When and where are anti-ice required for supersonic flight?

How fast do you need to fly so that heating makes anti-ice irrelevant?

The True Air Temperature (TAT) that the aircraft's skin will feel can be calculated from the Static Air Temperature (SAT) and the Mach number:
$$ \frac{\text{TAT}}{\text{SAT}} = 1 + \frac{\gamma - 1}{2} M^2 = 1 + \frac{1}{5} M^2 $$
(using $ \gamma = 1.4 $ for air). The SAT does not usually go below -56.5°C in the International Standard Atmosphere, which is the usual temperature in the lower stratosphere (where most supersonic aircraft fly).

At Mach numbers above $ \sim 1.24 $ the resulting TAT will be above 10°C, which is usually defined as the upper temperature, where icing conditions exist.

How does it depend on the part of the aircraft? Presumably the leading edge is the first part to warm up without anti-ice.

Yes, the leading edges would warm up most, but they are also the only part of the aircraft that could possibly accumulate ice. Aircraft that are certified for flight into known icing conditions typically have de-icing or anti-icing systems on the engine inlets, the propellers and the leading edges of the wings, vertical and horizontal stabilizer. But not all aircraft have these systems on all of these surfaces because they are not all affected equally. See e.g. these questions:

Why do only some aircraft require tail anti-icing?
Why are some parts of the wings not protected by the wing anti-ice system in the B737?

Are icing conditions different at typical supercruise altitudes? Is there meaningful water up there?

Humidity is usually quite low in the stratosphere, meaning icing isn't typically a problem here anyway:

The stratospheric air
masses sampled are dry, as expected, having mean
relative humidity over water of 12% and over ice of
23%, respectively. However, 2% of the stratospheric
data indicate ice supersaturation.

(A distribution law for relative humidity in the upper troposphere
and lower stratosphere derived from three years
of MOZAIC measurements)
Most weather phenomena only occur in the troposphere, which means you fly above the weather (although thunderstorm can push clouds to extreme altitudes).


Is it possible to totally override the flight computer on the Airbus A320-family (in simple non-technical terms)?

Autopilot vs FMS vs protection
The autopilot does not prevent a nose down, this task is done by the envelope protection, which is a different flight computer.
The FMS is what sends the autopilot commands, i.e., the autopilot is part of the FMS. The pilot interface with the autopilot is the CDU (which is basically a keypad and a screen), and the FCU (the autopilot panel on the glareshield).
When flying, it's either the pilot or the autopilot in control, it can't be both. (There are exceptions but this is to keep it simple.)
The commands of either are sent to a flight control computer, this is where the envelope protection lives.

Like any computer, there is input (stick forward), and output (elevator down).
The envelope protection has an additional input that comes from another computer, the ADIRU, and one of the ADIRU's inputs is the pitot-static system, so it can decide if pitching down is safe or not before sending the output.
If the ADIRU says the plane is over-speeding, the envelope protection will not pitch down.

What happens if the pitot-static is not working properly?

The engineers thought about your question, and decided to have 2 or 3 of each computer and pitot-static system.
The multiple ADIRUs are always chatting, making sure the inputs they get from each pitot-static system is similar. If they notice, by voting, that one of the data sources is not similar to the other two, the ADIRUs will tell the flight control computer, "our data is bad, don't trust it."
The advanced flight control computer will stop sending output and will disconnect the autopilot if it is engaged, then another simpler flight control computer will give more control to the pilots.
The pilots will be shown on their screens that there is an ADIRU issue, and from their training they will know what to do (memory items) to keep the plane from stalling (your example), and then they will run their checklists to make sure the ADIRU that is getting bad data is no longer voting. This is called a degraded fly-by-wire mode, i.e., not all the functions of the envelope protection are working.

The drawing is own work, which is a simplified version of the actual schematic.


How much power is drawn by a turbofan to power its own compressor?

To answer this question, it is best to start with the compression work which has to be performed on the air flowing through the engine. If you just want to know how much power is needed to run the fan on a mid-sized passenger jet, you can look at industrial installations of the Rolls-Royce RB-211, two of which power the Boeing 757 and four the Boeing 747-200. The electrical output comes directly from the low pressure turbine which would drive the fan in an airliner engine, and is up to 32 MW for the RB-211 (after generation losses).

Now to the core compressor: If we assume that no heat is exchanged between the gas and the surroundings we can use the formulas for the adiabatic process as presented in Wikipedia. The example given is actually a nice fit for the RB-211-535 or an EJ-200 engine:

Initial state (Index 0): 27°C/300 K and 1 bar/100 kPa

Final state (Index 1): 477°C/751 K and 25 bar/2500 kPa, 10% of the initial volume.

When we use this Wikipedia page, we get:
$$W = \frac{\kappa\cdot R\cdot(T_1 - T_0)}{\kappa - 1} = \frac{\kappa\cdot R\cdot T_0}{\kappa - 1}\cdot\left(\left(\frac{P_1}{P_0}\right)^{\frac{\kappa - 1}{\kappa}} - 1\right)$$

where $R$ = 287 $\frac{J}{kgK}$ is the gas constant and $\kappa$ = 1.4 for diatomic gasses like nitrogen and oxygen.. $V_0$ of 1 kg of air is 0.84 m³ and $V_1$ is 0.084 m³. The result is $W$ = 454 kJ per kg of air, and that has now to be multiplied with the mass flow. For the RB-211 I find mass flow data only for industrial applications where the engine runs at a reduced pressure ratio, but I will use the 203 - 212 kg/s regardless because it fits with the initial pressure and temperature data of my example. The result is in the order of 95 MW in a 200 kN thrust class engine.

Considering that the above equations are for the ideal, friction-less case, the true power need is probably 10% - 20% higher. However, at altitude the air density is only a quarter of that at sea level, so the compressor power needs are also only a quarter.

To put it into proportion, we need flight speed as well: At 240 m/s the 50 kN thrust at altitude translate into 12 MW of propulsive power, so the compressor power under the same conditions is twice as high.


Is spin recovery possible in an airliner?

There were a lot of other mitigating factors in the Colgan Air 3407 crash. Was that one recoverable? It depends. It never should have got to the point of a stall in the first place. It was more preventable than recoverable.

But in answer to your question, again, it depends. Every aircraft in the air can stall and be recovered, if responded to properly. But the plane may very well bend and break if the stall develops too far. Then it may not be recoverable. And most large airliners (or aircraft bigger than a few thousand pounds with multiple engines) aren't designed for the stresses of spins, so they never teach to a full stall. In those types of aircraft a full stall is much more dangerous, and they can be much more difficult to recover from, especially if you break something. Besides, in aircraft like that, you should receive plenty of direct warning long before you reach the point of a stall.

When I was teaching, stalls and spins were one of my favorite subjects for early pilots. Especially in light trainers like the Cessna 150/152s. Those aircraft were always incredibly good at stalls/spins and incredibly forgiving. You can put a Cessna into a hands-off full stall if you trim it right, and it will stop rotating in a spin if you simply let go of it (and have enough altitude). I always taught my students spin recovery from a full spin, even at the Private Pilot level. And usually shortly after teaching them full stalls. I would stall it, make it rotate at least 3 or 4 times, and have them recover the spin. Then have them do it themselves. I never had to worry about my students not knowing how to recover from an unintentional stall/spin. By the time my students were learning to fly multis, I was teaching them more stall recognition and avoidance than recovery. Recovery is essentially the same in all aircraft. You just have to be sure to not reach that point.

There's only one thing you really need with any aircraft in a stall/spin, and that's altitude. Unfortunately, takeoffs and landings are the most likely places for you to get behind the aircraft and let it unintentionally stall/spin. That's why you learn how to recognize them very early in your pilot training. You can't spin without a stall first, and just about any airplane will give you fair warning before you stall it. The trick is recognizing the situation before it becomes serious.


What is that ceiling compartment of a Boeing 737?

It holds a life raft. In case of ditching in the ocean, the raft would be removed from that compartment and tossed into the water, where it would inflate.


Does airspeed come into play with vertical speed, in terms of who will reach the ground first?

No, both would reach the ground at the same time, although the one with the higher airspeed would go farther before hitting the ground, assuming atmospheric conditions are invariant.

On the other hand, if both aircraft have the same flight path angle, the one with the higher airspeed would have a higher sink rate.


Why/How does the Pilatus PC6 Approach nose-down?

How: With flaps out and the engine at idle that is the pitch for this aircraft that will yield its maximum decent speed.

Why: Max rate decent are commonly trained to be used in emergency situations but in this case its likely being used to save time since jump planes make money jumping. In most situations passenger comfort and airspace organization limits decent rates and keeps them controlled. Jump planes simply serve the purpose of getting passengers to jumping altitude and then getting back on the ground to scoop up the next load so max decent is used to save time.


Can water-cooled brakes be used for takeoff aborts?

This solves the problem of rejected takeoff, which is certainly a major factor in brake design. However, dumping the water after takeoff means that benefit is unavailable for landing. Events such as flap issues can require an aircraft to land at a higher speed than usual, requiring more braking capacity. The difference between this and rejected takeoff may not be enough to justify the weight, complexity, and expense of the water cooling system.


Does the AIM really require anti-collision lights to be used during the day?

Anti-collision lights are required for day and night as specified in the AIM. There's an exception to turn them off if it interferes with the pilot's visibility (e.g. while in the clouds the strobes can be distracting).

  This is obviously not the practice?

This is the practice.


Can I log PIC time while flying solo in an R22 toward a helicopter addon?

Solo time is always PIC time. You're alone in the aircraft, so who else could be PIC?

14 CFR 61.51(e)(ii):

  (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-

  [...]

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


Can someone identify these two Bell helicopters seen in the Czech Republic?

The mystery has been solved.
Those two helicopters are Agusta-Bell AB 212 operated by Italian Air Force (Aeronautica Militare) coming for Tiger Meet in Poznan, Poland. Their flight route was a little bit confusing because they were VFR flight avoiding CTR.
The more colorful one wears new special tiger paint: https://www.planespotters.net/photo/836257/mm81151-aeronautica-militare-italian-air-force-agusta-bell-ab-212
The second one seems to wear standard camo: https://1.bp.blogspot.com/-czFFf-7KQyA/Wvu5eNjjgXI/AAAAAAAAMQs/qN9qakgSI9QTmqfosho3Dr6DVmHl-nTNwCLcBGAs/s1600/NTM05.jpg
Thank you, Walker, for your input!


