pilots and controllers have to learn by heart. In an emergency where time might be of the essence, trying to remember abstract information like this can be difficult.

"The first time it happened, I thought the plane was about to crash"

Why did you think that? 7700 is not some "we're gonna die" type of squawk. It's a general "umbrella type" of squawk for all sorts of emergencies. An intelligent pilot will squawk 7700 for any "small" or "big" type of emergency (and who is supposed to be the judge on "big" vs. "small"?).

"How is an aircraft going down to be differentiated from one carrying a sick passenger?"

It isn't, because it doesn't matter. The people that are familiar with the situation (PIC and ATC) are in communication, unless lost comm, in which case the controller who can't glean more info from the 7700 squawk can't help anyway, and nobody else needs to be informed because they can't help anyway. Squawk codes aren't meant for desktop people like you who download some app and watch.

"Would you recommend handling this issue differently than it is done now, if you were in the position to?"

No. There are good reasons to have an "umbrella" type of squawk for all types of emergencies.


What is the technical name for the “time boxes” on an instrument approach plate?

Per the FAA Aeronautical Chart User’s Guide for Terminal Procedure Publications, in the revision effective 29 March 2018 on pages 30 and 31, it is a Time/Distance Table.

  Time/Distance Table

  When applicable, a Time/Distance Table is provided below the airport sketch. The table provides the distance and time
  that is required from the final approach fix to the missed approach point for select groundspeeds.


How to measure the aircraft maintenance cost of a operator?

Maintenance costs are generally expressed as dollars per flight hour for a particular aircraft type.  Chargeable labour hours, parts, overhauls, delay costs, repairs etc., on airplane model X, divided by that airline's total flight hours on that particular type.

This kind of data will be broken down and tracked at the Line Replaceable Unit level as an hourly operating cost of the LRU itself.  Like, say, a hydraulic pump will have all expenses related to maintaining that particular part number, including repairs, overhauls, and chargeable delays/cancellations caused by failures, all added up to a global dollar amount per flight hour for that pump.  This is also tracked by the aircraft manufacturer for the entire fleet.

That number will be used to assess whether the pump is better or worse than the global fleet for that aircraft type, or compared to the same pump used on other aircraft models, to decide whether to pay for improvements, look into changing the maintenance practices, soft timing the pump (overhauling sooner than the legal requirement), and other actions.  There will be some alarm threshold established, say >$1.00 per hour, or 85 cents/hour or whatever, the airline will use to determine whether something should be done or not.

If the pump manufacturer introduces a product reliability improvement, it will be sold to the airline as providing X cents reduction in hourly costs of that LRU, along with X percent improvement in dispatch reliability. The airline will do a business case to decide if the long term saving is worth the up front expense.  They usually go by a payback period, where for example the projected hourly saving from doing an upgrade will pay for the cost of the upgrade within 5 years, or less depending on how cheap the operator is (over the last 10-15 years, a lot of US regionals have been only buying upgrades that pay for themselves in 1 year).


What material is used to make engine covers for passenger airliners?

There are potentially two answers to this question

If you are asking about engine covers used to keep debris out when the aircraft is parked like these

(source)

They are made out of any manner of fabric, nylon, canvas and often foam filled if they are inserted somewhere.

If you are asking about the exterior housing around an engine its generally aluminum like the rest of the aircraft. Much like the open panels that can be seen here.

(source)


What is this cylinder covered in threaded studs and what is it for?

It's the inner liner of a heat muff, either for cabin or carb heat (you can see the engine mount tubes right next to it and that's exactly where I'd expect to see it, and the black pucks behind are part of a nose gear shock absorber).  It could be home-made, using threaded rod welded to the inner liner, or maybe it's a manufactured component with the rods swaged in place like rivets.
An outer shroud will go around it with inlet and outlet bosses for SCAT hose running to the air inlet and outlet to the cabin or carb.  Sometimes springs are wound around, or some other metal that can act like cooling fins; some builders just stuff the space with stainless steel wool.
The threaded rods are to improve heat transfer from the inner shroud to the air flowing past them (the threads maximize surface area).  There will be a flange out of view at each end that creates an enclosed annular chamber.  The inner shroud itself typically has internal baffling to function as a muffler for the exhaust.  Crude sketch of what I mean below.  My own plane has this kind of thing, but without the studs, just an open space.


It varies.  Some airports charge by landing, others by operation (a series of landings if training).  Some charge through the FBO, who may waive the fee with fuel purchase.  Expect that multiple landings at BOS or JFK will result in multiple fees, often billed to the registered owner.  It was a while ago, but I did a series (about 12) of landings at BOS one night, and the owner/operator paid 25 dollars each. Someone told me recently that the fee was more like $65 now for a Cessna P210.

To be clear, call the airport and ask them, or check their web page, which may have their charges and rules on it.  And/or check with an FBO or two at the field.


From the FAA Chart User's Guide

  Minimum Safe Altitude (MSA)

  MSAs are published for emergency use on IAP charts. MSAs appear in the
  planview of all IAPs except on approaches for which a Terminal Arrival
  Area (TAA) is used. The MSA is based on the primary NAVAID, waypoint,
  or airport reference point on which the IAP is predicated. The MSA
  depiction on the approach chart contains the identifier of the
  NAVAID/waypoint/ airport used to determine the MSA altitudes. MSAs are
  expressed in feet above mean sea level and normally have a 25 NM
  radius; however, this radius may be expanded to 30 NM if necessary to
  encompass the airport landing surfaces.  Ideally, a single sector
  altitude is established and depicted on the planview of approach
  charts; however, when necessary to obtain relief from obstructions,
  the area may be further sectored and as many as four MSAs established.
  When established, sectors may be no less than 90° in spread. MSAs
  provide 1,000 feet clearance over all obstructions but do not
  necessarily assure acceptable navigation signal coverage.

  Terminal Arrival Areas (TAAs)

  The TAA icons will be positioned in the planview relative to their
  relationship to the procedure. The icon will not have feeder routes,
  airways, or radar vectors depicted. The TAA provides a transition from
  the enroute structure to the terminal environment with little required
  pilot/air traffic control interface for aircraft equipped with Area
  Navigation (RNAV) systems.  A standard TAA has three areas:
  straight-in, left base, and right base. The arc boundaries of the
  three areas of the TAA are published portions of the approach. A TAA
  provides minimum altitudes with standard obstacle clearance when
  operating within the TAA boundaries. TAAs are primarily used on RNAV
  approaches but may be used on an ILS approach when RNAV is the sole
  means for navigation to the IF; however, they are not normally used in
  areas of heavy concentration of air traffic.

  Non-standard TAAs may also be published; i.e., one base leg, no base
  legs.

