Do carrier-less militaries maintain carrier qualifications on allied boats?

The problem with the carrier landing is currency and recency of experience

  Example of use would be in an emergency, i.e., land their F/A-18's on
  a US carrier even though they won't be able to takeoff, and the
  aircraft will likely need to be shipped.

The approach to landing on a carrier is a specific technique, wherein an angle-of-attack approach is flown all the way to the deck(and a very firm landing) with the intent of landing on the centerline and catching the 3-wire.  An acceptable approach catches any of the wires (there are 4).  The counter intuitive(for someone not trained in CV landings) advance-throttles-to-full- power-upon-landing ensures that if the wires are missed (Bolter!) one goes around and tries again if there's enough gas.

An approach to an airfield typically does not entail this, but instead includes a higher speed approach, and a flare which reduces the impact force on the aircraft (but of course requires a lot more runway).

If the pilot of the F-18 has never had the initial qualification on a carrier(which takes hundreds of field landings and a Carrier Qualification flight), making that approach becomes a non-trivial exercise in risk assessment.

If you aren't trained for it, why are you doing it?

Is the captain of the ship willing to risk a mistake that will damage dozens of aircraft on the deck and perhaps kill a few people?
Is the pilot willing to risk the approach that he or she is
untrained for, with the known lethality of failed attempts?

The severity of failure can be seen in youtube videos of ramp strikes on carrier approaches.  I suppose the pilot could ask, but the Captain of the Ship and his Air Boss might refuse permission.  See risk analysis above.  During a shooting war ... who knows what people might try?
Here's an A-7 ramp strike that's a vivid example.

To demonstrate the complexity of the matter:

The USN requires both an initial qualification and currency in order for its pilots, who land on carriers as a matter of standard operating procedures, to do a certain number of landings per quarter/per year/etc in order to remain current. If you aren't current you have to get recurrent to land on the Carrier.

But what if that pilot had a PEP tour?

The US and Australia, among other navies, have a "Pilot Exchange Program" where we trade officers who fly in our services.  Part of building alliance relationship.  So, if this Australian pilot had done a PEP tour in USN hornets, and been a carrier qualified pilot, he may not be recent or current, but he knows the basics of how to fly a successful approach.  It's still a risk assessment issue since the Captain of the Ship, his Air Boss, and this pilot know that he isn't current, and that his kit may be out of configuration compared to USN hornets, so that he's flying a degraded or visual only approach.

He can ask, but a decision to try it will take the safety of the pilot, his aircraft, and everyone/everything on that carrier's deck into consideration first.  (Low probability, but on a given day, who knows?)


How do pilots see at night if airplanes don't have front lights?

Short answer: they do have front lights!

Longer answer: There's lots of stuff for a ground vehicle (such as a car) to hit, because there's lots of stuff close to the ground.  There's not much in the air for an aircraft to hit, besides other aircraft.  Lights on an aircraft in flight are to help the airplane be seen, not to help the airplane see.

On landing, forward-pointed lights are nice to have, but since runways are illuminated, it's possible to land safely without them.  Airliners in particular will probably never be landing on a darkened runway and need to worry about hitting invisible terrain or obstacles ahead, because they're always either above the obstacles or they're on a known safe descent path.


Why is the Airbus A320 permitted to carry 180 passengers, instead of the maximum 179 allowed?

See Page 9 of TCDS A.064 ANNEX - Airbus A318, A319, A320, A321 - Special Conditions

  TCDS A.064 ANNEX - Airbus A318, A319, A320, A321 - Special Conditions

EQUIVALENT SAFETY FINDING         E-2107: Passenger Extension to 180
APPLICABILITY:                    A320
REQUIREMENTS:                     JAR 25.807
ADVISORY MATERIAL:                N/A

  Statement of Issue:

  An application was made on September 30, 1992 to JAA for certification of maximum number of passengers of 180.

  Paragraph 25.807(c)(1) of JAR specifies for passenger seating configuration, the number and
  types of Emergency Exits for each side of the fuselage.
  The maximum seating capacity allowable under JAR 25.807(c)(1) for A320 exit configuration is
  179 (2 Type I and 2 Type III).

  However, the exits size for front and rear doors on the A320 is such (32x73 inches) that they
  are oversized Type I and therefore can be considered as a non standard exit arrangement.

  The same exit size is being used on a derivative of the A320, for which Latin Square Tests
  have been conducted in order to establish an appropriate rating for that kind of exits. These
  tests have shown that, when associated with the performance of the slide installed at these
  exits, a rating of 55 passengers is appropriate.

  It should also be noted that the full scale emergency evacuation demonstration of the A320
  with 179 passengers has demonstrated compliance with JAR 25.803(c) with sufficient margin
  to justify 180 passengers.

  Under those conditions, a maximum capacity of 180 passengers is requested for the A320.

  JAA Conclusion:
  Based upon the demonstrated higher rating for the floor level exits and the adequate margins
  for 179 passengers shown in the 90 seconds demonstration, and used as a basis to show
  compliance to JAR 25.803(c), the JAA accept 180 passengers as the maximum capacity for the
  A320 on the basis of an Equivalent Safety Finding.


How is optimal Glide Path Altitude calculated?

While @JohnK’s answer is more accurate, the usual rule of thumb is 3nm/1000ft to determine when to start your descent. This “pilot math” is much easier and faster to do in your head, and the error is within the variation due to wind anyway.
In your case, the question is reversed, so 1000ft/3nm, or 333ft/1nm.


What is the purpose of the black paint below the cockpit windows?

It reduces glare (specular reflection).

Football players paint black stripes under their eyes for the same reason.

The legend for the paint scheme is excerpted in the inset, upper right. Item #33 "Antiglare areas shall be painted aircraft black."

If you read this technical manual, which is publicly available, it describes in the body of the text the use of anti-glare paint.


Why does the aspect ratio of a wing become less important at supersonic speeds?

The two main reasons for wings with a subsonic leading edge are:

The lower lift coefficient in supersonic flight, and
the need to keep wing thickness down in order to minimize wave drag in supersonic flight.

Your observation is correct: The lift-related drag coefficient is proportional to the inverse of the aspect ratio, regardless of flight regime for slender bodies. In all cases, lift is created by accelerating air downwards, and efficiency is better when more air can be accelerated by less.

But another factor is the lift coefficient, the square of it to be precise. Again this influence on drag is equal for sub- and supersonic flight, but the magnitude of the lift coefficient isn't. Take the XB-70, for example (source):

Cruise lift coefficient:  0.1 to 0.13, $c_L^2$ = 0.01 to 0.0169
Takeoff lift coefficient: 1.3 to 0.73, $c_L^2$ = 1.69 to 0.533
Landing lift coefficient: 0.626, $c_L^2$ = 0.392

Even at the highest supersonic cruise lift coefficient, the approximated lift-dependent drag coefficient is only 4.3% of what it is at landing speed. Supersonic drag is dominated by pressure and friction, and the cost of lift creation is dwarfed by the other sources of drag. Or let's look at another aircraft designed for sustained supersonic flight, or more specific, it's flight envelope (source):

The aircraft operates in a narrow band of dynamic pressures, trading density for speed to stay within a corridor of 310 KIAS to 450 KIAS when flying at supersonic speed. Here the lift coefficient is roughly between 0.1 and 0.3 (depending on aircraft mass and load factor) and again much lower than at low speed, where minimum speed drops to 145 KIAS.

Note that the lift wave drag formula for slender bodies is only strictly true for $AR$ approaching zero. At higher aspect ratios and especially with a supersonic leading edge this relationship is diminished. In supersonic flow the aspect ratio only comes into play by influencing the part of the wing that is within the Mach cone of the wingtip. In other words: The supersonic flow around a slender body is everywhere influenced by tip effects, whereas the inner and forward part of a higher aspect ratio wing experiences two-dimensional flow, being blissfully unaware of lateral limitations to wingspan.

Now to the structural factor: Wave drag has two components, one from lift and the other from the displacement effect. Pushing air out of the way at supersonic speed must be avoided as much as possible, because it is doubly punished: Surfaces facing in flight direction experience higher pressure than ambient, and those facing backwards experience lower pressure (i.e. suction). In all, zero-lift wave drag increases with the square of the thickness ratio, so there is no space in supersonic wings for the beefy spar a high aspect ratio wing would require.


DP confusion. Do I turn left or right if not told?

The ROUTING is DHP 322 radial to WINCO.  So that's the course line that you'd intercept when so instructed.  There is no reason to actually start at DHP, and since you'll be flying the heading off the runway, the leg from the field to DHP in the Garmin is immaterial.  You can expect that they'll either clear you to WINCO, or (for a non-RNAV aircraft, most likely)  that they'll clear you on a heading to intercept the DHP 322 radial to WINCO (and thence as filed), so you'd cycle the active leg from the {OPF to DHP} leg, to the next leg, which is {DHP to WINCO} (which is the same as the DHP 322 radial), and then you'd intercept that active leg.

Nothing in those instructions is telling you to fly to DHP, nor should you expect that you'd get a clearance to do so.

To answer the question in the title, until you're told otherwise, you fly the initial heading in the text instructions.  You're on vectors, so don't turn until told to do so.

If you go lost comm, then AVE-F would tell you that you're on Vectors to WINCO, so get yourself there as best you can, probably by turning direct if you're RNAV equipped, or flying the radial if not.

EDIT: Note, though, that in the normal (with comm) case,the DP instruction is NOT to fly heading 273 to intercept the radial; it is to fly that heading.  That's your only CLEARANCE.  ATC will turn you to intercept on whatever heading they want you on.  Only in the case of lost comm would you turn to WINCO upon reaching the 322 radial.  In all other cases, follow ATC instructions.


Can "a drone" damage the wing of "an aeroplane" to the extent it actually threatens its ability to fly?

Mr Mann doesn't have a clue what he's talking about.

Wings aren't made from 2024-O aluminum, which is fully annealed and very soft.  The usual heat treat state is T3 through T6.

A Mooney would NOT have .040" wing skins.  The skins will be .016, .020, .025 and maybe .032 in high stress areas around the wing roots. Leading edges would be .025 or maybe .032 inboard, and likely .020 or .016 near the tips and on the control surfaces.  Skin sizes are for structural efficiency and rigidity for minimum weight, not "marketing"... geez.