Do flight simulators imitate turbulence effectively?

No, simulators cannot realistically simulate turbulence. Turbulence is characterized by significant changes in altitude that happen very quickly, and even full motion simulators aren't going to be able to re-create that. They can bump you around a bit, but not really prepare you for the real thing.


Why don't Russian aircraft sell as much as their European/American counterparts?

If you take out the political angle (which is by far, the most important), there are a number of reasons for this.

Basically, the Russians have a serious image problem. Russian (and Soviet) aircraft have a reputation for poor quality, reliability and safety issues. This will take a long time to fix. In contrast, Japanese have no such problems (In fact, the MRJ boasts of 'legendary Japanese reliability')
It is not easy to make airlines switch from an existing aircraft. Most airlines have a huge system built around the aircraft they operate (In fact, quite a few regional carriers operate only a single aircraft type). It would take enormous amount of investment in time and money to shift to a new aircraft and it would take a large incentive for them to put their eggs in a new basket.
US is probably the most important market at present and operating there gives other airlines a lot of confidence to buy the jet. If you see the orders for MRJ, most are from US (In fact, almost all orders are from either US or Japan). The Superjet, in contrast, hasn't even applied for FAA certification as far as I know.
Promising and delivering lower costs are completely different things. Airlines are more prone to believe companies that have a proven track record of manufacturing civil aircraft than a newcomer.
The Superjet is the first airliner to be developed in Russia since the end of cold war. As such there are questions about its industrial capability and quality control processes. Mitsubishi, on the other hand is engaged in a number of aircraft projects (it makes more than a third of 787 structure).
Sukhoi has to build a supply chain and support system from scratch (Superjet has a number of foreign components). Again, in the extremely cost sensitive airline industry with tight schedules, there is a perception that the Russian aircraft will not be supported as well as their western counterparts (For example, Boeing boasts of a >99% dispatch reliability for 737)


How is an aircraft aligned at a jet bridge?

How are aircraft aligned with these bridges

They are not (but read on)

Aircraft are aligned to a point on the concrete, not to the jetbridge(s).

It is the jetbridge itself that carries out the final alignment to the aircraft door.

Jetbridges are actually motor vehicles with wheels, tyres, motors and (often) steering. It just happens that their rear end is tethered and their bodies articulate and/or telescope to accomodate the motion at the "front" end..

You drive one using a set of controls at the end furthest from the terminal building

-jet bridge controls

- driving a jet bridge

I believe some also have what is effectively variable height suspension like old Citroens (except I imagine it is hydraulic or jack-screw).

The aircraft is driven to the terminal so the nose wheel follows a  guide line and stops at a marking appropriate for the aircraft type. Then the jet bridge is driven up to the aircraft door.

As the aircraft is gradually burdened with self-loading freight and sinks on it's suspension, the jetbridge metaphorically bends its knees so that the SLF don't trip up or fall into the aircraft. That is, the jetbridge maintains alignment, the aircraft is pretty passive in the job of alignment.

I have to admit I didn't notice these jetbridge controls for many years as I was usually either busy rushing to my seat or busy rushing to the baggage reclaim. One time there was a delay at the aircraft door that was long enough for my bored gaze to alight on the controls and for the thought to briefly wander across my mind - "I wonder what would happen if I pressed that ..."


Is it possible to build a turbojet engine with aluminum cans? (Soft drink cans)

No, you cannot make an entire model jet engine out of aluminium.
Most fuels burn at 1000+C and aluminium melts at around 660C: Even if you keep the burning contained in airflow (thus away from the walls) the heat transfer will still damage the aluminium.

You could make the majority of the engine from it, though: Just as long as you find something more suitable for the 'hot' parts.


Why do compressors constrict flow if this decreases pressure?

Your understanding of Bernoulli's equation is correct, but the situation in a compressor is more complex, because energy is being added by the rotating blades.

When subsonic flow decreases in speed, and no energy is being added, the total pressure remains the same. This means the static pressure must increase,  because the LHS of Bernoulli's equation isn't changing:

Pt = Ps + 1/2 x rho x velocity ^ 2

But, in the compressor, the rotating blades are adding energy from the mechanical work they are doing on the fluid, and hence the total pressure increases. So, while the above equation still holds, the LHS is now increasing. The static pressure is then given by the isentropic compressible flow equation:

Pt = Ps x (1 + 0.2 x Mn^2).

When someone talks about "pressure" changing, they need to be very clear if they mean static or total pressure.

What the compressor is doing, is increasing the total pressure. Total values are the measure of energy in the flow. But because the Mach number stays about the same from compressor inlet to exit, the static pressure goes up also. But, this isn't really important, increasing the total pressure is the significant factor. Total values represent the energy content of a fluid, because as you can see in Bernoulli's equation, the energy content can be traded between the velocity term and the static term as the fluid speeds up or slows down, but this is just shifting energy from one form to another, it's not changing the total energy content.

As the air in the compressor is being compresssed, it actually needs less space, as your intuition would suggest. A complicating factor is the air temperature is also increasing, so it's not just the same volume of air at only a higher pressure. But, if the compressor expanded as you suggest, the velocity would decrease too much, and then the air flow over the rotor and stator blades would be too slow. This would cause them to loose their aerodynamic performance. The rotating blades would be ineffective in adding energy, and the blades would stall, as the rotational velocity would be too high in comparison with a low axial velocity. A high rotational velocity of the blades and low axial velocity of the air makes the angle of attack of the air on the blades increase. They stall like a wing on an aircraft going slow at a high angle of attack. When the air in the compressor stalls, it no longer wants to flow in the direction of increasing pressure towards the combustor. It reverses direction, and flames can even come out the front of the engine. Not good!


Why does MAP show ambient pressure when engine is shut off?

The intake manifold is where the air flows from outside into the engine, so obviously it must be open to the outside. So when everything is calm, the pressure quickly equalizes and the manifold pressure is equal to the ambient pressure.

The non-obvious thing is actually why it differs when the engine is running.

When the engine is running, it sucks air in. The volume of air per unit of time is proportional to its rotational speed: higher RPM means more strokes per minute and each stroke has the same displacement.

Now without any restriction in the intake manifold, the air would still enter at the ambient pressure (speaking of normally aspirated engine). And with fully open throttle, the restriction is small enough that the manifold pressure is indeed only a little below ambient.

It is only as you close the throttle that you create significant restriction, which reduces the manifold pressure.

But the reduction is still proportional to the engine RPM. With engine not running there is no suction, so the pressure can't decrease and the gauge still shows ambient pressure.

This dependence on the RPM also means that it is not actually good indicator of the power the engine produces. When you increase RPM by adjusting the mixture, the engine power will increase—because it takes more power to sustain higher RPM—but the manifold pressure will decrease—because there is more suction. The same also happens when you increase RPM by advancing propeller pitch selector.

What manifold pressure is good indicator of though, and the reason it exists, is the engine wear. The amount of air, and fuel, are proportional to the manifold pressure, and therefore so is the peek pressure when the air is compressed and the fuel burnt. And the higher the peek pressure, the more wear on the components. That is why there is absolute maximum you should never exceed and continuous power limit that you should only exceed for limited time on take-off or in emergency.

Note that the relations are further complicated in turbocharged engines where higher engine RPM also mean higher turbocharger RPM and that increases the pressure gain on the turbocharger that adds to the manifold pressure.


Jet engines: are they owned by the airline or just rented?

These days, engine manufacturers are not any more in the business of selling engines, but selling thrust.

Rolls-Royce were the first to offer this, and today most Rolls-Royce engines send telemetry data to four centers, the biggest one in Derby, in Great Britain, where every engine is under surveillance. An inspection can be scheduled at or spare parts can be directed to the right destination even before the pilots or the airline know that one of their engines has a problem.

By now, 80% of Rolls-Royce engines are sold at a loss which is recouped by a hourly fee paid under the TotalCare (.pdf!) program, and that center in Derby is monitoring maybe 4000 of them at the same time. Rolls-Royce has accumulated a treasure of engine operations data, which enables it to consult airlines on best practices. This makes it very hard for a third party to steal maintenance business from Rolls-Royce. All maintenance cost is covered by the TotalCare fee which now accounts for more than half of Rolls-Royce's revenue.

GE and Pratt&Whitney have similar programs. In GE's case, it is called OnPoint, sold as "Power by the Hour". The airline does not pay for the engines, but for the time they are flying. Now the engine manufacturer has a strong incentive to improve the reliability of its engines, but also a strong lever to push out third-party maintenance providers.


In USAF are people WSO by choice or is it because they didn’t make the cut to be a pilot?

