In case of failure in the Electronic Flight Instrument System, how would they be transferred between each other?

On the Embraer 170/190-series, the normal display layout is as follows:

There is an automatic display reversion logic when one or more panels fail. The following image shows this logic:

There is also a manual reversion switch located near each pilot's outboard knee, which controls what is displayed on the panel:

All images sourced from an Embraer Airplane Operations Manual.


Definitive answer: yes, it does.  Lots & lots of them.


Is there a legal requirement to tell your doctor you are a pilot?

In the US, you are not required to inform a doctor that you are a pilot. However, on the application for a medical certificate (Form 8500-8) you must list all "visits to health professionals" in the last three years, including type of professional and the reason for the visit.

The medical examiner uses that information to guide questions to ask about your medical history: a yearly checkup with your family doctor will not be remarked on, while a visit to a specialist might invite scrutiny about that area of your medical status. Depending on any existing conditions, you may need a letter from your primary doctor explaining your condition, but you would specifically ask for this rather than expect it to be provided.


Why are engines angled toward the fuselage?

It's called 'toe-in' and it's done basically to match the local airflow which is slightly divergent (heading outboard along the underside of the wing). If the engines were mounted exactly parallel to the fuselage, they would be moving slightly obliquely through the local airflow and therefore incurring extra unnecessary drag.

Another view of a 777 showing the engine toe-in:

  Source: airliners.net

The Boeing 747 has a 2 degree toe-in on all four engines, as can be seen in the following plan:
[Key: BBL 0 = Body Buttock Line zero, the centreline of the fuselage; WBL = Wing Buttock Line, parallel to that centreline; NAC BL0 = Nacelle Buttock Line 0, the centreline of the nacelle body]

and in this photo:

For rear-engined aircraft, the opposite is true: the engines are mounted slightly' toe-out' to match the local airflow which is converging around the tail of the aircraft.


The title of the website (Aviation Humor) should give you a hint. It is a joke!
However, there are a few similar situations, one of which is a pilot requesting a turn to avoid weather. That could go something like this:

Pilot: ABC123 request right turn to avoid

ATC: ABC123 right turn approved, report new heading

Pilot: Approved, WILCO, ABC123

Pilot: ABC123 now heading 120

Though normally, the pilot will give a rough estimate of how much they need to turn ("Request right turn 20 degrees to avoid").
Another example is ATC giving a pilot a relative heading change, and asking the pilot to report the actual heading.

ATC: ABC123 turn right by 10 degrees, report new heading

Pilot: Right by 10 degrees, heading 250, ABC123

The reason ATC doesn't just give the target heading to the pilot directly is that in many cases ATC does not know the heading of a flight - only the track. In cases with strong wind especially, the heading and track may differ significantly.
ATC can also tell a pilot to turn without giving a target heading, during non-gyro operations (compass gyro inoperative, so pilot does not know his heading). But in that case, the pilot will not respond (so you won't be hearing "341, 342, 343..."). ATC will then time the turn, knowing that a standard turn is 3 degrees per second.

ATC: ABC123 make all turns rate 1, start and stop all turns on the word NOW.

ATC: ABC123 turn left NOW.

(wait for a specific number of seconds)

ATC: ABC123 stop turn NOW.


Winglets vs Sharklets vs Blended wingtips

Winglet advantages

With a winglet you see a 3-5% reduction in drag which helps increase efficiency in aircraft by reducing something called a wing tip vortex which forms by the high pressure(under the wing) wraps around the top part of the wing which has the low pressure and results in a wing tip vortex. A winglet works by deflecting the air so less high pressure wraps the wing tip.
Increases lift(the winglet generates lift also like an aircraft wing)

Winglet disadvantages

Adds about 300 lbs of weight to the aircraft depending on the winglet
Reduces maneuverability which is why you don't see a winglet on a fighter jet

Now a sharklet and a winglet are essentially the same thing.

Bts: Its called a raked wing tip

Raked wing tip advantages

Does the same thing as a winglet by deflecting the air. With a raked wing tip you actually see a greater drag reduction than a winglet can give you which leads to great efficiency in aircraft

Raked wing tip advantages

You actually loose a little bit of lift due to the raked wing

Sharklet- The sharklet deflects air just like a winglet and acts in the same way and is a winglet, but Airbus just named it differently.

A350 design- The a350 uses a sharklet and a raked wing. You see great numbers of efficiency in the design because you include a raked wing and a sharklet.

Between the 3 you mentioned there is a big difference and all 3 have different advantages and disadvantages. They all act in the same way by deflecting the air the design is just different for each one. I hope this helped you understand a little bit more about these devices.


How does EMAS reduce damage in case of an aircraft overrun?

There is a link in the FAA tweet you link to, you should probably read it.

  EMASMAX® is the latest, most durable version of ESCO’s EMAS, developed with and technically accepted by the FAA. EMASMAX arrestor beds are composed of blocks of lightweight, crushable cellular cement material designed to safely stop airplanes that overshoot runways.
  - FAA Fact Sheet – Engineered Material Arresting System (EMAS)

So yes it's like gravel runoff areas, where the crushable material slows down the aircraft by providing resistance through the landing gear. The difference being this is a bit more engineered so you don't get bits flying up into the engines etc. like gravel would.

As for specs, the same link claims it can stop an aircraft going 80 mph but doesn't state a size of aircraft.

  A standard EMAS installation can stop an aircraft from overrunning the runway at approximately 80 miles per hour.
  - FAA Fact Sheet – Engineered Material Arresting System (EMAS)


Is there a way for passengers to know which runways their flight will use?

No. As far as is reasonably practical, planes land and take off into the wind so the runways that are in use will depend on weather conditions at the time of the flight, as well as traffic and so on.

These things probably won't be known at the time when you're picking your seat.


What is the procedure following a near miss?

The categorization of nearly missing another plane is different between the UK and US. See: What is the relationship between the terms "airprox" and "near mid-air collision"?

UK

As for the procedure, for the UK (where it's called an AIRPROX) it should be reported over the radio if the controller's workload permits, else later in writing after landing.

  An AIRPROX Report should be made by any pilot flying in the United Kingdom Flight Information Region, the Upper Flight Information Region or Shanwick Oceanic Area when in his opinion, the distance between aircraft as well as their relative positions and speed have been such that the safety of the aircraft involved was or may have been compromised.

So if it is in the pilot's opinion that an AIRPROX took place, it should be reported. The message needs to start with, "AIRPROX report." Following the report it will be confirmed in writing within 7 days.

The contents of the message the pilot should transmit are:

  Aircraft Callsign
  SSR Code
  Position of AIRPROX Aircraft heading
  Flight level, altitude or height
  Altimeter setting
  Aircraft attitude (level/climbing/descending/turning) Weather conditions
  Date and time (UTC) of the AIRPROX Description of other aircraft
  First sighting distance and details of flight paths of reporting and
  reported aircraft.

Source: CAP 413

USA

Similar reporting is explained for the US in the FAA AIM 7−6−3 Near Midair Collision Reporting. They can also be reported after the fact in writing.

The reported items are similar to the ones above, extra items include but not limited to:

  Degree of evasive action taken, if any (from both aircraft, if possible).
  Injuries, if any.


What powers an aircraft prior to the APU being switched on?

Other than the APU, there are multiple ways to provide electrical power to an aircraft:

Battery: The battery is typically the first thing you would turn on and it usually provides DC power to emergency systems only (at least on an airliner, smaller aircraft are fully powered by the battery). Running only on battery power will however deplete the battery quickly. The battery can also be used to start the APU.
Ground Power: Most (maybe all) airliners can accept a connection to a Ground Power Unit (GPU), which will supply AC electrical power to run all aircraft systems on the ground. These can be either mobile units (typically powered by Diesel):

(source)

or direct cable connections to the airport power grid:

(taken from this question)
Engine: This would be the method of last resort, but you can run an engine to provide electrical power via its generator. Note however that starting a jet engine would typically require bleed air from the APU or an Air Start Unit (ASU). Some turboprops can run an engine with a stopped propeller to provide power (Hotel mode). The engines also provide all electrical power during the flight, which is also used to re-charge the battery.

Running an APU on the apron is typically discouraged or restricted1 by the airport because of the noise and pollution. It does however provide one advantage over ground power: the APU also supplies bleed air to the air conditioning systems. Without it, air conditioning is only possible via a Pre-Conditioned Air (PCA) hose. See What is this tube connected to a 757 for? for details.

The APU is usually switched off after starting the main engines. It can however be used in the air on some aircraft. See In what conditions is the APU used in midair? for details.

1 Some airports have restrictions on when an aircraft is allowed to run the APU, e.g. Amsterdam:

  The use of aircraft APU is forbidden in these stands in the period between 2 minutes after blocks for the arrivals and 5 minutes before off blocks for departure.

The APU will still be used to start the main engines during push-back.


Is a "T" (Tango) prefix required before the registration number for Part 135 flights?

Since you're asking if it's required then I believe the answer is no.

First, just to include the information from another answer, the AIM 4-2-4 only says "should", not "must" (my emphasis):

  4. Air Taxi or other commercial operators not having FAA authorized call signs should prefix their normal identification with the phonetic
  word "Tango."

  EXAMPLE- Tango Aztec Two Four Six Four Alpha.

Second, the FAA's Joint Order defining ATC regulations says in section 2-4-20 (my emphasis):

  Air taxi and commercial operators not having FAA authorized call
  signs. State the prefix “TANGO” on initial contact, if used by the
  pilot, followed by the registration number. The prefix may be dropped
  in subsequent communications

That's the only mention of this prefix in the entire ATC regulations, therefore it's safe to say that controllers don't need the prefix and aren't required to do anything when they hear it.

On the AOPA forums there are a couple of unsupported comments that the prefix was used to give commercial flights priority in the past, and that it's still used for gathering statistics on flights today (although it seems like a very unreliable mechanism for that).