To summarize:

MSA's are referenced to a primary navaid, waypoint or airport reference point associated with the IAP. They show safe altitudes for a 360 degree area around the reference.

TAA's are referenced relative to their relationship to the procedure.  Generally, that means one reference diagram for each IAF placed near the IAF depiction.


It is not a runway that you see there. It is the US Navy's Radar Cross Section Range at Junction Ranch. From what I know, that is the platform on which they put the object which they want to see the Radar Cross Section of on. There is a radar at the other end of the "runway".

This is what it looks like:

Image Source


Why do the two different "ground effect"s used by aircraft and automobiles do opposite things in almost the same conditions?

venturi effect occurs until the venturi is so extreme that the flow is "choked" and the venturi effect ceases to operate and you just have an air cushion? Is that the answer?

No. Neither answer to your linked question talks about venturi effect at all!

In the aircraft case the wing is still far enough above the ground there there is no significant venturi effect at all. The pressure field around the wing is still similar as in free flight, but because the air can't move down behind the wing, the effective angle of attack is decreased, which reduces the induced drag. It does not even increase the lift all that much, reduction of drag is the most significant effect.

In the car case the bottom of the car is much closer to the ground, but the venturi effect is still not the major part. The underside of the car acts as an inverted wing, which creates upward lift. The ground again prevents the, in this case, upwash, this time by preventing other air to fill in and this again reduces the induced drag. The point is again not creating more force, the point is creating the force with less drag, so the car can go faster with the same engine (most racing classes are limited by engine power or cylinder volume).

Also note that venturi effect would be always downward, so if it was true that venturi effect increases until it becomes “choked”, it would pull the aircraft (which has the wings higher, so definitely no choking) down and possibly (depending whether it would be choked under the car) push the car up, the opposite what is observed.


What exactly does "Commander" mean? Synonym of First Officer?

I know nothing about Cathay Pacific ranks/titles, but the plain words seem pretty logical.
The Captain, as Pilot In Command, is legally responsible for the entire flight. But who is actually in command while the Captain is required to be resting on long flights?
You don’t want the two most senior pilots resting at the same time; it would be unsafe to put a junior pilot in command for half the flight. So, you designate the second most senior pilot, who is still technically a First Officer, to be in command while the Captain is resting.


Yes, civil also aircraft have “Dry Bays” but they do not protect against fire. A dry bay is an area adjacent to a fuel tank that holds various components.

Some aircraft (mostly military?) have fire extinguishers or fire suppression equipment in dry bays but this will vary considerably with each type. (the B777 has no fire suppression in the dry bays)


Does opening of emergency doors over wings, lead to automatic lowering of the aircraft's wings?

Wings are static.

The wings do not move in response to emergency door opening. There is no requirement regarding position of flaps, in most cases involving an emergency evacuation after landing, flaps are likely to be extended, but I don't think this is guaranteed.

Evacuation assistance

On commercial transport aircraft, there are marked routes on the wing for passengers and, if the exit point is more than 6ft from the ground, there are self-inflating slides that allow passengers to reach the ground.

Image from video by "Airline_Alex"

Evacuation on water

The inflated slides also work as life-rafts in the event that the aircraft comes to rest in water and has to be evacuated. Generally this applies only to slides at main exits, over-wing exits have slides that are not designed to be used in this way.

 US 1549

Regulations

The regulations in the USA say

  Each passenger-carrying landplane emergency exit (other than over-the-wing) that is more that 6 feet from the ground with the airplane on the ground and the landing gear extended must have an approved means to assist the occupants in descending to the ground.

The manufacturer must demonstrate that they can evacuate all passengers and crew to the ground within 90 seconds using only half the emergency exits.

This applies to aircraft capable of carrying more than 44 passengers.

Variations in arrangements by aircraft

Not all aircraft need overwing exits and slides. Here are some B757 variants

From CRJ Resets

Boeing 737

As commenters have noted, the 737 does not have self-inflating slides for its over-wing exits.

Pessini

The 737 system does not always work very well

  Passengers climbed onto both wings, which
  were slippery due to the rain, but were able to see
  the markings indicating the direction of movement. It
  was difficult to see the ground in the dark and some
  passengers were not aware that they should slide down
  the flap surfaces. Others expected to find an escape
  slide. On the left wing, some passengers slid down
  onto the ground and assisted others. On the right
  wing, fewer people slid down to the ground, while
  others re‑entered the cabin and exited it using door
  escape slides when it was apparent that there were no
  visible signs of danger.

- from AAIB report


Nothing you say can convince this person that the Earth is round.  You need to show him.

Find a hill that is a few hundred feet high.  One of you stands at the top, the other at the bottom and observe the sunset.  You will, of course, be accompanied by a trusted flat-earth friend of his to validate your observations.

Each person will note the time that the sun disappears below the horizon.  Your times will be different.  You can even use math to calculate the expected time delta if you really want to drive your point home.  The higher the mountain, the greater the time delta.  Also, if you're at the top, you can flash him with a mirror to prove that you can still view the sun.  Be careful though...this might blow his mind.

This is a direct observation of the curvature of the Earth.  A rational person will accept this as proof of a curved surface.  An irrational bozo will continue to offer absurd theories.  Please let us know how your friend responds.


Airliner - "barking dog" after take-off and before landing

This sounds like the PTU, used to pressurize the hydraulic system when only one engine is running.

http://www.askthepilot.com/questionanswers/the-barking-dog-airbus-noises/


Do similar angles on a plane make it more stealthy?

The angle matters because radar works kind of like a mirror. Imagine holding a mirror out in front of you. If you start to twist it in any direction, you reach a certain point where the light coming off of you is no longer bounced back into your eyes, but is reflected off in another direction. Radar however cannot ever be completely reflected away, but this same principle allows a significant portion of the radar's energy to be deflected off in a useless direction, instead of back toward the dish.

The angles are similar because that angle was determined to have the smallest radar signature. So it makes sense that every other facet on the same (geometric) plane would be at the same angle. This means that the radar's energy is directed away in a very specific direction (away from the source), rather than a bunch of different angles (that would be more likely to return the energy to the source).


When does a pilot and when does a co pilot start/land?

You've asked a many-faceted question, the answers to which depend a little on FAA regulations in the U.S. but mostly on the policies and culture of individual airlines. Also, it's the captain's airplane, which means he/she may have, should we say, his/her own way of doing things. How much that might vary from the airline's "standard" can vary greatly, especially when you compare what would be typical in, say, the U.S. versus other countries, and especially third world countries. You could write a small book on this topic. A few items I can think of offhand follow.