Short answer:  #1 is the most correct statement, but it doesn't tell the whole story.  #2 can happen, but it's very rare for the reasons described below.
TL:DR
To understand this you need some understanding of how the USAF personnel system operates. One key factor that constrains how the system operates is that it's designed for a constant flow of personnel through the system where everyone starts at the bottom (for officers, that's a Second Lieutenant). Over time, each year group (people commissioned in the same year) will eventually go before a promotion board. Failure to be promoted normally results in being forced out. Add in people who just quit (after they've met any service commitments), and the year group gets smaller as you move up the ranks. This makes sense as there are fewer people at the top of the chain of command.
The downside to this is that the USAF can't go hire a bunch of 10-year Captains or 15-year Majors if they find themselves short of personnel in that range. So everything in the system is based on long term projections - not just how many do we need today, but 5 or 10 years down the road.
This process is applied to each career field, of which there are dozens. In general, when you start in a career field you will be in that field for your entire career. It is possible to change career fields, but it's not all that common. The biggest factor will be staffing level in your current field and the field you're trying to move into. Moving from an overstaffed field to an understaffed field is possible. The reverse is virtually impossible.
The pilot and WSO careers are complicated by the fact that it has a very long training pipeline and there's an age limit to start the training. So the process of selecting pilot and WSO candidates starts before you ever get commissioned. For the AF Academy and AFROTC cadets, this starts when they enter program where they get to state their desired career field. The number of available slots in each career field are set based on projected needs 5 to 8 years in the future.
Realistically, almost everyone wants to be a pilot. But it can't happen. When I went in the AF limited the pool by setting very high medical standards. The need for uncorrected 20/20 vision cut the candidate pool down to a more manageable size. The standard for WSO/Nav, etc. at that time was 20/70. So WSO was a backup for those who couldn't meet the 20/20 eyesight requirement (or get a waiver). Grades in school as well as performance as a cadet determined whether you got a slot. Some who asked for pilot were offered WSO slots. (I was an engineer and couldn't pass the eyesight for WSO.) And if you screwed up in school, you could lose it the next year.
My senior year (AFROTC) there was a force cut which cut the number of slots. Pilot candidates that lost their slot were given options. Some were offered Nav/WSO or Missile slots, others were given the choice of taking a non-rated career, going in the reserves, or just dropping out of the program with no penalties. I know people that took each of these options.
But even with all this planning, things change. So if you did come in as a non-rated officer, there are some limited opportunities to make it into pilot training. It's a long shot, but if you do really well as a Lieutenant there's usually a few selected each year to become pilots. You don't have much time to do this due to the age limit to start pilot training.
As to the second option, if you were to wash out of pilot training you would not be automatically considered for WSO as that pipeline is likely full. You could apply for it, but again that would be long odds (and the reason for washing out of pilot training would definitely have a bearing on your probability of success.)


What position was this photo of a jet engine taken from?

Based on the Linkedin page, this is a portion of an IAE V2500 turbofan.  Looking at the following images of the engine (in modules and awaiting final assembly), I can pick out a view that is really similar to the image you have up, namely the module of the engine in the bottom right hand corner of the image or the one in the background, behind the fan section that is near the center of the image.

Looking at a cutaway of the V2500 (below), you can pick out similarities between this section and the engine if viewed from directly behind the fan.

Based on this, a schematic of the V2500 engine modules (below), and the insulation laid out in the bottom of the photo that you posted, I think that the picture you found is taken from inside of the engine, directly behind the fan section and looking aft.  The only things that I'm unsure about are background (appears solid?) and perspective (looks like the engine is in a tube--fan was removed, but the shroud is still on?).


Where can I find runway usage statistics of USA airports?

Like @CrossRoads said in his answer, there is no data available on which runways are used most. You will need to listen to LiveATC on several days and keep track of the winds to get a rough estimate. For example, from listening to the tower at KSFO I gather that they usually land on 1L and 1R and take off on 10L and 10R. However, when the winds are too strong out of the east they use 10L and 10R for landing.

Likewise, if you listen to the tower at KJFK you can tell which runways are in use on any given day. There appears to be more variability there because the winds are much less consistent.

And then there are airports like KOAK and KSJC that have one runway or set of runways that GA aircraft use and one for the big guys.

The airports might keep that kind of information so a call to a few of them might give you some answers, but I am not aware of it being published anywhere.


What differentiates the entry procedures for spins and snap rolls?

A snap roll isn't a roll.  It's an "enhanced" spin, done horizontally.
A normal spin entered from level flight at 1G stall speed has an initial roll component along with the yaw component as the wing drops at the stall.
The same thing happens in a snap roll, except that the spin is entered with an accelerated stall, well above level flight stall speed and with power, with both the roll and yaw initiation enhanced with aggressive rudder and aileron input to get the horizontal auto-rotation roll-yaw going as fast as possible.
Because the snap is done in an accelerated stall, the stall can be broken immediately with forward stick, and aggressive opposite control inputs have to be used to overcome inertia to stop the snap roll.  You initiate the left snap with the hard stick back/left and left rudder, and recover with hard stick forward/right and right rudder when about 3/4s of the way around.
You don't actually need aileron; airplane can snap roll quite nicely with no aileron, just rudder, it'll just be a bit slower.  A pilot can enter a snap roll accidently just from mishandling, say pulling too hard in a turn and inducing an accelerated stall with the ball off center, and if the airplane has a sharp stall break, around you go, and before you've figured out what happened you're already right side up again.
If you hold the control inputs and keep the snap-roll going, you eventually arc down until you're snap-rolling vertically, or spinning the old fashioned way.


What does the "Caution" box mean on the sectional near Half Moon Bay, California?

This one is a bit confusing and interestingly there is nothing in the FAA's sectional guide on "Caution" boxes although they do appear on other charts as well.

This one in particular is a warning that you will need monitor the radio for the transition routes below 2000 ft. If you can zoom in or get TAC level map resolution you will see a different warning

(source)

If you note a bit south of half moon bay the chart makes note of the fact you should be using the TAC in that area:

(source)


Is there a way for the helicopter rotor to get its power half by wind, half by engine?

The problem is that as an autogyro, the air is going through the rotor from below, and as a helicopter, the air is coming from above and it has to be one or the other.
In any case, gyroplanes don't have a problem of low rotor rpm as long as you keep the rotor loaded (and you always keep the rotor loaded).  If you slow down, the rotor rpm doesn't decay, the machine just descends steeper.   You can slow a gyro to zero airspeed, and it will maintain most of the rotor rpm on its own and autorotate straight down, although the vertical speed may get pretty high. If you have a landing gear that can tolerate a 500 fpm descent, and start from only 20-30 feet or so, you can land like that.  This is why some small autogyros don't even bother with a rotor rpm gauge.
So to get low rotor rpm, you'd have to unload it to take away the aerodynamic forces driving the blades around by pitching over to go zero G or close to it, and at that point an engine might be useful to keep the rpm from dropping, but you'll have probably already chopped the tail off from the blades flapping down (low G maneuvers in gyros are to be avoided at all costs - as with 2 blade helicopters, for different reasons), and you'll already be on your vertical trip to your final resting place anyway.


Can anti-radiation missiles be used to target stealth fighter aircraft?

There are many anti-radiation missiles in many arsenals, they are designed for air to ground missions, attacking surface to air missile radars from a long distance. I don't know whether it would be possible for an anti-radiation missile to hit an air target.
If we assume it is possible your idea has a significant flaw in that stealth aircraft turn off their radars when they are on a stealth mission. Running a radar is like holding a flare in the middle of a field on a dark night, which is why they don't do it, at least not using conventional radars.
Some stealth airplanes don't even have a radar, for instance the F117. Typically attacks were done using GPS for precision navigation to the target, which is then attacked using precision munitions like laser guided bombs or GPS guided bombs or missiles.
Nowadays here are advanced radar systems that spread signals over multiple frequencies which will blend in with other signals, and can be directed in specific directions to avoid being detected. If a radar beam isn't pointing towards a sensor then the radar won't be detected.


How can two planes be on the same taxiway facing opposite to each other?

The taxiway is being used for parking. Specifically, parking of two MD-80s that have attracted press attention—The Australian: Clive Palmer’s $10m in tax-haven jets sitting idle:

  TWO 155-seat jets owned by Clive Palmer and branded with the name of
  his controversial and longtime loss-making company Mineralogy sit
  mothballed in a remote corner of Brisbane airport.

  The McDonnell Douglas MD-82 jets, worth roughly $5 million each, are
  registered in the Cayman Islands tax haven and have sat mothballed for
  months, possibly years.

  ...

  A spokeswoman from Brisbane airport confirmed the planes were owned by Mr Palmer and had sat idle for “at least several months”, but was unable to confirm exactly how long. “The space is leased from Brisbane airport and the owner pays leasing fees to have them there,” she said.

That article from 2014 shows them parked head-to-tail, but presumably they've been moved since then (the Google maps imagery is from 2017).

If you're wondering how I found this, I zoomed in on the satellite image and used 3D mode to get a better view of the side of the aircraft well enough to sort of make out the "Mineralogy" label on the side, and Googled from there.


What is the process of obtaining a commercial license after revocation?

If your pilot's certificate was definitely revoked then it's gone for good. You'll have to reapply and re-qualify for all your certificates and ratings again, although you have to wait a year first per 14 CFR 61.13(d)(2):

Unless otherwise authorized by the Administrator, a person whose
pilot, flight instructor, or ground instructor certificate has been
revoked may not apply for any certificate, rating, or authorization
for 1 year after the date of revocation.

Certificate revocation is the FAA's 'nuclear option' and they don't do it lightly. Your best option here is to contact AOPA (if you're a member) and/or an aviation lawyer for specific advice.


Sidesticks are smaller than yokes. To apply a control input one only needs to turn one's wrist while a yoke requires you to use both of your arms to make the big aircraft turn.

Side-sticks are used together with control laws. In an Airbus Normal Law (and Alternate Law which differs only by not providing the flight envelope protections), the system automatically trims for 1 G wing loading (which equals constant flight path angle) and zero roll rate and the side-stick deflection commands wing loading in pitch and roll rate in roll. The springs are sufficient to provide all feedback there is to provide as the deflection and the force both correspond to the command given.

Due to the way side-sticks work, extended deflection is rarely necessary, nor are very fine adjustments normally needed to stabilize the plane on desired flight path, because the computer handles that.

  Secondly, and this is the major question, as it appears, the sidesticks make it much harder, to be aware of the currently applied control input (especially) for the other pilot.

Feedback, on any kind of control, is provided by position and force. The other pilot can only feel the position. This allows them to notice that the other pilot pulled up, but not whether it is dangerously close to stall, because the stick position is biased by aircraft balance and, if horizontal stabilizer is used for trim (which all airliners do), also by trim. So the information it provides is rather limited.

On Airbus the side-sticks are not connected, so even this limited information is not available. But they have an advantage too. If the pilot flying is incapacitated or confused, the pilot monitoring can push a “control priority” button on the side-stick and the computer then only responds to their side-stick, so they don't have to fight with the other pilot on the controls.

  How is the general assessment of those sidesticks concerning safety?

I've not seen any specific study. But they were approved and I am not aware of any accident on Airbus where similar accident wouldn't have happened with other type with traditional control column.

  Is there any feedback to the pilots which stick is giving what input?

