Why is IndiGo adding A320NEOs more aggressively than any other airline?

It's quite common for the first customer(s) to serve as a proving ground.
Memorandums of understanding (MoU's) are signed that detail the specifics, which in 99% of the cases are not revealed to the public.
If IndiGo was upset, it would have been loud, but it hasn't been so:

IndiGo did not comment when approached by FlightGlobal.
In a statement to FlightGlobal, P&W says that it is supporting GoAir and IndiGo “to assess the situation and minimise any disruption”. However, the engine maker adds that the issues “are still under review so it would be premature to speculate on the cause(s)”.
"We are working closely with our customers and our suppliers in order to address and resolve these issues quickly," it adds.
— FlightGlobal

Not commenting hints at a non-disclosure agreement (NDA) in place and quite possibly discounts.


Is there any technical word to be used on Radio Telephony, to say that there is a "body air-shipped"?

The crew needs to be advised primarily, usually via the NOTOC(Notice to Captain) as this falls under Dangerous Goods classified as HUM under IATA.
But indeed, the controllers are not made aware of it, nor is it mentioned in the flight plan( as far as I'm aware).


What's the relationship between FANS and CPDLC?

Someone said FANS includes CPDLC, another said it does not.

It depends on the region and/or airplane generation.

There is the ICAO-compliant CPDLC used in Europe (via ATN-B1), and there is the Oceanic/US CPDLC (via ACARS).

A plane fitted with FANS 1/A+ has the Oceanic/US CPDLC, but not the European one.
New long-range planes like the 787 and A350 use FANS 2/B, which has both CPDLCs.$^a$

$^a$ This integration may be offered as a retrofit if it is possible. For example for Airbus – using Airbus' lingo – the A+B package was first introduced on the A350, then became available as a retrofit on the A380 (see slide below by Airbus).

(Airbus via ICAO)

For a brief historical context, see the history section I put together here.


Which Aircraft Models need a Tripod Jack for tail support at airport?

Tripods are mostly found in cargo aircraft (and combis) as the cg shift is severe there (particularly for front loading). A good example is the Boeing 747s. Also used in DC10/MD11s used as freighters.

Image from reddit.com

Some 747-400 combis also use these, though it is mainly for cargo loading.

Photo: Je89 W. / Source: PlanePictures.Net

Some passenger airliners are prone to tipping (737-900 comes to mind) and are usually supported by a pole rather than by a tail stand (same procedure is used in a KC-135 tanker too). For example, a Boeing 737-932ER with tail support.

Image from airliners.net

The tail supports are not strictly necessary and the loading can be carried out sequentially (from front to back) for safe operation, but are used as a  precaution. In some aircraft (like ATR-72 and Saab 340, called pogo sticks) small tubings are attached to the rear fuselage to prevent tipping over when loading/unloading.

Image from theflyingengineer.com

The nose can be tethered to prevent tipping during loading/unloading as done in this Korean Air 747F

Image from koreanair.com


How do I make a simple model to simulate a banked turn?

It's computed with centripetal force:

$$F_C = m \cdot V \cdot \omega $$

m = aircraft mass [kg]
V = aircraft speed [m/s]
$\omega$ = rate of turn [rad/s]

Centripetal force is a function of bank angle $\Phi$ and lift, or mass and flight path. For a coordinated, level turn:

Vertical lift $L \cdot cos(\Phi)= m \cdot g$ and turning lift $L \cdot sin(\Phi) = F_C$, so in a steady turn

$$ F_C = m \cdot g \cdot tan(\Phi)$$

$$\omega = \frac{g}{V} \cdot tan (\Phi) \tag{Steady Turn}$$

A more general equation, also valid for 90 degree bank angles and not concerned with the aircraft staying up in the air, can be found by considering horizontal forces only:

$$ \omega = \frac {L \cdot sin(\Phi)}{m \cdot V} \tag{always} $$

And then if you assume that lift L is still equal to weight $m \cdot g$ which means the aircraft is losing altitude in this turn, you're almost back at the Steady Turn equation but now with a sin instead of a tan.

The above is for SI units. For aircraft units with feet and knots, please check this answer, and here is one that introduces lift coefficient into the equation.


Has anyone built a paragliding simulator?

The popular simulator X-Plane allows you to build your own aircraft models it looks like some people have built paraglider models that you may want to take a look at. As for controls you can build all kinds of custom interfaces to simulate the controls of a paraglider but it will take some work.


Is the time pilots are commuting considered rest time?