It depends on a lot of things like the kind of accident, the wreckage state, accessibility etc.
First thing to consider is that in most cases, the wreckage is evidence- so the investigating authority will take control of it and release it only when the investigations are complete or has reached a stage where the wreckage is not needed anymore.
As far as air investigations are concerned, the first thing to do usually is to dispatch a team to the site. For example, NTSB has a 'go' team which is dispatched as soon as possible to the accident site. From NTSB site:

At the core of NTSB investigations is the "Go Team." The purpose of the Safety Board Go Team is simple and effective: Begin the investigation of a major accident at the accident scene, as quickly as possible, ...
During their time on the "duty" rotation, members must be reachable 24 hours a day by telephone at the office or at home, or by pager.

After a preliminary investigation, the team decides what to do with the wreckage- either these are returned to the owner or retained for further investigation, partially or in full. From NTSB Major Investigations Manual:

When the IIC and the group chairmen have determined that parts or all of the wreckage is no longer needed for investigative purposes, the IIC ..., in consultation with the OAS Director, will be responsible for preparing and signing Part I of the wreckage release form (NTSB form 6120.15). The form shall be executed by the NTSB representative and signed by someone acknowledging his/her receipt of the wreckage This is done in almost ll cases, except those where there is no accessibility to the wreckage, like he ocean floor.
Part II of the wreckage release form will include a detailed list of any parts or components of the wreckage that will be retained by the NTSB for further examination.

Note that the release of wreckage is decided by the investigating authority and it may be kept in storage, if necessary.

There should be no pressure to release all of the on-scene wreckage. Often it is better to arrange for wreckage removal and storage and to retain control of the wreckage in case there is a need to examine it later.

In some cases, the investigating authority will go to great lengths to transfer the wreckage to their place, so as to carry out full investigation. This happened in the case of TWA 800 investigation, where the wreckage was picked up from seafloor and reconstructed to investigate criminal activity.

Image from the NTSB aircraft accident report (NTSB/AAR-00/03) fig. 29, page 102, via Wikimedia Commons.
Another thing is that the disposal of wreckage is a costly business when its done. This is where the size and location of the wreckage comes in. Most of aircraft wreckage would be aluminum scrap, usually too expensive to move and too uneconomical to use elsewhere. Obviously there's a difference between a 747 wreckage downtown and a R-22 wreckage in a remote hill (I'm taking about wreckage disposal, not investigation here). The disposal is done either by the owner/insurer or the investigating authority, with the owner/insurer coughing up. From Singapore Investigation of Accidents Statute:

If  a  person  to  whom  custody  of  the  aircraft, parts,  wreckage  or  contents  is  to  be released refuses to take custody thereof or fails to take custody within a reasonable period, the  aircraft,  parts,  wreckage or  contents  may  be  disposed  of  in  such  manner  as  the  Chief Inspector considers fit.
The  expenses incurred  by  the  Chief  Inspector  in  disposing  of  the  aircraft,  parts, wreckage  or  contents  shall  be  borne  by  the  owner  or  operator  of  the  aircraft  and  be recoverable from either or both of hem.

Most other countries have similar rules. As for reusing the contents in the wrecked aircraft, this is usually not permitted (though it depends on the operator/regulator rules). In case it is permitted, the LRU logbook should contain details about it being in an accident and in general, they are sent to OEMs for tests and recertificaiton. Some companies do trade in salvaged aircraft.
And finally the 'stuff' is sometimes left to salvage for whoever wants it- it may be the most economical thing to do, after all.


Can some IAFs be skipped if more than one IAF exists?

Any initial approach fix (IAF) is a valid point at which an aircraft can start the procedure. Many procedures also have IAFs on multiple paths to choose from to get to the final approach. Standard Terminal Arrivals (STARs) sometimes include a certain IAF so that pilots can go straight from the arrival to the approach. Aircraft not on one of these STARs could use any other IAF.

Aircraft can also start even later in the procedure at an intermediate fix (IF), such as TELEX in the above example, provided it is coordinated with ATC and certain conditions are met.

After entering a procedure, aircraft are expected to fly the procedure as published. While it's not as common as with a SID or a STAR, ATC could certainly give an aircraft instructions for a shortcut on an approach, for traffic or other reasons. ATC would need to authorize this to ensure clearance from traffic and obstacles and compliance with restrictions such as noise abatement.


What pattern of position lights did early Soviet jetliners use?

That was a tough one. The USSR joined ICAO in 1970.[a] The colors and positions would have been the same, since those carried over from maritime conventions.
What isn't the same, based on checking warbirds, is the viewing angle. The red/green lights in ICAO/Western standards are not viewable from behind, but Soviet aircraft did not have that distinction. They also had separate top/bottom navigation lights, even the license-built DC-3 (Li-2) was modified to have that top/bottom arrangement.[1]
Judging by the Yak-40 (an early Soviet jetliner), they lacked the white wingtip lights[b] that are viewable from behind -- compare with the ICAO-compliant Il-62 (shown on the right):

Both aircraft are stored; sources: scalemodels.ru and elevation.maplogs.com

For the aforementioned warbirds, below shows an American F4F (annotated) and a Soviet Il-2:

Sources: primeportal.net and primeportal.net

1: http://www.dc3history.org/airlinesoftheworld/russianaviation.html
a: I'm not sure whether Soviet transport aircraft that flew internationally and were built prior would have been retrofitted
b: technically those are anti-collision lights, but unfortunately the Wikipedia statement is vague and lacking in-line citation -- the ICAO-equivalent became effective in 1962 according to SARPs Annex 6 part 1


Why does the Aurora D8 have vents on the bottom of its fuselage?

If you're talking about the dark spots here...

...then those are the tires of the main landing gear. This is the same approach used by the Boeing 737 — as discussed in another question here.

By skipping main landing gear bay doors, the aircraft's total weight is reduced. An aerodynamicist could provide a more confident answer, but the impact of the exposed wheels to the airflow would be relatively minor and not impact drag meaningfully.


How does the severity of barotrauma vary with rate of descent?

It's purely subjective, but I can tell you from personal experience descending in unpressurized airplanes that a 500 fpm descent is WAY less painful than a 1500 fpm descent if you have something like a blocked sinus passage.  The blockage is usually not 100%, so the pressure rate of change has a huge effect on the pressure differential that is allowed to build up in your head as pressure equalizes, but just not fast enough.

Your head and sinus cavities (or inner ear) are effectively turned into a human Vertical Speed Indicator (which simply measures the rate of air pressure equalization between an aneroid chamber and ambient static through a restrictor, like your blocked sinus), but instead of a VSI pointer on the dial, you have the pain receptors in your skull.  Like the VSI, a 1500 fpm descent will crank your pain receptor dial quite a bit higher than a 500 fpm one will if you have a sinus infection.

The important thing to point out however, is the typical airline passenger never experiences anything more than 500fpm in normal operations, because pressurization control schedules limit the rate of change in cabin pressure to that value.  In any jet you are normally descending anywhere from 1-3000 fpm on an arrival, and even on final on a normal glideslope at, say 130kt, you are descending somewhere around 750 fpm.

It's only in unpressurized airplanes do you generally try to limit climbs and descents to 500 fpm when passengers are on board.


The air doesn't notice or care that we humans use so many different names for those wingtip extensions. They all help to keep the pressure difference up between both sides of the tip and add some friction drag.

Since giving basically the same thing such a variety of names is a pettifoggery and there is no standardization for naming them, it is hard to give a clear, distinguishing feature. If I now say that endplates extend to both sides of the wing and are smaller, while winglets point up only and are larger, I am sure that somebody will rightfully point out an exception to this rule. Just look at the latest monstrosity Boeing added to their new 737NG.

Boeing scimitar winglets (picture source)

When the term endplate is used, the transition between wing and extension is sudden and sharp, while winglets tend to have a smooth, rounded transition. Maybe this would be a better guide, but also here exceptions can be found.


How often does an autopilot update control surfaces' positions?

So often that to any observer (visual or tactile) it appears continuous.

I say this as someone who has 2500 hours operating a transport category airplane. The flight director provides continuous guidance that the autopilot continuously follows. When holding the control column with autopilot on (below 10k feet you hold the controls even with autopilot engaged) you would interpret it as continuous input (the autopilot moves the controls just as if the other pilot were flying).


How much force can the Dukane DK 100 ULB (Underwater Locator Beacon) widthstand?

An exact model is too specific to find, but the FAA Advisory Circular 21-10A regarding ULD's from 1983 says:

There is also a patent from 1989 which lists specifications regarding most pingers:

Most pingers are cylindrical in shape. Typical dimensions for flight recorder applications are 1.25 inches in diameter and 3.8 inches long. The flight recorder ULDs can survive crash forces of 6000 g's (0.5 ms) and ocean depths of 20,000 feet.
— Google Patents (1989)

The FAA also mentions the SAE International’s Aerospace Standard (AS) 8045a, Minimum Performance Standard for Underwater Locating Devices, which is behind a paywall. But the aforementioned AC should suffice.


Can an aircraft get certified for different runway lengths through the FAA based on the amount of payload it is carrying during said takeoff?

Generally an aircraft will be certified for a range of runway distances based on headwind/air temp/weight, a correction chart will be provided in the POH allowing you to compute the runway distance for various conditions. For example here is the chart for the PA-28-161 I trained on

The big planes have similar charts, you can find the 737-800 numbers here and if you want to go to the really heavy metal the 747 info can be found here.

The AC that covers aircraft certification can be found here and interestingly the distances are computed from standstill to the point at which the lowest part of the aircraft is 35ft above the ground.

  (1) The takeoff distance on a dry runway is the greater of the two
  distances depicted in (a) or (b) below (see page 63 of above linked doc). The distances indicated below
  are measured horizontally from the main landing gears at initial brake
  release to that same point on the airplane when the lowest part of the
  departing airplane is 35 ft. above the surface of the runway.

Interestingly the FAR does not seem to address the weight at which the takeoff distance tests are done.


How does switching off pumps and putting on MAN switch resolve low pressure?

The procedure switches off the pumps, thereby resolving the low pressure. Low pressure means the pump is running but it is not pulling anything.