If both side-sticks are giving input, there is aural and visual warning “dual input”. If one pilot presses the “control priority” button, there is an announcement “control priority left/right” and visual indication. There is no direct indication of what the command is, but the pilots are looking for what the plane is doing anyway and they can usually judge from that. There is also indicator of control surface positions.

  Has there been any development in improving this situation?

I am not aware of any aviation authority thinking there is a problem to fix. Manufacturers are coming up with new schemes they consider good, but that may be as much marketing as genuine improvement.

  What are the accidents/incidents sidesticks more or less contributed to confusion/lack of information?

I can't think of any where it could be said the situation would have been significantly better if the controls were linked. If both pilots are confused, the connection would not help much and if only one is confused, the other can use the control priority to take over.

Even AF447, where some dual input was involved, is not really unique. There have been several crashes where pilots didn't realize a stall and didn't attempt recovery all the way from cruise level down to the ground (the most recent one) and all the others happened in planes with mechanically connected control column.


If flaps are used on takeoff, when should they be retracted?

The short answer is, it depends. The FAA Airplane Flying Handbook merely states that this can be performed once the aircraft has established positive climb, but does not specify exactly when.

Ultimately two situations arise:

The airplane is sufficiently large/high performance that normal operating procedures specify the use of flaps for all takeoff scenarios, in which case the manufacturer or the operator (if applicable) may well specify a flap retraction schedule, which seeks to allow the aircraft to accelerate effectively during climb out, avoid overstressing the flaps by having the aircraft fly past the maximum speed for each flap setting, while at the same time maintain a comfortable margin above stall speed.
The airplane only requires flaps for certain kinds of takeoffs such as maximum performance or soft-field efforts. In that case, procedures may be somewhat looser in defining the exact moment of flap retraction. A climb checklist, should you choose to use one, will likely mention the flap configuration as an action/verification item, so that would likely be a good moment to retract them if you haven't done so already. Personally , I usually retract them passing through 200-300 feet AGL, which usually coincides to the aircraft being at least half-way between clean configuration Vx and Vy (I've been mostly flying Skyhawks, Skylanes, Arrows, and Huskies). Whichever way you do it though, you want to avoid retracting them too low and too slow, but also forgetting about them and blowing through Vfe (which even light, slow airplanes can do quite handily).

With respect to the actual changes in aircraft behavior, you'll likely notice the following things:

A slight-nose down moment as wing's characteristics change, which influences the airflow reaching your horizontal stabilizer. The converse applies when extending flaps. Mind you, this is an airplane model-specific thing and one that seemed most noticeable to me in the Cessna family of light singles.
For the same power setting and pitch attitude, the aircraft will begin to accelerate quicker for each notch of flap retraction.
Climb rate is trickier as it is dependent on your power setting, airspeed, and pitch angle; your inputs will matter. However, generally speaking, the reduction in drag would lead to a greater difference between power available (or power set) and power required, so, all things being equal, you would likely see an increase in climb rate.


What is the role of discontinuous surfaces on the inside and outside elevons of the F-117?

I believe you are referring to the gaps between the elevons and the other control surfaces?  Those are called cats eye gaps and they’re used to reduce radar returns between the gaps.  Virtually all stealth aircraft use this technology.


What causes the reduction in speed across the shockwave?

If you look what causes the shock, there must be an obstruction at the root of it. See the sketch below for a straight and an oblique compression shock:

In case of the straight shock this can be a blunt body or an intake filled with slower moving air of higher pressure. In case of the oblique shock this is clearly the bend in the wall contour which forces the flow to change direction.

The index 1 denotes conditions ahead of the shock, and 2 those downstream of the shock. For weak straight shocks the product of the speed ahead of the shock $v_1$ and the speed past the shock $v_2$ equals the square of the speed of sound: $$v_1\cdot v_2 = a^2$$
If we call the local Mach number $Ma$, and if $Ma_1 > 1$, then $Ma_2$ must be smaller than 1, so the flow is always decelerated to subsonic speed by a straight shock. The same holds for the normal component of an oblique shock: It also becomes subsonic. Since the total energy of the gas doesn't change, its pressure, density and temperature rise when it is decelerated.

The incremental pressure change $\delta p$ due to the bend with an incremental angle of $\delta\vartheta$, expressed in terms of the undisturbed flow with the index $\infty$, is proportional to the change in the streamlines:
$$\delta p = -\frac{\rho_{\infty}\cdot v^2_{\infty}}{\sqrt{Ma^2_{\infty} - 1}}\cdot\delta\vartheta$$

Gas pressure on a molecular level is the number and severity of particle collisions. The air molecules experience more collisions on the downstream side of the shock, since air pressure is higher there. The average  direction of the additional collisions is indeed orthogonal to the shock, because it is the boundary between blissfully unaware molecules at ambient pressure ahead of the shock and their bruised brethren downstream which have just crossed that boundary. Once a molecule has passed the shock, the collisions are coming again equally from all sides and its speed does not change any more.

In subsonic speeds this pressure change can radiate in all directions and becomes a shallow pressure gradient. In supersonic speed, no information about the upcoming pressure change can travel forward, so the change is concentrated in the shock front.


What is the procedure for getting permission to operate an aircraft within a pop-up VIP TFR?

Usually when the President visits LA or San Francisco there are one or more inner rings and at least one outer ring. The inner rings are usually 10 nm in diameter and you can’t enter them under any conditions. The outer rings, on the other hand, are able to be flown into if you are on a VFR or IFR flight plan and in continuous contact with ATC. Here’s a portion of the TFR at Martha’s Vinyard.

  FOR OPERATIONS WITHIN THE AIRSPACE BETWEEN THE 10 NMR AND 30 NMR
  AREA(S) LISTED ABOVE, KNOWN AS THE OUTER RING(S): ALL AIRCRAFT
  OPERATING WITHIN THE OUTER RING(S) LISTED ABOVE ARE LIMITED TO
  AIRCRAFT ARRIVING OR DEPARTING LOCAL AIRFIELDS, AND WORKLOAD
  PERMITTING, ATC MAY AUTHORIZE TRANSIT OPERATIONS. AIRCRAFT MAY NOT
  LOITER. ALL AIRCRAFT MUST BE ON AN ACTIVE IFR OR VFR FLIGHT PLAN WITH
  A DISCRETE CODE ASSIGNED BY AN AIR TRAFFIC CONTROL (ATC) FACILITY.
  AIRCRAFT MUST BE SQUAWKING THE DISCRETE CODE PRIOR TO DEPARTURE AND AT
  ALL TIMES WHILE IN THE TFR AND MUST REMAIN IN TWO-WAY RADIO
  COMMUNICATIONS WITH ATC.

If you are departing or landing at an non-towered field, you need two radios (or an Garmin SL30 radio) to monitor ATC and communicate on the CTAF.

I have done it lots of times VFR into LA and it really isn’t much different than getting flight following.

I don’t have any experience with departing from a non-towered airport into the TFR, since the last time I entered the TFR the approach end of the runway at Catalina Island was in the 30 mile ring, but the departure end was not. So I don’t know for sure but from talking to the people at the FBO and reading the TFR, I think you need to open you flight plan either by phone or on the radio (Hawthorne radio would be who you call and the frequency depends on where you are in the LA basin), contact ATC (in this case LA Center, again frequency varies) on the ground before you take off, then make your normal calls on the CTAF. Then contact ATC again when you are airborne.


Details about video equipment used to help assemble X-59?

The system may have many names depending on detailed configuration, but it is  basically a mixed reality assisted manufacturing system.
One example is described in this pdf document.
The system consists of at least one projector that projects a predesigned guidline on a workpiece, to assist human workforce in their tasks. Additional hardware may include

camera(s) to document work and/or follow the progress and enable switching to new guidline projections as work proceeds; recognize different workpieces
sensors to verify correct orientation of workpiece
manipulators to reposition the workpiece as the work progresses
text or audio output further guiding workers as the work progresses (possibly the aforementioned camera verifies each step).

Depending on resolution of the projectors, the accuracy of the system might reach accuracy of millimeter scale, for example for the purpose of drilling holes into a workpiece, but it is best suited for work such as in the picture:

highlighting necessary tasks
providing guiding for correct order of tasks
highlighting "no go" areas or such on a workpiece
etc...

The bigger the workpiece, and/or the more complex the shape of it is, the less accurate the guidline picture projection will be. This can be overcome to some extent by using multiple projectors, but the system quickly becomes very complicated especially with workpiece with complicated contours.
This could be called a poor man's AR goggle, with the benefit of being rather low tech, but the downside of the workers limiting the visibility of the guidline pic as they move around the workpiece.
There most probably are two projectors on this system simply to cover a lager workpiece. Another solution might be to verify correct 3d orientation/placement of the workpiece by overlapping two guidline images, but the orientation of the projectors in this picture are such, that the images cast by the projectors do not seem to fully ovelap.
I was unable to quickly locate it, but there is a fine video of this type of system being used on assebly line of the F-35 fighter. I will keep looking...


What does it mean when autoland is fail passive / fail operational?

The quoted explanation about "fail operational" and "fail passive" is correct, in that "fail operational" means the system will continue to function after an failure, and "fail passive" means the system will not misbehave after an failure.

The exact number of autopilots required to make this work, however, is debatable; and much depends on how you define it.

Let's take the Boeing 777 because it is easy to begin with. It has three autopilots. It will say "LAND 3" or "LAND 2" respectively. In a system of three, a failure can be detected if one disagrees with the other two. In a system of two, it is uncertain which one has failed, so all units come offline.

Now here comes the interesting part: what if I can distinguish a failed unit from a functional unit, without using another functional unit? In other words, what if I have something that can monitor the existing units, but is incapable of functioning the same as one of the monitored units on its own?