His approach speed comments are more or less correct, but a Canada Goose will do significant damage to any aircraft it hits in flight and has a good chance of bringing down a Mooney at any contact point.  A Mooney running into a goose at the wing will, at minimum, completely crunch the leading edge in back to the main spar.  A goose will do significant damage to the slat or leading edge of any airliner.  There was a CRJ900 that hit a goose size bird just below the windshield on the takeoff roll near V1, and it came back into the pilot's instrument panel, distributing guts and feathers all over the place.

Geese are bad news and are a vexing problem in the spring in central North America.  The terrain is all browns and if you are descending with a flock below and in front they are nearly invisible until you are passing through their level.

A goose hitting the windshield in front of the pilot or horizontal tail of a Mooney or similar light aircraft will probably bring it down.  On the wing, maybe.

A 2lb drone will do obvious damage as the test showed but would not bring down a Mooney unless it hit the windshield, incapacitating the pilot.  It would certainly go though a windshield.  1/8" plexiglass has roughly the same tensile strength as .020" 2024T3.   You wouldn't want to hit anything heavier than a few ounces with 1/8" of acrylic in front of your face as the only barrier.

So from that standpoint, drones of any size can be considered a hazard to aircraft.


I think you are trying to ask

  What is the difference between a propeller and a turbo propeller?

A traditional propeller plane is powered by an reciprocating (piston) engine. These can be in the form of radial, flat, or V style engines with a few other configurations used here and there.

On the other hand a turbo prop is a propeller plane that is powered by a turbine engine. In this instance the shaft of the turbine is used to drive a propellor. One could think of this as putting a propellor on the front of a jet engine.


The 737 was originally designed to be a smaller aircraft serving more regional routes. The original JT8D low-bypass turbofans easily fit under the wings, and allowing the plane to sit lower to the ground made it easier for the plane to operate at smaller airports without support equipment. Passengers could use the built-in air stairs and the cargo bay was low enough that ground workers could climb in to load and unload baggage.

The low height also allowed shorter and lighter landing gear. The 727 had tail-mounted engines which allowed it to sit lower to the ground, so keeping the 737 low helped to keep some commonality there as well. Over time the airplane has grown longer, been fitted with larger diameter engines, and become capable of much longer flights.

The A320 was designed from the start for the larger family of CFM56 high-bypass engines. The main competition was the 737 Classic version, which was powered by similar engines and had grown substantially from the original 737 versions. Both planes ended up in a market where the low height of the 737 didn't have as many advantages.


I wrote an email to AirZeroG and asked them:

  Other than the interior, are your aircraft modified in any way to handle zero-g flight?

Here is the response that they gave me:

  Dear Sir,

  Except free floating area cabin configuration, there are very few differences with a “standard aircraft”. The most significant one is installation of Zero-G meters in cockpit and a very simple installation on the wheels to help one pilot to lead the aircraft only in vertical axis, and the other pilot to lead only in horizontal axis.

  Out of that, the biggest difference is maintenance program: each parabola performed to create Zero G onboard is considered as an aircraft cycle for the aircraft and its engines, and maintenance adjusted accordingly. Such consideration dramatically increases maintenance costs of the aircraft.

  Kind regards

  Gilles GOMPERTZ

I would say that if there were a fuel system difference they would say that is more significant than G-Meters in the cockpit. I'm assuming based on the response above that the fuel storage/delivery system is unmodified.


Why do aircraft sometimes bounce while landing?

The FAA covers this in the airplane flying manual quite nicely:

Bouncing During Touchdown
When the airplane contacts the ground with a sharp impact as the result of an improper attitude or an excessive rate of sink, it tends to bounce back into the air. Though the airplane’s tires and shock struts provide some springing action, the airplane does not bounce like a rubber ball. Instead, it rebounds into the air because the wing’s AOA was abruptly increased, producing a sudden addition of lift...

There is some more info in the doc worth reading as well.
In the simplest terms this can be one of the outcomes of an unstable approach; oftentimes, when the approach speed is too high, bouncing will result. Touching down on the nosewheel first can also cause a very dangerous bounce case known as a porpoise.
In some cases wind shear can cause bouncing. In this case the shear may cause an unexpected downdraft, forcing the plane down onto the runway vertically and inducing a bounce, or it may cause an updraft leading to an overcorrection by the pilot to descend; when the updraft stops, the plane falls rapidly.


Are there any limitations of diopters (corrected eyesight) in the US?

The FAA bases their eyesight limitations on total acuity and not on diopter correction strength. Although many people equate these as being the same thing, they are not.

Diopter correction is based on focal length. How well an image is focused onto the retina of your eye. An image not being focused on the retina is usually due to a distortion of the cornea. Either it is too curved or not curved enough. The image focal point can be on, prior to (cornea too curved), or after (cornea too flat) the retina.

The cornea might also not be completely spherical. More like a rugby ball and less like a soccer ball. This is called astigmatism.

Sometimes the issue could be with the lens. The stiffening (reduction of flexibility) of the lens due to aging is usually the cause of the need for bifocals and reading glasses. The lens can no longer adjust its own focal length as well as it used to. Making it harder to focus up close.

Misalignment of the focal point with the fovea due to a tilting or shifted cornea, lens, or retina is a prismatic issue. The inability to physically align the eye (lazy eye or amblyopia) can also cause this.

Acuity is based on how well the image can be distinguished clearly regardless of focal length. An image can be focused on your retina (0 diopter correction), and still not be clear or distinguishable. Eye diseases like cataracts (fogging or frosting of the lens), glaucoma (increased internal pressure of the eye pressing on the retina, causing damage), macular degeneration (damage to the fovea of the retina), etc. can degrade your acuity without affecting your focal length. No glasses of any diopter strength will improve acuity in these cases. Even eye injuries like a corneal ulcer or a scratched cornea can negatively affect the acuity of a person with normally perfect vision.

Although all of these issues affect acuity, all of them together add up to total acuity. Using only one measure can not accurately determine a pilot’s ability to see correctly. Diopter correction alone can not tell the entire story.


Has the FAA ever granted a LODA for compensated instruction in a non-LSA E-AB?

You may have to contact the FAA directly to get an answer on that but it seem like an unlikely case. Since you are looking for a LODA that covers "training flights" you would need a LODA SFA

  D.    LODA Special Flight Authorization (LODA SFA). A Flight Standards
  office normally issues a LODA in cases where frequent operations of a
  specific nature occur over a protracted period of time. However, there
  may be situations such as ferry flights, sales demonstration flights,
  and training flights where the 60-day requirement may not be feasible.
  For these situations, a Flight Standards office may issue a LODA SFA
  on a case-by-case basis for specific flights. A LODA SFA is a LODA
  authorizing an operator to accomplish short-term operations (normally
  a maximum of 30 days) in accordance with 14 CFR part 91, and can be
  issued for the following:

LODA SFA's are short term as discussed later on, specially they are typically 30 days in duration

  ...

  2)    A LODA SFA is conducted in accordance with part 91 rules. The maximum duration of a LODA SFA is normally 30 days.

  ...

To regularly provide instruction in the aircraft you mention you would effectively have to continuously apply for a LODA SFA on a rolling basis, something the FAA likely will stop approving eventually. I would say that your use case does not really fall under the broader spirit of the regulation

  ...

  LODAs to all of part 125 are issued for operational uniqueness

  ...

Although you could make a case if you were offering training to others specifically looking to buy that aircraft. If you are just looking to offer flight instruction the FAA is likely to tell you to go find an approved airframe and play by the rules. I cant find an exact price for a sling kit but Im seeing north of 100K for built ones, even if the kit costs half of that @ 50K you can get a whole lot of 172 or Cherokee 160 for that price and offer instruction without the hassle of special authorization (above whats normally needed).


Is my understanding of subsonic inlets correct?

Your understanding is correct.

However, you attribute too much activity to what is essentially a passive device. The inlet only guides the air such that it flows uniformly, without separation and at the desired angle towards the fan and the compressor. The pressure field resulting from this flow is doing the acceleration rsp. deceleration, and the pressure itself is a result of the compressor swallowing just as much air as it needs.

Converging streamlines indicate a pressure drop and acceleration, and diverging streamlines a pressure increase and deceleration. In the static condition, the engine creates suction inside the intake which causes air from all around to flow towards the intake. At high speed it cannot swallow more than a fraction of the air flowing towards it and partially blocks the flow through the nacelle. As a consequence, air gets pushed to the sides and the flow into the intake is decelerated.

It is really the engine, not the intake, that controls how much air is ingested. The intake only makes sure that this happens in an orderly fashion without separation and vorticity. Different flight speeds only mean that the pressure ahead of the compressor changes, while the speed of the air entering it is quite constant over flight speed.


How is fuel planning done for a VFR flight that involves multiple full stops?

This may not be what your CFI is looking for, but I found the changes in fuel consumption during takeoff/landing to be negligible. This is because the taxiing uses very little, the and extra fuel burn in the climb is largely compensated by the savings in the descent. So, I just look at the distance between the airports, take winds aloft, calculate ETE and make sure it's acceptable in respect to fuel reserves. Ditto for any foreseen diversions. You have to have enough fuel on board to reach your planned reserve airport if you arrive at your destination and find that it's closed (e.g. because of an accident). This may be less of a problem in North Carolina, but in New Mexico, you might need to return all the way. A 30 minute VFR reserve isn't going to cut it.


How many miles before the runway should an airliner put the gear down?

To answer the last part of your question, as ratchet freak said, the TCAS doesn't warn the pilot when he should deploy landing gear. However, the ground proximity warning system/terrain avoidance and warning system (GPWS/TAWS) does. GPWS Mode 4A is "Unsafe Terrain Clearance With Landing Gear Not Down".

If the plane is less than 700ft (based on the radio altimeter's measure) high and under mach .35, there is an aural alert in the cockpit saying "Too low - gear". The message is repeated until the situation is corrected.

So the warning is based on the height and speed of the aircraft. Not on its distance to the airport.