Fuel pumps can't draw fuel if the amount is too low. Imagine pumping water out of a swimming pool by attaching the pump to a hose. There will be smalls amounts that the hose can't reach. That amount is called unusable fuel and is part of the plane's operating empty weight (OEW).

See: What are different types of weights of an aircraft?

Some fuel quantity indicators are calibrated to not count this unusable amount of fuel.

If the captain really needs those 200 kg, they it's their decision to add a lot more in the center tank so it would be usable without any problems.

RE: What about the reason for putting the mode selector to MANual?

If the pumps are selected off with the mode selector still in auto, this will cause an auto feed fault warning as the normal operation of the auto mode (which is what causing the issue in the first place) requires the pump switches to be on the on position.

What does the auto mode do? See: Why are the center tank pumps deactivated when slats are extended on the A320?


Why do aircraft piston engines require priming?

Modern car engines are really very sophisticated compared to most airplane piston engines, which are 70 year old technology.

Modern cars typically have an electric fuel pump in the tank which is often started by opening the drivers side door, by the time your butt is in the seat the fuel system is pressurized. When the ignition system is activated the ECU (engine computer) looks at engine coolant temperature and outside air temperature and directs the electronic fuel injectors to meter the exact amount of fuel which is correct for the conditions, directly into the inlet valves. A cold engine needs a much higher ratio of fuel to air when starting (2-3 times when hot), which reduces as it heats. When it starts running the ECU also takes into account the mass of the air flow and oxygen content of the exhaust to maintain the ideal fuel-air balance for the smooth and efficient running of the engine.

This technology does exist for airplane engines, it's just expensive to fit so very few airplanes have it. Most light airplanes have very simple, completely manual systems. You shut down the engine by cutting off the fuel supply (closing the mixture), this ensures that the engine is completely dry of fuel so that if the prop is spun there's nothing in the cylinders which could go foom and spin the prop, potentially maiming someone.

Piston engines create a lot of suction as they operate, and rely heavily on vacuum suction to operate. The low pressure in the carburetor atomizes fuel, which then gets pulled into the cylinder, explodes which in turn pulls more fuel and air in. However, because the mixture was cut off the engine and carb are all dry (any fuel left in the carb bowl will evaporate over time), which produces little suction. No suction, no atomization of fuel, no foom. The primer pumps a very rich atomized mist of fuel into the intake for each cylinder, giving the engine something to foom, creating suction to pull fuel through the carb and sustain the engine. This is why you feel resistance when using the primer, you are forcing it through a bunch of atomizing nozzles. This is why you need to start right after priming, if you wait too long you lose atomization.

Note that many airplane piston engine carbs have accelerator pumps which jet raw fuel into the carb on quick throttle advances, this is to prevent a lean cut-off. Some people think it's the same as using the primer, but it isn't at all. Because there's no suction when you pump the throttle forward all you are doing is jetting liquid fuel into the carb, there's no vacuum to atomize it, so all you are doing is filling cylinders with raw fuel and they won't go bang. A single jet is good because having fuel in the carb bowl gives something to atomize once it catches, but too much will just flood the engine.

A hot start is very different from a cold start, the engine doesn't need as rich a mixture and the carb bowl still has fuel in it, so when you crank it you don't need to prime in most cases.


How often should an engine be run, to stay mechanically sound?

All your plane's systems are happier when you're flying, including the pilot.

Ideally, you'd fly often in order to keep your engine happy (distributing clean oil throughout the system to protect against corrosion and heating it enough to drive off water from the crankcase).
As a rule of thumb Blackstone Labs (the oil analysis folks) consider piston engines "inactive" if they've had less than about 5 hours of flight time per month. Their threshold used to be 10 hours, so I personally try to fly at least 10 hours a month much when practical, but 5 at a minimum.
Blackstone has a LOT of data on aircraft engine wear patterns accumulated, and I generally trust their insight in this regard (after all they're not trying to sell me an engine, just asking me to pay them to play with my used oil).

When weather or other factors mean you can't fly enough to keep your engine "active" you can preserve it in accordance with the manufacturer's instructions, but let's be honest, most of us aren't going to "pickle" our engines for the winter. It's a LOT of work, and it means you can't go fly on those nice winter days we sometimes get.

In situations like this, it may be beneficial to ground-run your engine (say at least on a monthly basis) just to keep things lubricated and happy. Ground runs at a little below runup power or a fast idle are usually the order of the day here. Taxiing around is also probably a good idea, if practical, to keep your wheel bearings and related components moving -- maybe take your plane down to the runup pad and back.

When doing the ground run you want to observe a few guidelines to make sure what you're doing is actually beneficial to the engine:

Make sure you've got clean oil in the plane!
Any time you think the plane is going to be inactive you want to have good, clean oil in the engine (and you want to have done a thorough ground run or flight to spread that clean oil everywhere). This gives you optimal protection against corrosion.
Treat it like a flight.
Preflight the plane like you're taking it up, even if you're not.  You may not be flying much because of the weather, so there's a real chance your plane's systems will be in less-than-excellent shape. That thorough walk-around may catch a potentially expensive problem before it becomes a real issue.
Preheat if necessary.
Hand-in-hand with treating it like a real flight, you want to make sure you're not abusing your engine in the name of protecting it.
Get the engine oil to normal operating temperature.
Part of the point of the ground run is to drive off water that has condensed in your oil -- oil is good for metal parts, and water is bad for them.
If you don't get the engine oil up to normal middle-of-the-green-arc temperatures and keep it there for a good while (20-30 minutes at least) you may not be driving out the water, which can lead to a very unhappy engine.
If you don't get the oil up to operating temperature long enough you may wind up doing more harm than good! Combustion blow-by leaking around the piston rings contains water (and a bunch of other corrosive things your engine doesn't like), and really short ground runs that don't bring the engine to temperature are mainly just causing wear from the startup and dumping these nasty things into your oil. Your engine is not going to like that.
Run long enough to recharge your battery.
Watch your ammeter/load meter after startup, and make sure that your battery has been replenished before you shut down.
This means running your engine at a high enough RPM that the charging system can charge the battery (a fast idle is usually fine), and long enough that the battery can be charged (which isn't a problem, because if you were paying attention to #4 you've noticed we'll be running the engine a good while anyway).
Monitor your cylinder head temperatures.
If equipped with CHT probes, make sure you're not exceeding the CHT limits for your engine during the ground runs.  This goes hand in hand with #7 below.
Lean your mixture to avoid fouling your plugs.
You should be using less than 65% of your engine's max rated power for these ground runs -- in fact, you should probably be somewhere around 50-60%.  Rather than running full rich, pull back on the red knob and let the engine burn cleaner (but keep an eye out for the warning signs of detonation/preignition).
You probably only want to do this if you've got Cylinder Head Temperature readouts you trust -- when in doubt you can always run full rich (for the added cylinder cooling) and just clean your plugs.

Depending on the outside air temperature your ground run may last anywhere from 30 minutes to 90 minutes (I've not personally had one last longer than that, though it's theoretically possible I suppose) -- it all depends on how long #4 and #5 above take.

A final thought: I use ASL CamGuard in my oil. It goes in with every oil change.  Mike Busch (a smarter guy than me) swears by it, and there seems to be ample real-world-anecdotal evidence as well as a good amount of actual materials testing research that indicates it's a pretty decent corrosion inhibitor.
I've not had my plane/engine long enough to know if this treatment is effective or not, but it certainly doesn't seem to be hurting anything, and while it's a little expensive it's not "liquid gold" prices, so it strikes me as cheap enough insurance that you may as well dump it in the sump. This is especially true when you weigh it against the price of a bottom-end overhaul because you got pitted cam lobes or lifters...


As a student pilot can I fly solo hours from any airport?

No, the airports you can fly from/to must be specifically endorsed by your instructor. Once you have your PPL, you can fly to any airport.


How does the outflow valve work on a cabin pressurization system?

Pressure does not rise because keeping the cabin pressurized begins with releasing air to the outside. The flight starts low, with low cabin altitude, as the plane climbs the cabin altitude rises (lower pressure than it started).

As for the air itself. When it is compressed by the ACM, the temperature does rise, that's why it is cooled before being introduced into the cabin.

See here: Where does the final cooling take place in the air cycle machine of the air conditioning system?

Work is done on the air, then the air does work by passing through a heat exchanger, and then a turbine, which runs the ACM.

There is one plane I know of that maintains sea level pressure up to FL 410. In that case air will still be jettisoned overboard to bring in fresh air, with the same ACM cycle of temperature regulation.


What to do when pneumatic air cycle kit stops working mid-flight on Boeing 737-800?

Different airlines may have different policies, but I think what my airline uses is probably pretty standard in this regard: no, you can continue at FL 390.

The limitation of not exceeding FL 250 on one pack comes from the MEL, which is a pre-takeoff document.  If the pack is known to be inoperative before takeoff, then the flight has to be planned at an altitude no greater than FL250, which means that the fuel planning has to account for the burn rate at the lower altitude.  However, when a system fails after you are airborne, the controlling document is NOT the MEL, but the QRH (i.e. your non-normal checklist for pack failure).  The QRH from Boeing does NOT direct you to descent to FL 250 for a single failed pack, for exactly the reason you allude to in the question -- you might very possibly have to divert due to the higher-than-planned fuel burn.

So in the case of a pack failure at FL 390, you can continue that flight at FL 390 as planned, but all subsequent flights until the pack is repaired have to be conducted at or below FL 250.

Some airlines may have a different policy, but that's the basic answer from Boeing's documents and philosophy.  Also, fuel permitting, some pilots might descend from FL390 to something a bit lower if they thought that the remaining pack might have an issue, just to provide a bit of cushion in case it does decide to stop working.  Packs fail rarely enough, though, that the risk of the second one failing on the same flight is pretty remote -- which is probably why Boeing is okay with continuing at the high altitude for the one flight, even though if you'll have to fly several more flights before getting repairs, they want the risk minimized for the others.  Risk management.


