A couple of questions about Aeroflot flight 593

The autopilot will disengage if the controls are manually manipulated while the autopilot is on.  The main issue with this particular airplane was that there was no audible autopilot enunciation that indicated that the autopilot turned off which is what the pilots were used to hearing on Russian made jets.  Rather there was only an indication light that would go on if autopilot disengaged and could go unnoticed.  The autopilot disengagement was not noticed right away and the aircraft entered into a spiral spin.  The pilots tried to recover from the spin but they pulled up too much (over corrected) and the plane entered a stall.

Autopilots can disengaged automatically for a number of reasons.  For example Air France 447 autopilot disengaged due to conflicting information from the airspeed indicators.  Incorrect actions by the pilots after the autopilot disengagement caused that accident.  In modern day aircraft the autopilot disengagement is heard as an audible signal so the pilot knows to take over.  If Aeroflot 593 had this feature the accident could have been avoided (besides not having your kids fly the airplane).

To answer your questions about he various levels of autopilots there is really only one autopilot that works in conjunction with other automated systems to fly the plane below is a description of the various systems:

Autopilot:  Automatically flies the plane according to instruments.  This system is responsible for manipulating the control column.

Auto-Thrust:  Automatically adjust thrust to maintain a constant airspeed.

Yaw-Dampening: Automatically adjust rudders for coordinated turns.  Yaw-Dampening can work when autopilot is on or when the airplane is manually flown.

Just because the autopilot disengages does not necessarily mean the other systems disengage.


Is wheel well overheat detection (not brake temperature sensor) necessary for commercial jet aircraft?

What's the main purpose of this detection system even there are brake temperature sensors.

Far more often than not, the need for brake temperature sensors is after landing to tell you how hot the brakes are. If you had to use heavy braking upon landing, they're going to be hot. How hot they are tells the captain in part how he needs to taxi and whether he should advise ground personnel to stay away from the sides of the tires where the thermal plgus are and possibly to use cooling equipment (typically a huffer) to cool them down.

Wheel well temperature sensors are needed after takeoff. The potential problem here is that you need to keep an eye on how warm the wheel well is getting from the hot tires you have retracted and enclosed in the wheel well.

As an example, let's say you have a 747 freighter loaded to a max takeoff weight of 825,000 lbs or more at Honolulu and taking off on RWY 8R. That's 20,000 feet of taxiing and another 10,000 feet plus of takeoff roll. The flexing of the tires during that taxi and takeoff generates a lot of heat. Once the wheels are in the wells, that heat transfers into the wells and eventually leaves the airplane. However, if for whatever reason, the tires already had a lot of extra heat before the taxi started or a lot of braking was done during the taxi, or the airplane was stuck down low in warmer air after takeoff, whatever, the wheel well temperature might exceed the safe limit.

The solution is usually simple, drop the gear and cool the tires. If you don't you risk a wheel well fire.

  Some aircraft do have this detection system (many Boeing aircraft), some do not. Why?

The short answer is that they have been designed so that they don't need it, which begs the question: why aren't all aircraft designed such that they don't need it. Essentially every aircraft design includes compromises. It's all part of tailoring the design to best accomplish what the aircraft's primary task is to be. Using the 747 example, you could, for example, install a cooling system in the wheel wells to take care of the heat, or you could use heavier tires that didn't flex as much and thus didn't heat up as much, or you could have additional structure able to resist the heat or dissipate it quicker. But whatever means you used, it would mean hauling around more weight and the attendant costs in fuel and loss of payload capability when you didn't need it most of the time. Far better to avoid those high costs, but in the interests of safety install a much lighter system that will alert you to the need to cool off the wheel well by dropping the gear.

Insofar as potential 747 wheel well overheats are concerned, baring mechanical failure, it's generally a problem only when the aircraft is used in a manner that it wasn't designed for. For example, the 747 was designed as a long-haul transport. As such, there would be plenty of time for the wheels to cool down in the wheel wells. As I remember we were told in ground school that 5.5 hours was the cool down time. So, if you have a short leg and then a quick turn with high weights, you might be taking off with tires that have more heat in them than the system was designed to handle.

When JAL decided to use the 747 for high-density, short hauls within Japan, Boeing came up with the 747SR (Short Range) which included a redesign of the undercarriage as well as several other things. The design goal was that that any commuter airliner needs: short legs, frequent takeoffs and landings, and it made sense to optimize the design for that criteria, and that optimization required a decrease in range and payload as I remember.


If ELAC 1 is under MEL why is it a NO GO item when carrying out EDTO on the A320?

Basically, operating ETOPS/EDTO takes into consideration worst-case scenario situations (EMER ELEC CONFIG) where you will only have ELAC1 working.
In addition, its mentioned that ELAC2 in MEL is a NO-GO item due to the logic behind the system operation where it will allow ELAC2 to work first always, and in case ELAC2 fails ELAC1 will take over.
According to :

A320 FCOM ATA (27-10-20) Architecture (Pitch control). In normal operations, ELAC2 controls the elevator and the horizontal stabilizer, if a failure occurs in ELAC2 the system shifts pitch control to ELAC1.
A320 QRH ABN-18 ELEC (ELEC EMER CONFIG SYS REMAINING), In the emergency electric configuration the ELAC2 wouldn't be available when the emergency generator is running and ELAC1 will be the only available.
A320 FCOM ABN PRO (ELEC EMER CONFIG), ELAC2 is written within the INOP SYS table to confirm what happens when the aircraft goes into the emergency electric configuration.


What is required for an EASA pilot to fly an airplane with retractable gear, flaps and variable pitch prop?

I can't find any equivalent definition for what the FAA defines as a complex aircraft for the purposes of endorsements. EASA defines a complex aircraft completely differently.

“‘complex motor-powered aircraft’ shall mean:
(i) an aeroplane:
with a maximum certificated take-off mass exceeding 5700 kg, or
certificated for a maximum passenger seating configuration of more
than nineteen, or certificated for operation with a minimum crew of at
least two pilots, or equipped with (a) turbojet engine(s) or more than
one turboprop engine, or
(ii) a helicopter certificated:
for a maximum take-off mass exceeding 3175 kg, or for a maximum
passenger seating configuration of more than nine, or for operation
with a minimum crew of at least two pilots, or
(iii) a tilt rotor aircraft;”


Wikipedia has an un-cited reference to the etymology being

  As with mayday (from venez m'aider, "come help me"), the urgency
  signal pan-pan derives from French. In French, a panne ([pan], "pahn")
  is a breakdown, such as a mechanical failure. In English, it is also
  sometimes[vague] pronounced as /pæn/ ("pan").

This article supports that history (and has many of the other emergency phrase histories as well).


Would a stationary WWII fighter fall on its nose with full throttle and brakes on?

(Wikimedia; arrows and CG icon are my additions) P-47 side drawing.

The thrust has a bigger moment arm around the tires contact points compared to the weight. It won't nose over below a certain RPM (it will be specified in the training). Below that RPM:

The weight will counter the thrust
The propeller downwash will produce downward force on the horizontal stabilizer
Applied brakes will resist the rotation of the wheels (airframe rotating around wheels)

From a training video for the comparable big-engined F6F Hellcat, the narrator says:

  You can't gun this engine to full takeoff RPM and manifold pressure while holding the plane with the brakes, if you exceed 2,000 RPM the tail will lift and you risk nosing over.

Answer is yes it can happen.

Note: for comparison, the max RPM is 2,700 for the Hellcat.


Yes, it is generally used that the broadcast wind is the magnetic heading for the direction the wind is coming from. This is because standard runway numbering is magnetic direction and pilots can easily determine the most appropriate runway given the wind.


What Caused the Engine-Failure of Southwest Airlines Flight WN-3472?

The currently known details are that it was caused by the failure of a single fan blade, due to a fatigue crack. The crack location was between the blade root and tip (the root of the blade stayed in the disk).

As the question states, the accident was in a Southwest Airlines Boeing 737-700. The Aviation Herald says here that it was:

  ...performing flight WN-3472 from New Orleans,LA to Orlando,FL (USA) with 99 passengers and 5 crew, [and] was climbing through FL310 out of New Orleans, about 80nm west of Pensacola,FL (USA) when the front section of the left hand engine (CFM56) separated, debris impacted and punctured the left side of the fuselage causing a loss of cabin pressure. The crew diverted the aircraft to Pensacola for a safe landing on runway 17, the aircraft vacated the runway and taxied to the apron with emergency services following the aircraft. There were no injuries, the aircraft sustained substantial damage.

It also says:

  [In] late Sep 12th 2016 the US NTSB reported, that one fan blade separated from the fan disk during the accident flight, the root of the fan blade remained in the fan hub, however, the rest of the fan blade was missing. The fracture surface of the titanium alloy fan blade, root covered by copper-nickel-indium alloy, showed evidence of a fatigue crack, however no surface or material anomalies were found during initial metallurgic analysis. The engine inlet separated from the engine and impacted fuselage, wing and empanage resulting in a 5x16 inch hole above the left wing.

I expect that's the extent that is publicly available at the moment, because the Aviation Herald report would have been updated if further info was available. So, it's not publicly known if the fatigue crack was low cycle fatigue or high cycle fatigue.

Low cycle fatigue is fatigue caused by large changes in stress amplitude, such as caused by a change in rpm from idle to max speed. Because the change in stress amplitude is large, it can fail in relatively few cycles, compared to HCF. (But still maybe ~10,000). Because it's driven by throttle movements, the number of cycles can be counted. Typically a single flight, even ~10 hours, in a civil aircraft only accumulates less than 10 cycles.

High cycle fatigue is fatigue caused by very small changes in stress amplitude, such as turbulence acting on a blade, every time a rotating blade passes behind a stationary vane. Hence, if a stage in a compressor has 30 vanes, every revolution sees 30 stress cycles on each blade in the following stage. Thus, the number of HCF cycles can accumulate very rapidly. They cannot easily be tracked. Usually, HCF failures need some sort of stress concentration to exist at the point of failure, such as a material anomaly, maintenance damage, or a nick from FOD (foreign object damage from an ingested stone from a runway, for example). HCF failures can require 100,000s of cycles to be accumulated, but if you get 30 every revolution, and the shaft is doing 7,000 rpm in cruise, these accumulate very quickly. Initiation to failure can be just a few flights.