OgiMet Professional information about meteorological conditions in the world is such a site that offers 30-day history for METARs/SPECIs and TAFs reports.
The coverage is said to be worldwide. Here is a glance at the query interface:

The site states these conditions of use for the reports:

About all the codified met. reports (SYNOPS, METAR ...), the copyright
are from every country or source institution. To use them,
read WMO resolution 40.

(essentially it says it's free for use.)
The site accepts requests for up to 31 days at once.
Example: METARs for month of September 2020 for Orly / LFPO:


Can anyone identify this aircraft in the AMARG area of Davis Monthan?

Problem solved, a close friend of mine pointed to these two very interesting articles on the topic:

http://foxtrotalpha.jalopnik.com/a-new-angle-on-this-shadowy-stealth-f-a-18-hornet-conce-1727910676

http://aviationweek.com/awin/super-hornet-stealth-test-rig-seen


Does ATC react to pilot position reports?

I controlled non-radar airspace for about 2.5 years.

On your end, we’ll probably just say “roger.” We may add instructions to report a future point, or a control instruction.

On our end, we would be using that information for any required separation. For example, we may update a flight strip with your groundspeed, recalculate how we anticipate bring traffic across that same point, or change how we are protecting airspace or altitudes according to where you are. It varies depending on the environment and traffic, but the general concept is ATC is protecting the entire block from where we last knew you were - your previous position report or where you were last in radar contact - and your next reporting point. Your position report allows us to modify that protected area.

But little to none of that information will be relayed to the pilot, unless it is operationally necessary. Even then, it will probably just be in the form of a control instruction.


Why are vectors used for sequencing rather than speed control?

Let's say you have two aircraft that will reach the same point in space at the same time, and your job is to keep them three miles apart.  One way to do it is to calculate how many knots the second aircraft should reduce their speed so that at the time the first aircraft reaches the point, the second aircraft will have fallen three miles in trail.

Unfortunately for you, this means that you have to work a time-speed-distance-wind problem for every single aircraft that you, as a controller, handle.

Alternatively, you pick a point three miles away and tell the second aircraft to fly there.

Air traffic controllers are human, and humans are better at angles than we are at numbers.  The simplest thing for controllers is usually the best thing - they've got lots on their mind already without making them do math too!  This might change in the NEXTGEN air traffic network (where everyone has a GPS position and speed readout right there on the screen) but for now, easy is better than hard.


How does a fire suppression system work?

The fire suppression system in an aircraft uses both passive and active systems to reduce and eliminate fires. Passive methods include the use of noncombustible materials, separation by routing, compartmentalization (use of firewalls), isolation, proper ventilation and drainage. The active methods include fire detection and extinguishing systems.

The fire extinguishing system in the aircraft consists of a number of components (excluding the fire detection system), which includes,

Portable (handheld) fire extinguishers in cockpit and cabin,
Fire extinguisher bottles for engines and APU
Cargo hold fire extinguisher systems and
Fire extinguishers for toilet waste bins.

All the transport aircraft are required to carry a minimum number of portable fire extinguishers depending on the number of passengers carried. The following table gives the minimum number of portable fire extinguishers to be carried in transport aircraft (the cockpit should have a minimum of one).

Table from FAA document Fire Protection Systems

In case of cabin (or cockpit) fire, the portable fire extinguishers (usually, $CO_{2}$ extinguishers are not used) are used by the crew to extinguish the fire.

The engines and APUs have their own fire extinguishing systems, which have a liquid halogenated extinguishing agent and pressurized gas stored in fixed (typically steel) fire extinguisher containers, which are discharged on pilot command.

The engines have their own fire extinguishing systems, which usually have a pair of fire extinguishing bottles (or a pair for each engine), which supply extinguishing agent (Halon 1301 or Hydrofluorocompounds) to the engine.

Image from Boeing Aero magazine- Fire Protection: Engines and Auxiliary Power Units

The fire detection system from each engine displays the status in the cockpit, which warns of any engine fire. In case the pilot pulls the fire handle, the fuel flow to the engine is shut off and an explosive cartridge is fired in the fire extinguishing bottle, releasing the agent into the engine.

Image from FAA document Fire Protection Systems

The APU fire suppression system is similar to the engine fire suppression system, though only a single fire extinguisher bottle is used. Again, the fire extinguisher operation is commanded by the cockpit crew and results in the shutting down of the APU and the source of air.

Image from Boeing Aero magazine- Fire Protection: Engines and Auxiliary Power Units

In ground, the APU fire extinguishing system can operate automatically.

The cargo hold fire extinguishing system is similar to the above, where the crew can activate the fire extinguishing system if the smoke detectors in the cargo hold activates the warning lights in cabin. The extinguishing system is of two types- a dump system that releases the extinguishing agent directly
when the cargo fire discharge switch is activated or a metered system, where metered bottles discharge slowly which keeps the correct concentration of extinguishing agent in the cargo compartment to keep the fire extinguished for 180 minutes.

Table from FAA document Fire Protection Systems

The toilet waste bin is the only place in the aircraft with an automatic fire extinguishing system (in addition to ashtrays), where the heat sensors (not smoke detectors) trigger fire extinguishers.

Some aircraft have On Board Inert Gas Generating System (OBIGGS), which is used to 'inert' the fuel tank using nitrogen (usually generated by membrane based gas separation).


Why are some airports not allowed as IFR alternates, even if conditions there are VFR?

There is a little bit of a misunderstanding in your premise. There is a difference between an alternate airport and a diversion airport. An alternate airport is your listed optional destination for the purposes of filing a flight plan. A diversion airport is the airport to which you head when you can not land at your original destination. They may be one in the same. For instance, when you divert to your alternate airport.
It is not that the airport can not be used as an alternate. It is that the approach can not be used to qualify the airport as an alternate. You can not use the standard precision approach, standard non-precision approach, nor non-standard approach alternate minima. You can, however, use the VFR weather minima to qualify the airport as an alternate. That means that both I19 and I73 are treated the same when filing. This is for filing purposes only.
Once airborne, the situation changes. If the weather or any other circumstance dictates a diversion to airport I19, you can use the procedure to shoot an approach down to the IAP minima regardless of if you filed it as an alternate or even if it qualified as an alternate when filing.  Therefore, you could possibly effect a landing at I19 in IMC, but not at I73 in IMC. You could divert to either one in VMC. Even if your filed alternate were an entirely different airport.


It is possible to overfill a wing. You fuel the aircraft when its wing is cold. Later as the aircraft sits on the ramp the outside temp increases causing the full to expand in an already full wing. So they have the overflow system dumps the excess fuel on the ramp. Its usually not a lot of fuel just a few gallons.
  It also prevents the fueler from over fueling the wind. It can sometime dump 50 gallons or more if the fueler it not paying attention.


Why are pilots asked to provide a reason for a go-around?

The reason 1 pilot goes around may also be the reason the next pilot goes around, The second pilot would like to know before hand whether the runway is safe to land on.

For example if it is wind related he can delay landing until it dies down.

If it is debris related then the tower can dispatch a cleaning crew.


How can I find our FAA airport designation number?

What you're looking for is the FAA Airport/Facility Directory (A/FD). You can search it on the FAA A/FD Advanced search page. If your runway is registered as an airport with the FAA, its airport identifier will be in the A/FD. It will also include the runway numbers (there will be one for each end of the runway,) as well as other information about the runway (surface type, exact heading, altitude, etc.) See How are runways numbered? for more information on runway numbers. Another website available for searching A/FD information is airnav.com.

Another way to find information on the airport is to look at a Sectional Chart. For most private airports, an 'R' with a circle around it will appear where your runway is located and it will have the name of the airport beside it. You can then use that name to look it up in the A/FD. Skyvector.com is an easy way to look at sectional charts. It works a lot like Google Maps, except that it shows you the FAA sectional chart for your area rather than a normal map. You can just zoom in on your area to find the airport marker.

Your airport will look something like the one that I've circled in red on this sectional chart image:

If your runway has a hard surface (i.e. it's paved with asphalt or concrete) and is more than 1,500 feet long, it might look like the airport circled in the picture below rather than having the circled 'R'. In this picture, the purple circle indicates the airport and the white line within the circle indicates the location and orientation of the runway.


What are the effects of different seasons on flight training?

Pretty much the only thing that is going to change season to season is the weather. Depending on where you are, there may be more aircraft traffic around a particular time of year, but I can't answer that for sure.

Obviously, the further from the equator, the more extreme the seasons. If you are close to the equator, it probably doesn't matter what time of year you start, since the weather is pretty much the same year-round.

If you are not at the equator, you need to consider the pros and cons of each weather season. Additionally, at extremes from the equator (near the poles), summer and winter months have extremely long days and long nights, respectively, which can make night and day flying difficult.

In the winter, the aircraft has better performance (airplanes like colder weather). However:

You have to deal with ice and snow, which is especially dangerous to light airplanes, which are often not as prepared to deal with them. It is dangerous in some degree to all airplanes
You have to be careful of low temperatures when starting the airplane before you take off

In the summer, the aircraft has worse performance (they don't like hot weather).

Many small airplanes have poor airflow inside the cockpit, which means they can get rather hot (it is easier to run a heater inside a small cockpit than cool it)
You have to be more careful to avoid overheating the engine
Some places may form thunderstorms constantly

In the rainy season, which is often in the spring, you will have degraded performance. Even if it is not rainy, the air will likely be more humid, which decreases aircraft performance

Depending on your latitude, other weather conditions may be more prevelant at a certain time of year (hurricanes/cyclones, high winds, tornados, sudden storms). This paper discusses wind differences based on season and latitude. In particular, page 7 of the document shows that summer months had slightly stronger winds at southern latitudes (southern hemisphere), and winter months had significantly stronger winds at northern latitudes. Some geographical areas may have changes in prevailing wind directions, which could also affect training depending on routes and runways too.

TL;DR: It's mainly a weather concern, which can affect your comfort (temperature inside, possibly air turbulence), aircraft performance, as well as grounding weather. Additionally, the most obvious concern is also length of the day - summer months will have more daylight, a particular concern if you can only fly in VFR conditions/do not hold a night rating.