That is how fail operational can be implemented with two autopilots. For example, the Flight Management and Guidance System (FMGS) on the Airbus A320 can switch from "Dual Mode" to "Single Mode". The FCOM does not detail how it does that. (A320 FCOM - Aircraft Systems - Auto Flight - General)

But the FCOM does state a "CAT 3 DUAL" automatic landing is fail operational

  the remaining part of the automatic system allows the aircraft to
  complete the approach, flare and landing

while a "CAT 3 SINGLE" landing is fail passive:

  there is no significant out-of-trim condition or deviation of flight
  path or attitude, bu the landing is not completed automatically

 A320 FCOM - Procedures - Normal Procedures - Landing Categories

The Boeing 737 has 3 inertial sources but only 2 autopilots. It implements fail operational on the inertial sources but fail passive on the autopilots.

  If a failure is detected, the flight controls respond to the A/P
  commanding the lesser control movement. If a failure occurs in one
  A/P, the failed channel is counteracted by the second channel such
  that both A/Ps disconnect with minimal airplane maneuvering and with
  aural and visual warnings to the pilot.

Boeing 737 FCOM volume 2 - Automatic Flight - System Description


Ceramic materials are starting to be used in jet engines.  E.g. the LEAP-1A is using a few ceramic matrix composite in the high pressure turbine.   (http://aviationweek.com/mro/ceramic-composites-enter-service). Future designs will likely expand the use of CMCs (e.g. http://www.geaviation.com/press/ge90/ge90_20150303.html)


There are a few ways that pilots are aware of potentially turbulent areas.

Eyesight
The most obvious way is just by looking outside and observing the sky.  Large billowing clouds, called cumulus clouds, indicated pockets of unstable air (the clouds are rising because the air under them is as well).  If the pilots must fly through these clouds then its a safe bet that there will be some turbulence.

Weather Radar
Just like using your eyes, except the radar can see further through haze and other clouds.  Typically this is useful for finding embedded thunderstorms, but it can also be useful to find areas of potential turbulence.

Communication
Pilots talk.  Both to each other and to air traffic controllers.  En route controllers frequently ask pilots for "PIREPS" (pilot reports), to build an accurate picture of the flight conditions at different altitudes.  Often commercial aircraft will request to change altitudes or deviate around weather/ turbulence, so it is in the best interest of the controller to know ahead of time where the bad flight conditions are, and have a game plan of how to route traffic.  This makes it much easier for the controller to route traffic, rather than getting request after request from individual aircraft.


Is it possible for more than one flight to have the same departure and arrival time slots?

When I was working at the FedEx hub in Memphis the pushback times were scheduled every six minutes from 1:48 to 4:00. That's 22 slots for well over 100 flights, so there were several scheduled in each slot. They were set up so only one aircraft in any particular section of ramp would be trying to push back at the same time. There would always be a queue at the runway.


The correct thing to do very much depends on the clearance that you were given.

If you were simply cleared direct to BEJCY and cleared for the approach, then your instructor is correct and you should have completed the procedure turn as charted.

If the clearance included the words straight in (i.e. "cleared for the straight in GPS 01 approach"), then you could not perform the procedure turn even if you wanted to, without getting permission first.

If you are receiving radar vectors to final (i.e. "Fly heading xxx, cleared for the GPS 01 approach") or if you are doing a timed approach from a holding fix then you may not perform the procedure turn either.

There are also charts which have notes saying "NOPT for arrivals between radials xxx and xxx." or similar, which would also preclude you from performing the procedure turn under the appropriate conditions.

By default, the procedure turn is required if depicted unless there is a specific reason not to.

The AIM says:

  5 − 4 − 9. Procedure Turn and Hold − in − lieu of Procedure Turn

  a. A
  procedure turn is the maneuver prescribed when it is necessary to
  reverse direction to establish the aircraft inbound on an intermediate
  or final approach course. The procedure turn or hold−in−lieu−of−PT is
  a required maneuver when it is depicted on the approach chart, unless
  cleared by ATC for a straight−in approach. Additionally, the procedure
  turn or hold−in−lieu−of−PT is not permitted when the symbol “No PT” is
  depicted on the initial segment being used, when a RADAR VECTOR to the
  final approach course is provided, or when conducting a timed approach
  from a holding fix. The altitude prescribed for the procedure turn is
  a minimum altitude until the aircraft is established on the inbound
  course. The maneuver must be completed within the distance specified
  in the profile view. For a hold−in−lieu−of−PT, the holding pattern
  direction must be flown as depicted and the specified leg
  length/timing must not be exceeded.

  NOTE −

  The pilot may elect to use
  the procedure turn or hold −in−lieu−of−PT when it is not required by
  the procedure, but must first receive an amended clearance from ATC.
  If the pilot is uncertain whether the ATC clearance intends for a
  procedure turn to be conducted or to allow for a straight −in
  approach, the pilot must immediately request clarification from ATC
  (14 CFR Section 91.123).


What are the requirements to get a private pilot's license in Indonesia?

The Indonesian air regulations include CASR 61 Licensing of Pilots & Flight Instructors, which has all the detailed requirements for getting a Student license (subpart C) and then a Private license (subpart D). To get a more 'friendly' overview of what they really mean, I would look for a local flight school that can explain the practical steps.

Interestingly, the Indonesian regulations appear to be very closely based on the US ones.


Why is the S-duct intake on the Tu-154 uniquely oblong?

This doesn't fully answer the question, but the B727-100 also had an oval engine intake.

AIRLINERS magazine Sept/Oct 99 edition:

"The oval shape inlet on the 727-100 series was changed to a circular design on the stretched 727-200. This was a direct result of the new aircraft's longer fuselage. In flight, the increased lengths from the nose to the center engine inlet increased the thickness of the "boundry layer" of air on the fuselage forward of the inlet. This would have caused aerodynamic "blanking," or disruption of airflow into the center engine, without changes to the design. The circular inlet allowed a smooth flow of air into the engine, as it elevated the bottom of the inlet away from the fuselage boundry layer and into the air stream."


Can 737NG GPWS and other warning voice lines/sounds be played in headphones instead of cockpit speaker?

No, the pilots cannot disable audio warnings or switch them over to headphones only. They are always send to the speakers and all headphones. The pilots cannot even adjust the volume for these warnings. This is to make sure that these warnings can always be heard regardless of any intentional or accidental misconfiguration of the audio control panel.

  Audio warnings for altitude alert, ground proximity warning, collision avoidance,
  and windshear are also heard through the speakers and headsets at preset volumes.
  They cannot be controlled or turned off by the crew.

(Boeing 737 NG FCOMv2 5.20.1 - Communications - System Description)

The typical altitude callouts from the GPWS are:

  Approach Callouts

  Radio Altitude Callouts

  [Option - Typical]

  The GPWS provides the following altitude callouts during approach:

  2,500 feet – TWENTY FIVE HUNDRED
  1,000 feet – ONE THOUSAND
  500 feet – FIVE HUNDRED
  100 feet – ONE HUNDRED
  50 feet – FIFTY
  40 feet – FORTY
  30 feet – THIRTY
  20 feet – TWENTY
  10 feet – TEN.

  Note: Callouts at 1000 feet and 500 feet are based on barometric altitude above
  the landing field elevation; callouts at 2,500 feet, and below 500 feet are
  based on radio altitude.

  DH/MDA Callouts

  The GPWS provides height callouts based on the altitude set by the Captain’s Minimums selector.

  Callouts are based on radio altitude when the MINS selector is set to RADIO. Callouts are based on barometric altitude when the MINS selector is set to BARO:

  DH/MDA plus 100 feet – PLUS HUNDRED
  at DH/MDA – MINIMUMS

(Boeing 737 NG FCOMv2 15.20.17 - Warning Systems - System Description)

All of these callouts are airline options and can be disabled by individual operators. There are also callouts at other altitudes, which are not listed here. See also Does the Boeing 737 NG have "5" radar altitude callout?.


When do commercial flights turn off the APU?

This varies due to operational need and airline standard operating procedures.

On my aircraft (an Embraer E-Jet) we turn on the APU roughly ten minutes prior to pushback and shut it down shortly after starting the engines.

If we plan on taxiing on one engine we will shut it down after the first engine start and perform a cross-bleed start on the second engine. Other operators leave the APU running for second engine start.

If performance requirements demand the engine bleed to be off for takeoff we will leave the APU on until after takeoff to provide cabin pressurization until the engine bleeds come back online.

We typically leave the APU off for the remainder of the flight and do not turn it back on until the next flight, unless ground power is unavailable or unreliable at the destination, in which case we will turn it on after landing as we approach the gate.

The APU can also be left on (or started in flight) to assist with various abnormal or emergency situations where bleed air or electrical power generation might be needed. Each APU installation will have a different flight envelope in which it can be started / used and is specified in the aircraft's operational limitations.


How can I troubleshoot an intercom interference issue in a Piper PA-28?

For the wiring, you need to do several things. First, obtain the Vendor's manual for the SL 300. Next you will need to trace out the wires going to the SL 300. I suggest labeling them.

This type of work is beyond normal pilot/owner maintenance, and I would urge you to work with your A&P or avionics shop tech to get support while you debug things, and also to provide guidance as you navigate the wires, controls, etc. that might need some displacement while you work on things.

A suppression capacitor can be installed, but I would identify the problem first. Again, the avionics tech should be consulted, and any filter you install will need to be documented, and "signed off" but you probably already know this as you own the plane.

Give a better description of the sound, or a recording, and you might get better ideas on where to look.


How can I find out if the FAA has ever sanctioned a pilot?

I asked FAA Airmen Services about this. There is no easy way to do what you want, as there is no online database that can be queried for pilot enforcement actions. They said you can send them a query by mail or email using this format:

                       In accordance with the Privacy Act

    Date:

    TO:
    FAA
    Aviation Data Systems Branch, AFS-620, ATTN:  Privacy Act
    PO Box 25082
    Oklahoma City, OK 73125
    Email:  9-amc-afs620-pa@faa.gov

    FROM:
    COMPANY NAME
    NAME OF COMPANY REPRESENTATIVE
    STREET/MAILING ADDRESS
    CITY STATE ZIP CODE
    Email address:  <Please enter your email address here>

    Under the authority of the PRIVACY ACT, I am requesting verification of
    current airman medical certificates, current airman certificates indicating level,
    category, class, and associated type ratings, including any limitations to those
    certificates and ratings and any and all information concerning FAA
    accidents/incidents, and/or FAA enforcement (AIE) history for the following
    airmen:

              Name:                              Date of Birth:            Certificate Number:
        1.
        2.
        3.
        4.
        5.
        6.
        7.
        8.
        9.
        10.