Since there were no material anomalies found on the fracture surface of the blade half they have (the outer piece was not recovered), that indicates the cause of the fatigue crack is unlikely to be a manufacturing issue, and hence a fleet-wide issue.

It is probably an HCF failure, since the crack location does not seem to be in the blade root. Usually, the location of the weakest points due to LCF are in the blade root or fir-tree base, and it sounds like it failed higher than that.

What About The Cowling Failure?

When the fan blade fails, it's pretty violent. Here's a video of a blade-off test done for certification. There is very high vibration at the time of failure, and high vibration while the engine is windmilling before landing. Fan blade failures should not result in cowling failure, because the whole point of the test is to demonstrate that the failure is contained. That means, no part is released at high energy, that may damage the aircraft. Having the cowling fall off, doesn't really align with that philosophy. But, clearly, there is a random element in such an energetic failure.

The most receny fan blade failure I believe was an AirAsia X A330-300 off the west coast of Australia, on Jun 25th 2017. It lost almost the entire blade, but the cowling remained very undamaged, as shown in the picture at the link.

The A380 Air France engine failure that occured in Sept 2017 had similar damage to the aircraft in the question, but the Air France incident was not a fan blade failure. The Airworthiness Directive issued after this states the incident was caused by failure of a fan hub. So, it's not a relevant comparison.

Some aircraft have suffered strutural failings of the fan cowl, without being caused by fan blade failure. Eg. This Egypt Air A330-200 and this China Eastern A330-200 both lost a portion of their cowling. But these failures are a hole blown in the side of the cowling, not loss of the entire duct forward of the fan. These were caused by a structural defect in the composite duct.


Is it possible to suffer barotrauma during decompression?

Briefly: yes, it's possible (but very unlikely); small pressurized aircraft are the more likely scenario; maybe it has happened but if so it's very rare.
According to the FAA's AC on Aircraft Operations at Altitudes
Above 25,000 Feet Mean Sea Level or Mach
Numbers Greater Than .75 it's possible and more likely to happen in a smaller pressurized aircraft:

(a) Explosive Decompression. A change in cabin pressure faster than
the lungs can  decompress. Most authorities consider any decompression
that occurs in less than 0.5 seconds as  explosive and potentially
dangerous. This type of decompression is more likely to occur in small
volume pressurized aircraft than in large pressurized aircraft and
often results in lung damage. [...]
(b) Rapid
Decompression. A change in cabin pressure where the lungs can
decompress faster than the cabin. The risk of lung damage is significantly lower in this decompression compared to an explosive decompression.

Unfortunately they don't cite any statistics or source for the statement "often results in lung damage" so it isn't clear when it has actually happened. Other sources suggest that it's very rare, for example Beyond the Black Box: The Forensics of Airplane Crashes says this:

The Air Force reports no serious injuries resulting from rapid
decompression with open airways, even while wearing an oxygen mask.
However, disastrous, even fatal consequences can result if the breath
is forcibly held with the lungs full of air. [...]
Lung damage is considered nearly impossible in a commercial aircraft
because of the large volume of air inside the plane. [...] Even Aloha
Flight 243 [...] did not decompress fast enough to cause internal
injuries.

In other words, it's not going to happen unless you hold your breath, but another source says that you won't be able to do that anyway:

I've had pilots tell me they would be able to hold their breath [in order to extend the time of useful consciousness]. That won't happen. First of all, the surprise of
the event will override any defensive measure you may have thought you
could put into place. Secondly, the rapid change in pressure
differential will make it impossible to hold your breath. (Remember,
we can be talking about a pressure differential of 8.8 PSI. Let's put
these pressure differentials into perspective. A differential of 8.8
PSI is 1267 pounds per square foot.

I think the surprise is a key point here: the flight or fight response increases your breathing rate so even if it were physically possible to hold your breath it's extremely unlikely that you would do so.
Interestingly, Google finds numerous sources that claim lung injuries are commonly caused by aircraft decompression, but I couldn't find any source that mentioned a specific incident or even any statistics on it. I did find one book that studied 47 incidents of aircraft decompression but there was only one single barotrauma event among them and it affected the ears, not the lungs.


Can the overwing exit slide be used when ditching in an A320?

The over overwing exits are secondary exits in a ditching and they should be used only if it becomes absolutely necessary to use them. The reason is because, the escape slides of the overwing exits are just slides and not rafts as they cannot be used as long term flotation devices. Moreover, unlike the slide rafts, the escape slides on the overwing exits cannot be detached from the aircraft. If the aircraft sinks, it takes the slides with it. The rafts can be separated away from the aircraft and can be used as small dinghy to hold the passengers. Furthermore, the rafts also have a loop to which you can attach the survival kit.

Here you can see that the A320 has four slide rafts (fwd and aft doors) and two overwing escape slides.
If the usage of overwing exits become necessary then they can be used in a ditching. In the Hudson landing, they used the overwing exits because the aft exits were rendered useless due to the considerable amount of impact damage received by the aft fuselage of the aircraft. Nonetheless, there are ditching related safety devices in the overwing exit. This is because in a ditching, the wing may get slippery. So, there are life lines that can be attached to assist passengers to escape the aircraft over the wing. This is what that yellow hook you see on the A320 wing is used for. So, yes wing exits can be used in a ditching, but they remain as secondary exits as long as all the other four exits are in working order.


Could the Boeing 747's 'hump' be improved aerodynamically?

The 747-300/400 has a longer hump than the original 100/200. Surprisingly, this longer hump had lower aerodynamic drag than the 200 hump: at higher mach numbers compressibility starts to cause serious drag increase. The speed at which this "drag divergence" occurs depends on the variance of cross section area of the plane. If the cross section of the plane would be a constant value, drag divergence speed would be closest to mach 1.

The longer bump on the 747-300 resulted in a more constant cross section and therefore higher drag divergence number => higher cruise speed.

Could it be made more efficient aerodynamically? Yes, by trying to match the Area Rule as closely as possible.

Source


Why are some parked aircraft angled away from the taxiway center line?

If the pavement is wide enough and strong enough (both of which will vary depending on the model of plane) for staggered parking, then that is the most space-efficient option.

If not, then you have to park them single-file. Simple geometry tells us that turning planes roughly 45 degrees (◼◼◼) will be more space-efficient than nose to tail (). For the same reason, some very congested airports have tighter angled parking at gates, whereas those with plenty of room use faster straight-in parking.


The rules for operations in the Grand Canyon Special Flight Rules Area (SFRA) are governed under 14 CFR Part 93, Subpart U.

Please review these rules here and all applicable GCSFRA NOTAMS prior to departure.  Also perform your performance calculations for the predicted density altitude on the day of your flight to verify your aircraft will be capable of ascending to at least 9500 ft MSL, else it may not be legally or physically possible to make the flight.

For an eastbound flight like that departing 1G4, I’d recommend a takeoff and climb to 9500 ft MSL (eastbound VFR altitude which meets the minimum requirements of both the Pearce Ferry and Diamond Creek sectors of the GCSFRA) prior to overflying the Pearce Ferry sector enroute for 1Z1.  Be advised for both fixed wing and rotor wing aircraft over the northern sections of the Pearce Ferry and Diamond Creek sectors.  Commence your descent into 1Z1 only once clear of the northern edge of the Diamond Creek sector.

Aside from the legal aspects, keep in mind that you are going to be flying over some pretty rugged country out there.  Have a plan of action should an engine failure or other inflight emergency occur enroute, requiring you to set the aircraft down somewhere.


Why is a contra-rotating High Pressure section more efficient?

These marketing type documents don't always mean "efficiency" in the true technical definition of the word, nor is it clear if they are talking about turbine stage efficiency (i.e. efficiency of the nozzle/turbine blade expansion process), or overall engine thermal efficiency.

The main advantage of contra-rotating is the removal of the nozzle guide vanes (NGVs) between the high pressure turbine and low pressure turbine. These LPT inlet nozzles require cooling air, that needs to be from a reasonably high pressure source because it has to be at a higher pressure than where it is being introduced back into the hot gas stream. Hence, it is usually bleed from within the high pressure compressor exit. (See reference below to "HPC S7 Air" - which means stage 7, this is the GE90 engine which has 9 or 10 HPC stages depending on the model).

In comparision, HPT inlet nozzle guide vane cooling air has to be bleed from the HPC exit, as an even higher pressure is needed. (see reference to "HPC exit air", or "CDP", compressor discharge pressure).

(Pic from here)

Given the LPT nozzle guide vanes require cooling, removing them reduces the cooling air required, and hence this air, which has been compressed which required turbine energy to do so, and hence represents an energy investment by the engine, is still available in the combustor, and for extracting (recovering) work from in the high pressure turbine. Therefore, the thermodymanic cycle efficiency of the engine is increased, as parasitic cooling air requirements have decreased.


Why was NWS shifted from green hydraulic to yellow hydraulic system in the A320?

This enhanced package (green to yellow change) since serial number 1939[1] had the following objectives in mind:[2]

Objectives:

Avoid simultaneous loss of Normal braking and nose wheel steering functions on a single hydraulic failure. [normal braking is green]
Avoid loss of nose wheel steering function due to ADIRU or LGCIU failure. [ADR 1+3 failure results in NWS failure; ADIRU 1 and 3 control the Green shut off valve once the L/G is retracted and speed is above ~260 knots]
Make the nose wheel steering function available after a landing gear free fall extension. [L/G extension is green]

(My explanation is in square brackets.)
As a bonus, it would have permitted the eTaxi option (announced in 2013; scrapped in 2019). This way, the APU would have supplied power to the powered-wheels, as well as hydraulics for steering and braking (alternate), all without a tug, and without having to power the Green system via the PTU.[1]

1: Airbus FAST magazine #51
2: A320-family flight deck and systems briefing for pilots


What happens to Vyse and Vxse above the OEI ceiling?