Does a Mexican citizen studying in the US with an FAA license need a visa when landing at airports in Canada?

You should call the Embassy of Canada in Mexico for advice on your situation. They will best be able to advise a Mexican passport holder on their entry requirements. Their number is +52 55 5724 7900.


What is the purpose of the sharp pods under airliner wings?

They are Anti-shock bodies.

In the transsonic speed range (above about Mach 0.7), aircraft drag is governed by Whitcomb area rule, which basically says that to minimize drag, the aircraft cross-sectional area must change as smoothly as possible, independent of its actual shape. It is somewhat counter-intuitive, but well established.

Compare this Junkers patent drawing (via Wikipedia):

which shows various combinations of positioning engines to adopt the area rule.

For the usual aircraft design the cross-section increases over the engines that hang ahead of the wing leading edge and then the thick part of the wing and wing box (the thicker part of fuselage where wings connect), but the wing tips are too thin and the cross-sectional area would decrease too quickly, so something needs to be attached to the trailing edge to make the reduction of cross-sectional area smoother. The anti-shock bodies are usually conveniently combined with flap actuator and track fairings.

There are however some aircraft that have anti-shock bodies combined with other functions, e.g. Tu-134 (and many other designs by Tupolev Design Bureau) retracts landing gear in its anti-shock bodies (which are just one large on each side):

The flap actuator and track fairings exist on all aircraft that have flaps that extend aft as well as down (Fowler flaps and their double-slotted variants), but on slower planes they are much thinner. Compare e.g. ATR-72, which does not need to be area-ruled with its maximum Mach 0.55.


I want to be an airline pilot. Would becoming a NON-COMBAT Air Force pilot be a good way to become one?

It depends on which part of the world you're in.

Airlines based in a country with a healthy General Aviation scene will probably prefer civil pilots. If there General Aviation scene is limited then it would make military pilots an attractive source.

I'm not saying that Military pilots are any worse/better but there have been airlines where the safety record was quite poor as a result of poor CRM from the military pilots, China Airlines and Korean Air are examples. These airlines have recognised and rectified the problems and today are up to industry levels in terms of accidents/incidents.


What is the difference between aircraft integration and assembly?

I was many years with an OEM.  Integration is process of coordinating and incorporating, harmonizing you might say, the unique engineering of systems and processes of two engineering and production organizations or products, to make them work together in the final product.  To integrate them.
For example, a manufacturer designs and builds an airframe.  An avionics suite, or some other system, designed and manufactured by a second party, not specifically for a given type, is selected to be used in this new airframe.
Someone has to integrate, or adapt, the pre-existing avionics suite into the airframe and systems of the host.  The integrator is responsible for all of the activities of incorporating that system;  where/how it fits, how it interfaces with host systems, etc. In other words, the integrator is responsible for making the second party system work smoothly in the host system.


How does the RQ4-Global Hawk improve stability?

What you are looking for is "gyroscopic-stabilization".

As you can see in this video, the camera is mounted on gimbals that can rotate over all axis. Movements are controlled thanks to gyroscopes. For sensors mounted on larger aircraft, optronics systems are ball-shapes. That way they can rotate without modifying aerodynamics. There is no need to compensate for translation as targets are far away.

I didn't find any sources for shake reduction thus I can only assume techniques are the one that Wikipedia name "vibration reduction" and "anti-shake".


How is the emergency locator transmitter of the A320 fixed, activated and carried away?

It's a self-contained unit with its own battery, GPS transmitter and antenna, with a port that can be plugged into the antenna connector of the aircraft. Just disconnect, stick out the whip antenna, and swim downstream the Amazon :)

Image source

Here is Australia boats are required to bring a similar device on board called an EPIRB if going off-shore for more than a couple of miles, also a really good idea if driving from Darwin to Adelaide with a detour through the desert.


In Ethiopia, what are the minimum hours to be a pilot in a passenger jet?

For Commercial Pilots: 250 hours; For ATP: 1500 hours.

Source: ecaa.gov.et (PDF; see Sections 3 and 6).

The flight hours requirement does not seem to be different for Pilot and Co-pilot. (See Section 6.6)


When are winds given with respect to true vs. magnetic north?

The general rule is:

If you read it, it's true. If you hear it, it's magnetic.

All charts and textual sources (METAR, TAF, winds aloft, surface analysis charts, etc) use true north as the reference.

ATIS/AWOS/ASOS broadcasts, or any information a controller gives you over the radio, is magnetic.

  Wind direction broadcast over FAA radios is in reference to magnetic north.

AIM Section 7-1-11 (page 7-1-26 in the 5/26/16 edition)

One exception to the "if you hear it" rule is that a FSS briefer will read you the winds referenced to true north, since they're just reading you the charts/textual information.

(This is at least true in the United States... other countries may vary in some instances)


When were civilian aircraft first directed between aerodromes by air traffic control?

In 1920, Croydon Airport, London was the first airport in the world to introduce air traffic control.

In the United States, air traffic control developed three divisions. The first of air mail radio station was created in 1922 after World War I when the U.S. Post Office began using techniques developed by the Army to direct and track the movements of reconnaissance aircraft.

In 1930, the first radio-equipped control tower in the United States began operating at the Cleveland Municipal Airport.

(Source)


The canard flap is like any other control surface in the trailing edge of a canard. The canard flaps are there mainly for trimming the aircraft.

At transonic speeds, the center of pressure of the aircraft moves rearward, resulting in instability. This could be countered by trimming with the elevons; however, this increases the angle of attack (the elevon deflection in XB70 was between $0^{\circ}$ and $10^{\circ}$)- resulting in increased drag. The small flaps in the XB70's canard was used to counter the movement of center of pressure without changing the main wings AoA, which eliminated the speed and range penalty due to increased drag.

Another advantage is during the landing. The landing attitude of delta aircraft is usually steep and fast compared to other aircraft. The deflection of canard flaps in the XB-70 pitched the nose up, enabling the elevons to be operated as trailing edge flaps- this helped the to keep the landing attitude shallower and speed, lower.

Actually, in case of XB-70, the canard was exclusively a trimming device- the longitudinal control was provided solely by the elevons.

During landing, the use of flaps cause a negative pitching moment- In aircraft with horizontal stabilizers, flap deployment may increase the downward airflow on the horizontal tail, producing a pitch up moment. in case of aircraft without stabilizers, it is not possible. In order to trim the aircraft, the canard flaps in Saab Viggen were deployed; in case of Beechcraft starship, a variable sweep canard was used for the same purpose.

The main disadvantage of having flaps in canard was the increased complexity. The canard can in itself be used to provide the required trim; the flaps are used only when the canard is highly loaded and may not have sufficient spare lifting capacity to accommodate large movements of the centre of pressure or of the centre of gravity. Note that in case of XB-70, initially, the canard was fixed and the flaps were adjustable; later the canards were made trimmable with the flap deflection set at two positions- $0^{\circ}$ and $20^{\circ}$.

References: WarbirdTech: North American XB-70A Valkyrie by Dennis R. Jenkins and Tony Landis; Summary of Preliminary Data Derived from the XB-70 Airplanes by William H. Andrews, NASA Technical Memorandum TM X-1240


What are the guidelines and regulations for building a helipad for multiple aircraft?

The FAA publishes an Advisory Circular on heliport design.  It applies to heliports serving helicopters with a single rotor.  I don't believe that there are any regulations regarding "ownership".  They just have to be operated in compliance with appropriate FAA, state and local regulations (but these can get complicated)


Has Jeppesen announced plans to stop supporting the Microsoft platform for Flight Deck Pro?

Only 6 months ago Jeppesen announced a common interface for iOS 9 and Windows 10.
And why would they deliberately lose their airline customers that use Windows? The integrated Class 3 EFB's on Boeing planes for example, run Windows.

The open architecture of the EFB
Class 3 system will allow airlines
(or third-party suppliers) to develop
software for the Microsoft Windows
processor using a software development kit provided by Boeing and
Jeppesen.

Regarding the FliteDeck, only a couple of weeks ago:

ForeFlight and Jeppesen Announce Strategic Alliance
Jeppesen and ForeFlight will work together on a next-generation release of FliteDeck Pro for both iOS and Windows that will deliver a combination of the familiar capabilities in FliteDeck Pro and significant features and functionality from ForeFlight Mobile.


Are any software or aeronautical engineers yet attempting to design pilotless passenger planes (PPP'S)?

Serious discussion of removing passenger jet pilots?  No.

Serious discussion of making pilotless VTOL aircraft? Yes.

Uber, for one, is already working on this. Check out this quote from page 40:

  To fast-forward to the safest possible operational state for VTOL
  vehicles, network operators will be interested in the path that
  realizes full autonomy as quickly as possible.


Do aircraft engine intakes require air filters?

In addition to Rachet Freak answer I'll add that helicopter engines are subject to much dirtier air. Aircraft operate from runways which are relatively clean. Due to their speed, most dust and debris that is kicked up is behind the engine inlet so it is not sucked in.

Helicopters hover and land vertically and therefore their engines ingest air contaminated with kicked up dust. Especially when operating outside paved surfaces this results in considerable pollution. A filter is much more useful here.


What is a Terminal Radar Service Area (TRSA) and what are its operational requirements?

A good explanation of a Terminal Radar Service Area (TRSA) can be found in the Aeronautical Information Manual 3-5-6.

  TRSAs were originally established
  as part of the Terminal Radar Program at
  selected airports. TRSAs were never controlled
  airspace from a regulatory standpoint because the
  establishment of TRSAs was never subject to the
  rulemaking process; consequently, TRSAs are not
  contained in 14 CFR Part 71 nor are there any TRSA
  operating rules in 14 CFR Part 91. Part of the Airport
  Radar Service Area (ARSA) program was to
  eventually replace all TRSAs. However, the ARSA
  requirements became relatively stringent and it was
  subsequently decided that TRSAs would have to
  meet ARSA criteria before they would be converted.
  TRSAs do not fit into any of the U.S. airspace classes;
  therefore, they will continue to be non−Part 71
  airspace areas where participating pilots can receive
  additional radar services which have been redefined
  as TRSA Service.