I understand that the response to my request should be mailed to me within 20
federal working days.  If you have any questions, please contact me at:  XXX-XXX-XXXX.

Sincerely,

I am surprised there isn't a faster mechanism for this. Enforcement actions should be public record, same as criminal conviction records. But I guess this process is geared towards background checks of pilots by potential employers, not the general public. Odds are it would take an act of Congress to change this.


Much of aviation has a history in Nautical terms, lore... and law.

Ships were referred to as "she" perhaps for one of the following reasons

The latin word for Ship is "Navis" which is a feminine noun
Or perhaps mostly male ship owners would name their ships after/for their (invariably female) loved ones.
Ships were often dedicated to godesses, or women of significance in order to bestow on them good luck when seafaring

Some further reading and Why are ships always female? - english.se


What is the relation between clouds and radar effectiveness?

Radar relies on electromagnetic wave propagation: from a source, to the target and back to a receiver.

Anything that alters the behavior of these waves along the way will impact the performance of the radar station. For example:

A target hiding behind terrain will be harder (but not necessarily impossible) to detect, because the terrain will absorb the outgoing emissions before they even reach the target.
If the target is in plain sight but shaped in such a way that all the incoming radar energy is reflected in a direction different from that of the receiver, then it will not be detected (this is the method employed on the F-117).
If the target is in plain sight but the return signal comes back accompanied by a lot of duplicates purposefully emitted by the target, it will complicate the task of figuring out which is the correct reflection, delaying or preventing a valid solution.
If the target is coated in a material that absorbs all the incoming energy, the radar station will never see a return, and thus think there is nothing there to detect (another technique used by Low Observability aircraft). This one is relevant to your question!

The media between the emitter and the target needs to allow the waves to travel, and while the best media is vacuum, air is not terrible either. At least normal, ISA air, things get complicated in the high atmosphere, or at high temperatures, or when electromagnetic fields (caused by thunderstorms, the Earth's core, etc.) come into play.

In the case of water suspended in the atmosphere, it can absorb the radar emissions and thus limit their effective range. However, it does so mostly at certain wavelengths, which are the ones at which water molecules can best capture incoming energy. One such wavelength is the one used in microwave ovens, because food tends to contain water, and heating the water is a fast way of heating the food.

So the ultimate answer to your question is, there is some kernel of truth in those statements, but how large it is is very debatable. Some radars, particularly modern high-frequency ones, operating in the millimetre band, will see noticeable losses due to coulds. Other radars, particularly those in the low GHz range or lower, will fare considerably better, although the lower frequencies have their own disadvantages in terms of resolution and antenna size requirements. Ultimately, defense organizations are quite aware of their equipment's capabilities and usually take steps to mitigate any drawbacks, so it is unlikely that some cloud cover will substantially impair a modern IAD network.


What are the consequences of turboclair system on restriction due to turbulences?

I found a Turboclair addon checklist for the SE.2 Caravelle landing procedure and it says nothing about turbulence.  This procedure is intended for ferry flights without passengers and specifies the use of a braking parachute, so it is not for normal flights. It is possible that this was the checklist used during 1968-69 testing of the system before general approval and that a turbulence warning or restriction was added later, but it seems likely that any severe turbulence problem would have been recognized very early.

There are standard weather checks at the destination. There is evidently a Turboclair specific approach that must be requested and the pilot must announce arrival at outer marker, at 400ft, that he has landed and again when he has cleared the runway. He is to continue the use of instruments when on the ground due to poor visibility.

Initial testing in 1961 was conducted using modified De Haviland SE 252 jet aircraft as heaters, which could be re-positioned to find most effective locations.

Under construction from 1970 to 1974, the system's jet engines were permanently installed in underground pits. The reference shows the installation on Orly runway 07, remnants of which can still be seen in Google maps which now shows the runway as 06.

The system was also installed at Charles DeGaulle airport. It was used for fewer than 1000 landings between the two airports before being decommissioned in 1982.


ATA stands for Air Transport Association (today called Airlines for America). The numbering standard is called ATA 100 and was widely used for various types of aviation documents and manuals from 1956 until 2015 according to Wikipedia:

ATA 100 contains the reference to the ATA numbering system which is a common referencing standard for commercial aircraft documentation. This commonality permits greater ease of learning and understanding for pilots, aircraft maintenance technicians, and engineers alike. The standard numbering system was published by the Air Transport Association on June 1, 1956. While the ATA 100 numbering system has been superseded, it continued to be widely used until it went out of date back in 2015, especially in documentation for general aviation aircraft, on aircraft Fault Messages (for Post Flight Troubleshooting and Repair) and the electronic and printed manuals.


What is the purpose of aileron droop used in some commercial airliners?

The purpose of aileron droop is to use the ailerons as wing flaps. Wing flaps increase the lift generated by the wings at low speed. They occupy a good part of the trailing edge of the wing, except for the outer part, where the ailerons are. By deflecting both the ailerons downwards, they change the wing camber and act like simple plain flaps. They can still act as ailerons, by normal differential deflection.

Image source


How does airfoil affect the coefficient of lift vs. AOA slope?

The airfoil affects the lift curve slope only very little; theoretically the slope should be a bit steeper for thicker airfoils.
But that pales in comparison to the effects of wing planform. Here the biggest influence is from the wing's aspect ratio and sweep. Another factor is the flight Mach number and the Reynolds number.
But there is one trick to artificially increase the lift curve slope for a given planform and flight speed: Add a camber flap and move it in sync with angle of attack. This will shift the zero-lift angle inversely to the change in angle of attack. A purely mechanical solution would use a flap with a large control horn, so that $c_{r\alpha}$ becomes positive while $c_{r\eta}$ stays negative. However, this is prone to flutter at higher speeds, so depending on the planned speed range a hydraulic or electric actuator, driven by a control unit which is hooked up to an AoA sensor, might be the better solution.


Does the dew point affect density altitude?

Density altitude is the air density expressed as an altitude above MSL.  Both temperature and humidity affect air density; however, temperature has a far greater impact.

Electronic E6Bs account for the effect of humidity by using both temperature and dew point temperature, the latter of which provides a measure of the air's water vapor content (technically it measures the temperature to which the air would need to be cooled for saturation to occur).

In contrast, the simple rule of thumb provided above only addresses the impact of non-standard temperature on density altitude. However, the effect of humidity can be "roughly" approximated by multiplying the dew point temperature (in degrees Celsius) by 20 and reading the results in feet.

This correction is then added to the above temperature correction rule of thumb for density altitude.  Note the correction for humidity is highly non-linear and so it provides only a rough approximation.  It should only be used in the dew point temperature range of 5-30 degrees Celsius.

Details can be found in Guinn, T. A., & Barry, R. J. (2016). Quantifying the Effects of Humidity on Density Altitude Calculations for Professional Aviation Education. International Journal of Aviation, Aeronautics, and Aerospace, 3(3). http://dx.doi.org/10.15394/ijaaa.2016.1124


At what altitude does a wing become useless?

Maybe wings never mattered...

Altitude:

The answer depends a bit on the design of the craft in terms of control surfaces/wings. Atmospheric reentry begins at the Karman line at an altitude of 100 km (62.14 mi / ~ 54 nautical mi) (327,360 feet) above the surface. Which is generally when air resistance starts to matter but that does not mean control surfaces will do anything at precisely that altitude. In terms of practical vehicles that have been flow:

The space shuttle starts maneuvering with its aero surfaces ~30 miles up

  At an altitude of approximately 30 miles [158,400 feet/50km], the orbiter makes a series
  of maneuvers and S-turns to slow its speed. At 9.5 miles in altitude
  and at a speed of Mach 1, the orbiter can be steered using its rudder.
  The on-board computers fly the orbiter until it goes subsonic (slower
  than the speed of sound: Mach 1). This happens about 4 minutes before
  landing.

Neil Armstrong famously flew the X-15 high enough to need the reaction control rockets to keep from skimming off the atmosphere, he was up around 207,500 feet.

So somewhere up around ~175,000 feet, practical control surfaces start to work. Its possible aircraft could be built to get above this region but they would need the ability to either fly up there or survive the decent which is a whole different can of worms.

Speed:
Any speed so long as your thrust to weight ration is greater than 1. All rockets start from a speed relative to ground of zero. Rockets simply have engines capable of providing 100% of the thrust needed to move (generally directed in the up direction). Planes have enough thrust to overcome drag then use the wings to help them with the lift (up direction) portion of the problem. There are aircraft that have a thrust to weight ratio greater than 1 and are capable of "flying" in a way without wings.


Where can I find a list of past flights at LHR?

If you're lucky, you might just get it for free (see halfway down this page):

  We have provided a data drop of historical flight information for
  specific airports or airlines, on a one-off basis.

As for the runway data, it's harder, since I don't know of any website which records it. You can have a look on Flightradar24 for which runway is in use at the moment depending on the aircraft positions, but apart from that it's probably not going to be easy. You might want to email the airport directly and ask if they could provide a figure for that month for each runway, but I'll doubt that a single source has the details for each and every flight.

If you get to it, have fun sorting out 40,000 flights ;)


How realistic is the plane scene in Captain America: The First Avenger?

Though 'getting on/off aircraft through landing gear' is a favorite trope in movies, it is practically impossible in most of the modern airliners. Airliners are pressurized, and as a result, the cabin (and cockpit) area is in reality one big cylinder, cut off from everything else. So, no accessibility from the landing gear area.

For example, the following image shows the landing gear bay (the area into which the landing gear retracts into) of a Boeing 787.

Image from dailymail.co.uk

As a result, though the list of stowaways in landing gear area is long, to the best of my knowledge, no one has entered the aircraft through it.


Regarding N1 and N2, what does the "N" stand for?

As far as I can tell, the N comes from the physics behind turbines in general, whether they be water pumps or wind turbines, a subset of mathematics called fluid dynamics.  Many thanks to ROIMaison's answer for steering me in the right direction.