Vx increases with altitude while Vy decreases with altitude.  When they coincide, you have reach the airplane’s absolute ceiling, which it can no longer climb and can only maintain altitude at that specific calibrated airspeed.  Vx and Vy do exist above you maximum single engine ceiling, however, should an engine fail above the maximum single engine ceiling the airplane will begin to descend in order to maintain a given airspeed.  Pitching the airplane for blue line, Vyse, and maintaining the correct bank angle in the direction of the good engine (3°-5° typ.) will result in the minimum descent rate during drift down.
I have no idea why EASA would state that the airplane should be flown at Vxse above the maximum single engine altitude to minimize drift down; every source of information I’ve ever encountered indicates your airspeed should be maintained at Vyse, in addition to maintaining proper coordinated flight with OEI, in order to minimize your drift down rate.  This makes sense, since the airplane will have the most power available to it for climbing and will result in the least loss of altitude over time in this configuration vis a vis conservation of energy.


This is a broad question that has no real specific answer as there are no specific training sorties dedicated specifically to "muscle memory", let alone muscle memory specific to weapons switchology.

Military currency requirements exist for multiple functional skills, air to ground attack, air to air 1v1 ACM, Defensive ACM, carrier landings, instrument approaches, etc.  During any and all training events, whether in the aircraft or simulator, muscle memory is reinforced, but it is more of a by product of all the other things going on around it such as flying the aircraft, scanning the instruments, and executing the procedures.

These currency requirements are generally captured in some sort of a training matrix that is maintained by a squadron training officer, who communicates the requirements to the schedules officer.  Both of these individuals report to the squadron operations officer, who has overall responsibility for maintaining aircrew combat readiness.

Intervals between training simulator or flight sorties may vary by type aircraft, skill-set, and where the squadron is in their deployment/readiness cycle.  (i.e. just got back from war, or getting ready to head out?)

The closest thing to what you are asking is what we referred to as "blind fold cockpit checks".  Early in simulator training the instructor would have you close your eyes, then locate certain switches by feel, reinforcing muscle memory to both locate them and identify them by their often unique shape.

These drills, however, generally focused on switches related to emergency procedure memory items.  And more specifically, to items related to loss of electrical power, smoke and fumes in the cockpit, and other emergencies where vision could be impaired.


Is it possible that as the Reynolds number increases, a laminar bubble increases in extension?

The laminar "bubble" on the bottom is caused by the wavy contour. There is a pressure rise at about 25% on the lower side which causes the boundary layer to thicken, but the subsequent flat pressure profile keeps the boundary layer laminar until it separates at the trailing edge. Here is the plot from XFOIL and I placed a green circle over the spot:

With a higher Reynolds number the flow is less stable, the boundary layer is thinner and the waviness makes itself felt more than at lower Reynolds numbers. That explains the larger "bubble" at Re = 1,000,000. With Re = 8,000,000 the boundary layer transits to turbulent flow ahead of the disturbance and no "bubble" can be observed.
I guess you play around with XFOIL. Go to MDES and PLOT the Qspec, then MODI the contour so it becomes more smooth. The result below (first pressure, then H) should prove my point:


Does the explanation of why slower airfoils are more efficient involve less energy loss from heating or compression of the working fluid?

So you asked a whole bunch of things, and I'm not sure I really understand most of what you are asking, but I can maybe clarify this one part for you

  I have yet to fully understand why "it is better to move a lot of air a little than a little air a lot".

The equation for thrust is just Newton's second law F=$\dot m \Delta$V, where $\dot m$ is mass flow rate (kg/s) and $\Delta$V is the change in velocity of the air (exit velocity minus inlet velocity).  So, if you move 1 kg/s of air at 10 m/s, or you move 10 kg/s of air at 1 m/s, the thrust is the same.  Doesn't matter.

But, the equation of kinetic energy (well power really in this case) is $P=(1/2) \dot m (\Delta V)^2$.  So if you move 1 kg/s of air at 10 m/s, it takes $0.5*1*10^2$ = 50 W of power to do that.  But if you move 10 kg/s of air at 1 m/s it takes $0.5*10*1^2$= 5W of power to do that.  Exact same amount of thrust, but with literally 10X less energy required.  i.e. you need to burn way less fuel if you can move a lot of air at a low velocity than if you move a little bit of air a high velocity.


Can you request a new squawk code if you don’t like the one being assigned?

No, there is no procedure for assigning a new squawk code because a pilot is superstitious. The whole system behind assigning squawk codes is fairly complex, and requesting new codes for non-operational reasons would put extra load on the system for no reason. In many cases, the controller doesn't even have the option to manually change the code, and doing so could result in significantly increased workload (actually getting the code, updating the flight data record, communicationg with the pilot, coordinating with downstream sectors etc.).
Squawk codes are a limited resources, we only have 4096 of them, and the system is already near its limit in busy airspaces. If we started to change codes just because we feel like it, we may very well run out of codes. And how should we choose which codes to avoid? Some probably wouldn't like codes such as 4666, others 1313. What about a pilot not liking 2403 because it happens to be the date a relative of his died? 4 is an unlucky number in Chinese culture, should we avoid all squawk codes with 4 in them?
We use numbers in aviation for all sorts of things, all the time, and it simple does not make sense to avoid some of them for non-operational reasons.


Why do I not always hear ATC read back by pilots (on required instructions)?

The O'Hare Eight Departure is the only departure procedure out of ORD.  This is what it looks like:

Notice that there are three departure control frequencies:

Chicago Dep Con West: 125.4
Chicago Dep Con East/North: 125.0
Chicago Dep Con South: 126.635

Airplanes are usually given the frequency appropriate for the sector that their first departure fix is located in.  If they are very busy, each sector will have its own departure controller and they will be talking to different people.  If it isn't as busy, they pilots will still be talking on their individual frequencies, but one controller may be listening to and transmitting on two or all three frequencies at once.

For instance, if a particular aircraft is cleared over POLO VOR (due west of ORD) they will be given a departure frequency of 125.4 as part of their clearance.  Let's say that the traffic is slow and only one controller is being used to cover all three frequencies.  If you are listening to the East/North frequency on 125.0, you will hear the departure controller issue a clearance to the aircraft, but never hear the response because the aircraft is transmitting on 125.4.


During which phase of the mission profile, the airplane fastest?

Mach number is likely to be highest when the aircraft is highest.

Mach number is related to true air speed (TAS) while the power required is related to the indicated air speed (IAS). As a plane flies higher, the air becomes thinner. Typically a plane will fly at a constant IAS, so the aerodynamic forces remain constant, but the TAS (and ground speed, and Mach number) increase.

As a plane burns fuel and gets lighter, it can fly higher, so just before the descent could be the highest Mach number.


Can a CAP Form 5 flight evaluation be used as the flight portion of a flight review?

A flight review consists of both a ground portion and a flight portion. You just need a CFI to sign off on the ground training for the flight review.
Alternatively, you could sign up for the FAA Safety Team WINGS program. You get three Flight Activity credits for the above mentioned CAP evaluation. You can earn another three Knowledge Activity credits a number of different ways of your choice. With the three Flight Activity credits and three Knowledge Activity credits, you will complete one phase of the FAASTeam WINGS program. Completing a phase counts as a flight review


How can I use a window for an emergency exit?

I personally would doubt the veracity of the quoted report, since they say

  I have no recollection after I got out of the plane

I would wager that their recollection of the moments just prior could be faulty.

Nevertheless, to try address your question, my answer is: you don't need to, and you better not try, you would be wasting time.

Aircraft are designed such that complete evacuation must be completed within 90 seconds using only half of the available doors. Trying to open a breach through a window would take much longer than that, would cause otherwise avoidable injuries, and in general would create an opening that is generally quite small for a person to go through.

Your time and efforts are much better spent in reaching a normal emergency exit.

The only situation where exiting through other passages could have sense, is when the impact has created breaches (large enough to pass through) in the hull for you, but the likelihood of you being conscious then is quite low.


The Boeing 737 fuselage (among other components) in Wichita for a variety of reasons

Before Boeing sold the Wichita portion of the Boeing Commercial Airplanes business to the Onex Corporation in 2005, Boeing was manufacturing structures for their aircraft in Wichita. The engineering, manufacturing, supply chain, and storage resources already existed in Wichita, so it wouldn't make sense to try to move all of that back in house at another location.
The cost to transport large components from Wichita to Renton or Everett via train is likely more economical than to manufacture and store them at the final assembly plant

On a similar vein, Boeing also uses the modified 747 Dreamlifter to transport components between suppliers and Boeing. Wichita is one of the cities that the Dreamlifter flies into, landing at McConnell Air Force Base.


What is the purpose of these movable panels on the MiG-35?

The aerodynamic devices in question here were already present on MiG-29KUB which is a parent version of MiG-35: Wikipedia: MiG-35

The devices are in fact, as some have suggested, Krueger flaps, as Russian test pilot Pavel Vlasov describes in this article: The MiG-29KUB: in the Russian and Indian skies for 9 years

  "It is a modern multirole plane with revolutionary fighting capabilities, with an increased payload and a longer list of weapons," said Pavel Vlasov, Honoured Russian Test Pilot, Hero of the Russian Federation, and General Director of the Gromov Flight Research Institute (and Head of the Flying Service at MiG until 2010). He noted at the same time that the MiG-29KUB featured a range of new solutions, such as Krueger flaps, a new flap design, a modern fly-by wire control system, and significantly improved piloting conditions

In addition to calling them Krueger flaps, this article also gives the devices the acronym LEVCON, leading-edge vortex controllers: SlideShare: Fulcrum Reloaded (see page 4)

The purpose of Krueger flaps is to increase the coefficient of lift of the wing, and to improve slow speed handling: Wikipedia: Krueger flap

After facts some speculation: the reason the Krueger flaps are not deployed in some of the pictures with gear extended is probably bacause they are not used in take off configuration, and the pictures most likely have been taken in t/o situation, not while the aircraft is landing


Are there fees for international flights crossing through another country's airspace?

Most countries have implemented route charges billed to aircrafts overflying their territory and by doing so using their control infrastructure. Those fees are usually computed according the distance flown and aircraft weight, small aircrafts (eg. less than 2,000 kg in Europe) may be exempt. They are collected for every flight over the territory, both domestic and international.

In the same way, some countries charge terminal fees when the airport control infrastructure is used.