Within the new fatigue regulations in Part 117 and the older Part 121.471, the word commuting is not defined. Deadheading is defined as follows (Part 117):

  Deadhead transportation means transportation of a flightcrew member as a passenger or non-operating flightcrew member, by any mode of transportation, as required by a certificate holder, excluding transportation to or from a suitable accommodation. All time spent in deadhead transportation is duty and is not rest. For purposes of determining the maximum flight duty period in Table B of this part, deadhead transportation is not considered a flight

Time spent deadheading must be included in the flight duty period calculation (Part 117.25):

  (g) If a flightcrew member engaged in deadhead transportation exceeds the applicable flight duty period in Table B of this part, the flightcrew member must be given a rest period equal to the length of the deadhead transportation but not less than the required rest in paragraph (e) of this section before beginning a flight duty period.

Deadheading and commuting are not the same. In section 11 of Advisory Circular 117-3, the FAA provides clarification. It defines deadheading as used to reposition flight crewmembers while commuting is considered an "individual initiated function".

To address the scenario, it would depend on if the time traveling from Florida to California was scheduled deadhead transportation. If so then the flight time is considered part of the duty period. If such a flight was individually initiated, then the time is commuting and is not part of the duty period.

Despite the potential legality of the situation, the FAA considers fatigue a joint responsibility between the flight crewmember and the certificate holder. This situation would put the flight crewmember at risk for fatigue. Individual airlines may place additional policy restrictions on commuting since Part 117 does not.


How to obtain true altitude from indicated altitude, temperature and QNH?

You need to correct your pressure altitude (FL85) for the barometer setting QNH first before you apply the temperature correction.
I assume a 30ft / hPa offset here:
$\textrm{barometric altitude} = \textrm{pressure altitude} + (\textrm{QNH} - 1013.25)\cdot 30 = 8500 -907.5 = 7592.5 \textrm{ft}$
Based on the pressure difference between sea level and your altimeter's measurement, the estimated altitude is 7592.15, assuming an ISA temperature profile.
Now, due to the fact that the actual temperature is lower, the atmosphere shrinks, and you end up flying lower.
Note that I will use -10° C for $\Delta_{ISA}$, because that was given in the question:

Outside Air Temperature: ISA - 10°

Now applying your correction formula yields:
$A_T = (4\times A_{Ik}\times\Delta_{ISA})+ A_I = (4 \times \frac{7592.5}{1000}\times -10)  + 7592.5 = -303.7 + 7592.5 = 7288.8 $
Rounding that to the nearest 50 ft results ins 7300 ft.
This is an approximation which is a bit on the low side. But underestimating true altitude is usually safer than overestimating.


How to justify that M_AC=0 for a symmetric airfoil?

Per definition the moment coefficient in the Aerodynamic Centre is independent of the angle of attack.
Since the airfoil is symmetrical, the moment around the a.c., $M_{a.c.}$ for an angle of attack $\alpha $ will be of equal magnitude and opposite sign at angle of attack $-\alpha $:
$M_{a.c.}(\alpha)=-M_{a.c.}(-\alpha)$

The two statements can only hold if $M_{a.c.} = 0$


How should I request an IFR approach at the end of a VFR flight?

Since you are already on flight following you are already in the system (ATC has a flight strip for you and a datablock on the radar).  Just call ATC and ask them for IFR to your destination.  Don't bother asking for a frequency change to FSS to file a flight plan, only to come right back on and ask to pick it up.

Austin Approach, Cessna 12345, request IFR to Austin

Since you have flight following ATC already knows your type, equipment suffix, location and altitude, so don't repeat it.  ATC should ask

Cessna 12345, verify you are qualified for and capable of IFR flight?1

and after you (hopefully) reply in the affirmative will issue:

Cessna 12345, cleared to the Austin Bergstrom Airport via fly heading 270, vector to ILS Runway 35-Right final approach course, maintain 2000.

If you are already in the approach environment you probably won't get a climb to an IFR altitude, you'll just be given whatever altitude they need for the arrival flow.
This method is faster than filing with FSS and easier for ATC (they don't have to approve a frequency change, wait around for you to file, then have you come back and wait further while your flight plan works its way through the system).  However, bear in mind that none of the "extra" search-and-rescue information you would give to FSS (fuel and souls on board, emergency equipment, filed alternate, aircraft color and markings) will be recorded.2
If you are landing at a towered airport you will not need to cancel IFR as the local controller will do this for you.  If you are landing at a non-towered airport you will need to radio ATC or FSS or telephone FSS to cancel your IFR service.