These airports can't be redrawn as class B or class C airspace so they became TRSAs. The airspace at the airport is class D and the airspace in the TRSA is usually class E. The operational requirements are no different than any other class E or class D airspace, but aircraft are encouraged to avail themselves and participate in the TRSA when inside its bounds.

It should also be noted that many TRSAs have their own approach control.


Is there any System to warn of Runway Incusion?

Yes, there are several systems.

The simplest are REALLY BIG WINDOWS (and binoculars):

When the entire wall in front of you is a big expanse of glass looking out over the runway there's a good chance you'll notice something trying to roll onto the runway.
Many runway incursions are detected visually.

Really big windows don't work as well when you have multiple runways and larger airport complexes though, so we have some technological solutions too. The most common is Automated Surface Detection Equipment (ASDE), the one being deployed today is ASDE-X.
This is basically "radar on the ground" which interrogates aircraft transponders and shows the controllers which aircraft are where on the airport surface:

There are also systems on the ground designed to prevent incursions, but those are mainly for use by pilots.
These include Runway Status Lights, taxiway guidance lights (which include "stop bars" that light up on hold-short lines), and "runway guard lights" (which may be mounted either in the pavement or alongside the taxiway/runway intersection).

Many of these systems can be controlled from the tower, either by automatic systems or manually by the controllers.


Are there limits to speeds at certain altitudes?

The following maximum speeds apply in the US (A few aren't based on altitude, but I've included them to be more complete):

91.817: Mach 1 over land (with a few exceptions that are noted in Appendix B to 91.817)
91.117(a): 250 KIAS below 10,000 ft. MSL
91.117(b): 200 KIAS below 2,500 ft. within 4NM of the primary airport for Class C and D airspace (unless within Class B airspace)
91.117(c): 200 KIAS under the shelf of Class B airspace
91.117(c): 200 KIAS in a VFR corridor through Class B airspace
AIM 5-3-8(2): Maximum holding speeds:

At or below 6,000 ft. 200 KIAS
6,001 to 14,000 ft. 230 KIAS
Above 14,000 ft 265 KIAS

Some NOTAMs specify a maximum speed when operating within their limits.
AIM 5-7-2: Maximum speed as assigned by ATC

91.117(d): Any of these speeds may be exceeded if the minimum safe airspeed for the aircraft is higher and you notify ATC.

91.101 and AIM 5-7-2 NOTE 2 state that none of these apply when more than 12 NM from the coast of the united states.  Because of this, you will often see pilots fly at greater than 250 KIAS when below 10,000 feet and more than 12 NM off-shore.

Aircraft specific limitations must also be complied with.


Where is Transport Category aircraft defined in CFR 14?

According to the FAA:

  Transport airplanes are airplanes for which a type certificate is
  applied for under part 21 in the transport category and that meet the
  transport category airworthiness requirements. Multi-engine airplanes
  with more than 19 seats or a maximum takeoff weight greater than
  19,000 lbs must be certificated in the transport category.

In other words, there are two possible reasons why an aircraft is transport category: the manufacturer applied for a transport category type certificate, or the aircraft has more than 19 seats or MTOW greater than 19,000lbs.

The first reason refers to 14 CFR 21.21:

  An applicant is entitled to a type certificate for an aircraft in the
  normal, utility, acrobatic, commuter, or transport category, or for a
  manned free balloon, special class of aircraft, or an aircraft engine
  or propeller, if—

  [...]

  (b) The applicant submits the type design, test reports, and
  computations necessary to show that the product to be certificated
  meets the applicable airworthiness, aircraft noise, fuel venting, and
  exhaust emission requirements of this subchapter

The "applicable airworthiness, aircraft noise, fuel venting, and exhaust emission requirements of this subchapter" for transport category aircraft are in part 25, AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES. If your aircraft meets those requirements and you get a type certificate from the FAA, then you have a transport category aircraft.

The second reason refers to 14 CFR 23.2005(a):

  Certification in the normal category applies to airplanes with a
  passenger-seating configuration of 19 or less and a maximum
  certificated takeoff weight of 19,000 pounds or less.

That means, if your aircraft exceeds 19,000lbs then you can't certify it in the normal category (part 23), which leaves only transport (part 25).

By the way, the 23.3 regulation you quoted doesn't exist any more because part 23 has been completely rewritten.


What are the rules for PIC change during flight?

@ymb1 is correct in that it does not matter who the legal pilot in command is per §1.1.  What does matter is following the rules in §61.51(e).

  (e) Logging pilot-in-command flight time. (1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-

    (i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;

    (ii) When the pilot is the sole occupant in the aircraft;

    (iii) When the pilot, except for a holder of a sport or recreational pilot certificate, acts as pilot in command of an aircraft for which more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is conducted; or

    (iv) When the pilot performs the duties of pilot in command while under the supervision of a qualified pilot in command provided—

If in your example both pilots are rated to fly that airplane on your license whether or not you have the required endorsements or ratings to act as the legal pilot in command you can log PIC time.  It does not matter who the legal pilot in command is at that time.  Both pilots will log the flight time as PIC and total time for the time you are the sole manipulator of the controls.

Other ways both pilots can log PIC time is where one pilot who is the safety pilot is the legal pilot in command while the other pilot who is flying the airplane and sole manipulator of controls is under simulated instrument flight.

Let me be very clear here.  If both pilots were to log PIC time under this condition, and many pilots do, they are making the statement in their logbook that could get them in trouble later on.  Let me explain, pilot A and B go out and fly together; Pilot A is under the hood and the other is the legal pilot in command.  On another day, Pilot B is under the hood and the other is the legal pilot in command.  Both pilots log exactly the same amount of flight time for both PIC and total time on these flights.  At this point, a precedence is set.

What is that statement you are making in your logbook?
Who the legal pilot in command is for each flight.  Read the regulation again.  If the safety pilot logs PIC time they are accepting legal pilot in command responsibilities and all that goes with it.  If the pilot under the hood has an incident or accident or airspace infraction the FAA will want to know who the legal pilot in command was during that flight.  The logbooks tell the story regardless what the pilots say at that moment.


On the Ka-50 coaxial helicopter, why does the bottom rotor flap up on the right side instead of in front during forward flight?

This is does appears to be partially correct behavior for a Ka-50 in forward flight (in the low speed example)--but not because of gyroscopic procession.  It also may be plagued with transient artifacts from the DCS flight mechanics model.
According to DCS, the Ka-50 rotor is modeling using blade-element momentum theory with some inflow model, so the basics of its aerodynamics should be correct.  That said, this shouldn't account for blade/vortex/body interactions or other higher order effects.  Based on the same source, DCS implies that they use a rigid-blade model (that is, a rigid blade rotating on flap/lag hinges) for their rotor blades, which allows them to model blade motion and couple their aerodynamic model with some rotor dynamics.  This is impressive for a sim to have, but remember that they are missing significant interactions between rotors, let alone the body.  They can reproduce the performance from certain phenomena in flight, but they don't go into detail of what else goes into their model, so I cannot comment any further.  However, I can say the following.
Gyroscopic precession does exist, this is true, but it is a much simplified explanation of why helicopter rotor blades exhibit a phase lag that delays a blade's physical response to an applied load.  Rotor blades are not gyroscopes, and, in fact, the phase lag for rotor blades is not always 90$^\circ$ but varies depending on the design of the rotor system.  As for why the FAA and other pilot-oriented groups continue to teach that gyroscopic precession is the reason why it occurs: I have no authoritative answer, but, as with how the FAA incorrectly teaches about lift, teaching the "actual" reason why an aircraft does what it does will not necessarily teach you how to fly the aircraft better (unless you have an extremely well-developed understanding of fluid mechanics).  Getting the explanation "good enough" (so that you have a useful hermeneutic for how the vehicle interacts with the air is sufficient to enable you to use the aircraft safely) seems to be the mantra--which makes some sense.  Else, no one* would be allowed to fly!
Regardless, to the point.  Let's talk about phase lag, how to control a helicopter using a rotor, and how those two come together.
Phase Lag and Helicopter Controls
Phase lag refers to the difference in when a force is applied to a dynamic system in resonance and when its physical effect manifests itself.  This gets a little complicated in a helicopter's rotor system since, in order to control the vehicle, the rotor itself has to be tilted in the desired direction of motion.  Keep in mind that the rotor (I speak in the singular, but I'll apply this to the Ka-50 in a minute) is the primary source of propulsion for the helicopter, so, to move anywhere, the rotor has to be pointed in the direction of motion, as illustrated below.  The purple line is the plane connecting the tips of the rotor blades (or the tip path plane) during hovering flight, and the orange line is the tip path plane in forward flight.

You can also see this in this video of a hovering UH-60 Blackhawk (note the level tip path plane) as compared to this video of a Blackhawk in forward flight (note the tip path plane tilted in the direction of motion--more evident during the first half of the video).  A caveat, though: the rotor on the Blackhawk is actually set at a small angle forward to decrease parasitic drag and decrease the body pitch angle in forward flight.  This is particularly evident in the first video, wherein the helicopter is actually pitched upward when the rotor tip path plane is horizontal.  I'm using the UH-60 as an example, but this is a fairly common practice.
In short, you have a single force vector, and you have to point that force vector in the direction you want to push the helicopter.
DISCLAIMER: if you don't want to learn about phase lag and just want the answer, skip to the last section now.  A digression on phase lag is ahead.
Hence, whether the rotor is articulated or some form of rigid, it is designed such that the blades can flap as needed.  The Ka-50 rotor does have flapping hinges, as you can see in the image below from how the blade is slightly angled relative to the blade grip extending from the rotor hub.