Those fees are most usually levied for flight performed according IFR (Instrument Flight Rules), not VFR (Visual Flight Rules).

In Europe, the EUROCONTROL organization is empowered by States to collect route charges and terminal fees.


Are passive or active headsets preferable in an open cockpit?

First we should see how active noise reduction works. The simplest definition would be:

Active Noise Cancelling uses electric signals to reduce unwanted sounds.

The following picture on Active noise control depicts it in a simple manner:

Then we can see what unwanted sounds ANR can actually reduce. As mentioned in A Guide To Buying An Aviation Headset:

  ANR headsets work best at frequencies below about 400-450 Hertz. This
  represents the normal frequency range for speech, and also much
  propeller and exhaust noise is in this region. ANR headsets are
  therefore a significant advantage where intelligibility of
  transmissions is affected by engine and propeller noise.

  In general, ANR Headsets offer greater hearing protection in
  high-noise environments but will do little to reduce noise at higher
  frequencies such as wind or airflow noise.

In a flying airplane (even in a slow flight), wind flow would be quite high. This PDF (page 1, paragraph 3) states:

  The wind noise spectrum is dominated by the lower frequencies (< 500
  Hz), although at 27 mph when saturation is present, the wind noise
  level can be greater than 60 dB SPL at 8 kHz.

Since passive noise control is sound reduction by noise-isolating materials such as insulation, sound-absorbing tiles, or a muffler rather than a power source, in an open cockpit, passive NR headsets work better than active NR headsets.


How does the environment influence the aircraft engine demanded thrust?

All modern engine control systems take 'environment' (most importantly inlet total pressure and temperature) into account.

Takeoff and maximum continuous thrust are normally limited by the turbine temperature (which is controlled internally) and N2 (high-pressure rotor) RPM. So such settings on the throttle usually preset a certain N2, and then the thrust will be whatever the engine develops in present conditions. However, this limiting N2 may, and often does, depend on the environmental conditions. The max max (takeoff) is usually a hard limit, but the max cruise N2 may increase with altitude (falling temperature/pressure). Thus when you are climbing with a constant throttle setting, the control system may increase the RPM - even though the actual thrust will be falling due to engine physics.

Idle thrust is limited by stability of the flame. Idle RPM on the ground may be substantially lower than what can be sustained in the air (at speed). Thus the engine control systems often have a weight-on-wheels input signal and apply different control on the ground, primarily with regards to idle power.

Idle can also be significantly affected by the amount of bleed air taken from the engine, but this is not quite the 'environment', I suppose.

Of course, real control systems are a lot more complicated, even if we consider just the environmental parameters. For example, they can have numerous logical rules like: "if idle is selected after having maximum thrust for more than X seconds, ignore the pressure sensor and hold its value for Y seconds", or some such.


Is there any plan to make flights more interactive using smartphones?

Actually some airline did it already.

Many Airways including Qantas, Virgin American, Delta, Lufthansa and DragonAir (but Cathay not) has installed Wireless inflight entertainment system which allows passengers to access entertainment system and track flight via their mobile/tablet.

Surprisingly some LCC like Virgin Australia and Southwest also provides wireless on-flight entertainment system, though some contents is not free of charge.

On the other hand, several airline use Tablet to replace the original inflight entertainment system in upper class like La Compagnie (All business class airline), as well as some paid onboard entertainment services in LCC.


What is 20NM reference point in "CTC SOCAL WITHIN 20NM"?

Short answer:

The primary Class C airport

Longer Answer:

Your question refers to the magenta boxes on sectional and TAC charts that read CTC SOCAL APP WITHIN 20 NM on 134.2 338.2, or equivalent:

These boxes are used in connection with the nearest Class C airspace on the chart. Arriving pilots are requested to contact approach within 20 NM of the primary Class C airport. This is the answer to your question, the primary airport of that Class C airspace. Which airspace and airport exactly will depend on which magenta boxes you look at on the Los Angeles TAC. In the chart examples above and below, that airport would be Bob Hope (KBUR).

The deeper significance behind this instruction is the procedural Outer Area of the Class C airspace which is not depicted on the charts. Though not mandatory, this outer area of the Class C airspace is still considered part of the controlled airspace, and pilots are asked to contact approach before entering this area. See section 3-2-4 of the Aeronautical Information Manual (AIM)

  3-2-4 c. 2. (b)
  NOTE-
  4. Though not requiring regulatory action, Class C airspace areas have a
  procedural Outer Area. Normally this area is 20 NM from the primary
  Class C airspace airport. Its vertical limit extends from the lower
  limits of radio/radar coverage up to the ceiling of the approach
  control's delegated airspace, excluding the Class C airspace itself,
  and other airspace as appropriate. (This outer area is not charted.)

Note that the locations of the boxes on the chart (see image below) roughly correspond to the various approach sectors, with the frequencies contained in the boxes varying accordingly.

Also note that the blue boxes similarly correspond to Class B airspace, though the 20 NM note is absent, since Class B does not have the unmarked Procedural Area.


What was the Vmca of the 2-engine 747 config the El Al 1862 crew faced, and could they have landed the plane at a corresponding Vref?

The accident report says

  2.4.2 Performance

  An energy analysis was performed based upon altitude and airspeed
  data from the DFDR. It should be realised that this method does not
  allow extrapolation of performance capabilities in other conditions
  then those encountered during this flight. Based on this analysis the following conclusions can be made:

  Marginal level flight capability was available at 270 knots and go
  around power with a limited manoeuvring capability;
  At MCT thrust and 270 knots IAS there was no level flight capability;
  Performance degraded below about 260 knots at increased angles
  of attack. Deceleration to 256 knots resulted in a considerable sink
  rate.

(my emphasis)

My interpretation is that it is not appropriate to define a Vref for a 747 in that configuration.

Glossary

Vmca = Minimum Control (air) Velocity. Min speed that directional control can be maintained. Vmca2 for two engines (critical and inboard on same side) of a 4-engine aircraft.

Vref = Speed required as the landing runway threshold is crossed at a height of 50 feet in landing configuration.

MCT = Maximum Continuous Thrust. Thrust levels higher than this can only be maintained for a short time (e.g. minutes).


Why don't airliners have rudders on the winglets?

The purpose of the rudder is to control the heading of the aircraft. It turns the aircraft by creating an aerodynamic moment about the vertical axis of the aircraft. The moment is product of the aerodynamic force and the arm.

image: NASA

The aerodynamic force is the the side force on the rudder, the arm is the distance between the rudder and the centre of gravity of the aircraft.

If the rudder would be on the winglets, the side force of the rudder would act at a short distance behind the centre of gravity, reducing the effectiveness very much.

It would be possible the have airbrakes on the winglets / wingtips and use differential braking to create the rotating moment. This is done for example on the B2 which doesn't have a vertical stabilizer. The added complexity and weight increase makes it an unattractive option for conventional aircraft.


Is there a radio frequency that is sure to be quiet?

From the document referenced by mongo,

  Frequencies (MHz): 121.425 - 121.475Use: Band Protection for 121.5
  Frequencies (MHz): 121.525 - 121.575Use: Band Protection for 121.5

It seems that these frequencies exist only to be silent space around Guard/121.5.

No one should transmit on them, and you should probably hear total silence there.

I think these are an excellent place to look for quiet space.


Why does the Comet's horizontal stabilizer have so much dihedral?

As mentioned in this question, the two major factors are:

Lifting the tail plane out of the jet efflux area. Placement of the stabiliser root is structurally optimal when at fuselage mid, dihedral can then lift the surface out of the efflux stream. Note that the Comet has a relatively straight aft fuselage cone, which is better for low drag. And like @DaveGremlin mentions in his comment: the jet engines on the Comet are higher than those of the B707 and need to be lifted up higher.
Reducing sudden main wing wake effects: with a pronounced dihedral, there is always some of the tailplane sticking out into a less affected streamline.

The tailplane dihedral does contribute to roll stability, like main wing dihedral does as mentioned in this answer.


What is the difference between fuel control unit and fuel flow meter (transmitter)?

The Fuel Control Unit controls the flow of fuel to a turbine, it is in effect the mechanism by which the throttle works.

A fuel flow meter is simply a device that measures fluid flow (in this case the flow of fuel) through a line. The location, quantity and operation of flow meters varies by aircraft and configuration. Broadly speaking they are used to calculate actual fuel burn as well as to make sure the proper amount of fuel is flowing to an engine.

The fuel pump is the device that drives fuel to the engine/FCU from the tank. Again systems vary heavily but broadly pumps are used to move fuel from the lowest point in the tanks to an engine that may be above that point as well as to build sufficient fuel pressure to allow injectors/delivery systems to work.

In the simplest of systems a fuel pump sends fuel over a fuel line to an FCU. Somewhere on that line is a flow meter so that you can measure fuel flow out of the tank, into the engine.


How does Integrated Modular Avionics (IMA) improve reliability and obsolescence mitigation over the federated architecture?

Software faults are not included in reliability calculations because a software fault is a design issue. Developing SW in accordance with DO-178C (or predecessors) is intended to ensure that these faults are minimized. The reasoning that it's not measured as reliability is that when there is a SW fault it's not a broken box on the plane that has to be fixed, that fault is a potential failure on every aircraft that has the same system.
Swapping out a unit for a SW fault doesn't solve the problem. It's going to take a service bulletin (SB) with new SW deployed to the fleet to fix it.
So reliability is about hardware failures. Basically, parts break. Some break more often than others. The more parts you have, the more likely something will break. So making things more reliable is about minimizing parts and using the most reliable parts you can. But there are limits to what you can do. A power transistor will be less reliable than a resistor, but if you need it, you have to have it. But having one or two instead of 3 or 4 will improve reliability. I suggest a read of MIL-HDBK-217 which is the industry standard for predicting reliability.
So an IMA improves reliability by reducing the number of Line Replaceable Units (LRUs). Fewer LRUs means fewer cables, connectors, power supplies, and processors. An IMA can run multiple functions on a single processor card instead of having a dedicated unit for each function. All that means fewer parts to fail and higher reliability.
Aside from parts count, the biggest drivers of electronics failures are heat (high temps and high temperature swings) and vibration. Which is why some manufacturers perform Highly Accelerated Life Test (HALT) to identify weak points in the design early.
Nothing will solve the issue of parts obsolescence. Parts will go obsolete. It's a huge problem in aviation where products hang around for 20 or more years. An IMA does help manage the obsolescence issue. It does it by having a bunch of common processor boards. Not only do IMAs have fewer total parts, they have fewer unique parts which mean fewer parts that can go obsolete. Fewer parts going obsolete will mean less work to replace them.
It's still a complicated process to deal with, but if a part becomes non-procurable on an IMA processor board you'll need to modify the board design to use a new part. That can be a fairly straight-forward part replacement (equivalent part) to a major redesign of the circuit board. In the end, the new board has to be equivalent to the old one. That way it can be swapped out without impacting anything else (software or hardware).