All four of the airlines I flew for (two commuters and two 747 carriers) required the captain to do the engine starts. These days there is FADEC, so it's an automated procedure. Pre-FADEC, somebody had to move the lever that introduced fuel to an engine and, in the case of a hot-start, had to cut off the fuel and handle the heat properly. Failure to do so meant you might trash a multi-million dollar engine.

At all four of my airlines, the usual procedure was for the captain to fly the first leg and then alternate with the f.o. after that. At the two 747 carriers, however, new captains were required to do all the landings for their first 100 hours.

The second commuter I flew for had a rule that when the nose-wheel steering of the aircraft (SA-227 Metroliner) was inoperative, the captain had to taxi the aircraft.

The second 747 carrier I worked for had a rule requiring the captain to do all the taxiing. I ignored that rule as I felt it was unnecessary and ill-advised.

There were rules that required the captain to do approaches when the weather was below certain minimums.

The standard way of doing things was always well covered in initial and recurrent ground schools, simulator training, and CRM (Cockpit Resource Management) classes and sim exercises. IOE (Initial Operating Experience) for new cockpit crew as well as later periodic line checks by check airmen provided continuing standardization.

During a flight, the pilots continually talk to each other as required, and on long flights typically a fair amount of visiting, although below 10,000 feet only essential conversation is the rule. There is an old joke that goes something like, "When pilots are in the cockpit, all they talk about is women. When they're with women, all they talk about is flying." Obviously it's a sexist joke and is, I hope, disappearing with increasing numbers of women in the cockpits. It was never really true anyway.

Concerning verbal communication, both 747 carriers, as a part of Cockpit Resource Management had a procedure for handling subtle incapacitation of a pilot. If at any time you did not get a verbal response from your fellow pilot when a response would normally be expected, you were to turn to him and say distinctly, "Are you okay?" If they didn't answer, you were to take control of the aircraft.


What will be the performance penalties of increasing the wing area of a delta winged aircraft to obtain a lower approach speed?

What you describe would probably work. In fact rate of climb and operational ceiling would improve. So too would maximum payload. But Mach 1.4 would have been a bad joke.

But your question reads a bit like "How can we improve on the Mirage III wing without doing all the things that were subsequently done to improve on it?"

One approach taken on the contemporary Convair deltas; F-102, F-106 and B-58, was to apply leading-edge camber with a conical profile, apex at the root and widening towards the tip. Developed by NASA, the technique significantly improved low-speed handling and, because it was designed to stay within the root shock cone, had surprisingly little effect at supersonic speeds. The second two designs were both capable of Mach 2. Even the F-102 just about reached your Mach 1.4, despite poor area ruling.


What are the regulatory categories of aircraft defined by the FAA?

The FAA defines several different types of aircraft, which have different applicable regulations. For fixed-wing aircraft, airworthiness for normal, utility, acrobatic, and commuter categories is covered in Part 23.
Note: Seat number excludes pilot seats. Weights are maximum certificated takeoff weights.

Normal category

Seats: 9 or less
Weight: 12,500 lb or less
Allowed maneuvers:

Any maneuver incident to normal flying;
Stalls (except whip stalls); and
Lazy eights, chandelles, and steep turns, angle of bank 60 degrees or less

Utility category

Seats: 9 or less
Weight: 12,500 lb or less
Allowed maneuvers:

Normal category, plus:
Spins (if approved for the particular type of airplane); and
Lazy eights, chandelles, and steep turns, or similar maneuvers, angle of bank can be more than 60 degrees but not more than 90 degrees

Acrobatic category

Seats: 9 or less
Weight: 12,500 lb or less
Allowed maneuvers:

Anything not prohibited due to flight tests

Commuter category

Seats: 19 or less
Weight: 19,000 lb or less
Engines: 2 or more
Allowed maneuvers:

Any maneuver incident to normal flying;
Stalls (except whip stalls); and
Steep turns, angle of bank 60 degrees or less

  Except for commuter category, airplanes may be type certificated in more than one category if the requirements of each requested category are met.

Beyond commuter category, there is the transport category. Multi-engine airplanes satisfying either of the below requirements must be certified in this category. Airworthiness for the transport category is covered in Part 25.

Transport category

Seats: 20 or more
Weight: more than 19,000 lb

For rotorcraft, there are two main categories: normal and transport. Airworthiness for the normal category is covered in Part 27.

Normal category

Seats: 9 or less
Weight: 7,000 lb or less

Multi-engine rotorcraft satisfying these conditions may be certified under transport Category A (see below) if they satisfy certain conditions.

Airworthiness for the transport category is covered in Part 29. There are sub-categories here as well.

Transport category

Category A

Seats: 10 or more
Weight: more than 20,000 lb

Category B

Seats: 9 or less
Weight: 20,000 lb or less

If a rotorcraft only satisfies one of the requirements for Category A, it may be certificated under Category B with certain additional requirements.

  A multiengine rotorcraft may be type certificated as both Category A and Category B with appropriate and different operating limitations for each category.

There is also a manned free balloon category covered in Part 31.

  A balloon is a lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater.

Part 21 addresses the certification process itself, and includes special types of certificates for other aircraft.

Primary category

Power sources allowed:

None
Single naturally aspirated engine (stall speed 61 kt or less)
Rotorcraft with 6 lb per square foot main rotor discs loading limitation (sea level standard day)

Weight: 2,700 lb or less (seaplanes 3,375 or less)
Seats: 3 or less
Unpressurized

The restricted category allows a plane to not meet certain requirements under the normal regulations. The aircraft must meet one of the following conditions:

Restricted category

Requirements of any regular category, except any that are "inappropriate" for the aircraft's purpose
Armed Forces aircraft modified for a special purpose

US Armed Forces surplus aircraft can also be certified under one of the below conditions. The FAA has some leeway to waive requirements or add additional ones.

Surplus aircraft of the Armed Forces

Designed and constructed in the US, satisfies certain regulations
Counterpart of previously certified civil aircraft, complies with those regulations

Special certificates are issued for cases where the aircraft is not certified under the regular categories. These allow operation of certain aircraft for certain purposes.

The experimental certificate is for special cases.

Experimental certificates

Research and development
Showing compliance with regulations
Crew training
Exhibition
Air racing
Market surveys
Operating amateur-built aircraft
Operating primary kit-built aircraft
Operating light-sport aircraft

The light sport certificate is for light aircraft that may be operated under special conditions. There are 5 categories of LSA.

Light sport certificates

Airplanes
Gliders
Powered parachutes
Weight-shift-control aircraft (commonly called trikes)
Lighter-than-air aircraft (balloons and airships)


How did pilots maintain the Vomit Comet's parabolic trajectory?