So where does this leave us?  I'll explain phase lag in a minute, but the confluence of phase lag and blade flapping is important to grasp first.  For instance, if I put in a control input to a rotor to make the vehicle move to the left, I would expect the rotor disc to tilt to the left by way of the blades flapping up on the right side of the helicopter and down on the left side.  However, since the physical response and the aerodynamic loads are out of phase, I have to put in the control input prior to when I want the effect to manifest.  If this effect was gyroscopic, I would have to pitch the blades as they passed over my tail or nose (90$^\circ$ prior to the flapping effects I want to see).  However, if we look at a Robinson R-22, it ends up being more like 72$^\circ$ prior instead of 90$^\circ$.  And it's not the only one (though typical values for articulated rotors do end up being closer to 90$^\circ$, if memory serves)!  However, this is because the effect is not due to gyroscopic precession, but is a result of rotor design.
A flapping rotor system is the product of the a variety of forces, including mechanical damping (think of a dashpot, although that particular item is not necessarily the case), stiffness (think of a spring), aerodynamic damping (resistance to motion proportional due to changing aerodynamic forces), aerodynamic forcing (think lift, or what's causing the flapping in the first place), centrifugal or inertial forces (what's trying to keep the blade level), and "coriolis" forces, to name a few.  These interact with a rotor blade that is hinged with some amount of offset from the center of rotor as well, which we can see on the picture of the Ka-50 rotor hub, which also changes how the blade responds to aerodynamic forces.  As a result, we can tune the rotor system we design to respond in a particular way to aerodynamic forcing.  However, it changes the phase lag of the system.
Visualizing the Effect
One way to visualize this (if you like math -- if not, I'll provide a physical example too) is using an Argand diagram, which can be used to show components of a spring/mass/damper system (a rotor system is an example).  This would come from the Fourier transform of an equation having the following form, where $I$ is inertia, $b$ is the damping coefficient (higher the coefficient's magnitude, the more resistance to motion there is), $k$ is the stiffness of the flapping hinge (the "restorative" force in the diagram), $\beta$ is the flapping angle, $\dot{\beta}$ is the flapping velocity, and $\ddot{\beta}$ is the flapping acceleration.  $F(\Psi)$ is the aerodynamic forces that create the blade flapping motion.
$I\ddot{\beta}+b\dot{\beta}+k\beta=F(\Psi)$
For example, the diagram below shows a system where the spring (rotor system: the restoring force which is dependent on actual flap angle) is dominant, making the system's physical response pace closely with the input force.  Conceptually, that makes sense -- if I have a stiff spring, the amount of force I use to compress the spring will match very closely with the spring's compression (in the absence of a damper or much inertia).  I can get that from the Argand diagram from doing vector addition with the 3 components I have plotted.  If I did so, the resultant vector would lie very close to the "restorative" axis, or to the right side of the horizontal axis.

However, what if the damping is much larger and closer in magnitude to the restorative vector?  This more usual for a helicopter with articulated rotor blades.  If so, we get an Argand diagram that looks more like this:

If I do my vector addition here, I see that the resultant vector, and thus the physical manifestation of my input force, is $90^\circ$ out of phase with my input.  A physical analogy would be if I connected a spring to a pneumatic cylinder and then tried to, alternately, compress and extend it.  The amount of force I apply is no longer directly proportional to the compression or extension of the spring, but is out of phase with the spring's physical motion due to the presence of the damper.  If I had a spring with a lot of mass, you could see how that would further complicate the problem.
Putting it all together: what does this mean for the Ka-50?
Right: so, in the pictures provided (copied below), you show the Ka-50 rotor flapping by small amounts during lower speed forward flight (quoted IAS was 60 kph).

Note that both rotor discs are flapping up as they pass over the tail.  As said, in order to maintain speed, the Ka-50's rotors need to be tilted in the direction of motion, though this should only be a transient feature as the vehicle pitches into the direction of motion.  If they were not, parasitic drag (and other sources) would slow the vehicle down.  To maintain speed, a force has to be continually applied in the direction of motion.  Hence, the aerodynamic forces are applied earlier in the rotation to induce both rotors to flap up as the pass over the tail of the aircraft.  The 60 kph case is also useful because flapping due to advancing/retreating blade effects are relatively small as compared to the second case, shown below.

In this case, the rotors are obviously tilted left and right, respectively: which is strange.  Judging from the horizon lines in both pictures, it would appear that the helicopter is pitched down more in this higher speed case as well, which makes sense, since the blade flapping angle over the tail seems to be relatively small.  The vehicle also seems to be in a shallow right bank.
As a result, and I'll be perfectly honest, I'm not entirely sure why the rotors are tilted in opposite directions, and this is where I doubt the veracity of their model.  Due to the high speed, which should be leading to some interesting aerodynamics, I'm placing a bet on their modeling starting to break down.  If they are using an inflow model that approximates wake motion, some of the assumptions of that model may be breaking down at this high of an advance ratio, leading to unexpected blade motion.  An Jan Hudec says in the comments, both rotor planes should be parallel to each other.
*If I may perpetuate the legend: no one, that is, except Peter Kämpf.


What are the limiting factors for high altitude planes (e.g: U2 or SR71) preventing them from going higher?

The limiting factor for subsonic aircraft, including the U-2, is well explained here.

For supersonic aircraft this answer simply says the limit is "a combination of wing loading and maximum speed". If you look at the flight envelope of the SR-71 below, it becomes clear that more altitude can be best bought with more speed.

SR-71 flight envelope (picture source). Tower buzzing at Mach 3 is clearly impossible.

Supersonic speed limits

Intake design: If the kinetic energy of the flow cannot be efficiently converted into pressure in the intake, thrust will suffer and will drop when the flight Mach number is increased beyond the limits of the intake.
Airframe efficiency: If the leading edge sweep of flight surfaces is not high enough to keep those leading edges within the Mach cone, drag will rise and limit the top speed of a design. The desire to reach Mach 2+ speeds was the driver for the many swing wing designs of the 1960s.
Compressed gas temperature: Once the compression heating in the intake brings the gas temperature close to its dissociation temperature, the chemical energy in the fuel cannot be fully converted into heat. This reduces engine efficiency and is the reason for supersonic combustion in designs for speeds in excess of Mach 4 or 5.
Aerodynamic heating: Metals and composites show decreasing strength with increased temperature. Fly fast enough for some time, and the structure cannot tolerate the flight loads, even if dynamic pressure is kept constant.

The order in which I listed those limits ranks them with increasing speed. Once you move beyond Mach 1.6, every consecutive tenth of the top flight Mach number must be bought with increasing expenses and compromises. Going beyond Mach 5 with current technology will only be possible with rockets, so those designs quickly become low-orbit satellites. In the end, it is simply not worth it to push the limit yet further.

EDIT: It seems the answer is not explicit enough. If we try a thought experiment and modify the SR-71 to reach higher altitudes, the possible options are:

Just pull on the stick: This helps in the short term, but flying stationary at lower density would require a higher lift coefficient and a higher angle of attack. This would lower the overall L/D of the plane and slow it down because the engines could not develop sufficient thrust.
Increase engine thrust: This could be tried in flight by advancing the throttles at top speed, and the aircraft would accelerate. This would quickly exceed the limit of the compressor inlet temperature, though, leading to a shorter life time or even damage of the engine's hot section. Next, range would suffer due to the higher fuel consumption. If the engine is improved by using better materials, a moderate increase in cruise Mach and, consequently, flight altitude is possible.
Lower wing loading: A lighter aircraft can cruise at a lower density, all other parameters being equal. At the end of a trip the SR-71 could reach the highest altitude, just like any other plane. Structural changes to lighten the structure beyond removal of all reconnaissance equipment, however, would have only limited potential: The SR-71 was already designed efficiently, so there is very little potential for weight savings without compromising structural strength. And removing the cameras and side-looking radars would strip the plane of its operational value.


May time be logged for an aborted flight?

Interesting question, I found myself in exactly that position a couple of months ago (more on that below).

First, I found an FAA clarification on this, which is a legal interpretation from 2007 and it partly answers your question. The questioner asked the FAA three questions about logging flight time (in a helicopter in this case); questions 1 and 2 are very close to yours. Question 1 is:

  May a pilot log as "flight time" to qualify for a certificate or rating under 14 CFR Part 61, or for purposes of qualifying under 14
  CFR 135.243(b)(2), that time accrued in a helicopter when the aircraft
  is sitting on the ground with the engine running and rotor blades
  turning, but the aircraft has not moved from its parking place and
  flight has not yet commenced?

Question 2 is almost the same, but it asks about logging time after parking but when the engine is still running. I know that this is slightly different from your scenario, because you're asking about logging time after the aircraft has moved from its parking place, but the FAA response says the following:

  [...] flight time [...] commences the moment that [the aircraft] moves under its
  own power away from its parking place for the purpose of flight -
  whether departure is commenced by lifting off or taxiing.

So according to that interpretation, you can start logging time as soon as you start taxiing but it goes on to say that you cannot log time after the aircraft lands. That means that your question is still a grey area, and if you want a definite answer then you should probably ask the FAA for your own interpretation. But my personal take is that the FAA is only concerned about people trying to cheat the system by sitting with the engine running, and for practical purposes you can log time as soon as you start taxiing.

And turning to the real-world situation, I don't think it matters at all. Every instructor and pilot I have ever met simply logs whatever time the Hobbs says, regardless of what happens in between. The FAA has absolutely no way to accurately verify what you're logging and there's a large degree of trust in the system.

In my case, the AI gyro didn't spin up and although I didn't need that instrument (the planned flight was VFR in CAVU conditions) I elected not to fly anyway: better safe than sorry, and if one thing is broken it may be a symptom of a bigger problem. I taxied back with 0.2 on the Hobbs: I didn't log it (and the FBO didn't charge me). My thinking was simply that I didn't really 'fly' and 0.2 is irrelevant for all practical purposes. I'm sure that someone somewhere has found themselves 0.1 short of what they needed for a rating and really wished that they had that extra time, but if you ever find yourself in that position, it's no big deal to do a couple of turns in the pattern.

Note: there is another FAA interpretation on this, but it looks like it only applies to part 121. They said yes, you can log it, but that's based on the assumption that after you taxi back to the gate, the airline finds a second aircraft and you fly that one to the original destination. They didn't say what happens if the flight is cancelled completely.