Do carrier-borne aircraft pilots count the seconds on the downwind leg of the carrier?

According to the F/A-18's manual, the pilot starts the 180° from downwind when abeam the landing signal officer's platform:

  With a 30-knot wind over the deck begin the 180° turn to the final approach when approximately abeam the LSO platform.

Here's the illustration (of course the ship is not fixed, it's moving):

Click to view


Is there a specific aviation term for suicide by pilot?

According to the German Wiki article about CFIT a pilot's suicide is indeed not a CFIT. It is instead denoted as SEC.
They refer to the document CAST/ICAO Common Taxonomy Team: Aviation Occurence CategoriesPDF (Rev. 4.7, page 21)
which says

SECURITY RELATED (SEC)
Criminal/Security acts which result in accidents or incidents (per Annex 13 to the Convention on International Civil Aviation).
Usage Notes:

While security-related acts can lead to accidents as defined as by Annex 13 to the Convention on International Civil Aviation, they are not considered accidents by some organizations. Regardless, these events have similar consequences in that they result in serious injury or death to person(s) and/or substantial damage to the aircraft. For these reasons, they are categorized as security-related occurrences for prevention purposes only.

Examples include, (a) hijacking and/or aircraft theft, (b) interference with a crewmember (e.g., unruly passengers), (c) flight control interference, (d) ramp/runway/taxiway security, (e) sabotage, (f) suicide, and (g) acts of war.

Also, (same document, page 9) about CFIT:

Usage Notes:
[…]

Do not use this category for occurrences involving intentional flight into/toward terrain in manned aircraft or intentional ground impact of unmanned aircraft. […] Code all suicides under Security Related (SEC) events.

[…]

(Emphasis mine)
So according to ICAO, all suicides are SEC but not all SEC are suicides.


What's the reason for pilots wearing uniforms?

The Smithsonian's National Air and Space Museum says:

By the early 1930s, airlines were introducing distinctive uniforms for their employees, and women were entering the ranks of flight attendants.
Pilots were given military-style uniforms to reflect their status. Pan American emulated luxurious ocean liner service by calling its flying boats "Clippers" and its pilots "Captains," and attiring its crews in naval-style uniforms with white hats and navy-blue, double-breasted jackets and rank insignia on the sleeve cuffs. Other airlines followed suit. Many of these customs continue today.

This is why choice b is the correct one. A military-derived uniform projects importance / reflects [high] status. While a flight jacket—or a cap that reads 'pilot' for that matter—might adequately serve the purpose of identification (choice a).
Look no further than Wilhelm Voigt, an imposter in an officer's uniform can command real soldiers, place people under arrest, and make away with a treasure.
(Navy Officer, Pilot) Side-by-side comparison.


You don't need an optimal design to have fun.  General guidelines:  Your model should weigh around 500 - 700 grams.  Wing span around 1.5 meters.  Chord around 0.2 meters.  But you really need to nail down your speed envelope.  Too fast will be difficult to control, too slow and it's an indoor delight but an outdoor nightmare (due to wind).

A good place to start would be a chunky reliable design similar to a Piper Cub or Cessna 152.  Shorter more highly loaded wings should help you find the sweet spot of around 7 to 25 mph, which is good for R/C planes.

Build an engine/battery/servo frame that can easily change out wings and empennage as you fine tune your design with gliding and powered flights.

You may wish to start with a slightly cambered KFm 1.  Slower speed and lower wing loading should give more endurance, but will be blown around by the wind and will actually be less efficient distance wise into the wind.  Go conservative on your first build.

Control surface dimensions can be had from foamies at your local hobby shop or R/C club, and more information is available at the RC Groups website.


Are experimental aircraft exempted from the 2 year transponder and avionics checks?

When you operate in airspace that is under FAA regulations, FAR 91 applies (unless you are flying military)

FAR 91.413 a) states:

  (a) No persons may use an ATC transponder that is specified in
  91.215(a), 121.345(c), or §135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested
  and inspected and found to comply with appendix F of part 43 of this
  chapter;

So when you haven't performed the two year transponder check, you are not allowed to use the transponder. The way to fly then is to fly VFR in airspace where no transponder is required AND not to use the transponder at all.

This is not specific to experimental aircraft, there is no exemption.

There is good reason not to have an exemption for experimental aircraft; a malfunctioning transponder can cause many problems to the ATC radar systems.


What is the result of increasing number of propeller blades on the same engine

What it means in practical terms is if you replaced a 2 blade Warp Drive prop on a 100 HP engine with a 4 blade prop with double the total blade area, and if the blades of the 4 blade were set to the same pitch as the 2 blade, the torque requirement of the 4 blade would be significantly higher and you'd find the engine can't make the same static RPM it was making with the 2 blade at wide open throttle.
You would have to re-pitch the blades of the 4 blade prop to a lesser angle and retry until you regained the original static RPM.  You're basically offloading the individual blades until the total torque demand matches the original prop.  You might find you've lost a lot of efficiency from the blades now operating at less than their optimum blade angle of attack.
If the 4 blade prop had much smaller individual blades, so the total blade area was the same as the 2 blade, the difference in pitch would be minimal, although some adjustments in pitch would still need to be made to match static RPMs, and the static thrust you are getting at the target RPM would be reduced somewhat from the 2 blade because of the lower efficiency of the 4 blade.
If it was a constant speed propeller, the propeller governor would be doing all that for you.
If you are after the maximum thrust efficiency for a given horsepower, 2 blades are always better if the power can be absorbed and the target RPM can be achieved with 2 blades.  What makes multiple blades attractive, as a conversion to an existing engine, is the desire to limit noise, or limitations on diameter due to tip speed limits or ground clearance requirements. For example, 3 blade propellers are popular on DeHavilland Beaver seaplanes because the noise levels are lower because the tips speeds are lower, and the shorter blades get a little bit less water spray erosion damage, benefits sufficient to live with a small reduction in prop efficiency compared to the 2 blade paddle prop it originally had.


Can I attach a camera to the outside of my aircraft in the USA?

The NTSB actually recommended the use of exterior cameras to the FAA in 2012.

It appears to be something of a grey area, but it looks like you should contact your local FSDO for approval of an external load if you're permanently fixing a camera to a plane.

The grey area comes in that if the camera is temporarily attached, you shouldn't need special approval, but in practicality it could come loose and damage the plane.

GoPro says this about affixing their cameras to planes:

  Industrial strength suction cup. Strong enough to pull dents out of a car door or stay attached to an airplane at 200mph+, proven though not endorsed by GoPro per FAA rules.

There's a forum thread where someone asked the FSDO to sign it off as a Minor Alteration, and it was determined that a short logbook entry would suffice:

  Temporarily installed a GoPro camera mounted to a standard inspection panel on (Left/Right) lower wing in place of the standard inspection panel. There are no electrical connections associated with this installation. This is a minor alteration as it has no appreciable effect on performance, flight characteristics, or other qualities affecting airworthiness (refer to FAR 1.1 Major Alteration and FAR 21.93). A net weight change of 9 oz is incurred with the temporary installation; therefore, the weight and balance change is negligible (refer to AC 43.13 1B, 10-2 (c)).


Use or check? NOTAMs can give pilots of a wide range of information, so in terms of use each NOTAM is different. For example, they might tell the pilot that a frequency has changed - so that's something they may need to integrate into their flight at the relevant point.

Or, the classic, is that there are standing NOTAMs in the UK that overflying Ukraine and Syria aren't recommended. Not something most pilots need to worry about.

There is no expectation to check NOTAMs after departure, however.


What causes airliner tyres to burst as often as they do?

Car tires aren't really comparable.

Car tires:

make a lot of miles, but in mostly benign circumstances. Low speeds mean little heating (and slow changes in temperature).
failures are often caused by debris in the road rather than structural failure of the tire itself. (Although on trucks, structural failure is more common)
must be replaced when the tire profile reaches a minimum depth, which means you can't keep using the tire until structural failure happens.
are generally thrown away when the profile reaches minimum depth, because car tires are cheap enough that retreading is not necessary

Airplane tires:

rapidly go through temperature cycles (in-flight: -50 ºC, and on touchdown they rapidly heat up to several hundred ºC)
are kept at much higher pressures (13 bar versus 2 bar for car tires), so if there's a failure it's more likely to be catastrophic.
need to run at high speeds (300 km/h and more)
carry a lot of weight (up to 38 tons, vs. 500 kg for a car tire and 5 tons for a truck tire), which explains why they need such high pressures.
have to be lightweight
are often refurbished


What kind of work you can get with a private pilot licence?

You cannot do so.  A private pilot’s license - at least in the US - prohibits you from offering airman services for compensation or hire.

If you intend to fly professionally, you will need at least a commercial pilot’s certificate.  An instrument rating is also highly recommended as is multi engine class ratings for the greatest chances of employment.  Air carrier operation will require you to hold an airline transport pilot’s license for part 121 operations.


What is the difference between redundancy and fault tolerance?

Redundancy is when there are multiple ways of doing the same thing; quite possibly by having multiple gadgets, or ways of interconnecting gadgets, that can perform the same function with the same or at least very similar fidelity even if a non-zero number of them fails. One likely effect of this is that there is no single point the failure of which will cause the failure of the entire system (no "single point of failure").

Fault tolerance is when the overall system can tolerate the failure of a component without going into a dangerous state, but it won't necessarily maintain the safe state by having full functionality or fidelity. The system may operate in a degraded state, but it won't immediately be in a dangerous state.