Assuming that thrust is entirely in the direction of travel and the flight path angle is constant, the Lift is equal to the weight times the cosine of the flight path angle:

$L = W\cos(\gamma)$

For small $\gamma$, $\cos(\gamma) \approx 1$

E.g. for a flight path angle of 10 degrees, the error introduced by the approximation is ~ 1.5%

For unaccelerated climb, the sum of all forces in the along path direction cancel each other out:

$ T-D-W\sin(\gamma) = 0$

The gradient is $\tan (\gamma)$.

Again, for small angles, $\sin(\gamma)\approx\tan(\gamma)$

From there it is a small step to see that the calculation suggested by your colleague is acceptable for unaccelerated climbs at small flight path angles.


Does the sterile cockpit rule mean flight attendants could not inform the pilots if a passenger is in the lavatory while on final?

"Sterile Cockpit" refers to the concept that pilots should not discuss anything not related to the flight during certain phases of flight (often defined as below FL100).

A passenger occupying the lavatory while the flight is on approach and passengers are supposed to be in their seats definitely does have an impact on the flight, so it does not fall under the "sterile cockpit"rule.


Why does the V-22 Osprey have twin stabilizers?

The V-22 was designed to be operated by the US Marine Corps on-board US aircraft carriers. Any airplane that operates off of a carrier has to be relatively compact in order to be able to fit onto the carrier's elevators and short enough to fit into the hangar deck. A twin tail spreads the elevator authority over 2 smaller control surfaces instead of 1 big surface, making the aircraft shorter, and the placement at the ends of the elevator reduces its overall size footprint.

The other benefits of a twin tail are a reduced radar cross section (the V-22 needs all the help it can get there) and increased redundancy as if one tail is damaged there is another one available. The wide placement of the stabilizers reduces the chance that enemy fire will take out both at once.


How does skydiving flight cause shock cooling?

Skydiving flights are abusive on engines for a number of reasons, but it's all tied to the fact that these flights are all about getting up to altitude, kicking the jumpers out, and putting the plane back on the ground as fast as possible so you can pick up the next group and do it all again, as many times as possible in a day.

While all skydiving descents aren't as dramatic as the video I linked to its not uncommon for skydiving pilots to make a very rapid descent at or near idle power. This causes a more drastic temperature change in the engine (particularly the cylinders, which are not producing as much heat but still have lots of air blowing through the fins).

In addition to the potential damage from rapid temperature changes the engine is also spending relatively little time at cruise power (it's either at full throttle climbing or near idle descending), and depending on the operation may be shut down between jumps. This is far from the ideal situation where the engine would run at 60-75% power as long as possible.


Is there an audible warning on commercial aircraft if you try to land gear up?

All turbine-powered aircraft used in scheduled airline service under CFR Part 121 are required to have an approved TAWS installed;

  §121.354   Terrain awareness and warning system.

  (a) Airplanes manufactured after March 29, 2002. No person may operate
  a turbine- powered airplane unless that airplane is equipped with an
  approved terrain awareness and warning system that meets the
  requirements for Class A equipment in Technical Standard Order
  (TSO)-C151. The airplane must also include an approved terrain
  situational awareness display.

  (b) Airplanes manufactured on or before March 29, 2002. No person may
  operate a turbine-powered airplane after March 29, 2005, unless that
  airplane is equipped with an approved terrain awareness and warning
  system that meets the requirements for Class A equipment in Technical
  Standard Order (TSO)-C151. The airplane must also include an approved
  terrain situational awareness display.

  (c) Airplane Flight Manual. The Airplane Flight Manual shall contain
  appropriate procedures for—

  (1) The use of the terrain awareness and warning system; and

  (2) Proper flight crew reaction in response to the terrain awareness
  and warning system audio and visual warnings.

The TAWS system includes the functions of the older Ground Proximity Warning System (GPWS).

GPWS Mode 4, Flight Into Terrain with Less Than 500 Feet Terrain Clearance and Not in Landing Configuration, provides for alerts to the crew when entering a defined envelope below 500 feet (based on height and rate of descent) and the gear is not in landing configuration. There is also an alert envelope for Flaps not in landing Configuration.

The Mode 4 alert consists of an audible alert "TOO LOW, GEAR. TOO LOW, GEAR."


What causes a taildragger to lift its tail during the takeoff roll?

Yes, when the plane exceeds a certain speed (known to the pilot!), the pilot then pushes the stick slightly forward and this lifts the tail off the ground. This reduces rolling drag and sets up the angle of attack of the wing for takeoff. For very powerful airplanes, the tail will sometimes come up on its own and surprise the pilot during the takeoff roll.
In some planes, the resulting angle of attack is enough that the plane will fly itself off the ground and begin climbing when it has picked up enough speed in the roll. In other designs, the pilot will wait for the right speed and then gently pull back on the stick to increase the AoA a bit and the plane then takes off.


Can the iPad use GPS data from a Garmin aera 660?

Most bluetooth external GPS devices conform to NMEA and are compatible with CloudAhoy. I don't know if that's the case with Garmin Aera 660.

However, if used with Garmin Pilot, then you can always export GP's track log to CloudAhoy. (I'm associated with Cloudahoy)


What term is the EASA equivalent of the DER in the FAA safety assurance process?

The closest EASA equivalent would be the Design Organisation Approval (DOA). According to EASA:

A Design Organisation Approval is the recognition that a Design Organisation complies with the requirements of Part 21 Subpart J.
Privileges: A DOA holder can

Perform design activities within the scope of approval

Have compliance documents accepted by the Agency without further verification

Perform activities independently from the Agency


Why don't stealth aircraft designs use podded engines?

Yes. From the PoV of stealth aircraft, the podded engine has significant disadvantages:

The engine pod has a high Radar Cross Section; In fact, stealth aircraft bury the engine inside their fuselages to minimize radar cross section. For example, the B2 Spirit engines were located inside the fuselage, as shown in the schematic below.

The exposed compressor blades in the podded engine reflects radar waves, which is not good. For example, in Boeing X-32, the location of the engine meant that the compressor blades will be exposed to the Radar and baffles were (proposed to be) added to reduce the Radar cross section. On the other hand, it can be seen that it is practically impossible to see the F-22 compressor blades from any angle of the inlet.

Source: f-16.net

In case of podded engine, it is difficult to shield the exhaust thermal signature. Compare the infrared signature of the typical airliner in the following picture with that of the B-2 Spirit in the next picture.

Source: laserfocusworld.com

Source: bestfighter4canada.blogspot.in

Of course, contemporary combat aircraft don't use podded engines at all (with the exception of the A-10, which is a ground attack aircraft).


What is minimal altitude that aircraft (rocket?) can fly above any country without any permission?

Actually, what you're asking are two different questions- According to ICAO ( ICAO Annex 11: Air Traffic Services), Class G airspace is uncontrolled and aircraft can fly in the without ATC permission. The definition if Class G is left to the regulatory authorities of individual countries (in US, it is where the other airspace classes are undefined).

Where does the airspace of the country end is a completely different one and as of now, there is no agreed definition. The United Nations General Assembly Committe on Peaceful Uses of Outer space is still in the process of defining what exactly an outer space is.


Why is the flight path from Taipei to Tianjin not a straight line?

This will be due to routing and the airways available. Looking at the Enroute Chart for the Taipei FIR, you will notice that there is no direct route northbound, but all routes have a north-east direction to remain clear of restricted area RCR8 (GND - FL370).

(Source: http://eaip.caa.gov.tw)

The flight most likely, as I cannot find the flightplan, departed RCTP - Taipei via the DRAKE1A or DRAKE1B SID, leading to SULEM. Thereafter it continued westbound on the respective airways within China to then join another airway north.

This is consistent with the flightprofile tracked on flightware for EVA730 from RCTP to ZBTJ.

(Source: www.flightaware.com)


Will the G1000 cut off transmission over 35 seconds?

I haven't tried it for real with PTT, but from what I know about G1000, it has generic protection against any stuck keys (including those on remote keypads/panels). When a key is detected to be pressed for longer than about 30-35 seconds, it is declared stuck and the respective CAS message appears on the PFD. It is then temporarily disabled; however, when another press is detected, it will work again. You can try it yourself with any of the bezel keys.

In this vein, it doesn't matter if you speak or not. If you keep PTT pressed for longer than 35 s, it will cut the transmission, but if you release and press it again, it will start transmitting again.

(Note that most normal keys in G1000 are activated on release (this is very common in software). But if a key is stuck or you hold it for long, its function will activate after about 0.6-0.8 s anyway. Some keys have 'press and hold' operation (e.g. holding frequency transfer for 2 s tunes in the emergency frequency 121.5), and it will also execute after the elapsed hold time. And only much later the key will be declared stuck.)


How does the throttle position affect the speed of airflow to the engine?

That's because it's not the restriction created by the throttle plate itself, that you see as manifold pressure (or vacuum), that is creating the suction that pulls fuel from the carburetor float bowl.  It's the restriction of the venturi, where the main discharge nozzle is, which is upstream of the throttle plate.  Since it's in in the upstream flow, the suction created at the venturi, being a fixed cross section, is a function of air velocity entering the carburetor, which is a function of throttle opening and engine speed.

In other words, the fuel metering system at the venturi doesn't care about the pressure differential created by the throttle plate farther down, it only cares about the velocity of the total mass flow that engine is able to pull past the venturi upstream of the throttle.

Open the throttle, the velocity of the air going through the venturi goes up, the suction generated by the venturi increases, and more fuel is pulled into the discharge nozzle.  And vice versa.


Where can I find airport taxi instruction "code names"?

Excerpt from the FAA Publication "Instrument Procedures Handbook":

  Standard taxi routes improve ground management at highdensity
  airports, namely those that have airline service. At
  these airports, typical taxiway traffic patterns used to move
  aircraft between gate and runway are laid out and coded.
  The ATC specialist (ATCS) can reduce radio communication
  time and eliminate taxi instruction misinterpretation by
  simply clearing the pilot to taxi via a specific, named route.
  An example of this would be Los Angeles International
  Airport (KLAX), where North Route is used to transition
  to Runway 24L. [Figure 1-7] These routes are issued by
  ground control, and if unable to comply, pilots must
  advise ground control on initial contact. If for any reason
  the pilot becomes uncertain as to the correct taxi route, a
  request should be made for progressive taxi instructions.
  These step-by-step routing directions are also issued if the
  controller deems it necessary due to traffic, closed taxiways,
  airport construction, etc. It is the pilot’s responsibility to
  know if a particular airport has preplanned taxi routes, to
  be familiar with them, and to have the taxi descriptions
  in their possession. Specific information about airports
  that use coded taxiway routes is included in the Notice to
  Airmen Publication (NTAP).