The NASA Vomit Comet was flown manually.
From The dynamics of parabolic flight: flight characteristics and passenger percepts

The control inputs required by the pilots of a parabolic flight aircraft are relatively simple, although precision is required to make the 0 g phase as close to freefall as possible, and care is required not to exceed the load limits of the aircraft which at times flies near its maximum rated speed. The pilots modulate lift L with the elevators and wings, which indirectly changes attitude θ, and thrust T with the engines (Figure 5).

....The pitch angle of the aircraft is not directly controlled by the pilots, but is a secondary result of other control inputs. During level flight the wings produce an upward lift, while the tail-mounted elevators produce a small downward component of lift in order to maintain a desired pitch angle. When flight conditions change, such as when the pilots deflect the elevators down during freefall, the relative forces from these two surfaces change. Since their moment arms are different, this causes a shift in the center of lift so that it no longer coincides with the aircraft center of gravity, resulting in a torque that causes a pitch rotation of the aircraft.

..At approximately 225 KT IAS (360 KT TAS, 185 m/s, Mach 0.61), when the aircraft is pitched nose-up 45°, the pilots commence the 0 g parabola. They push forward on the control yoke ("push over") to lower the angle of attack of the wings, which reduces wing lift, and simultaneously reduce power to a level just sufficient to overcome drag.

...After 25 seconds, at the end of the parabola, when the nose is pitched down 45° and airspeed is close to 350 KT IAS, the pilots pull up (pull back on the control yoke) and increase thrust to change the aircraft’s downward velocity into upward velocity, and restart the cycle.


Third Class medical license, what changed, if anything?

Short answer: politics killed the "driver's license medical" idea for private pilots, but there are still reasons why BasicMed has significant advantages for some pilots.

The literal answer to your question is "nothing": the third-class medical hasn't changed at all. What you're referring to is an additional option called BasicMed, which you can hold instead of (for some operations) or even in addition to a third-class medical.

I won't get into the details of BasicMed itself (the regulations are in 14 CFR 68), but AOPA has a lot of great information about it. Instead, I'll focus on your "why is this any better than a third-class medical?" question, which seems to be quite a common one right now.

In summary, if you're under 40 and healthy then BasicMed may not seem very interesting. But if you're over 40 and especially if you currently have a Special Issuance then BasicMed could be a much easier and cheaper way to fly.

As you said, as a new pilot you still have to pass a third-class medical once so let's assume that you've done that successfully. It's certainly true that some people aren't happy with that requirement because they were hoping for a "driver's license medical" where a private pilot could fly without any medical certificate, as sport pilots can do. That idea didn't survive the political process, however. If you want to fly without any medical you still have gliders, ultralights or LSAs.

But when it comes time to renew, here are some reasons that you might consider BasicMed (most of this information comes from the AOPA FAQs):

If you're over 40, you need to renew a third-class medical every two years, but you only need to see a doctor every 4 years under BasicMed
Special Issuances still exist under BasicMed but for a more limited number of conditions than for a regular medical. Practically, that means you may be able to avoid expensive tests that the FAA requires for a third-class. This is a huge benefit for some pilots because it can save a lot of time and money (health insurance typically doesn't cover 'unnecessary' tests).
Any state-licensed physician can sign off on BasicMed, but only an AME can sign off an FAA medical. That means in theory it should be easier and cheaper to find a doctor for BasicMed. In practice people's experiences have been mixed on this, but BasicMed is still very new and it's not surprising that some doctors may not be comfortable with it.
Because the BasicMed medical questionnaire is effectively a general physical exam, some people have successfully combined it with an annual checkup paid for by their health insurance

There may be other reasons, but those are some common ones I've read about. If you're a member, the AOPA forums have a lot of discussions about individual experiences.


How do I modify the aircraft weight and balance after a battery replacement?

Is the Concord battery on the approved equipment list?  Is it approved to be in your airplane due to it being PMA'd?

The point is that the battery has to be approved by the FAA and if it isn't you'll need to get it approved.  It's not a major redesign requiring form 337 but a minor alteration to it's approved type certificate.

To answer your question, you can alter your weight and balance but it must be signed off by an A&P mechanic.


Does 14 CFR 91.146 (Charitable Events) apply if the pilot does not seek compensation or hire?

Let's look at this from two angles -- first, what's OK under 61.113 (basically "no compensation except the pro-rata sharing of expenses" when acting as a private pilot).
The FAA has an incredibly broad interpretation of "compensation" - The foundational counsel opinion is an interpretation to Joseph A. Kirwan, and if you search counsel opinions for Kirwan you find a bunch of additional opinions referencing it.
Basically Kirwan and the other opinions state that the receipt of anything of value is compensation.
That could include:

Money, obviously.
Free or discount fuel/oil
Free meal
Lodging
Logging of flight time (if you're not responsible for the operating expenses of the aircraft)
The receipt of a benefit (usually money) by the organizer (charity)
(Weybrecht, 2010 - if they get the ride in exchange for a donation or attendance fee it's 91.146)
"Valuable Good Will"
(Again in Weybrecht from above - so yeah, If you fly your buddy somewhere and they "owe you one" that might be a violation.)

There's really almost nothing you can do under 61.113 except fly somewhere for a hundred-dollar hamburger and split the cost of gas (under the FARs you even have to pay your pro rata share of the burger) - it's very restrictive.

Now let's look at 91.146 - like DJClayworth pointed out what this  basically does is carve out a small set of exceptions that allow community groups and charitable organizations which have friendly pilots to offer "airplane rides" in exchange for a donation without being in violation of the FARs (risking the friendly pilot's certificate, and the possible wrath of the FAA on the organizer).
There are lots of restrictions (Like the 500 hour requirement, the requirement that flights be "Nonstop, beginning and ending at the same airport, and within 25 miles of the airport of origin", the limit of reimbursement for the pilot being "pro rata share of expenses", and notification of the local FSDO).
The FAA wants to basically make sure pilots are not flying tons of these charity flights every year to basically build time, and that charities aren't operating de facto air tour companies under the exemptions of 91.146.

So what's the answer to your question?
Basically If the organization is getting donations/admission fees/raffle proceeds, etc. in exchange for these flights the operation falls under 91.146 (because the charity is receiving compensation -- the donation).


How is metal fatigue detected in an aircraft?

How do the engineers, maintenance team, etc know if an aircraft has metal fatigue?

First of all, is not an "aircraft" that has fatigue, but a component.

To the naked eye, there is no way to detect metal fatigue until it starts being too late: you can only see cracks that are already forming and/or propagating.

There are tools available to allow for early detection, my bachelor's thesis was about one of these: the photoelasticity of certain materials is used. A light coat of one such material is applied on the new component and the photoelastic properties and exams done during the lifetime of the component tell the maintenance people what is the current status of the inner layers of the piece.

Another method uses electric resistance, as metal fatigue, by cracking the metal, increases the resistance.