Redundancy can be a way of providing fault tolerance in the larger system, but redundancy on its own does not guarantee fault tolerance, particularly against all kinds of faults. It's only redundancy if each separate way of accomplishing a goal can function without the other ways of accomplishing the same goal. Fault tolerance is a result; redundancy is one way of achieving that result.

For example, there are two basic ways by which you can cause an airplane to assume a new heading; either by using the ailerons to bank, or by using the rudder to skid. Normally these are used together in a coordinated turn, but if you're really in a pinch, either one can be used to turn (but watch that stall speed). This is one crude example of fault tolerance, since either the ailerons or the rudder can fail and you are still able to make a turn (other effects of the failure, or other effects from the cause of the failure, notwithstanding). — Redundancy, on the other hand, would be more like if you had multiple independent sets of rudders and ailerons, each with its own, independent control system.

Commercial aircraft often have two or three of each flight-critical instrument; one for each (of two) pilot, and one backup instrument. For example, each pilot will have their own attitude indicator ("artificial horizon"), and they will have a shared instrument that can be used to, for example, determine which instrument is faulty if there is a disagreement between the two main instruments. This is an example of redundancy, because if designed right, any one of them can be used fully independently of the others to determine the aircraft's current attitude; the ability of the instrument to carry out the intended function at full fidelity does not depend on the others functioning properly, and there is hopefully no single failure which will cause two or three to fail in the same way, or at all.

An example where having redundancy doesn't necessarily provide fault tolerance can be having multiple hydraulic systems to control deflection of control surfaces. If all hydraulic systems are routed through a single location, and that location is damaged, there exists a possibility that you will lose all hydraulic systems at once due to that single failure. Therefore the hydraulic system is redundant but not necessarily fault tolerant.


Available Ratings:

  You can add class ratings to the NPPL to allow you to fly microlights, self-launching motorgliders (SLMGs) and simple single-engine aeroplanes (SSEAs).

The above are the only available ratings for an an NPPL. An NPPL (and LAPL) is strictly a VFR license, therefore you could not get rated for IMC. However, you can continue your training to receive your PPL, at which point you could recieve a rating for IMC, which would be your IR(R), or Instrument Rating Restricted.

Most flight instructors will provide basic IMC training just in case you find yourself in a bad situation, which can happen to even the most cautious pilots.


When does root bending moment start to become important?

Root bending isn't an issue for braced structures using wires or struts.  The root fitting is just a pin joint on most wire and strut braced aircraft, and even if there is a one piece beam going across, like some hang gliders, it's not under significant bending, except at the point where the wires/struts attach outboard.
Root bending only matters on cantilever wings, and the structural considerations and calculations will be the same for any cantilever wing aircraft, depending on the design G limits, and the dimensions and loads involved.  It's a beam with a tension member and a compression member and you work out how strong the top and bottom caps need to be as with any cantilever beam whether it's an RV-6 or a 747.


Why do similar Airbus and Boeing aircraft use different flap and slat mechanisms?

While the aircraft you mention would appear to be similar, this is not really entirely true. Specification wise yes, but the period it was designed in has a huge impact. For instance:

The first flight of the Boeing 737 was in 1967, with the Airbus A320 following considerably later in 1987. (20 years later)
Boeing 747 first flew in 1969, the Airbus A380 followed in 2005. (36 years later)

Each redesign is expensive and time-consuming so if there is no conceivable benefit it is not done. There is no clear cut equation on when a certain type of slat and flap mechanism is chosen:

The operating environment changes over time. One important consideration is the landing speed (and corresponding runway length). This for instance limited the Boeing 707 greatly, and it was likely that Boeing might not wish to run into the same problem with the B747 to enable it to serve as many markets as possible at a time when airports were not so advanced. For this reason they put in the very complicated triple-slotted flaps. (For comparison, look at the A380 which has caused headaches as airport operators have to modify and/or rebuild facilities to accommodate it)
Aircraft have become lighter over the years with the introduction of new materials, production techniques and better optimized engineering.
Technology has become better at modelling, so we can be less conservative in design choices as there is a better idea of the end result. This applies not only to the structure but also aerodynamics.

The bottom line is that you take the values and look at a few different designs. You choose the one that best fulfills your criteria (not only in performance but also what you can build) and go with it, and this choice would change over time. If the Boeing 737 would be built today, the details most probably be fairly different.

What does this mean?

The A380 for instance only has single slotted slats. When the B747-8i recently received a new wing design, it shifted from triple to double and single slotted flaps.
Both the A350 and B787, designed roughly around the same period, both have the rear single slotted flaps and (to large extent) the same slat design.


What makes the ailerons on an aerobatic airplane different than the ailerons on a non-aerobatic airplane?

The term "fast ailerons" is an informal term that generally refers to the response of the plane relative to the pilot's input to the aileron controls on the stick or yolk. The faster the plane responds, the faster the ailerons (or other controls).

The roll rate is the speed at which a plane can complete a roll. This depends on a number of factors, including aileron size, maximum aileron deflection, wing length, and speed.

Ailerons that can deflect a lot of air without disrupting the airflow over the wing too much are desirable in an aerobatic plane, so the roll rate can be increased and so the plane will have better roll control at lower speeds. While larger ailerons are desirable on an aerobatic plane, they are also more susceptible to flutter at high speeds, which is not desirable because it tends to rip them off the wing. There are several design techniques that can be used to mitigate this, such as gap seals, counterweights, countersurfaces, etc.


For protecting non-wallet documents, consider using a vacuum seal bag for food. To prevent warping the simplest thing is to squeeze the air out and only use the seal function, without vacuum.

This way way if somebody has an issue or you need to modify the documents, you can cut open the pouch and retrieve them in original state.


What is the difference between company routes and pilot routes?

A company route, or coroute, is just an easy way for the pilots to download the flight planned route into the FMC, without having to enter every route segment manually. It saves a bit of time, especially on longer routes, and eliminates the risk of input errors.

I haven't heard the term "pilot route" before, but presumably it just means the lack of a company route - i.e. a route that the pilots have entered manually.

Functionally, once the route has been entered in the FMC, there is no difference between a company route and a route entered manually. The only difference between the two is the way they are entered.


How does ATC handle arriving/departing runways that cross?

Chapter 9 - Departure Procedures and Separation of the FAA Order titled "Air Traffic Control" covers the procedures that are used for aircraft departures, including those cases where they have intersecting runways.

There are numerous procedures that they follow that are specific to intersecting runways, including:

3-9-4 - LINE UP AND WAIT (LUAW)

If the tower has an airplane Line Up And Wait (taxi onto the active runway but not actually takeoff) because of another airplane that is landing or taking off on an intersecting runway, they must inform them of the other airplane and why they are not taking off.

3-9-7 - WAKE TURBULENCE SEPARATION FOR INTERSECTION DEPARTURES
3-9-8 - INTERSECTING RUNWAY SEPARATION

This probably covers most of what you are asking about, and has some great pictures showing when they are allowed to clear another airplane for takeoff in different situations.  For instance, they can't clear an airplane for takeoff with another airplane landing on an intersecting runway until after they have passed their runway.

Note that there are similar procedures in Chapter 10 - Arrival Procedures and Separation

In short, there are lots of extra procedures that must be followed when using intersecting runways simultaneously, but they also get a lot of operational benefits when they can do it so are able to get a lot more airplanes on and off the ground in the same amount of time.


Would it be feasible to use graphene in the gearbox of a large turbofan engine?

Well, just because it is stronger than steel does not mean that it is a useful structural material.  For example, the tensile strength of spider silk is higher than steel, but no one is building gearboxes out of spider silk.  For a graphene gearbox, the big challenge as I see it: graphene by definition is one atom thick. You aren't going to build a gearbox which is one atom thick. You can stack multiple sheets together to get something thicker, but the sheets will just slip against each other, so not useful as a structural material.  i.e. you can build a gearbox out of a big chunk of solid aluminum, but nobody tries to build a gearbox by taking 10,000 sheets of aluminum foil and laying them on top of each other.  What you would need is a graphene composite.  E.g. like we make carbon fiber composites today, which consists of carbon fibers held together by a polymer matrix.  Graphene composites are an active area of research, but I don't think they have reached the point where aerospace companies are considering them.


Is "Pull up and be ready" standard phraseology?

After the fact, I can guess that he meant, "Pull up to the runway hold short line, staying on the taxiway, and be ready for immediate takeoff when cleared".

But his phrasing was non-standard, and definitely confusing.

I think the proper way to say it would have been, "N12345: Hold Short; You are #1 for departure; be prepared to go without delay."

The key parts being:

"Hold Short" is an unambiguous instruction
Informing you that you are next in line.
Informing you what is expected, using the official term "without delay"

Even that is slightly risky, as the "without delay" could be misinterpreted if the pilot misses the initial "hold short" instruction.

I think the proper responses available to the pilot are one of:

"Holding short.  Ready to go without delay"
"Unable"  (I'm not ready yet, perhaps in part because I don't understand)
"Please Clarify" (You used confusing terms; Spell it out for me like I'm 5)


How is oil distributed through the engine in a wet sump system?

The short answer is "The same way as in a dry sump system." – There is an oil pump which sucks oil out of the oil pan and forces it through the engine oil galleries under pressure.
Wet and dry sump oil systems only really differ in where they store "extra" oil.

Wet Sump Systems
In a wet sump system the oil is stored in the oil pan under the engine. The oil pan serves as both the oil tank (holding the supply of lubricating oil) and the oil sump (where oil eventually collects after making its way through the engine). The pressure pump sucks oil directly from the oil pan and circulates it through the engine's oil galleries.

Dry Sump Systems
Dry sump systems store their oil in a separate tank, which feeds the pressure pump. Dry sump engines have a smaller oil pan which only serves as a sump, and a "scavenger pump" that drains the sump back into the main oil tank. They are termed "dry sump" systems because under normal operating conditions very little oil remains in the sump.

Note that there are other engineering differences in dry-sump systems, but they're largely beyond the scope of your question.
Illustrations thieved from https://www.slideshare.net/jesscar/piston-engines-oil.


I just saw a plane drop off online radar; should I do anything about it?

Really there's nothing you should do in cases like these.