NTAP can be found on: https://www.faa.gov/air_traffic/publications/notices/

At the time of writing the KLAX North Route example can be found on page 4-SW-11, and reads:

  North Route
  Taxi towards taxilane Sierra (S) taxi northbound on taxilane Sierra (S), and at Check-point-1 contact Ground
  Control on frequency 121.65, hold short of taxiway Delta (D).
  Taxilane Sierra (S) is not visible from the ATCT

There's also FAA Advisory Circular 7110.116 regulating Standard Taxi Routes (STR's) as bilateral agreements (LOA's - Letter of Agreement) between each ATC unit and their users (airlines). The document contains information on what the LOA needs to contain.

Outside of the US, standard taxi instructions, if any, could be expected to be found in the AD-section (Aerodromes) of that respective country's AIP (Aeronautical Information Publication).

As an airline pilot, this information might be integrated into your company's nav data solution, ie. information about standard taxi routes available to you would be written/drawn out bundled with your airport diagrams etc.


How are aircraft identified as unregistered?

Aircraft don't have to be actually flying for people to notice something fishy going on. In particular, there are always people hanging about at airports keeping an eye on everything going on. Furthermore (at least in the US), aircraft registration details are a matter of public record and can be easily looked up online.
For example, here is the registration detail page for John Travolta's private Boeing 707: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=N707JT
As you can see it contains complete registration details including type, validity status, expiration dates, owner name and address, and airworthiness status.


Are there pilot weight limits for the Rutan Vari Eze?

According to the Owner's manual,

  The air plane can structurally accommodate pilots or passengers weighing up to 250 lbs.

Of course, this is subject to the maximum allowable takeoff weight.

The manual also gives the forward and aft cg limits (in page 30). In case of very light pilots, the aft cg limit may be exceeded and it may be required to carry ballast for bringing the cg within limits.


How can I know where wind is coming from by looking at water?

The easiest way to tell the direction of the wind when you're near the water is to look for something on the shore that indicated wind direction (beaches often have flags on them)

Barring that there are a bunch of other clues that should be familiar to any sailor (or seaplane pilot) which you can borrow:

Boats lying at anchor weathervane and automatically point into the wind
This isn't 100% reliable: Some boats will set two anchors (fore and stern) and won't weathervane. Also when the tide is shifting boats will swing to align with the tide if it's stronger than the wind.
Boats lying at anchor sometimes have a flag on them
Flags on a boat at anchor work the same way as flags on land - they're excellent indicators of wind direction.
On calm bodies of water the wind creates visible surface ripples
The concave side of these ripples is the windward side.

(Visualize the water as being a large bowl of soup - now blow on the soup. The ripples will have the same shape.)
This same principle applies to larger waves as well (other factors could cause the dominant breeze along a shoreline to not be quite perpendicular to the waves, but if your concern is ground reference maneuvers it's "close enough").
"Wind Streaks" on the sea indicate wind direction
Wind streaks are somewhat ambiguous in that they're aligned with the wind, but don't tell you which way it's blowing: You have to figure that out for yourself (for example by looking at the shape of the waves as described above).

Surf spray gives wind speed and direction
Waves breaking will produce spray that blows downwind - I couldn't find a good illustration for this, but the finer spray tends to blow, while heavier drops just fall. The distance the spray blows gives an approximate indication of wind speed.
It would take some pretty heavy seas to produce visible spray at altitude though, and you're more likely to see foam and whitecaps in that case
Foam or Whitecaps provide wind speed and direction
Foam or whitecaps provide an indication of direction (the foam appears to move upwind - into the wind) and speed (it generally takes winds of 10-15 knots or more to produce whitecaps and foam).


What is the purpose of the vertical splitter and the NACA duct at the MQ-9 Reaper engine scoop?

The NACA duct is probably routed to a gearbox oil cooler. The turboprop engine has its air inlet at the prop end of the engine, which means a splitter is needed to divide the incoming air flow into two ducts, one on each side of the engine, in order to conduct the air back to the inlet.


What is the minimum weight aircraft in which someone can build logged flight time?

There is no weight limit, requirement, nor restriction for logging time in a logbook. However, there is a requirement to only fly aircraft that are properly certificated, registered, and airworthy regardless of if you log the time or not. Part 103.7 allows ultralights to fly without certification or registration. If you are flying an aircraft not meeting certification, registration, inspection, and airworthiness standards, you are flying illegally unless it meets the weight, horsepower and other criteria of Part 103.1.

  §103.7 Certification and registration.
  (a) Notwithstanding any other section pertaining to certification of aircraft or their parts or equipment, ultralight vehicles and their component parts and equipment are not required to meet the airworthiness certification standards specified for aircraft or to have certificates of airworthiness.

  (b) Notwithstanding any other section pertaining to airman certification, operators of ultralight vehicles are not required to meet any aeronautical knowledge, age, or experience requirements to operate those vehicles or to have airman or medical certificates.

  (c) Notwithstanding any other section pertaining to registration and marking of aircraft, ultralight vehicles are not required to be registered or to bear markings of any type.

Combining this with Part 61.51(j) would prohibit the logging of ultralight experience gained today for the purpose of initial certification or currency.

  (j) Aircraft requirements for logging flight time.
  For a person to log flight time, the time must be acquired in an
  aircraft that is identified as an aircraft under §61.5(b), and is—

  (1) An aircraft of U.S. registry with either a standard or special airworthiness certificate;

  (2) An aircraft of foreign registry with an airworthiness certificate that is approved by the aviation authority of a foreign country that is a Member State to the Convention on International Civil Aviation Organization;

  (3) A military aircraft under the direct operational control of the U.S. Armed Forces; or

  (4) A public aircraft under the direct operational control of a Federal, State, county, or municipal law enforcement agency, if the flight time was acquired by the pilot while engaged on an official law enforcement flight for a Federal, State, County, or Municipal law enforcement agency.

Furthermore, Part 61.52 does not allow for the logging of ultralight experience gained today for the purpose of initial certification or currency.

  §61.52 Use of aeronautical experience obtained in ultralight vehicles.
  (a) Before January 31, 2012, a person may use aeronautical experience obtained in an ultralight vehicle to meet the requirements for the following certificates and ratings issued under this part:

  (1) A sport pilot certificate.

  (2) A flight instructor certificate with a sport pilot rating;

  (3) A private pilot certificate with a weight-shift-control or powered parachute category rating.

  (b) Before January 31, 2012, a person may use aeronautical experience obtained in an ultralight vehicle to meet the provisions of §61.69.

  (c) A person using aeronautical experience obtained in an ultralight vehicle to meet the requirements for a certificate or rating specified in paragraph (a) of this section or the requirements of paragraph (b) of this section must—

  (1) Have been a registered ultralight pilot with an FAA-recognized ultralight organization when that aeronautical experience was obtained;

  (2) Document and log that aeronautical experience in accordance with the provisions for logging aeronautical experience specified by an FAA-recognized ultralight organization and in accordance with provisions for logging pilot time in aircraft as specified in §61.51;

  (3) Obtain the aeronautical experience in a category and class of vehicle corresponding to the rating or privileges sought; and

  (4) Provide the FAA with a certified copy of his or her ultralight pilot records from an FAA-recognized ultralight organization, that—

  (i) Document that he or she is a registered ultralight pilot with that FAA-recognized ultralight organization; and

  (ii) Indicate that he or she is recognized to operate the category and class of aircraft for which sport pilot privileges are sought.

Weight is not a factor in logging time. And, there is no prohibition against putting things in your logbook that can not be counted for the purposes of initial certification or currency. Although, care should be taken with this. Your logbook is your property. However, your certification gives the FAA the right to inspect your logbook however it chooses. I have co-pilot time logged in a turbine-powered helicopter that I can never count towards anything.

There is also no prohibition against getting an ultralight registered and certificated as airworthy. It might be a lengthy and expensive (and probably improbable) endeavor. But, as soon as you do, it becomes an ultralight no longer according to Part 103.1

  §103.1 Applicability.
  This part prescribes rules governing the operation of ultralight vehicles in the United States. For the purposes of this part, an ultralight vehicle is a vehicle that:

  (a) Is used or intended to be used for manned operation in the air by a single occupant;

  (b) Is used or intended to be used for recreation or sport purposes only;

  (c) Does not have any U.S. or foreign airworthiness certificate; and

  (d) If unpowered, weighs less than 155 pounds; or

  (e) If powered:

  (1) Weighs less than 254 pounds empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation;

  (2) Has a fuel capacity not exceeding 5 U.S. gallons;

  (3) Is not capable of more than 55 knots calibrated airspeed at full power in level flight; and

  (4) Has a power-off stall speed which does not exceed 24 knots calibrated airspeed.


Does the FDR record data about the cockpit door lock system?

While it is not on the required parameters list, it would not surprise me if it would be recorded- most FDRs record considerably more than the 88 mandatory parameters, and cockpit doors are of course interesting in accident investigations.

That being said, it should also come across pretty evidently on the Cockpit Voice Recorder if somebody was trying to get in. The normal request is a pretty distinct buzzer and the emergency request is the same buzzer for 5 minutes unless denied/ cancelled by the pilot. The door also locks quite loudly. Both should be able to be picked up by the general cockpit area microphone (CAM).


The vertical axis starts at 350 Klbs since the Boeing 777 is made to transport payload, not just itself. Any operator will be interested more in the upper part of the diagram, because only then the aircraft will earn money. This explains the gap of 30 Klbs - the people for whom this chart was made are simply not interested in the range without payload.