Depending on the scenario, X-rays could also be used.

  What do they do to "minimize" metal fatigue or repair it?

You cannot minimize fatigue, once it starts setting in, it is an irreversible process. You can delay the likely catastrophic failure by applying strengthening elements around the affected one, but the safest course of action is to replace the component and recycle the old one.


Why do airplanes start descending when we initiate a left turn?

This is because when you roll left (or right), the lift changes from pushing up to pushing up + left. This is what makes you turn. Since some of that lift is being used to the left, not as much is pushing up, causing the plane to lose a bit of altitude. On FlyByWire aircraft, since it is computer controlled, the computer automatically compensates for this by adjusting elevators to pitch up slightly.


Why do low wing aircraft have higher dihedral than high wing aircraft?

There are several sources for a sideslip-induced rolling moment:

The dihedral angle $\nu$ of the wing, which will increase the local angle of attack $\alpha$ on the windward wing according to $\Delta\alpha = \beta\cdot sin\nu$; $\beta$ being the angle of sideslip,
The sweep angle $\varphi$ of the wing, which in a sideslip causes a de-sweeping of the airflow over the windward wing (and an increased sweep effect on the leeward wing). The local change in angle of attack is $\Delta\alpha = (cos(\varphi±\beta)-cos\varphi)\cdot(\alpha-\alpha_0)$ and is proportional to the angle of attack,
The crossflow around the fuselage (see sketch below for illustration, sorry, no simple formula here), and
The location of the vertical tail, or more precisely, the side force created on it by a sideslip angle in relation to the location of the center of gravity. This effect dictated the anhedral of aircraft like the F-104 Starfighter.

Please see this answer for a more complete explanation of effect 3. The sketch below is taken from the linked answer and shows a high and a low wing configuration in sideslip. The thin blue arrows indicate the sideways component of airflow $v_{\infty}\cdot sin\beta$.

In the end, some rolling due to sideslip is good, but too much must be avoided, and dihedral is used to complement the other effects such that the total is just right. A high wing already provides some positive rolling moment due to sideslip (negative $c_{l_{\beta}}$: When you deflect rudder to the left, the resulting sideslip should roll the aircraft to the left, too), so the wing doesn't need to contribute as much (by means of dihedral) as in low wing aircraft.

Dihedral (or for that matter, even a low center of gravity) will not roll the aircraft level: There is no aerodynamic way to achieve that! Dihedral will only give you a rolling moment when the aircraft sideslips.


What is the FAA's definition of "for hire"?

Without combing through the regulations, and the vast collection of LOI on the subject, I will give a general answer.

For hire for the purposes of 91.409 applies to the carriage of persons. So the carriage of a student pilot, with a flight instructor is "for hire."  The carriage of people receiving a scenic tour that they paid for, is "for hire."

If you belong to a flying club, essentially operated as a partnership, then the aircraft is not for hire, as the fixed and variable expenses are shared among the members of the club.  Essentially, you are paying your share for your aircraft, assuming the club or partnership owns the aircraft.  In that case the landing light and 100 hour examples do not apply.

In general, if operating part 91, and the pilot is paid in furtherance of the part 91 entity, then for hire does not apply. This would include for example a corporate pilot, paid by the owning entity of the plane.

In general, flight instruction is not considered a for hire operation, when the person receiving instruction is one of the "owners" of the plane, as in a partnership or flying club.

So, you have some examples for your second to last question.

For the last question, it covers the operation, and the purpose of the operation. So your paid pilot flying your TBM taking your family to your private island, is not for hire.

There are no less than 20 FAA Letters of Interpretation which have been written on this topic. The interpretations have even impacted states and how they charge sales and use tax.

Addendum #1: For the FAA, under 91.409, the term "for hire" applies to the carriage of the aircraft.  So if a flight school owns a plane, and a student gets instruction in the aircraft, it is subject to 100 hour inspections, because the student is being carried by the plane and CFI which the flight school is providing.


Can I derive the wind speed and direction?

No, you need the True AirSpeed (TAS).
The Indicated AirSpeed is not a realiable measure of it, since it is not even calibrated against the instrument mounting position and is not intended to measure the speed relative to the airmass (what you actually need to derive the wind components).


Why don’t aircraft undergo contaminated-runway landing-distance and rejected-takeoff certification testing?

Baseline performance data was developed some years ago by an FAA test program called the Joint Winter Runway Friction Program to develop mathematical models of the effects of the different types of surface contamination.  Manufacturers apply the models to develop their own aircraft's performance correction factors for various contaminated runway conditions.

Otherwise, as Ron comments, the manufacturers would have a massive test burden to develop customized data for a huge range of contaminants, and would have to go find the test conditions somewhere for each, adding eleventy jillion dollars to the typical development program.  The mathematical models, along with the safety factors built into the calculations, do the job just as well.

This Advisory Circular talks about it.


Just how inaccurate are (Las Vegas) VOR radials?

I guess it depends on what you consider to be a "high level of integrity and safety." VOR is a perfectly acceptable means of navigation if you know how to use it. And, I guess, if the transmitter hasn't been flooded.

Let's take a look at the data for the Las Vegas VOR:

Now, that does look like a lot of "unusable" radials, but it's not actually as bad as your friend claims. First of all, you're not "only" guaranteed service on legs of instrument approaches. You're also guaranteed service along Victor airways, and within a standard service volume. Think about it: certainly you can't expect to pick up the Las Vegas VOR in Florida. So where should you expect to be able to use it? The answer is on flight tested legs (approaches and airways) and within its service volume. According to the AIM, a VOR must "conform to flight inspection signal strength and course quality standards throughout the published SSV". The (H) after the VOR name indicates that Las Vegas is a high-altitude VOR. Let's look at its service volume:

Notice first that the service volume only has a radius of 40 NM to begin with at low altitude. Most of those cutout unusable radials reduce this to 35NM instead. So it's not that much of a cut. And above 16,500 feet? It's all usable, and that's where most of its service volume is. So in fact, the vast majority of the Las Vegas VOR's service volume is usable, that is to say, meeting FAA standards of signal strength and course quality.

Where it doesn't, it's usually because of terrain in the vicinity of the transmitter. As a radio signal, the VOR beacon bounces off of nearby hills and mountains.

Now, what does it look like to the pilot using the system if they're in one of those unusable regions and not receiving an adequate signal? VOR receivers are also FAA approved and if they are not receiving a strong enough signal with enough integrity, then they will display a flag. It should not present totally false data without a flag. The problem with your Ethiopian flight seems to be that the VOR transmitter was transmitting the wrong info, which of course the receiver can't know anything about and it did not flag.