Flightradar24, FlightAware, and similar services should not be used for flight safety purposes, and most of them specifically state so in their terms of service (such as sections 12 and 14 of Flightradar24's terms and conditions). Their sources may go down for whatever reason -- that does not mean that the plane has crashed.

These services can only track what ATC controllers can (for the most part), so it's more likely that if there is a real issue, that they'd notice without the general public making a fuss.

In this specific case the flight was being tracked using MLAT (designated by the radar type T-MLAT, which is shown in your animated image file). MLAT flight track accuracy relies on the accuracy and number of the receivers in the area, and according to Flightradar24's website, MLAT generally only works above 10000 feet:

  MLAT

  In some regions with coverage from several FR24-receivers we also
  calculate positions of aircraft with the help of Multilateration
  (MLAT), by using a method known as Time Difference of Arrival (TDOA).
  By measuring the difference in time to receive the signal from
  aircraft with an older ModeS-transponder, it's possible to calculate
  the position of these aircraft. Four FR24-receivers or more, receiving
  signals from the same aircraft, are needed to make MLAT work. That
  means that MLAT coverage can only be achieved above about 10000-20000
  feet as the probability that signal can be received by four or more
  receivers increases with increased altitude.

  MLAT coverage is today limited to some parts of Europe and North
  America, but expanding fast.

So as the aircraft descends below 10,000 feet there is an increasing chance that you will lose it on Flightradar24's tracking system.


When does the overspeed alarm goes off in a plane?

The overspeed goes off when either the indicated airspeed exceeds that limit or the mach speed exceeds the mach limit. At least that's how it worked on 747-100/200 aircraft.

The 350 knot figure for the max operating airspeed sounds reasonable to me as long as you're low. From memory that was around the max operating INDICATED airspeed for 747-100/200 aircraft. Remember, though, that indicated airspeed decreases with air density. A 747 cruising above 30,000 feet at around 550 knots TRUE airspeed is going to show an indicated airspeed of less than 300 knots. However, that cruising true airspeed of 550 knots or so is going to be around mach 0.86. The max mach number for the 747 was 0.92.

If you were at, say, 15,000 feet and speeded up to 350 knots, the mach number would be much less than 0.86.

Take your sim up to 35,000 and see what you get.


Is Autopilot engaged when an engine failure above V1 occurs on modern airliners?

Most non-normal ops in an airliner follow the same concepts for light aircraft - make sure the aeroplane is under control and following the desired flight path before you do anything - which includes engaging an autopilot.

So for the Boeing aircraft I fly, ensure you've got a positive rate of climb, speed should be V2 - V2+15, ensure the aeroplane is in trim (pitch first, then rudder) and your following any prescribed engine failure routing.

In terms of autopilot use, part of our company SOP is to engage the autopilot at 1000ft AAL, this is not to relieve the pilot of the responsibility of maintaining control - it won't control the rudder - more to reduce the immediate workload and allow more effective management of the non-normal situation. Once the autopilot is engaged the aeroplane can be accelerated, flaps retracted and any non-normal checklist completed.


How do the engines of a multi-engine airplane shut down after fuel starvation?

On multi-engine aircraft the engine on one side is normally fed by the respective tank, so the left engine(s) is fed by the left tank etc... it is possible to cross-feed to allow access to all the fuel in the event of an engine failure.

In order for a simultaneous run down to occur - both tanks would have to have precisely the same amount of fuel loaded and both engines would have to burn fuel at exactly the same rate, which is unlikely.


Is it harder to get a first pilot certificate in a motorglider compared to a normal powered aircraft (near St. Paul, MN.)?

It will be harder to get initial training in a motor glider near St. Paul, because motor gliders are kind of rare around here.

However, consider this:

Instruction in a un-powered glider is mind-bogglingly cheap compared to power instruction. And it has the other mentioned benefits - stick and rudder skills, low age limits, etc.

After getting a first pilot certificate in a non-motor glider (and after suitable further training), one may add Motor Glider ("self-launch") privileges with only an instructor endorsement - no Designated Pilot Examiner needed!

One may also add Light Sport - Airplane privileges with a two-instructor endorsement process - also no Designated Pilot Examiner needed! If you or your son want to fly LSAs, starting with a glider rating can be a great bargain.

And you have options! Some clubs: Minnesota Soaring Club in Stanton, Red Wing Soaring Association in Osceola (* note NOT in Red Wing, despite the name); and a commercial operation: Cross Country Soaring in Faribault. Not to mention any private instructors you may ferret out in the community.

I personally am a member of RWSA and hope to get my self-launch and LSA endorsements one of these days, but I'm having plenty of fun soaring in towed gliders in the meantime.


You don't measure TAS. You measure IAS (or CAS), then correct for altitude and nonstandard temperature to get TAS. As a rough rule of thumb, add 2% to the IAS per 1000ft of density altitude.
With modern avionics, you know your GS from GPS or similar systems, so the difference between TAS and GS tells you the head/tailwind component and course vs heading tells you the crosswind component, which will be combined to display the direction and speed of the actual (not forecast) wind.
With older (or no) avionics, you get a winds aloft forecast before departing, and you do the reverse of those same calculations with an E6B to find out what heading to fly to get the desired course.


Why do the engine nacelles on the P2V Neptune extend so far back?

That shape was adapted after wind-tunnel tests showed the original less-tapered nacelle creating downforce, which meant the rest of the wing had to deal with more upward bending (lift distribution more toward the tips). To solve this problem, the beaver-tail-shaped end was used – reducing the flow separation that caused the downforce. The thrust-axis was also tilted 3 degrees down to reduce the overall bending moment (like how the weight of the fuel does that for big jets, here it's a tiny bit of downward thrust).
Nacelle-extension isn't unique to the P2V; you can find it on the B-25 bomber for example, although not as flat.

Wassall, J. B. "The Development of the Lockheed P2Y Neptune: A Paper by a Senior Engineer of the Lockheed Aircraft Corporation Describing the Evolution of a New Aeroplane." Aircraft Engineering and Aerospace Technology (1950). https://doi.org/10.1108/eb031906


The first step for repairing damage to a fuselage skin panel is to cut out the damaged area1. Cracks tend to propagate, so an area much larger than the damage will be removed to ensure that all damaged material is removed. The stiffeners that are behind the fasteners will need to be inspected for damage as well.

A filler plate will be cut to fill the hole in the skin. One or more doubler plates larger than the removed area will then be cut and all plates will be riveted together. The doublers will possibly be on both sides or at least thicker than the surrounding skin. See here for some examples.

It's likely that a larger repair such as this one will need to be inspected regularly to ensure that the repair holds strength.

It's hard to tell where exactly this damage is located, most of the aircraft skin is part of the pressure vessel. However, the airplane is not completely airtight, so a certain amount of leakage is normal. A hole of this size will probably not prevent the fuselage from pressurizing, though larger ones will.

The cost will depend on the extent of the repair, but could be from \$5,000-\$15,000 (300,000-1,000,000 INR) based on this estimate.

1Actually, the first step in repairing damage to an airplane is consulting the structural repair manual (SRM). This is provided by the manufacturer and describes general methods for repairing minor and typical damage to airplane structure. If the damage is beyond the allowances in the SRM, the manufacturer will be consulted. All of this is to ensure that the repair will meet or exceed the strength and life of the original structure, or if this is not feasible, that the limitations of the repair are documented and understood. Major repairs will require extra inspections to ensure that the structure is still in good shape. Aircraft skin will not be welded, since this can cause heat damage to the metal, requires careful skill and care to do properly, and will not hold up well to fatigue.


What is the proper procedure to change VFR altitude when changing heading from east to west?

If you are on VFR Flight Following you usually don’t need to ask permission to change altitudes. The exception would be if you are given an altitude to fly from ATC. For example, last week I was flying west from Corona and approaching Burbank’s airspace. While climbing through 4,000' I was given an altitude restriction of “At or below 5,000'”. ATC had me fly over Burbank’s Class C altitude (4,800') but wanted to keep me below the departing traffic. I could see a big jet pass me and once it did I was told to “resume own navigation”. On my initial call I had indicated that I was going to fly home at 6,500' so I climbed to that altitude. I could fly at any appropriate altitude, e.g. 4,500', 6,500', 8,500' etc. but given how busy the airspace is and the expectation of ATC that I would remain at 6,500' I would not change altitude unless I first arranged to do so with ATC.

On the flight into Corona, at around 15 miles from the airport, I was given instructions to fly at or below 3,000'—presumably to avoid traffic departing Ontario. There was no need to inform ATC that I was leaving 3,000' when I had the airport in sight and began my descent.

On the other hand, once I got past Ventura, the traffic volume was much lower so I wouldn’t necessarily talk to ATC if I wanted to climb to go over a mountain or avoid a cloud.

As a general rule, when you begin your descent to land ATC can figure it out. In many cases the beginning of the descent corresponds with picking up the ATIS. Since ATC likes to know that you have the ATIS I will usually combine the descent and ATIS call in one transmission.

In your specific example, since you will be flying at the wrong altitude for 30 minutes, you should either climb or descend—unless your current altitude was assigned by ATC.

FYI, in SoCal when ATC says  “At or below 5,000'” they really mean “at exactly 5,000'”.


Is the induced drag independent of wing span?

Aspect ratio $AR$ can be written as $\frac{b}{c}$ which is equal to $\frac{b^2}{S}$.

Before we start substituting, note that $C_L$ also depends on the wing surface area $S$.

$L = \frac{1}{2}\rho V^2 C_L S$

or

$C_L =  \frac{L }{\frac{1}{2} \rho V^2 S}$

Substituting all this in the induced drag formula yields:

$D_i = \frac{1}{2}\rho V^2 S \frac{C_L^2}{\pi  AR \epsilon} =
\frac{L^2}{\frac{1}{2}\rho V^2 S \pi AR \epsilon} = \frac{L^2}{\frac{1}{2}\rho V^2   \pi b^2 \epsilon}$

This shows that the induced drag is proportional to the inverse of the square of the wingspan.


Which channels to listen to on liveatc concerning arriving flights?