What material is used for the skin of a modern fighter jet?

The F35's skin consists of a/several composite(s). Although it's obviously classified, I suspect the main reason it's chosen has something to do with stealth rather than strength. Interestingly, there seem to be more information about the F22 than F35, which is supposed to be, err, more secretive? For example, the F22's airframe bulkheads and twin booms are known to be constructed from titanium, and there are aluminum elements in its wings, and its skin is composite as well. That's pretty much all that's let on.

If you are asking for some not-so-secretive fighters, they are made from more mundane materials, not that these are any less expensive:


Why does the NTSB release transcripts of Cockpit Voice Recordings, but not the actual recordings?

From NTSB site, regarding FOIA requests:

  "Cockpit Voice Recorder (CVR) tapes. Title 49 U.S.C. § 1114(c)
  prohibits the release of any CVR tape. However, the NTSB may release a
  CVR transcript (edited or unedited), in accordance with 49 U.S.C. §
  1114(c)(1)."

Transcripts may be disclosed, but not 'tapes'. Which makes sense, as transcripts may be edited to remove parts that are not meaningful for the investigation, but can be  unnecessary intrusions into private life.

In addition, when the NTSB is participating to foreign investigations:

  Records or information relating to the NTSB's participation in foreign
  aircraft accident investigations. 49 U.S.C. § 1114(f) prohibits the
  release of this information before the country conducting the
  investigation releases its report or 2 years following the accident,
  whichever occurs first

See 49 U.S. Code § 1114 - Disclosure, availability, and use of information


Can anybody confirm which aircraft is in this picture?

Based on what I find from the marking on the plane of "8-MV", it appears to be a Dassault Mystère IV A. The image on the non-Wikipedia page looks identical to the one in your image (I can't put that image here because it is copy-protected).

Image Source


TAPS means Twin Annular Premixing Swirler, a cyclone mixer / combuster designed to keep the NOx emissions of the General Electric GEnx engines low.

source: FAA report

AIAA report


Determining the number of blades is one of the steps in designing the main rotor of a helicopter, but not the first one. The main rotor design process is an iterative process with quite a few input parameters, which depend on the mission type:

Max. TO weight
Max. speed
Installed engine power
Autorotation performance
Noise
Manoeuvring g
Blade profile
Blade area
Vibratory loads

Using these inputs, the design process determines:

Rotor diameter. This determines the disk loading: lower disk loading results in better hover performance and auto-rotational performance, higher disk loading in better cruising flight performance.
Tip speed. As close as possible to the drag divergence speed in cruise, also a limiting factor in selecting rotor diameter.
Rotor solidity. How much disk area is actually occupied by blade area, determined by blade stall limits in manoeuvres. Increasing the rotor solidity requires more engine power, but increases the blade stall margin.
Number of blades. Mostly based on dynamic criteria, less on aerodynamic ones. The Bell 212 shows that rotor solidity can be increased by using wider blades, but using more blades minimises vibratory loads and the noise per blade passing.

The rotor design process is quite broad, and can best be found in the theory books which also contain statistical data to aid the initial stages. The plot below is from Leishman and shows that light helicopters have a blade length of about 4 meters, apparently a good length for this weight and mission type.

The overlapping twin rotor disks of the Chinook result in one rotor operating in the wake of the other, reducing efficiency and requiring more disk area. So total disk loading will reduce.

Two good books on helicopter stuff: Helicopter Aerodynamics, Stability and Control by Ray Prouty, and Principles of Helicopter Aerodynamics by J. Gordon Leishman.


How are aircraft controlled that have no forward view out of the cockpit?

You don't need a panoramic view to land, and in Lindbergh's time there was no other traffic to avoid. Navigation is easy enough through side windows (in many modern airplanes you can't see the ground out the front unless the nose is pointed down) and you can just yaw the plane left and right for the times you do want to line up with something. Airfields 100 years ago were quite literally fields, so you didn't need to be all that precise about it. Lindbergh had a periscope and was used to flying mail planes with the front seat occupied with the bag, so it wasn't anything new.

Even today, tail draggers have basically zero forward visibility on the ground so they taxi by watching the edge of the pavement with the occasional sharp s-turn to check ahead.


This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff

This is almost a duplicate of another question: What is the GE90-115b turbine power output in horsepower?
With the fan removed, and power used for e.g. ship propulsion or a power plant, the engine core can deliver about 66 MW or 90,000 horsepower continuously.
Takeoff thrust is higher than continuous, and the core does contribute some thrust. So to match 130,000 lbf, a fan this size would require external power in the range of 80-85 MW or about 110,000 hp.


Why don't commercial passenger safety videos ever explain policy instead of merely dictating it?

There is no time. You need to convey the information in as little time as possible or people (those few that watch at all) lose interest and start doing other things.
Reasoning tends to invite arguments, there's always someone who thinks he knows better. You don't want that.
Simplicity. Make things as easy to understand as possible using simple words. That way less intelligent people and people who have trouble with your language are more likely to understand what's expected of them.

There might be other reasons, but those are the ones that come to mind.


What are the effects of headwind on ground speed and take off run?

Short Answer: Yes, you have it right.
For a longer answer consider an example aircraft that has the following characteristics:

Takeoff Speed: 60 knots (Indicated Airspeed)
Landing Speed: 50 knots (Indicated Airspeed)
Cruise Speed: 100 knots (Indicated Airspeed)

Note that all the speeds are airspeeds, which are what we usually measure in flight.
To find the groundspeed you add or subtract the effect of wind, which will become important as you'll see:

A headwind gives the plane a lower groundspeed for a given airspeed.
If our example airplane has a 10-knot headwind it has the following practical effects:

On takeoff the aircraft only has to gain an additional 50 knots to reach takeoff speed:
It effectively has a 10-knot "bonus" from the headwind, and will thus reach takeoff speed in a shorter distance, and need less runway.
Once in the air the headwind works against the aircraft's progress: The groundspeed of the aircraft is equal to its airspeed minus the headwind, so while you're cruising at 100 knots airspeed you're only making 90 knots over the ground. A 100-mile flight will take an extra 7 minutes to complete.
On landing the aircraft will arrive at the runway with a 50-knot indicated airspeed, but because of the headwind will be making 40 knots across the ground. It will thus have less energy to get rid of once it lands, and will require less runway to slow to a stop.

A tailwind gives the plane a higher groundspeed for a given airspeed.
If we reverse our earlier example and give the aircraft a 10-knot tailwind it has the following effects:

On takeoff the airplane must accelerate to a 60-knot airspeed, however it's also being pushed along by a 10-knot tailwind, so it effectively has a -10 knot airspeed standing still: The wind is blowing forward over the wings. When it reaches its 60-knot takeoff speed it will have a 70-knot groundspeed because it's being pushed along by the wind, so it will have a longer takeoff roll.
In cruise the wind continues pushing our example airplane along, so its 100-knot cruise speed gives it a 110-knot ground speed. A hypothetical 100-mile trip would take a little over 54 minutes.
On landing the aircraft arrives with a 50-knot indicated airspeed, but a groundspeed of 60 knots (the wind is still pushing it along), so it will have more energy to dissipate when it lands: A longer ground run, and more braking required.

A chart of the effects of headwinds and tailwinds on takeoff and landing can be found in the Pilot's Handbook of Aeronautical Knowledge, it's reproduced below.

Effects of winds in cruise can be calculated using an E6B Flight Computer


Heard on LiveATC that ATC wants to "cancel" something. What did the ATC mean by that?

If the airport is non-towered, then ATC may not be able to have radio contact with the aircraft after landing. However, the flight plan still needs to be cancelled or closed after landing. Usually this is done by the pilot calling ATC on the phone, but in this case it seems ATC offered to do it without the call.

Without closing the flight plan within approximately 30 minutes after the scheduled arrival time, the Flight Services will start looking for you. They will try to contact you by phone call and if that goes unanswered, eventually a search and rescue will be started.

On ATC controlled airports the flight plan will automatically be closed after the aircraft landed.


Does the altitude or attitude of an aircraft affect GPS accuracy?

Altitude has little effect, as long as you don't descent into a valley. Mountains shield the GPS signal, resulting generally in lower accuracy and lower integrity levels.

Attitude does matter, steep turns can result in the airframe shielding GPS signals from the antenna. Again, the effect is a lower accuracy and integrity.


How could the Helios 522 passengers have survived so long without oxygen?

To add to Daniele's answer, from the final report:

  The  forensic  report  concluded  that  the  aircraft  occupants  had  heart  function  during  the  impact.    The  report  noted  that  this
    did  not  necessarily  imply  that  they  were alert.    The  report  further  estimated  that  they  were  in  deep  non-reversible  coma  due  to
  their prolonged exposure (over 2.5 h) to the high hypoxic environment.

So, again, saying that they were alive does not mean that they were well.


Is multi element wing good option for slow flight airplanes?

Excellent application inverted on the drag racer, which brings home the point perfectly.  If you have enough excess thrust, devices like these can dramaticly increase Coefficient of Lift, but at the cost if loss of lift efficiency, or lower lift to drag ratio.
In the case of the dragster, more propulsion efficiency is lost if tires break loose from the pavement, so the drag of the "inverted Fowler flap" is an acceptable trade-off to the downlift increasing traction.
As mentioned in comments, this is why the Fiesler Storch requires 240 HP to achieve its legendary STOL performance.
And just as flaps 10 is better for lift than flaps 30 for taking off, one might question the need for the second and third flap on a lifting wing, but heavy airliners love them when coming in to land as Fowler flaps.


What is so special about new Russian jet engine called PD-14?

Well, development of any large high bypass turbofan is something extraordinary. It probably took thousands of engineers and specialists working for many years to develop this engine, with a development cost measured in billions of dollars.  Only a handful of companies in the entire world are able to achieve this.

But, if you compare the publicly available specs for PD-14 to a similar size modern engine such as LEAP, you'll find that while the PD-14 engine is competitive, it's not anything that will have P&W, GE, or RR too worried.