That would be a pretty terrible scenario. That is not what is ever going on around Las Vegas. NAVAIDS in the USA are monitored for integrity. The worst that will happen in a receiver in Las Vegas will (hopefully) be a flag that indicates the receiver is not receiving an adequate signal.


How were large pieces of the A300-600ST and the B747LCF transported?

The answer may be that parts were transported the same way A380 parts were transported

  The A380’s size means its fuselage and wing sections are shipped via a surface transportation network that includes specially-commissioned roll-on roll-off ships to carry these sections from production sites in France, Germany, Spain and the United Kingdom to the French city of Bordeaux. From there, sections are transported by barge along the Garonne River to the Toulouse final assembly line.

From Airbus - TRANSPORT OF MAJOR AIRCRAFT SECTIONS

According to All about Guppys

  The A300-600ST was built in Toulouse, France.

All the smaller pieces would have fitted into an existing transport aircraft.


What does it mean when your destination airport is currently "below IFR minimums"?

It would be very helpful to know where you read or heard the phrase, to get some context. But, it likely means that weather conditions at the airport are below the IFR takeoff minimums in 14 CFR 91.175:

  (f) Civil airport takeoff minimums. This paragraph applies to persons
  operating an aircraft under part 121, 125, 129, or 135 of this
  chapter.

  (1) Unless otherwise authorized by the FAA, no pilot may takeoff from
  a civil airport under IFR unless the weather conditions at time of
  takeoff are at or above the weather minimums for IFR takeoff
  prescribed for that airport under part 97 of this chapter.

  (2) If takeoff weather minimums are not prescribed under part 97 of
  this chapter for a particular airport, the following weather minimums
  apply to takeoffs under IFR:

  (i) For aircraft, other than helicopters, having two engines or less—1
  statute mile visibility.

  (ii) For aircraft having more than two engines— 1⁄2 statute mile
  visibility.

  (iii) For helicopters— 1⁄2 statute mile visibility.

Landing minimums are per-approach so it wouldn't make sense to say that the whole airport is below IFR minimums based on landing criteria. However, without reading or hearing the phrase in context, I may be wrong.

As for landing there anyway, even in zero visibility a private pilot operating under part 91 is free to take off, or to start an instrument approach. You can't legally land if visibility is below the approach requirements, but you can still fly the approach to 'take a look'. It might not always be smart, but it's legal.

On the other hand, commercial flights under part 135 or 121 can't even start an approach unless conditions are above certain minimums (e.g. see 135.225(a)). Those minimums are usually just the ones required for the particular approach, but they can also have operator-specific requirements. Of course, many commercial aircraft have crew and technical capabilities that light aircraft don't (like shooting a CAT III ILS), so they might still have a better chance of landing in marginal conditions.


Is this "bearing" sentence utterly incorrect?

Short answers

Here's my answers to your questions, in order:

Yes, you are correct that the quote is wrong.
Yes, you are being too dogmatic.

2(a). By the way, you are also wrong.
The quote is incorrect.  Bearing is properly used the way you describe.
I misuse words all the time, but it's not common for me (or anyone I know) to swap bearing and track.

Longer explanation

The quote isn't correct because magnetic track properly refers to the actual direction that the aircraft is moving, as read off the magnetic compass. However, you say that you refer to:

  the "forward course of the aircraft" as either track or heading. (Track, vector over ground, heading, z-axis of vehicle airframe.)

Track and heading are not the same thing, and neither one is necessarily the forward course of the aircraft.  Track is the actual vector over the ground.  Heading is the direction in which the longitudinal axis of the aircraft is aligned.  Course is the correct word for the forward course of the aircraft; the intended (not actual) vector over the ground.

So you've got the definition of bearing right, but you've got track, heading, and course all mixed together.

I've been known to say "bearing" to mean "track", but it's usually only just after I've said "What be our", and just before I'm about to say "ye scurvy dog?"


Is it fairly common for student glider pilots to have wing tip strikes, especially in gusty cross wind conditions?

Most gliders have dihedral, giving more wingtip clearance than you probably are envisioning.  Many glider pilots routinely use the wing-down (slipping) method of crosswind correction.
As far as general handling while landing in gusty crosswind conditions, most tailwheel airplanes sit in a much more nose-high attitude than most gliders, and have the landing gear much further forward ahead of the CG, and therefore are much more prone to ground-looping.  And groundloops often involve wingtip contact with the ground-- on the downwind side.
On the whole the crosswind limits below which a safe landing without damage to the aircraft can reasonably be expected, are likely higher for most gliders than for most tailwheel light airplanes.
As for the part of your question contained in the actual title-- no, it is not common for student glider pilots to strike the wingtip into the ground before the main wheel touches.


On average, how often (in flight hours) will a pilot face an emergency situation?

The answer is going to vary wildly according aircraft type, pilot rating and proficiency, number and type of engines, aircraft size, and part of the world.

In this 2016 study by the FAA for GA pilots, the median period of time for non instrument rated pilots was over 3 times as often as instrument rated. 250hrs vs 823hrs. The report describes some of the hardships involved in arriving at the less than precise determination.

I have asked this question to many airline pilots and about half of the 4000-6000hr pilots have a story to tell. Just guessing but I would say modern airliners are perhaps every 10,000 hours.

I must be doing something wrong, because I averaged about every 500-600hrs but then I was mostly flying very old run down Beech-18's in Alaska.


Does a CFI have to be a CFII to fly with a student in IMC?

No, a pilot with CP-ASEL-IA and CFI-ASE who is instrument current can take a student into actual IMC, and can even log it in both logbooks as dual training if the instruction is on the area of operation described in FAR 61.107(b)(1)(ix) "Basic Instrument Maneuvers" (etc) because that AOA is towards a private pilot certificate. However, this would be a Dumb Thing to Do because a CFI with no -I does not have any training flying instruments from the right seat, which is a skill that takes quite a bit of practice.

The thing that a CFI-I allows a person to do is to provide training on the areas of operation in FAR 61.65 towards an instrument rating.


What are the lowest authorized minimums for each ILS category?

As Carlo mentioned in the comments, the minimums may vary from place to place to place. Here in the US you can find all that information here. Or you can buy a printed copy from a variety of aviation suppliers.

This order published in 2012 sets some minimum performance guide lines for minimums as well. For example,

  (2) The following is the minimum class of performance (refer to
  Appendix B) required for an ILS to support a published Title 14 of the
  Code of Federal Regulations (14 CFR) part 97 CAT II or III SIAP:

  Class II/T/2 for operations not less than RVR 1200.
  Class II/D/2
  for operations not less than RVR 1000.
  Class III/D/3 for
  operations not less than RVR 700.
  Class III/E/3 for operations not
  less than RVR 600.
  Class III/E/4 for operations less than RVR 600.

See appendix B in that order for more information.