Footnotes
1This is a relatively new requirement after a non-IFR-rated pilot accepted an IFR clearance and subsequently crashed.
2Some facilities will have you rattle all that information off on the controller's frequency or a separate unused frequency and then mark that down in the flight plan remarks, just to have it on the tapes in case it's needed. If you're only 15 miles from your destination they probably won't do this but it's a possibility.


Are taller landing gear bad for aircraft, particulary large airliners?

Tall landing gear has been used in the past:

The Tu-114 needed really tall gear to clear the really big props. The drawbacks are extra weight and volume, as described in the other answers.

The Tu-114 was so tall, on its first flight to the US (the prototype was used to ferry Nikita Kruschev to the UN for some shoe banging) the available boarding stairs weren't tall enough. That arrival raised some eyebrows in the West because they'd done a nonstop flight from Moscow (the Tu-114 was the first aircraft that made that possible).


Why does the DC-9-80/MD-80 have this cusp in its fuselage?

It's not a stress concentrator; it's just the opposite.  What you're missing is that the floor itself at the pinched part forms a tension bridge that allows a more or less 'ovalized' circle while still maintaining tension loading on the skins and frames as if it was a pure circle.

If I had a rubber balloon filled with air and was able to run a string internally from one side to the other, attached to the walls of the balloon, and then drew the string in to pinch the sides of the balloon into a figure eightish profile, I'd have the same thing.  All the loads on the skins are still in tension, as well as the bridging floor beams (the string).


Why were there pneumatic headphones on airliners in the 70's and 80's?

Well, the rubber hoses themselves were used instead of traditional electromag transducer headphones for two main reasons; first, the hoses were much cheaper than a decent pair of traditional headphones at the time, and to an extent they're washable, so airlines could provide a pair for everyone at a much lower pricepoint than traditional headphones. Second, the hoses were more or less useless without the driving system aboard the aircraft, largely removing the incentive for passengers to walk off with them, again reducing costs of providing the system to passengers. The system was phased out in favor of simple 1/8" stereo jacks at each seat in the '80s and '90s as portable audio became mainstream, and as airlines looked to dramatically slash costs in the face of deregulation beginning in 1978. Economies of scale meant that buying cheapo Walkman-style headphones in bulk became cheaper than maintaining the aging pneumatic systems, and the electric-based system was more reliable and had several advantages (such as volume control for each passenger, and if standard 1/8" jacks were used, the ability for a savvy flyer to bring their own, nicer pair for use on the flight).

As an aside, this pneumatic audio system is still used today for a very different purpose; newborn hearing screenings. A pair of flaps with a mild adhesive are stuck to baby's ears, then hoses lead back to a finely-calibrated audio system coupled to an EEG. Audio is played and the EEG is monitored to detect the response to the sound in baby's brain. The hose system is used because it allows the expensive, fine-tolerance part of the audio system to be reused from test to test, while the hoses themselves are disposable and (as hospital equipment goes) fairly inexpensive.


What modifications would be required to use a DHC-6-400 for Carrier Onboard Delivery work?

DHC-6 has a reported takeoff roll of 210m and landing distance of 155m and as such can be operated from most of the aircraft carriers in service, albeit with limited capability. If required, the aircraft can takeoff into the wind and for arrested recovery rear fuselage can be strengthened, though this looks unnecessary.

It may need some changes for operating in marine environment like,

better corrosion protection
strengthened landing gear
Required naval equipment (for TO/landing).

Of course, all these modifications will eat into the payload. DHC-6 would be a rather small COD aircraft. The C-2 Greyhound used in USN has a payload greater than the MTOW of the twin otter.


Do aircraft always have the right of way on the ground? Or must they yield to police/fire/ambulance?

Just because one has the right of way, does not mean they must exercise that right.

If a pilot sees an emergency vehicle, and is able to, I expect he would stop, and either flash his lights or wave visibly to allow an emergency vehicle to proceed.

The aircraft has right of way, however, because the pilot may not see an emergency vehicle, or may not be able to stop quickly and safely.

So, yes, the aircraft always has right-of-way over ground traffic, according to the rules.  They are reasonably expected to yield in certain circumstances.


What is “abnd” on the U.S. VFR Sectional Chart?

ABND, according to the United States of America Aeronautical Contractions means:

Abandon

A link to this document can be found here:
FAA Website


How much can 3 fans 7 inches in diameter and each a generating 160 cubic feet per minute airflow rate lift?