If you want arrivals the relevant feeds on live ATC are:

NY app (CAMRN)
NY app (ROBER)
NY app (FINAL)
KJFK Tower
KJFK Tower #2
KJFK Tower 119.1
KJFK Tower 123.9

CAMRN will receive approaches from the south and ROBER will receive approaches from the east. They will then pass planes to final to be lined up to the runways. Final will then pass planes to the appropriate tower frequencies, depending on which runway they are assigned. There are two separate tower frequencies of which there are two separate feeds. Items 4 and 5 are both frequencies combined (usually one in the left ear and one in the right) from the two different frequencies. The feeds are done by volunteers so there's no way to know their location. I haven't listened to KJFK so one feed might be better to hear planes from different directions. Feed #1 includes the TCA. I find it daunting to hear two feeds at once so I would recommend using either 6 or 7.

To be honest, unless there's something unusual going on, tower feeds are pretty boring. By the time they get to tower freq they are done maneuvering and are established on final. All tower does is clears them to land and and gives them exit instructions. If you are watching FR24 the approach feeds are more interesting.

Another interesting approach to watch, at least for me, is KMEM between about 2230 and 2330 Central time when all the FedEx flights are coming in to the hub. Gives you a good idea of the flow of ATC.

As Dave mentioned in comments, none of the UK airports will be on LiveATC for legal reasons.


Are retired airline pilots allowed and able to help in an emergency situation?

United 232 might be close to what you're thinking about: a United flight training instructor on board helped the pilots to land the aircraft, although he wasn't retired. But for this scenario to happen you need a fairly specific combination of circumstances:

The passengers have to know there's an emergency
Your father has to believe he could help significantly
The cabin crew have to decide it's worth passing your father's offer to the pilots
The pilots have to decide it's worth bringing another, unknown pilot into the situation

The basic question would be: is your father's help going to be important enough that it's worth increasing the communication and CRM workload for the crew? That's not necessarily an easy decision to make, especially if time is very limited or the nature of the emergency isn't clear.

Being "allowed" to help isn't really a consideration here, by the way: pilots have very broad emergency authority to do whatever they think is best.

Overall, it's certainly possible and it would be the pilot in command's decision to accept your father's offer or not. It's just very, very unlikely.


How to find capture area of an engine inlet?

It is not so hard, actually.
You need to know the speeds ahead and inside the intake. You can deduce their ratio from the pressure recovery factor, and normally the Mach number inside the intake is between 0.4 and 0.5, so this, combined with your design flight speed, is a good starting point.
In supersonic flow the air is rammed into the intake face, producing a shock. This will be a straight shock in case of a pitot intake or an oblique shock in case of an intake ramp. Use the appropriate shock tables to find the corresponding speed and density ratios.
For subsonic flow you can use a Gedankenexperiment: Your intake is flying through a densely packed array of stream tubes. Some of them will end up inside the intake, others will be pushed aside as they come close to the intake lip and will flow around it. The speeds in those tubes varies between flight speed well ahead of the intake and your eventual intake speed inside the intake. In between, things change continuously in subsonic flow or via shocks in supersonic flow. Now assume that all the air which passes through the intake will have to pass through their corresponding stream tubes, both ahead and inside the intake. No air is allowed to cross between tubes. If the air inside the intake flows faster than flight speed, the flow in the tubes will be accelerated as they approach the engine face, so the intake has to ingest a lot of tubes to keep mass flow the same. Conversely, if flight speed is higher than intake speed, some of the tubes will be pushed aside to get a match between the mass flows ahead and inside the intake. Don't forget to adjust stream tube area for density changes: The change in stream tube cross section has to be inversely proportional to the change in air density as the air inside the steam tube changes speed, like this:
$$\frac{\delta\rho}{\rho}=-Ma^2\cdot\frac{\delta v}{v}$$


Why a parachute for aerobatics only when carrying a passenger?

Well, as with many issues involving the FAA, the "why" is a bit of a mystery.  Perhaps they thought that the pilot can "lead by example" if a bail-out is needed.  I'd imagine that a lot of passengers would be a little reluctant to jump out of an airplane, but once they see the pilot go I can see them becoming highly motivated!

As far as not needing the parachute if only crew members are on board, the FAA has long held the view that they aren't protecting pilots from doing stupid things to themselves since they are knowledgeable and informed, but their regulations are to protect the "general public", or the passengers in this case, who don't know any better.


The link you provided has a poor choice of words: "restoring moment".

Damping forces are not restorative, i.e. they do not attempt to return the body to equilibrium, but rather oppose its movement. That is an important nuance.

Imagine a classic spring and dashpot vehicle suspension: the spring tries to restore the vehicle to its regular position, while the dashpot damps the velocity. By itself, the dampener will not restore equilibrium, it will stay at whatever position you extend it to, despite fighting the movement itself.

How does this apply to your question: aerodynamic damping is exactly that, the opposition  of the aircraft to rotation. You can observe it without flying: just imagine an aircraft hanging by its nose and tail, in such a manner that its CG is right between the supports. You can roll it by hand, but the drag on the wing will eventually stop this roll, but it will not level out the wings.

In flight, there are other forces at play that do provide a restoring moment, but aerodynamic damping does just what it says on the tin, it damps.


What is the process to remove frost off an airliner?

Frost is removed through the application of (typically) Type I de-ice fluid (information about de-/anti-ice fluids). Fluid application is generally from a truck with a lift so that the operator can spray the aircraft from above. The fluid is generally hot, diluted with water and under pressure so you'll see lots of steam coming off of the fluid spray. The truck will drive around the airplane spraying the wings, tail and fuselage as necessary to completely remove snow, ice and frost.

Some airports have static mounted de-ice towers that are more like cranes and some operators have automated trucks where there is no operator in the lift and they can do the whole operation from the cab of the truck.


Where can I find blueprints for the Wright Model HS?

You may want to reach out to the national archives they seem to have at least some of the Wright Brothers Blueprints. The Smithsonian may also be of help as they seem to have some stuff of theirs as well. This organization also has some of their early plans and seems to be knowledgeable on the topic you may want to reach out to them.


Can a small plane be floated off of an aircraft carrier?

As far as I'm aware this has never been attempted (and I doubt the Navy would let me try - though I'm certainly game if they are!), but:

A Piper J3 Cub stalls at 38mph (33kts).
The USS Enterprise (CVN-65) had a maximum speed of 38.7mph (33.6kts).

So, given a lightly loaded cub and an Enterprise-class carrier at flank speed, it is at least theoretically possible to float that aircraft off the deck (if it were lightly loaded, and thus had a lower stall speed).

Achieving zero relative motion would require a little more effort - specifically you'd have to seek out a headwind, and the Cub would have to be operating at an airspeed above stall, but still pretty close to it.
For example, if the Enterprise were making 30 knots and steaming into a 10 knot headwind the relative wind on deck would be 40 knots. That's enough to lift the Cub, but as soon as it was in the air it would need to pull itself along (via its engine) to maintain that speed. The Cub would have zero relative motion above the deck at an airspeed somewhere around 40 knots).

As a (slightly ridiculous) bonus: The Belite Superlite has a stall speed of 28 mph (25kts). It would be theoretically possible to fly such a plane like a kite from an aircraft carrier. Its advertised takeoff and landing distances (both ~500ft) are also such that it could operate from a carrier deck without need for the catapult to launch or arresting wire to stop.


Why, and how, are barometric altimeters accurate enough for approach and landing?

A difference of 1 hPa results in an error of 27ft in the altimeter. To have the altimeter showing 3000ft when the aircraft is actually at sea level, the altimeter must be off by 111hPa. Standard air-pressure at sea level is 1013 hPa (that's converted to 29.92 inHg for you Americans).

For comparison, the pressure in Hurricane Katrina reached as low as 902 hPa. So if you were flying into a hurricane but left the altimeter setting at 1013 (which is used as the standard setting at cruising altitude), you could theoretically pop out of clouds at what you thought was 3000ft but instead hit the ground.

Ignoring the fact that nobody tries to land in a hurricane, this mistake is prevented by the airfield pressure being reported by ATC, in the ATIS, and even an alert from the aircraft if it is advanced enough.

  While on approach, you enter a localised low-pressure cell that the airport’s AWOS, being at the airport rather than back along the approach path, doesn’t know about. Seeing your altitude apparently ballooning up, you idle the throttles and push the nose over to correct the altitude excursion; unfortunately, since you were never actually too high in the first place, this action instead sends you below the glidepath, and straight into the ground.

Pockets of low pressure as you describe just don't exist to that degree. Hurricanes take hundreds of kilometres to reach their low point. And anyway, this is why airliners have a requirement for the approach to be stabilized at a specific point -  typically 1000ft above the aerodrome level. Any significant deviation from the glideslope below this point mandates a go-around.

  During a go-around, you set TOGA power on the throttles and pull back on the yoke; as the elevators are quicker to respond than the engines, the aircraft pitches up before it can accelerate much, resulting in the aircraft’s angle of attack temporarily increasing. Ram air enters the static ports, the altimeter says you’re lower than you actually are, and, in an attempt to avoid hitting the ground, you pull the yoke as far back as it’ll go, stalling the aircraft.

Altimeters are calibrated with multiple static ports and designed so AoA changes do not noticeably affect the altimeter. For the rest of this example, I mean I suppose a pilot could just forget the basics of flying but it's unlikely. Pilots know how to select the correct pitch and power to guarantee maximum climbing performance.

You didn't mention that altimeters are also affected by temperature, and in cold air they will read higher than reality.  There is no correction for this, and so some approaches will have limitations in very cold weather. EDIT: See John K's comment below.


Who was the US military pilot who crashed his plane and was accused of selling it to the Russians?

According to the relevant Wikipedia page Lt. David Steeves of the USAF bailed out of a T-33 trainer in 1957 near King's Canyon National Park in California and was not found until 52 days later.  When the crash site could not be located Steeves became the subject of various rumors, despite the T-33 being a relatively unimpressive trainer aircraft.

Steeves left the air force after the incident and reportedly conducted some of his own searches on the ground and in the air before being killed in an unrelated crash in Idaho in 1965.

A canopy located in the park in 1977 was as identified as being from this aircraft in 1978 but the remainder has not been found.  While no developments appear to have taken place in the story since then, it has occasionally been the subject of articles over the years.