In Turbomachinery: Basic Theory and Applications, Second Edition, Earl Logan, Jr. provides a symbol reference list at the end of each chapter starting in chapter 2, defining $N$ as rotor speed, in units of rad/s; an angular change per unit time, and $N_s$ as the specific speed, a dimension-less quantity derived from a ratio of the flow and head coefficients.

N1 and N2 seem to be derived from both.  Wikipedia mentions the speed as a percentage paradigm as a human factors consideration, though as of 5/14/2015 there are no references to support this.  However, there may be a scientific basis behind this as well, since a change in N is proportional to the resultant change in airflow (i.e. thrust produced):


Are there any future regulations planned for electric multi-motor LSAs?

Light-Sport is a category for pilot certification and flight rules. The aircraft themselves are simply part 23 normal category risk classification level one, low speed.

Part 23 was fully rewritten in 2016 it now describes the desired safety outcome but lets manufacturers develop new methods of complying, nothing is bias against electric multi-motor planes in the new part 23.

The issue is that the pilot must be rated for multi-engine operation and you must have at least a private pilot certificate for the multi-engine rating. Most multi engine training is actually about operating with an engine failure and the associated aerodynamics.


According to an FAA guide to creating NOTAMs (see pages 14 and 21), the "condition text", i.e. the body of the NOTAM...

  has a max length around 1200 alpha-numeric characters. If necessary,
  the system will allow a user to create up to ten parts with 1200
  characters each

But, that doesn't include other parts of the NOTAM, like location, date/time, graphical elements etc. I don't know if there's a limit (in kB?) for the complete NOTAM file or not; the document doesn't seem to mention anything about that. It also isn't clear from the FAA document if the ~12,000 characters is a format limitation/specification, or a tool limitation.


What exactly do "captain", "pilot", "co-pilot" and "first officer" mean?

Capt left, 1st officer or copilot right. On older airlines with a flight engineer, he is behind and is called 2nd officer.

It's the same as a ship.  Capt is boss, 1st officer is second in command, 2nd officer if on board is 3rd in command.

Capt always starts the engines and taxis the airplane since most airliners only have a steering tiller on the left, and FO usually handles radios and checklists, FMS programming etc when on the ground.  FO, if it's his/her turn to fly, only controls the airplane from the start of the takeoff roll until completion of the landing roll.

On a pairing (sequence of trips over 2 or 3 or 4 days), capt and FO normally alternate on each leg of the trip as pilot flying with the other as pilot monitoring.  But as I said, if FO is PF for a particular leg, he/she will still do the radios until the start of the takeoff roll, then takes control of thrust and stick once the capt has lined up, upon which capt looks after comms/FMS/button pushing, until completion of the landing roll, when the FO hands control of the airplane back to the capt and the FO (who only has rudder pedal steering and can't make sharp turns) takes over the radios again.

On an older airliner with a Flight Engineer/Second Officer, that person is type rated on the aircraft as a pilot but never actually flies the plane until he/she moves up to right seat as FO.  So in the old 3 crew days a new pilot would be hired as a Flight Engineer in an airline with only 3 crew aircraft and might go several years in the 3rd seat before actually flying the plane, or if upgrading from 2 crew to 3 crew in the same airline.

Up until the 60s you also sometimes had a 4th crew, a Navigator.  Don't think there were any Navigators left by 1970.


Why didn't the A330neo and A320neo share the cockpit of the A350?

The short answer is that it's what the market wanted.  There is  always a lot of discussions between the airlines and manufacturer's before Airbus or Boeing commits to building a new aircraft.  In this case both Boeing and Airbus came to the same decision -- the airlines were being driven by one single factor to replace their A320 or B737 fleets, they just wanted to reduce fuel expenses.  That's why the Airbus is the 'neo' new engine option.

The airlines made it clear that any new aircraft purchases would be based on operational savings and that's primarily driven by fuel burn and the resulting costs.  The solution to that is a new engine.  Putting in a new flight deck is a huge expense for the manufacturers which would drive costs up and the airlines won't pay extra for something that doesn't save them money.

There's no cost benefit to a new flight deck, especially when (as others noted) you have a huge investment in an existing fleet.  In fact, all it's likely to do is add costs.  With a new flight deck you'll have a huge increase in maintenance and spares costs due to the need for stocking more parts with new part numbers (just adding a part number to a logistics system costs significant money.)  You'll also need new crew training simulators due to the different displays and controls, whereas the neo option can be handled with software upgrades.  And if it drives a need for new type ratings, that would mean more training costs and making sure you have the crews with the right rating at the right time.

In my experience in 20 years dealing with this market, airlines only spend money for two reasons:

It will increase their profit margins
The FAA (or other regulatory agency) mandates that they have it.

Aside from that, you should consider Airbus' side.  They're trying to sell airplanes and they have to compete with Boeing.  Since the avionics architecture is quite different between the A320/A330 and the A350, moving to it would add huge costs and a couple years delay in entry into service.  They also have to deal with the fact that airlines don't want to see a big price increase.  Prices for the A320neo and B737MAX are not significantly higher than the current/older versions.  If the competition can offer a 7 to 9% reduction in fuel burn for approximately current prices, spending an extra 2 or 3 years to match that with a new flight deck means a lot of lost sales in the interim.  And you probably won't make enough margin to recoup the new flight deck costs.


In what way(s) will making an airplane electric help to make it "quiet"?

You are right, propeller noise is dominant in case of GA aircraft, but not all propellers make the same noise. Much depends on blade loading and tip speed - making the propeller larger and letting it turn more slowly will improve efficiency and reduce noise. This has worked very convincingly for model aircraft over the last 30 years. GA engines are normally ungeared, so their propeller speed and diameter are the same. Switching to a geared IC engine like a Rotax 914 not only makes the engine lighter but also the propeller less noisy. Switching to an electric motor, which can produce high torque at low speed, will allow to exploit this effect to the fullest.

Other sources of noise will profit from electrification, too. The exhaust noise will be completely avoided, and airframe vibrations will be greatly reduced. Radiator noise will fall away, too. It is a small source of noise, but every bit counts.

What will be left is the noise of the slower propeller(s) and aerodynamic noise. Now landing gear retraction would be the next big step in noise reduction.


Can you climb at Vxse when you cannot at Vyse in a multi-engine aircraft?

I'd recommend reviewing Chart 5-23 from the PA-44 POH - Climb performance one engine operating - gear up for specific numbers based on aircraft weight and atmospherics.

If you're not seeing a positive rate of climb at your best rate of climb, single engine airspeed, then you're not going to see it at the best angle of climb airspeed single engine either.  By definition, Vyse is the best rate of climb that you're going to see on a single engine; any other airspeed, including Vxse, is going to give you a lower rate of climb, or greater rate of descent if a positive rate is not possible.  And attempting to acquire and hold Vxse you're getting close to the reverse side of the power curve, combined with ever decreasing rudder authority, it would be easy to have the aircraft drop below Vmc and depart from controlled flight.


What was the first commercial aircraft to have a 'built-in' oxygen system?

The B307 may have been the first pressurized airliner, but it was usually flown at 12,000', and did not have a passenger supplemental oxygen system.

Boeing 307 / C-75 Stratoliner
1938

"Captain Frank E. Adams, 23.02.2011
I flew the S-307 2 years for Pan American Airways (1943/1944) and today remain one of the few pilots in the world who is still rated for this aircraft. My biggest complaint about this description is that the aircraft could only be pressurized to a maximum of 2.4 psi so that the advertized service ceiling of 26,200 feet is greatly exagerated. A flight altitude of 22,000 feet would result in a cabin altitude of 14,000 feet and we had no passenger emergency oxygen on board. Also,the Wright engines had no turbos and so were basically sea-level engines which could not retain cruising power output above 12,000 feet. For this reason we flew the S-307 at 12,000 feet southbound and 11,500 feet northbound between Miami and Panama."

Later pressurized airliners like the Douglas DC-7, Lockheed Constellation and De Havilland Comet were flown much higher and I expect they would have had some form of built-in supplemental oxygen system for the passengers. (unfortunately I can't find any evidence online)

I did find an advertisement from January 1957 which shows a Scott passenger oxygen system which would represent what was used on the Boeing 707. (first entered service in October 1958)

Flying Magazine Jan 1957


Where can I find airport diagrams for the Philippines?

The easiest way is to type the IATA code into Google along with "airport charts". The PDF you are looking for will be high in the search results. Here are the diagrams for Manila and Cebu.


On ATC's radar, does an aircraft that loses its transponder simply disappear?

It depends on the system. Assuming only secondary radar is available, in some systems, the track will indeed just disappear when radar contact is lost. Other systems will put the track in "coasted" mode, continuing to show the track (but with another track symbol), waiting to pick up the transponder again. The track will then be terminated after a specified time limit.

Of course, if primary radar coverage is available - which works independently of aircraft equipment, such as transponders - the system would still be able to track the aircraft, but automatic flightplan correlation would most probably be lost, along with mode C data (altitude). So all flight information would vanish from the screen and the controller would have to re-identify the flight using proper procedures.

Producing an alert when a track is lost could be useful, but it could also potentially result in a lot of nuisance alerts, particularly in areas with spotty radar coverage. So alerts should only be shown for areas and levels where radar coverage is expected to be perfect, otherwise the controllers would likely develop a habit of ignoring such alerts. Also remember that radars lose contact with flights all the time - as they move out of the range of the radar. No ATC station has global radar coverage. Showing an alert every time an aircraft leaves the area of radar coverage would also be pointless, and the range of a radar can vary from day to day depending on atmospheric conditions, so defining a precise area in which alerts should be suppressed might not be a trivial task.


How do pilots clear an aircraft to fly through a hurricane?

The aircraft they're flying is an Lockheed WP-3D Orion, not a jet- the NOAA doesn't fly its Gulfstream IVs into the storm, as I've noted elsewhere.

There is always a risk associated with piloting an aircraft through weather that pilots are usually told to avoid. But they have been doing it for decades, so, with proper training and planning, it appears that it's not that risky. The top speed of the WP-3D is listed as over 750 kmph. The $V_{ne}$ would definitely be over that. The top wind speeds in Category 5 hurricanes (the highest in the Saffir-Simpson scale, of which Matthew is one) are over 250 kph, though most hurricanes aren't quite that strong.