This may also be of some interest.


How heading bug is calculated during cross wind and tail wind?

First thing first, let's go over some concept: heading is which way the plane's nose is pointing at, track is which way the plane is travelling on the ground. E.g. if your heading is 360 (North), and the wind is blowing from 090 (blowing East to West), the plane's track may be 350 (slightly left of North).

With that in mind, it's not hard to deduce most of the time pilots want to fly track, rather than heading. The purpose is to navigate from point A to point B on the ground. In our example, you have to turn the plane slightly to the right to compensate for the crosswind. To figure out exactly how many degrees to turn, you will first need to decide how fast you want to fly. After that, it's simple geometry.

A mechanical flight computer can be used to calculate the drift angle easily. Using it is a matter of marking dots on a transparent disc, then sliding and rotating it to the correct position and read off the pre-calculated figures below.

If you are flying manually, or flying a plane with an elementary autopilot, you will need to calculate the drift angle, then add (or minus) that to your desired track to get the heading. You will then set the heading bug to that value. Theoretically, that heading should compensate just enough crosswind that you stay on your desired ground track. In practice minor adjustments are often necessary. Provided that the numbers you use are not awfully off, you should end up with an estimation good enough for the safety of your flight.

If you are flying a plane with an advanced flight computer which has the ability to detect winds aloft, your autopilot will fly the track you dial in and automatically compensate for crosswind.

So to answer your questions:

You will use simple math or tools to compute the heading which will let you fly the desired track.
It does not matter when you have an exact headwind or tailwind.
Heading bug denotes the desired heading, not track. You always turn your plane towards the heading bug.
Advanced autopilot fly track, fundamental ones fly heading. Some autopilots can read the heading bug position on the instrument, others must be set explicitly on another panel.


What is the differences of ADS-B and geometric height?

ADS-B, and the older Transponder Mode C, report pressure altitude. That is static pressure where the plane is expressed as altitude at which that pressure occurs in international standard atmosphere.

In low pressure area, the same pressure density corresponds occurs at lower geometric altitude with similar difference at all altitudes. In higher temperature, the air is denser and the isobars closer together, so the same pressure altitude occurs at lower geometric altitude and the difference increases with altitude.

However for purpose of traffic separation, pressure altitude is always used. Due to physical properties of air, the pressure always decreases with altitude and at the same altitude changes only slowly with position, so we can always rely on close aircraft observing sufficiently different pressure altitude being at sufficiently different geometrical altitude.

The reason is that while barometric altimeter is simple, accurate to less than 100 ft and every aircraft has it since the early days of aviation, there was no way to measure geometric altitude before selective availability was turned off in GPS in 2000.

Geometrical altitude is altitude above the reference geoid (usually WGS84), a.k.a the sea level. It is only used internally in EGPWS where it is provided by GPS.

In contrast height is in aviation always used to mean height above terrain. It may be measured directly using radar altimeter or it can be estimated from pressure altitude by correcting for sea-level pressure at the nearest airfield.

Radar altitude is used in GPWS as a backup datum and in older such systems  from before GPS was available (those systems could warn if you were too low, but not if you were approaching high ground, because the radar altimeter only measures down while the new GPS-based systems have a terrain map and compare the GPS position with it) and is shown to pilot for reference, but it is not broadcast anywhere.

Approaches are normally flown in reference to the barometric altitude that is corrected for pressure at airport (the altimeter has setting for reference sea-level pressure, QNH), but not temperature. So the barometric altimeter shows true altitude at the airport, but when it's cold, it shows more than true altitude above. That's why some approaches have minimum temperature.

However, both Mode C and ADS-B broadcast pressure altitude, i.e. as calculated for standard pressure of 29.92 inHg/1013 hPa.


How is the central hub / shaft casing of a two-spool jet engine assembled?

The first thing to know when designing jet engines, is everything leaks. But the OD of the engine core is generally pretty tight. This is achieved using large solid structural pieces, for example the entire LPT outter casing is generally one piece. These large pieces are bolted together with an excessive number of bolts to make them very tight. Any penetrations will have various types of seals and gaskets, as well as high clamping forces. Although the outer case is pretty tight, the cavity between the core case and the bypass duct is still actively purged with air from the low pressure compressor (labelled as undercowl cooling on the image below).

GE90 Engine Airflow Diagram (This is actually a widely available training poster but I stole it from here, you can find similar for just about every engine)

As for the inner side of the core, this is where literally everything leaks. As you can see in the picture above, Stage 1 (S1) High Pressure Compressor (HPC) bleed air is used to actively purge the cavity under the Low Pressure Compressor (LPC) and early stages of the HPC. It is then plumbed though a small duct around the low pressure shaft to the Low Pressure Turbine (LPT) (zoom in on the image and flow the arrows in the yellow fill).

Your location number 1 is the split between the LPC rotors (spinning) and the Fan Frame (stationary). Your location number 5 is the split between the LPT (spinning) and the turbine rear frame (stationary). In these locations (and in all gaps in the ID of the core) the air is allowed to flow back into the flow path. The purge air must be at a higher pressure the flow path air, and allowing it to flow back into the main flow path actively purges these gaps and in the turbine prevents hotter gas path air from backflowing into the rotor cavity.

Your location 4 is at the end of the compressor and beginning of the combustor and is known as Compressor Discharge Pressure (CDP) air. The image below (source) shows what is going on here. A faction of the air is directed directly into the combustor through the fuel nozzle assembly, while the rest bypasses and is used as dilution air, as well as combustor liner cooling. Another faction is taken off the OD to cool the S1 HPT Vane and Shroud, while a larger fraction is taken off the ID to cool the S1 HPT Vane, Blade and rotor, as well as actively purge the gap between the S1 blade and vane. If this cooling air was ever lost, the HPT would literally oxidize/melt/creep away in a matter of seconds. The gap at location 4 is sized so the correct about of flow goes into the combustor dome and the right amount bypasses the fuel nozzles. Note that in ultra modern combustors, the diluation holes no longer exist and a much larger fraction of air enters at the fuel nozzle location.

Torque is transferred from the HPT to the HPC through the spool arms (basically a shaft), which is what connects each rotor to each other. I have highlighted this in red in the image below. The full spool is created in multiple ways. Some of the HPC rotors are forged together into sub-spools. Some of these sub-spools are welded together (becoming more common) and then some joints are done with bolts. In the second image below, is the HPC spool for the CFM56, I have circled the bolted connections. Bolts are generally used when there is a change in materials so welding can't be done. The first couple of stages will be Ti, while the later stages are a Nickle based super(ish) alloy. The HPT rotor is a Nickle based super alloy but is generally being pushed to the limit too much to be welded. When it is all put together, you have a very stiff shaft.