The range varies with flight parameters, and the upper left corner shows the most important ones, albeit in quite imprecise terms. If the flight speed is reduced, range will become higher until the aircraft flies at optimum range conditions. Airlines like to fly their aircraft faster that that to optimize transport performance (the maximum product of speed and payload relative to operating cost). If power extraction and air condition are run at their bare minimum, again less fuel will be needed per mile of flight. Flown this way, the 777 will easily fly more than 10500 nm with a zero-fuel weight (OEW + payload) of 350,000 lbs.

To eke out the maximum possible range, high-density fuel is used and the aircraft is flown at an optimum altitude and speed for range. The records which have been set this way (11,664 nm for the 777-200ER), however, are of little relevance to everyday operation. The longest commercial flight of that type will be the Dubai-Panama City connection of 7,463 nm which Emirates will begin to serve on February 1, 2016.


To what extent are (non-urgent) PIREPs used by meteorologists?

This NOAA newsletter lists a number of specific ways that PIREPs are used by meteorologists:

To "assess the strength and position of the jet stream"
For thunderstorm and snow level forecasting
For forecast discussions of regional weather phenomena, like "downslope wind storms in the lee of the Sierra Nevada"
To "determine the likelihood of clouds thinning or burning off"

Their summary is:

  Better reports and observations, not only from PIREPS but also storm
  spotters, Webcams and road weather networks help improve the picture
  of what’s going on in the atmosphere. Automated temperature, wind and
  humidity reports from MDCRS and the Aircraft Communications Addressing
  and Reporting System in commercial aircraft also get incorporated into computer models. All of these observations lead to improved forecasts and warnings.

There are a few very generic references out there too. A 2014 edition of FAA Safety Briefing says:

  The information will then be added to the distribution system to brief
  other pilots, help generate inflight advisories like AIRMETs and
  SIGMETs, as well as updates to the Current and Forecast Icing Products
  (CIP/FIP), and improve overall forecast accuracy.

And an AOPA article has a brief mention:

  when the Aviation Weather Center (AWC) receives a pirep,
  meteorologists use it to verify that their weather forecast is correct
  or amend it if the pirep contradicts the forecast.

Finally, PIREPs (and AIREPs) are shown on the NOAA website, although that probably isn't what you had in mind by meteorologists 'using' the information.


At what point can Approach mode be engaged in an A320?

The conditions for arming the ILS APPR mode are given in the FCOM:

Arming Conditions
The pilot arms the (ILS) APPR mode (LOC and G/S in blue on the FMA) by pushing the APPR
pushbutton on the FCU, provided that:

An ILS approach is selected,
The aircraft is above 400 feet RA,
The ILS and RA are available,
Go-around or takeoff or final mode is not engaged,
ILS frequency and course are identically set on both receivers.

(Airbus A320 FCOM - Autoflight - Flight Guidance)
These are just the technical limitations for when you can arm the APPR mode, not when you should. The FCTM has some more details on that:

INTERCEPTION OF FINAL APPROACH COURSE
When cleared for the ILS, the APPR pb should be pressed. This arms the approach
mode and LOC and GS are displayed in blue on the FMA. At this stage the second
AP, if available, should be selected.
If the ATC clears for a LOC capture only, the crew will press LOC p/b on the FCU.
If the ATC clears for approach at a significant distance, e.g. 30 nm, the crew should
be aware that the G/S may be perturbed and CAT 1 will be displayed on FMA till a
valid Radio Altimeter signal is received.
[...]
MISCELLANEOUS
The ILS or LS PB is to be checked pressed in the first stage of the approach. The
crew will check that

LOC and GS scales and deviations are displayed on PFD
IDENT is properly displayed on the PFD. If no or wrong ident displayed, the crew
will check the audio ident.

(Airbus A320 FCTM - Normal Operations - ILS Approach)


How does a fighter “thump” an intercepted aircraft?

'Thumping' is an (unofficial) term for maneuvering the aircraft so that the other (target) aircraft is caught up in its wake. As a practice, it seems quite widespread, atleast during cold war scenarios, and is explained elsewhere:

  Aircrews call it “thumping” — the aviator’s version of a baseball hurler’s brushback pitch. A fighter jet zooms up behind a lumbering reconnaissance craft, then blows past with afterburners blazing, pulling up and away just in front of the larger plane so its jet wash disrupts the airflow around it.

The effect is the same as flying into other aircraft's wake turblence, though the effects may not linger as long as the aircraft passes quite fast (that being the idea- to harass, rather than to cause an accident).

That said, I doubt it was done deliberately in this case as it is quite dangerous to both the aircraft and intercept procedures are quite clearly defined.

Intercept procedure; from FAA media release

Note that it specifically states to be cautious of wake turbulence. Maybe the author got caught in the wake turbulence of the fighter accidentally and it brought back memories of his service days.


If an airliner turns back midway, how is the route planned?

A diversion is a diversion, regardless of whether it is to the nearest airport, back to your origin airport or some other airport that is attractive, which may depend on what sort of facilities are needed (gates, fuel, maintenance, etc.).
The pilot simply tells ATC their new destination, and ATC amends their flight plan and gives the pilot a new clearance to follow. Depending on how far it is, the pilot (with the help of their dispatcher, if applicable) may request a specific route, or they may leave it up to ATC. That flight plan update is also automatically forwarded to all the relevant FIRs, just like the original version was.


Is there less vertical space for an engine under the wing of a 737 Max than for an A320neo?

The short answer is:

Yes, there is less vertical space under the wing of a 737 Max compared to an A320neo.

In the image below I have put the two airplanes side to side and the height difference is very apparent. Please note that the images are from the respective predecessors of the aircraft. The only thing that has changed regarding the height is that the 737 MAX has slightly larger tires than the 737 Classics, which should raise the MAX by 2 inches.

The reason for the lower height of the 737 is that it was developed a lot earlier when engines were a lot smaller in diameter. Therefore, they designed shorter landing gear. Choosing longer landing gear would have seemed unreasonable because this comes with a significant weight penalty. Redesigning the landing gear now would basically mean designing a completely new aircraft, because it would interfere with so many other systems.

Image Source A320, Image Source 737

It is difficult to accurately compare distances in photographs, because they come with all kinds of distortions. I have resized the images so that the main gear track is according to scale. Therefore the height comparison of the wings is fairly accurate.


Do GA aircraft pilots use predefined routes (via GPS or DME/VOR vectoring) or methods such as GPS-direct/ VOR-to-VOR in UC airspace?

By definition, there are no defined airways or routes in uncontrolled airspace, so the answer to that question is no.


What is the validity of doing 2D airfoil simulation for axisymmetric bodies?

Xfoil analyzes airfoils, not wings, and as such does not account for wingtip effects so its results are invalid for bodies of revolution or even low aspect ratio wings.

More generally, you can reference this answer about the derivation of wing lift from airfoil data. It boils down to the fact that aspect ratio has a massive impact on the 3D flow around the wing. For high AR wings the flow at most sections is close to what can be predicted with a 2D method, but this condition does not hold for slender bodies or near wingtips.

To phrase it differently, we can only apply the results from 2D simulations to wings by avoiding 3D effects. In the case of slender bodies, the entire flowfield is impacted by 3D effects.

Since flow separation is dependent on the pressure field around the body, you need to have an accurate idea of the 3D flow to reliably predict separation points.


If a pilot takes a MEL checkride and later a SES checkride, is the pilot now also qualified for MES/SEL?

No. You must take the training and pass the practical test for each add-on rating. See 14 CFR 61.63(c).


I don't know if you're asking about a specific country, but in the US it seems that you can just use it in place of a regular airport identifier and add supporting information in the remarks.

Specifically, the AIM 5-1 has several references to it, including:

  (b) If no four-letter location indicator has been assigned to the
  departure aerodrome, insert ZZZZ and specify the non-ICAO location
  identifier, or fix/radial/distance from a nearby navaid, followed by
  the name of the aerodrome, in Item 18, following characters DEP/,

  (c) Then, without a space, insert the estimated off-block time.
  EXAMPLE-

  KSMF2215
  ZZZZ0330

The same wording is used for both FAA and ICAO flight plan instructions.


There are a few factors and it may also depend on the relations of the nations.

If the aircraft is unarmed and simply surveilling it may be covered under the open skys treaty. This is largely about overflying other nations territories but presumably applies to over flying marine areas as well.

If the aircraft is armed and potentially making a move to attack the fleet may respond by intercepting. This is more or less the plot of Top Gun.

If the aircraft hails from a friendly nation, they may attempt to contact them and may interrogate their IFF system


How to apply the TO/GA time and EGT limits?

The TO/GA time limit and the EGT limit are hard limits mandated by the approved flight manual. They must be adhered to independently and cannot be traded off between the two.

Takeoff performance is calculated so that if a safe altitude above terrain and obstacles cannot be reached within the time limit, aircraft mass must be reduced rather than the TO/GA time increased.

Having said that, if things don’t go as planned during takeoff e.g. for reasons not known beforehand, I‘d recommend to bust the time limit rather than fly into the side of a mountain, if the choice is only between the two...


During an instrument approach, what are the obstruction clearance given?

The FAA lays this out in Order 8260.3c the three main relevant sections for requirements, level flight and climbing/decent segments are:

  2-1-2. Required Obstacle Clearance (ROC). This order specifies the minimum measure of obstacle clearance considered by the FAA to supply
  a satisfactory level of vertical protection. The validity of the
  protection is dependent, in part, on assumed aircraft performance. In
  the case of TERPS, it is assumed that aircraft will perform within
  certification requirements.

...

  2-1-3. Level OCS. The level OCS concept is applicable to “level
  flight” segments. These segments are level flight operations intended
  for en route, STAR, feeder, initial, intermediate, and NPA final
  approach segments. A single ROC value is applied over the length of
  the segment. These values were determined through testing and
  observation of aircraft and pilot performance in various flight
  conditions. Typical ROC values are: 1000 feet (2000 over designated
  mountainous terrain) for en route, STAR, and feeder segments, 1000
  feet for initial segments, 500 feet for intermediate segments, and
  250-500 feet for final segments.

...

  2-1-4. Sloping OCS. The method of applying ROC, in segments dedicated
  to descending on a glidepath or climbing in a departure or missed
  approach segment, requires a different obstacle clearance concept than
  the level OCS because the ROC value must vary throughout the segment.
  The value of ROC near the runway is relatively small and increases
  throughout the segment.