Thrust to weight ratio is comparable to LEAP
Bypass ratio is a little lower than LEAP, which would be expected to translate to slightly worse fuel efficiency.
Overall engine pressure ratio is comparable to LEAP
Thrust specific fuel consumption looks a little worse.

There are also several key parameters that are not publicly available, such as the manufacturing cost, purchase price, the lifetime of the major components (i.e. how many flights before you have to replace the turbine blades), the cost to repair the major components, and the reliability (how often to you have to cancel a flight because something broke just as you were loading passengers). Because this data is not easily available to the public, I'm sure they will claim it's great, but there is no easy way to verify.  Probably they are comparable in all regards and it's just marketing spin.


What considerations drove the choice of the Solar Impulse engines configuration?

It reduces moments in the wing spar. Major points of axial drag in this design are the wings and the fuselage. You'll see that two engines are close to the fuselage, and the other two are midway along the wing.
By placing two engines further out, they are also located where the lift is generated, reducing the necessary strength of the wing spar.

Both of the above are especially important since it's such a large wing.

There might also be some possibility of using asymmetrical thrust to ease crosswind landings with this configuration from the yaw from the outboard engines.


How to calculate the lift starting from the vertical speed?

Yes, it is, at least for small pitch angles and low thrust. Here is how:

$$L = m\cdot g\cdot n_z\cdot\cos\gamma$$

If thrust or pitch attitude become significant, you need to modify $m\cdot g$ by the vertical thrust component. Then the answer must be no, because the thrust information is missing:

$$L = \left(m\cdot g - T\cdot\sin(\Theta + \sigma)\right)\cdot n_z\cdot\cos\gamma$$

$L\:\:\:$  lift
$m\:\:$ mass
$g\:\:\:$ gravitational acceleration
$n_z\:\:$ load factor (= 1 in horizontal, unaccelerated flight)
$\gamma\:\:\:$ flight path angle, with $\gamma = asin\left(\frac{v_z}{v}\right)$
$v_z\:\:$ vertical speed
$v\:\:\:$ flight speed (TAS)
$T\:\:$ Thrust
$\Theta\:\:$ pitch angle (up is positive)
$\sigma\:\:$ thrust angle relative to airframe's x axis

Note that the altitude is only needed if you use the altitude-specific value of $g$. Using the standard value will give you a negligible error.

Please note also that lift > weight will result in an upward acceleration. In a quasi-stationary climb or sink the lift will be slightly smaller than the weight.


Can a VFR flight reference a waypoint in communication?

J. Hougaard is correct. With Tower, Approach and Center, yes you can use waypoints in communications. Be prepared for them not to know immediately where a lesser used waypoint is. I have had Center not know where particular Class G airports in their jurisdiction were. Some know the names by heart, but not the airport codes.

When it comes to communicating with FSS, best practice is to reference your position by distance and direction from a VOR. Especially on your initial call. If you are on a flight plan, reference the points in your flight plan. Referencing an airport will also work.

When communicating over CTAF, it is best not to use waypoints. Instead, use distance and direction from the airport. Even if you are flying IFR or you are on an IAP. Otherwise reference your position by very well known Visual Reference Points. Preferably ones that are charted on your sectional. There are a lot of non-instrument rated pilots who may also be flying. A waypoint may not mean anything to them. Lack of ATC will mean lack of separation control unless you communicate in a way that is universally understood using the lowest common denominators.


MH370 blackbox - is it still possible to retrieve data from it?

There are precedents: the flight recorders of AF447 spent two years at the bottom of the ocean, and revealed all that had happened after being retrieved. So they had survived being immersed in salty water at high pressure, making it very likely that MH370s boxes have survived as well.

Time of immersion is less relevant: oxidation (rust forming) is much slower at greater depth, due to much less dissolved oxygen and lower temperatures. The corrosion that does take place is mainly anaerobic, through bacterial sulfide formation. As posted in for instance this link.


What is the rod attached to the top of the Bell UH-1N's rotors?

It is a stabilizer bar used on some two blade helicopters. The spinning weights want to stay in one plane and are used in conjunction with the cyclic to control changes in pitch and roll. Depending on how it is designed, it counters these changes making the helicopter more stable (less maneuverable).


What is the regulatory landing distance for turboprops under FAR 121-135?

Each aircraft manufacturer is going to supply that data as part of its Aircraft Operating Manual. Operators must use these documents to determine required landing length, and this computation must be calculated during the planning phase of the flight by taking into consideration the estimated weight of the aircraft at the arrival time, as well as forecast winds, runway conditions and types of runways.

The regulatory "mandate" for doing these computations is found in the text of Parts 121.195 and 121.197, as well as 135.385 and 135.387. The relevant parts of each are pasted below, but the full text should be consulted for additional requirements and possible exemptions.

  121.195. Detination Airport. no person operating a turbine engine powered airplane may take off that airplane unless its weight on arrival, allowing for
  normal consumption of fuel and oil in flight (in accordance with the
  landing distance set forth in the Airplane Flight Manual for the
  elevation of the destination airport and the wind conditions
  anticipated there at the time of landing), would allow a full stop
  landing at the intended destination airport within 60 percent of the
  effective length of each runway described below from a point 50 feet
  above the intersection of the obstruction clearance plane and the
  runway.

  121.197.   Alternate airports. No person may list an airport as an alternate airport in a dispatch or flight release for a turbine engine
  powered airplane unless (based on the assumptions in §121.195 (b))
  that airplane at the weight anticipated at the time of arrival can be
  brought to a full stop landing within 70 percent of the effective
  length of the runway from a point 50 feet above the intersection of
  the obstruction clearance plane and the runway.

  135.385. Destination Airport. No person operating a turbine engine powered airplane may take off that airplane unless its weight on
  arrival, allowing for normal consumption of fuel and oil in flight (in
  accordance with the landing distance in the Airplane Flight Manual for
  the elevation of the destination airport and the wind conditions
  expected there at the time of landing), would allow a full stop
  landing at the intended destination airport within 60 percent of the
  effective length of each runway described below from a point 50 feet
  above the intersection of the obstruction clearance plane and the
  runway.

  135.387. Alternate Airports. No person may select an airport as an alternate airport for a turbine
  engine powered airplane unless (based on the
  assumptions in §135.385(b)) that airplane, at the weight expected at
  the time of arrival, can be brought to a full stop landing within 70
  percent of the effective length of the runway for
  turbo-propeller-powered airplanes and 60 percent of the effective
  length of the runway for turbojet airplanes, from a point 50 feet
  above the intersection of the obstruction clearance plane and the
  runway.


Is the Tower (Local) Controller responsible for "separating" VFR traffic in the pattern in the U.S. in Class D airspace?

Separation requirements depend on the class of airspace, per ICAO Annex 11.

Class D: VFR aircraft are not separated from any other aircraft. ATC only provides traffic information about VFR aircraft.

Note the separation can be done visually. Considering the size of the typical class D airspace, this is the usual method for multiple VFR aircraft in the area.

Once the aircraft get to the runway, the ATC regulation JO 7110.65 3−10−3 states that ATC is responsible for making sure an arriving aircraft doesn't cross the threshold before an aircraft ahead of it on the same runway is either landed and clear of the runway (or a certain distance past the threshold), or has departed and crossed the opposite end of the runway.

Also per 7110.65 2-1-1:

  The primary purpose of the ATC system is to prevent a collision
   involving aircraft operating in the system.

So while there may be no hard requirements for ATC to separate VFR aircraft, they will do their best to make sure that the VFR aircraft have the best chance of seeing and avoiding each other.


Is the phrase "going missed" standard in the US?

According to the Pilot/Controller Glossary (the closest thing to "regulatory" documentation regarding phrases pilots are supposed to use on the radio) there is no GOING MISSED - there is GO AROUND as an ATC instruction (and by analog GOING AROUND as a pilot's response or notification to ATC to inform them the pilot is doing so), which covers both VFR and IFR operations:

  GO AROUND −
  Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., “Go around” (additional instructions if required).

(There is also an IFR-specific EXECUTE MISSED APPROACH in there.)

GOING MISSED is not proper/correct phraseology (though much like "tally one" or "got 'em" in place of "traffic in sight" it will generally be understood by ATC - probably with about the same grinding of teeth as the other two phrases get).

Informing ATC (tower or approach) that you are executing a missed approach by simply saying N12345, Missed Approach is correct phraseology however:

  MISSED APPROACH−
  a. …
  b. A term used by the pilot to inform ATC that he/she is executing the missed approach.
  c. …

and is probably what should be used in place of "Going Missed".


How does the airflow above an airfoil account for the downward turning-action of the airflow below the airfoil?

The answer is buried in the linked Wikipedia article if you read it carefully a few times.
In a nutshell, at least in my interpretation, the "zone of suction" you might call it, the Bernoulli effect low pressure region above the airfoil, induces air outside the zone to accelerate toward it; to "fill the void".  On a zone of suction that is moving, like the top of the wing, it means that a large region of the air stream above the wing wants to accelerate toward the zone, which being below, means that the net result is the a large package of air is induced to move downward in response to the wing's passage below it.
Maybe half or more of the total package of air that is redirected downward is above the wing.  This air is being induced to move by "pressure trickery" as opposed to being shoved down directly by the pressure wave of physical wing's passage like the air below.  A water ski works by deflecting only the fluid below it.  A wing works by deflecting the gasious fluid below, and also inducing the gaseous fluid above to join in by careful management of pressures.
This is partly why disruption of the flow above has a more drastic effect than disruption of the flow below - spoilers go on top instead of underneath.  Air below is just being physically deflected; the air above, for quite some distance, is being "coaxed" to be pulled down toward the low pressure region, and if you disrupt the low pressure region, all of the air that was ready to be induced to move down doesn't have to, and you lose most of your Newtonian force reaction.
The result is that this contraption flies fine with all that junk obstructing the flow under the wing, but if you put it all on top, it would never get off the ground.