 (Source PDF)

The stators are attached to the outer casing. Generally there is a circumferential slot in the case, the stators slide into this slot. Generally the stators are brazed together in multi-vane assembles to reduce air leakage. There is also a labyrinth seal on the ID of each stator to reduce air leakage.

The S1 and S2 HPC rotors (your location 2) have a larger ID than the other rotors so they can fit over the bearing race when they are unbolted from the spool and to allow tool access to the bolts. The S3 rotor is the largest because it support the arm going to the bearing, a still largish blade and the bolted joint of the spool join. As you go aft the rotors get a little smaller because they support smaller blades, but that is counter acted by raising temperatures that reduce the material capabilities.

Overall engine assembly (Youtube Video of GEnx-2B being assembled). Depending on the engine it'll be assembled from Fan back or LPT forward. So from LPT forward (Very simplified). First take the built up LPT module and attach the LP shaft (aka fan shaft/fan mid shaft). Next, you would build up the HP section including outer casing seperately, then slide this onto the LPT, attach the HPT outer casing to the LPT case with an excessive number of bolts, if there is a mid turbine frame it would be installed between the two turbines with bolted joints on both sides. Then you install the fan frame to the HPC case and then the fan spool to in the LP shaft and the fan case to the fan frame. With the right tools, it all slides together pretty easily. One way the LP shaft is connected to the LPT and Fan Spool through splined connections and a large coupling nut is installed on each end of the shaft to prevent the splines from backing off. Sometimes the shaft is bolted directly to the LPT or Fan spool directly.

Sorry for being so long winded, but I hope that answers your questions.

Here is one more flow diagram for reference (source):


Airbus is to fly-by-wire as Boeing is to...?

Boeing uses a more direct approach to control (but both systems have warnings). In short it boils down to who has final authority of control surface actuation. Fly by wire does not just mean that control surfaces are controlled electronically (even the Cessna 172 has electric flaps) but that a computer in some way takes the pilot (or pilots) inputs and generates a control surface output. In the airbus case the computer has the final say, so if the pilot commands the plane to do something it should not, the computer will not move the control surfaces and allow it to enter such an attitude or speed. Boeing takes the reverse view and gives the pilot final authority so what ever control inputs are made translate to control surface movements.

With that in mind Boeing does have things like a yoke shaker in the event of approaching a stall and a yaw damper etc. Airbus will allow full control surface actuation with Direct Law however the plane is not normally in this mode. Boeings Standard protections and augmentations is similar but will allow the pilot to enter the conditions

  "...to inform the pilot that the command being given would put the
  aircraft outside of its normal operating envelope, but the ability to
  do so is not precluded."
  (source)

On the contrary vertical stick motion in an airbus in flight actually controls load factor and not necessarily pitch directly. So its always some form of proportion to the aircrafts speed.

If memory serves Boeing control surfaces are set up such that movement of one yoke will move the other yoke in tandem, likewise they can not be simultaneously moved in opposite directions while airbus controls can be moved in opposite direction and the computer will summate the inputs (although an override button is present on each stick to disconnect the others should something be improperly acting on it).


How much energy is "wasted" in an aeroplane's descent?

A meaningful numeric value is going to be hard to calculate, because so much depends on the aircraft you're working with.  In practice, if I can pull off power at the calculated Top of Descent point, descend, meet any ATC crossing restrictions, fly the approach, configure as late as possible, and push up the power right at the point where I'm required to be stabilized for the approach, then I've flown an efficient approach & wasted none of the energy that I started with.

If I have to add power sooner than that, I started down too soon (or wasted energy in some way); if I have to deploy drag (which includes configuring early), then I started down too late & so I have excess energy that I need to dissipate.

I suppose "amount of time speedbrakes were up" would be one way to score how much energy had to be wasted; add to that how long flaps & gear were out before they were "needed" (given the requirement to be stabilized & configured at a given point in the approach).

Here's the complication, though.  If I see early on that I have too much energy, I can push the nose down & gain speed, which increases the parasite drag of the aircraft -- thus dissipating energy.  If you have enough time at the higher speed (not just push the nose down, gain speed, pull the nose up, lose speed -- that doesn't accomplish very much), then you can get rid of excess energy without having to deploy speedbrakes or configure early.  And the reverse, if my standard descent is at 280 knots (above 10,000', obviously) but I slow up to 250 knots early enough, I can "gain" some energy, since I'm losing less with less parasite drag.  How you could account for all of that in a "score" is beyond me.

In the ideal case, I can descend to glideslope intercept altitude, level off there, let the speed decay, then at the point when I need flaps to fly any slower, I extend the first increment of flaps, let the speed keep dropping off, start down the glideslope (speed decreases more slowly or if the aircraft is light enough, not at all), at about 500' above the "stabilized approach" gate I'll lower the landing gear & extend more flaps, so that as I approach that gate I'm extending the last increment of flaps, my speed reaches VTarget, and I add power.  No extra time with power above idle, a fuel-efficient approach.

ATC may not let me do that, though; they may keep me fast until close to the runway, in which case I'm extending flaps & gear closer to their maximum speeds so as to dissipate more energy more quickly and still be configured & stabilized at the appropriate point.  (The 737 dissipates speed pretty quickly fully configured at idle power, even descending on the glideslope.)  So did I "waste" some energy in that scenario?  Yes.  But keeping ATC happy so they can get efficient runway utilization is a worthy goal as well.


Yes. Your interpretation is the correct one. Several FAA legal interpretations cover the "calendar months" phrasing; the best I could find was the Harvey interpretation from 2012:

  Based on the facts that you have presented, a biennial flight review accomplished on April 2, 2002, would not lapse until May 1, 2004.

Basically, your flight review is legal until the end of the month (ie, June, or August) it was completed in two years before. The same calendar logic applies to maintenance like the annual inspection.


What is the broadcast rate of an ADS-B message?

It depends on the Message Format TYPE Code and the aircraft state. In your example, being on final approach would have no effect as the primary state criteria is being airborne (vs. surface). The rates are 'nominal' rates in that there is a programmed 'dither' to the nominal rate to avoid synchronous garble.
The nominal rate for TYPE codes 1 through 4 (ID and Type) is 5.0 sec airborne and 10.0 sec surface.
TYPE Codes 5 through 8 (Surface Position) rate is 0.5 sec in motion and 5.0 sec when stationary.
TYPE Codes 9 through 18 and 20 through 22 (Airborne Position) rate is 0.5 sec.
Type Code 19 (Airborne Velocity) rate is 0.5 sec.
Type Code 28 (Aircraft Status, e.g. emergency/priority) rate is 1.0 sec.
Type Code 31 (Aircraft Operational Status) rate is 1.7 sec.