The document is lengthy and lays out various formulas and charts, to keep form copying the whole thing here please reference the document directly for anything more specific.


Engine shearoff, though rare, has happened in a number of cases.

Boeing 747F experienced a number of engine falloffs:

On Dec 1991, China Airlines flight 358, a 747-200F, lost an engine near Taiwan and crashed.
On October 1992, a El Al 747-200F crashed after takeoff due to engine separation, at Amsterdam, the Netherlands.
Another 747F from Evergreen Airlines lost an engine over Anchorage, Alaska soon after.
On October 2004, a Boeing 747-132SF of Kalitta Air lost an engine while climbing and landed without further incident.

Engine separation has been reported on 737s too:

In November 2007, Flight CE723, a Nationwide 737-200 lost an engine during takeoff; the aircraft was landed without further incident.
On December 1987, USAIR FLT 224, B737, lost an engine during climb; the aircraft was landed successfully.

There are cases where engine separation has occurred in B707, B727, and DC-10. aviation-safety.net has a list of engine separation incidents.


Where are the first two waypoints for runway 4R departures from KBOS?

Checking the IFR departure plates for KBOS, the first two waypoints for all departures from Runway 4R are NHANT and HURBE. You can see where they are on the Google map below.

BLZZR THREE departure plate for reference.


Were airworthiness certificates revoked for B737 Max?

The grounding of the 737max is a Prohibition of Operation, not a revocation of Type Certificate. This is done by each jurisdiction around the world. China suspended flights two days before the FAA did.

Technically, if you could find a country that never prohibited its flight, the Max could still be used there. Repositioning flights of grounded aircraft, as to a storage location, are authorized on a case by case basis.


Why are HUDs usually green instead of red?

A few thoughts (a bit of personal research):

Eyesight

The eye is most sensitive to green color, as can be seen in this diagram:

  At moderate to bright light levels where the cones function, the eye is more sensitive to yellowish-green light than other colors because this stimulates the two most common (M and L) of the three kinds of cones almost equally. At lower light levels, where only the rod cells function, the sensitivity is greatest at a blueish-green wavelength.

(source: wikimedia.org)

Dotted R line is (night-vision) human rhodopsin 'rods'.

As I understand, any powerful light depletes rhodopsin down requiring that they regenerate, which takes time, just that depletion takes longer with red wavelengths. I think this does not imply that green color 'automatically' screw up night vision if the display intensity is lowered enough.

Technical Limitations

The light has to be collimated to not interfere with depth perception, which complicates having multiple colours. At least in old CRT displays, this would have left you with the choice between blue, red or green. Green and Red is perhaps the color which stands out the most, but this diagram would suggest the red occurs at different wavelengths, perhaps again interfering with collimation:

  Due to the complexity of wide field-of-view reflective HUD optical systems, the optical designer must use all means available to meet display accuracy and parallax error requirements. All certified reflective HUDs today are monochromatic, generally using a narrow-band green emitting phosphor. The addition of a second color to the HUD is a desirable natural progression in HUD technology, however, one of the
  technical challenges associated with adding a second (or third) display color is maintaining the performance standards available in monochrome displays. One method for solving this problem uses a collimator with two independent embedded curvatures, one optimized for green symbology, the other optimized for red symbology, each with a wavelength-selective coating. Avionics Handbook, Chapter 4

Compounding to the previous point, it may be difficult to filter through a single red color through the screen, ending with a rather broad spectrum instead:

Further thoughts:

I think the night vision would be disturbed anyway by the variety of instruments such as maps and radar. I'm also doubting a bit of the importance of night vision in combat situations.
Night vision googles also use monochrome green light, despite having perhaps the greatest benefit of red light should they break and you need to continue without.
Even in a pretty new BMW I drove there was only monochrome green from their own HUD. I read forums accusing systems featuring multiple colours as having inferior display quality.


What is Transponder Code 2000 actually used for?

The purpose of squawk code 2000 is to prevent aircraft entering a Secondary Surveillance Radar (SSR) area from transmitting a code that is the same as a discrete code assigned by ATC to an individual aircraft.

If you are flying in the USA under Visual Flight Rules (VFR), you will be assigned (implicitly) code 1200. Upon entering a SSR area you might get assigned another code, but often you will keep code 1200 if you are not near class C airspace.

If you are flying Instrument Flight Rules (IFR) outside a SSR area (e.g. entry into the US from oceanic airspace), you will use code 2000. Upon radar contact you will then get assigned a discrete code.

From FAA Advisory circular 91-70A - (Oceanic and International Operations):

  2.  EXPANDED OCEANIC CHECKLIST.

  .......

  g.
  After Oceanic Entry

  (1) Squawk 2000.  Thirty minutes after oceanic en try, crews should
  Squawk 2000, if  applicable. There may be regional differences  such
  as Squawking 2100 in Bermuda’s airspace or  maintaining last assigned
  Squawk in the West Atlantic Route System (WATRS). Crews  transiting
  Reykjavik’s airspace must  maintain last assigned Squawk.

Another use of code 2000 is on the airport: before power up you can select code 2000 to avoid code conflicts that could occur when you would maintain your code from a previous flight. It is standard practice in many airlines to select code 2000 after arrival at the gate.


How much was the engine moved in the B737 Max w.r.t. older versions?

The Boeing 737-800 and 737 MAX 8 both have the exact same fuselage length of $ 39.47 \, \mathrm{m} $, so I chose these two models for comparison.

Boeing publishes CAD drawings for all aircraft models. I used the two CAD files for the 800 and MAX 8 to compare the engine size and location:

Since I do not know the units used in the CAD files, I used the known total fuselage length to scale the numbers:

Distance from the nose to the front of the engine nacelle:

$$ \text{737-800:} \; 13.544 \, \mathrm{m} \; , \; \; \text{737 MAX 8:} \; 13.180 \, \mathrm{m} $$

Length of the engine nacelle including exhaust:

$$ \text{737-800:} \; 5.075 \, \mathrm{m} \; , \; \; \text{737 MAX 8:} \; 5.345 \, \mathrm{m} $$

Diameter of the engine nacelle:

$$ \text{737-800:} \; 1.978 \, \mathrm{m} \; , \; \; \text{737 MAX 8:} \; 2.407 \, \mathrm{m} $$

Distance from the top of the engine nacelle to the bottom of the fuselage:

$$ \text{737-800:} \; 1.359 \, \mathrm{m} \; , \; \; \text{737 MAX 8:} \; 1.554 \, \mathrm{m} $$

Based on these measurements, the new engine nacelles are $ 270 \, \mathrm{mm} $ longer and have a $ 429 \, \mathrm{mm} $ larger diameter. They start $ 364 \, \mathrm{mm} $ further forwards and the top is $ 195 \, \mathrm{mm} $ higher.

Therefore, the center (geometric, not necessarily center of gravity) of the engines has moved $ 229 \, \mathrm{mm} $ forwards and $ 19 \, \mathrm{mm} $ downwards. While the geometric center may have moved downwards, the center of gravity probably moved upwards because the old nacelle was not symmetric (flattened at the bottom).


What is the asymmetric feature on the rear of a Sukhoi Su-47?

The Su-47 has two tailbooms of unequal length outboard of the exhaust nozzles. The shorter boom, on the left-hand side, houses rear-facing radar, while the longer boom houses a brake parachute.

Source: Wikipedia

Related: What is this part between the Su-35's jet exhaust nozzles?

Note: Your second image is mirrored. Here's a real photo with the right (starboard) boom being the longer one:

  Su-47 (aka S-37) in lead, also notice the tail numbers of the formation (no mirroring); source: wikimedia.org


What is "Defense Area" on a VFR Sectional Chart?

FAR 99.3 defines a Defense Area as an area in which air traffic can be controlled in the interest of national security. In other words, non-ADIZ airspace in which SCATANA or a similar plan can be implemented. In other words, all domestic airspace. It used to be clear that all airspace was Defense Area until FAR 99 got rewritten a couple of times in 2001-2004 when they were trying to figure out if the DC SFRA was an ADIZ. Now, the FAR that explicitly says that all non-ADIZ airspace is Defense Area is gone (to who knows where).

Nonetheless, all airspace that isn't an ADIZ is Defense Area, from sea to shining sea.

So why is it depicted on the southern border? To clarify that the airspace is not an ADIZ.

Take a look at this piece of the San Diego TAC. Notice how out in the ocean, the ADIZ is an actual 2-dimensional region. It's depicted with solid magenta lines with dots protecting the inside of the ADIZ. But at the beach, it devolves into a 1-dimensional line. But it's still depicted as the magenta line with dots. Look right there at the beach what has to happen, how the dots have to jump over the line. Thing is, since the ADIZ is a line there, the dots are actually outside of it, they can't protect the inside of it (since there is no inside to protect) and it looks like maybe all of California is an ADIZ, when it isn't. So the words DEFENSE AREA are printed there across the border from CONTIGUOUS US ADIZ to emphasize that the dots aren't actually protecting an ADIZ area; the ADIZ is too narrow to be correctly depicted.


Does speed or angle of attack generally have the greatest impact on total induced drag?

The change in angle of attack --as an end result of changes in speed-- causes the greatest difference in induced drag.

Induced drag drops with increases in speed because the faster-flying wing needs to deflect air by less in order to create the same lift.

Please read this answer which tries to explain induced drag much more intuitively than what you probably have read until now. With more air flowing past the wing per unit of time at higher speed, less deflection is needed, so the backward tilt of the lift vector is smaller. Since the weight of the aircraft should not change with speed, the same aerodynamic force has a smaller backward component at higher speed or in denser air.


Are there specific mass breakdowns for aircraft?

I can point you at some reference materials you can use. These methods involve estimates for different types of aircraft and formulas you can use to estimate the component weight based on the MTOW and OEW, for example.

You can use the following books:

Roskam - Airplane design (a series of books)
Egbert Torenbeek - Synthesis of Subsonic Airplane Design
Jane's All the World's Aircraft (over 600 aircraft)

scholar.google.com is another good source for finding articles about landing gear systems and design in general.