The NOAA seems to be aware of this issue; in this reddit AMA, they agree that wind shear could damage the aircraft and lead to loss of control:

  Planes are generally not destroyed by strong winds while in flight. Airliners routinely fly in jet streams with winds exceeding 150 mph over the U.S. during the winter. It's the shear, or sudden change in horizontal or vertical winds, that can destroy an aircraft, or cause its loss of control.

However, with proper training and by avoiding the most dangerous areas using real-time data, they can fly the aircraft within the safe limits.

  NOAA pilots and crew routinely fly in the high-wind environment of the hurricane and don't fear it tearing the plane apart. However, they are always monitoring for "hot spots" of severe weather and shear that they can often identify on radar and avoid if it's too severe.

The aircrew has things to worry about other than $V_{ne}$- the high velocity winds in the up and downdrafts can result in high 'g's, while the wing is susceptible to flutter in these conditions. This blog chronicles cases where the mission was abandoned due to aerodynamic flutter and a case where nearly 5.7 'g's were experienced. Another blog describes the penetration of Hurricane Hugo, that resulted in a near fatal disaster and grounding of the aircraft. From hurricanescience.org

  As they flew through the storm’s ey(e)wall they encountered sustained winds of 297.7 km/h (185 mph) (gusting to 315.4 km/h [196 mph]) and extreme updrafts and downdrafts (32-72 km/h [20-45 mph]). The massive jolts rocked the aircraft, causing gear such as tools, computers, all items in the galley, and even the 200 lb life raft to be dangerously thrown about the aircraft’s interior. The cockpit gravitational force(G)-meter, became pegged at 5.6 G's and -3.9 G's . Upon reaching Hugo’s eye, one of the engines exploded and had to be shut down. In the calm of the hurricane’s eye, the plane made repeated circles, a risky maneuver with the loss of one engine. NOAA 42 was able to successfully exit the hurricane ...

The crews also take some safety measures, such as flying at higher altitudes (UAVs are used at lower altitudes) to reduce the associated risk. As every hurricane is different, risk assessment is difficult and the crew has to fly sometimes based on imperfect information. From hurricanescience.org:

  Flying into the eye of a mature hurricane presents significant hazards as strong updrafts in the hurricane’s eyewall can give way to equally strong downdrafts on the measure of a few hundred feet. Horizontal wind speeds can also change by more than 161 km/h (100 mph) in a few seconds of flight time as the plane moves through the eyewall, putting strains on the airplane and its crew. Because of these hazards, Hurricane Hunter flights are typically done at 10,000 ft (3,048m).

There are two types of flights these aircraft are used for- reconnaissance and research. While satellites may give quite a bit of data, there are some things they can't provide and can be obtained only by flying into the storm. The main purpose of reconnaissance flights is to track the center of circulation and gather data, which will help determine the threat posed by the hurricane and the path it will take. NOAA notes:

  The primary purpose of reconnaissance is to track the center of circulation, ... , and to measure the maximum winds. But the crews are also evaluating the storm's size, structure, and development ... . Most of this data, which is critical in determining the hurricane's threat, cannot be obtained from satellite.

The research flights are for varied purposes such as to gather data about the structure of the storm and its interaction with environment, which will help them predict future hurricanes better. In fact, in the above mentioned flight into hurricane Hugo, the crew observed a long suspected phenomenon for the first time, which would not have been possible using satellites:

  Later analysis of the data taken during our amazing flight into Hugo revealed that we hit a tornado-like vortex embedded in the eyewall when the hurricane was at its peak intensity. These eyewall vortices had been suspected but never before observed, and ongoing research suggests that similar vortices may be responsible for some of the incredible damage hurricanes can inflict when they strike land.

While it is true that it is possible to drop probes while overflying hurricanes, it is not always possible- some of the larger ones have cloud tops reaching over 50,000 ft, higher than the ceiling of aircraft available (for example, the cloud tops of Hurricane Matthew reach over 16km), making it quite difficult to drop dropsondes and the data is relayed to the aircraft which then transmits to the center using satellite.

In recent times, UAVs are being used increasingly for this purpose (NASA uses a Global Hawk for this purpose) and, maybe, in the future, they'll replace the manned aircraft altogether.


Your radio shop may be able to test the SWR of the antenna working with the COM radio.  That would be my starting point.  However, sometimes problems like these are intermittent and difficult to isolate.

You can test the antenna with an ohm meter but that will not measure the impedance at transmit frequencies.  An SWR meter will.

Unfortunately, unless your other hobby is ham radio, you may not have the equipment on hand to check out transmitter operation.  But your radio shop will.

They will also have a dummy load for testing the transmitter.

I have to say that I am surprised that the unit blew a fuse.  Most aviation radios I have experience with (I am not an avionics tech only a ham) have protection against shorts or opens on the output of the transmitter, which usually shut down the power of the transmitter, for example when a high reflected signal comes back. So blowing fuses is normally extremely rare.


What is this yellow section around the cockpit window?

You're right. The aft no. 3 fixed window has a reusable retainer with 2 rows of fasteners- one for holding the window glass and another for attaching to the fuselage, as can be seen in this PPG document- this is the two rows of fasteners in the image.

A320 aft window, image from Cockpit Windows Technical Data from PPG Aerospace

My guess is that there was some damage to the area and the airline replaced the whole assembly and sent the aircraft before the primer could be painted over. When painted, it would look some thing like this:

A320 window, image from miles-around.de

Note: The A320 does have an emergency (sliding) window in the cockpit- however, it is in the no.2 window, the details of which can be seen in this document


The radio-controlled model sailplane that recently exceeded 540 mph while dynamic soaring has to be a contender.  Minimum speed in this flight (immediately after launch) may have been as low as 10 mph, which probably could have been sustained by staying on the front side of the ridge.
Link to You Tube video--

Though any plane capable of routine flight at 0 mph would automatically win I suppose-- e.g. pretty much any hang glider or sailplane given the right conditions.
Or did you mean airspeed?  The radio-controlled sailplane in the video may well be one of the top contenders.


What is the difference between turn rate and yaw rate in aircraft?

Rate of turn is easy to define: it is the rate at which the direction of aircraft motion changes with respect to the ground (rate of change of track). If the aircraft is not slipping and there is no change in wind, then it is equivalent to the rate of change of heading.

Yaw rate, on the other hand, is slightly messier. Technically, yaw rate of the rate of change of the z-axis Euler angle. As an industry standard, the Euler angle in the aviation industry is defined by the z-y-x rotation, which means that the yaw occurs first, followed by pitch, followed by bank. Therefore, yaw rate is technically exactly equal to the rate of change of heading.

In many applications and loose technical speaks, however, yaw rate may also refer to the third component of the angular velocity. Angular velocity is the instantaneous rate of rotation about its axis of rotation. If the aircraft is rotating about the vertical axis only, then the third component of the angular velocity is, again, exactly equal to the rate of change of heading.

In a coordinated turn, however, the aircraft is pitched and banked, and therefore it is not rotating purely about the vertical axis. In this definition, then, yaw rate is not equal to turn rate.

As an aside, it's mathematically incorrect to call any component of the angular velocity a "rate", since angular velocity is not a derivative of any quantity, even though angular velocity can be transformed into Euler rates if you know the current Euler attitudes.


Could high density abrasion-resistant ceramic turbine blades allow for the use of borane fuels?

Borane fuels are not practical for a multiple-use aircraft, primarily because there are no naturally occurring sources they could be easily derived from. This rules them out commercially, and gives a military disadvantage of being unable to utilize local supply chains.

Note that the XB-70's borane fuel was to be carried in addition to kerosene, for one high-speed dash. Even though capable of multiple flights, the military purpose of nuclear bombers would have been fulfilled in a single mission.

Modern turbines are built with tighter tolerances than those of the 1960s. This would make a fuel that deposits solid particles, as pentaborane does, more of a problem, not less.

These considerations essentially limit pentaborane to simpler and single-use engines that can tolerate this, such as rockets.

However, the fact that no space missions have used pentaborane, even when it cost nothing and had to be destroyed, suggests that its toxicity and near-impossibility of safe handling on industrial scale outweigh its advantages even in such applications.

To quote the paper,

  When reading about pentaborane, a TLV of .005 ppm and indications that it is pyrophoric over a wide range of oxygen concentrations meant this was toxic material prone to ignite very easily. What is difficult to comprehend from these numbers and quantitative data is that pentaborane is as toxic as some of our Nation’s nerve warfare agents and will spontaneously burst into persistent flame in nearly oxygen deficient atmospheres.

Spacecraft are no strangers to exotic and highly toxic fuels, such as hydrazine. However, pentaborane turned out to be on another level of difficult. It's also not as high-performing as hydrogen or the record holder Li-F2-H2 tripropellant, also not used for similar reasons.


What is the sequence of ATC frequencies for final approach at JFK?

"Final 132.400" is final vectors (sometimes called 'final sector'), an intermediate stage between approach and tower. Whichever route an aircraft arrives, the relevant approach controller will hand it over to 'Final' for final vectoring onto the relevant final approach. Once the aircraft is established on that final approach (with proper spacing), it is handed over to tower.

I would recommend listening to Final first, whilst simultaneously watching a certain well-known flight radar website. It may take a few minutes to get 'in sync' with what's going on there, but you should soon get the gist of it. Then listen-in on the approach sector(s).


What conditions cause the gear-up warning to sound on a Bombardier DASH-8?

According to smartcockpit.com, warning is given when the gear has not been extended and the aircraft is in the landing configuration. Specifically,

• All landing gear not down and locked, flaps selected to 15 or 35$^{\circ}$, and both power levers at any position less than 50% torque.
• Landing gear not down and locked, one or both power levers at or near FLT IDLE and airspeed below 130 kts.

The warning also sounds when the aircraft landing gear is up and terrain clearance is inadequate during the cruise and approach phase
of flight.

Image from Dash8-200/300 - Warning Systems from smartcockpit.com