What's the rule of thumb for power and rpm in a constant speed prop?

The answer to your question is actually really simple: do not exceed the limitations specified in the POH.

Really, that's it!  Note that LIMITATIONS are not the same as RECOMMENDED PROCEDURES.  Recommended procedures are just that: recommendations.  Limitations (exclusively from the "limitations" section of the POH) are the hard and fast rules you must adhere to.

Full RPM in Cruise
As long as your POH does not impose a limitation on takeoff RPM (the Seneca II has such a limitation, for example), then there is nothing wrong with using max RPM from takeoff to shutdown. You won't damage the engine.  If the POH provides a limitation on engine RPM (specifically in Section II of the POH), you must adhere to that limitation.  It's common to see a 5 minute "max RPM" limitation on some turbocharged engines.  Great, takeoff at max RPM then pull the engines back to the top of the green arc until you land.  Easy!

Manifold Pressure & RPM
Mike Sowsun said:
"You should always follow the manufacturer's procedures but a general rule for direct drive normally aspirated engines is to keep the manifold pressure less than the RPM for cruise power. (eg. 24 inches of MP at 2400 RPM)."

If you decide to apply "rules of thumb" to all phases of flight you will be voluntarily handicapping your airplane's full potential.

Some definitions:
Oversquare - manifold pressure > RPM (23" @ 2100 RPM)
Undersquare - manifold pressure < RPM (23" @ 2500 RPM)
Square - manifold pressure = RPM (23" @ 2300 RPM)

Do not embrace the idea that manifold pressure should never, ever exceed the value of the first two digits of the engine RPM (sounds pretty arbitrary when I put it that way, right?).  It actually may be beneficial to run an engine "oversquare" in some cases!  This is another example of why knowing your aircraft's "Section II" limitations is important.  If 23" @ 2100 RPM falls within the limitations, go for it!!  You won't hurt the engine.  Same with 25" @ 2300 RPM or 26.756431" @ 2196.454634 RPM.  I think you get my drift.  As long as your manifold/RPM combination falls within the limitations set out in Section II of the POH, you're golden!!

Now, climbing out on a hot day with a garden variety Lycoming or Continental (like in 170)?  29" @ 2100 RPM probably isn't wise.  30" @ 2700 RPM?  Yeah, that's better!  25" @ 2500 RPM isn't bad but it's no better or worse that 26" @ 2700 RPM or 30" @ 2650 RPM.  Remember, there's nothing special about "square" manifold/RPM values.  I'd routinely run the IO-520 in my Bonanza at max manifold pressure and max RPM from takeoff to cruise and simply leaning to an EGT target as I climbed (and watching CHTs, of course).  Only when leveling off in cruise did I pull it back to an economical setting (sometimes oversquare, sometimes undersquare; always lean of peak).  The engine ran beautifully with good CHTs and incurred no unusual wear.  In fact, the engine's health improved.  Exhaust and plugs became noticeably cleaner and compressions improved.

In cruise, set the power to any combination of manifold/RPM you desire provided that setting falls within the limitations in your POH.  You won't hurt the engine with a valid manifold/RPM setting.  It's possible to put undue stress on a motor with a bad mixture setting, though.  POHs are notorious for giving poor guidance with regard to mixture settings.  Mixture settings require a little more attention above ~65% power but that's another topic entirely.

I recommend that everyone with engine questions read John Deakin's "Pelican Perch" articles.  He's THE source for fact based, accurate engine operation information. He happens to have touched on this "oversquare" myth here.  See Myth #2.

Edit: I credited John Deakin with my linked article.  I was mistaken.  The author of the linked article is Linda Pendelton.  She links to a Deakin article, though.

Mike Busch also addresses the oversquare myth here.


On a constant speed propeller, how is blade pitch related to airspeed and efficiency?

A propeller has an optimum AoA, where the thrust/drag ratio is highest. A variable prop can maintain this optimum AoA at a wide range of speeds, thereby reducing fuel consumption. That's all it does.

Fixed wing propellers have a dilemma that at take-off they require maximum thrust, and in high-speed flight the engine will need to be throttled back to prevent overspeeding. Maximum engine power cannot be utilised at every airspeed.

  why is it that if airspeed increases, for a fixed rpm, your blade pitch will increase?

To maintain optimum blade AoA. Increased airspeed causes reduction of blade AoA at constant pitch.

  On takeoff, you want max thrust/power.

You want maximum thrust. This is generated by making the propeller spin as fast as possible (not exceeding tip Mach), with a maximum blade pitch where the blade does not stall. Reducing blade pitch to increase RPM results in no increase in thrust: Power = Thrust * RPM.

  If you increase the blade pitch in these flight regimes, you get a smaller AOA with respect to wind

No a larger AoA. More thrust and more torque on the propeller axis.

  Is it more efficient to give power to blades to move larger loads of air

The engine runs most economically at the RPW where maximum torque is generated, the constant speed propeller speed control wants to maintain that RPM.

  would a blade generate more lift if it had a higher AOA, but at the expense of additional drag on the blade which in turn requires more engine power? Is this drag induced drag because it's an airfoil?

Yes and yes :)


Why wouldn't a helicopter ejection seat eject sideways? Or forwards?

Well to me it seems that in your question you consider the helicopter flying straight and level and clear of any terrain. Well that's not true so let's take each case separately:
Eject forward
That seems like the most dangerous option to me. What if you are into CFIT? The ejection system will actually "spit" you into terrain with your helicopter's speed plus the speed of the acceleration. Ouch. Even if you survive this, the point is to escape the helicopter. And guess what its trajectory is: forward.
Also consider that the free stream works against you so you will need more acceleration to get away of the incoming helicopter.
Finally, right in front of you there is equipment like dashboards machine guns sensors et al. that need to get out of your way before you go.
Eject sideways
That sounds a least dangerous option. But what if the helicopter is banking to one of the sides? If the crew is seated side by side do they have time or even the option, "I go first you go after"?
Also bear in mind that attack helicopters' nature is to fly low and maneuver a lot. So there are high chances to be low and bank at the same time when in need to eject.
So the above 2 leave you with one option: eject upwards. But then you have one (or maybe 2) big propellers rotating above your head. But that's "easy": you get rid of them the same way you get rid of the canopy and then eject. Once the blades are released, the centrifugal will do what it knows best and the blades will be out of your way in no time. Well, hopefully.
Considering the "too many explosives above ones head", it's not rare practice to use explosives to get rid of things that are in the pilot's way like for example the canopy. That's been around for a while. But changing the trajectory of escape that will be a new concept and it will need lot's of testing.


How long did it take to set up a portable runway?

Google is your friend. Try it. "perforated metal airstrip"

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

"A runway two hundred feet wide and 5000 feet (1500 m) long could be created within two days by a small team of engineers."


What is the reason for KSFO PRM approaches being decommissioned?

PRM approaches require recurrent crew training, additional ATC personal (you monitor a PRM controller in addition to the tower controller), and don't increase efficiency into SFO or PHL (which decommissioned their PRM years ago) that much.  Today's airports are being built with runways separated enough to allow simultaneous ILS approaches.
In short - Training cost + Personal cost > operational savings.


Are elevator trim tabs required for an aircraft equipped with movable horizontal stabilizer?

Is the aircraft also equipped with trim tabs?

From the images available online (this is a youtube screenshot, click it to see the larger version), no. And see point 3 on why I was not expecting any different.

  If an aircraft has both trim tabs and movable stabilizer

I do not see the need of such a solution, a trimmable stabilizer is already optimal, adding trim tabs would increase the complexity of the system with no significant benefits, as the use of tabs increases drag, something that a THS does not.

I do not know of any aircraft that uses both THS and tabs, but, should one exist, I presume one would use the tabs only if significantly faster than the THS actuation system, allowing the aircraft to be trimmed more rapidly, but afterwards the THS would take care of the trim allowing the tabs to go back to neutral and reducing drag.

This solution would be hardly beneficial, since commercial aircraft (as the one that prompted your question) do not preform manoeuvers that require such fast (and eventually frequent) re-trimming.

In addition, as GHB has pointed out in the comments, the elevator is already able to take care of fast transients, the trim tab would only provide unneeded complications (in the design, the maintenance, the control).


When are the engine bleed air, APU and packs turned on in the B737?

The general answer is, the engine bleeds stay on almost all the time.

The times they're turned off:

For a bleeds-off takeoff to get more power from the engines.
During deicing on the ground, so that deicing fluid doesn't get in the bleed air system.
When you are using the APU bleed air, the #1 engine bleed switch needs to be off IF that engine is running above idle power. If you're using APU bleed air & the isolation valve is open, the #2 engine bleed switch also needs to be off (if that engine is running above idle power).

The reason for the last requirement is because the engines, running above idle, put out greater bleed air pressure than the APU does, and you want to avoid the situation where the failure of a check-valve could put high pressure bleed air into the APU -- back-pressuring the APU, which could cause serious damage.

That scenario plays out if you're using the APU to run the cabin air conditioning (typically, on a hot day with lots of passengers), since it puts out a greater volume of bleed air than the engines do when they're operating at or near idle (i.e. typical taxi power settings). In that case, you close the engine bleeds, open the APU bleed and the isolation valve, and let the APU run both packs.

That scenario also plays out when starting an engine while taxiing; the switchology is reasonably intuitive but a little lengthy to describe.

There is no need when starting the engines initially to close the engine bleeds, since the normal procedure is to close the APU bleed & turn it off before taxiing the aircraft.

For a bleeds-off takeoff, the configuration is, engine bleeds off, APU bleed on, packs on, isolation valve closed. After takeoff, the steps are, #2 bleed on, pause, APU bleed off, pause, #1 bleed on, then isolation valve to Auto.

There is a procedure for a bleeds-off landing (to get more engine power for a go-around), and there are some QRH instances when you might turn a bleed switch off, but all of that is fairly rare.

If the OP is using a flight sim, the simple general answer, always leave the engine bleed switches on, will work fine.  Turn off the APU bleed after start. If you get the Master Caution for "Dual Bleed", you forgot to turn off the APU bleed, do so.

Edit, pack switches: off for engine start, on otherwise (except as directed by the QRH).