You have volumetric flow rate and diameter, so you have the $\Delta v$ ($v = A \dot V$) and you have the mass flow rate ($\dot m = \varrho \dot V$) and that gives you the momentum per unit of time a.k.a. force ($\dot p = \Delta v\cdot\dot m = F$).

Run the numbers yourself, but don't get high hopes—the result is tiny (of course; you need a couple of metres diameter to lift a human with useful efficiency).


How do messages get from the destination airport to a pilot?

When the crew got their clearance for the trip from Clearance Delivery over the radio in the flight deck, it would've included a departure time window with the delay, and they may have been told by the CD controller why, or may have figured it out for themselves because it's a routine occurrence for the airport they were headed to (like Chicago).

Or, they were told prior to that during the planning brief with Operations. All the planning and filing is done by specialists in the airline's Operations department. The crew just shows up at Operations and picks up a package with everything prepared; the route, weather, provisional loading, fuel, etc. Going to an airport with a reservation protocol in place, they would have been briefed on that by Operations. That is all provisional however, the final routing, loading, fuel etc is determined when getting ready at the gate, and also when they get their ATC clearance by calling Clearance Delivery over the VHF radio before programming the Flight Management Computer.


Does TCAS II equipment satisfy the required ADS-B installation?

TCAS II and ADS-B are two entirely different systems, with entirely different functions, and they have different regulations. Having TCAS II installed & functioning does not satisfy any of the ADS-B OUT mandates.

ADS-B regulations European Union

For Europe, the regulations for ADS-B are published in the surveillance performance and interoperability requirements Implementing Rule (SPI-IR), Commission Implementing Regulation (EU) No 1207/2011, amended by Commission Implementing Regulation (EU)  No 1028/2014 and Commission Implementing Regulation (EU) 2017/386.

TCAS regulations European Union

TCAS II, version 7.1 is regulated by Commission Regulation (EU) No 1332/2011 amended  Commission Regulation (EU) 2016/918.


Does Active Thermal Imaging (NDI method) detect all types of structural faults in modern civil aircraft?

No. There is no single NDT method that can identify all types of structural faults in the aircraft.

Active thermography refers to the use of (thermal) exciters like ultrasound, (halogen and xenon) lamps, eddy current transducers and detecting the defects using that fact that the heat produced is different in those areas, usually using infrared cameras.

Though this is a very effective method for detecting defects, especially in composites, there are some disadvantages as well.

The test specimen has to be 'hooked up' to some form of (thermal) loading device. This limits the size of the tested part.
This is an excellent method for detecting subsurface defects; however, as the depth of the defect increases, the defect size has to be larger for detection.
The method requires that the temperature of the region (containing the defect) be uniform. This is a problem especially for materials with high thermal diffusivity like metals, which may require high speed IR cameras.
Though automated algorithms are available for defect detection, most of the (older) methods of thermography depend on the operator for interpretation of results.
The type of excitation technique used can be limited in some cases to prevent damage to the tested part.


Where can I get information about the FAA "restricted like" license to fly a N aircraft in Italy / Europe?

I don't know what an FAA "restricted" license is, but I guess it may be a foreign-based license issued under 14 CFR 61.75; see this answer for more information.

It's an FAA private license that's linked to your Italian one and it gives you all the privileges of a regular FAA private license, including operating N-reg aircraft anywhere in the world. But note that if your Italian license has more restrictions than the FAA one (e.g. no night flying) then you still have to obey those restrictions.

The process to get one is described here but I believe you have to physically visit an FAA office in the USA to get it.


What type of aircraft uses this long flashing pattern?

I'm assuming your question is : "What type of aircraft was it?".
Actually, we can't answer your question but you could try using Flightradar to identify the aircraft by watching a playback of the regarding time and place.

To hand you some trivia: If it was a red flashing light (the beacon) it is totally normal that the kind of flash varies. Modern aircraft use 360 degrees flashing lights (depending on the manufacturer it flashes faster or slower). Older (and most small aircraft) use rotating beacons which is just a red light shining in one direction which is turned by an motor (turns faster or slower depending on the motor).

If it was a big white light it could possibly have been the landing lights (which flash only on some aircraft) or the strobe light in the wings outer edges. They usually flash 2 times in one second and repeat the two flashes after 1 second of pause.


What is the tablet/application being used in this 737?

The screens on both electronic flight bags show airspeeds, which would indicate performance data. Specifically, the first officer has a speed card up.

I can't say for certain, but I think the pilot is using the iPad version of the Boeing Onboard Performance Tool. This application is used for weight and balance and performance calculations (which is especially appropriate, since they're flying a Boeing aircraft).


EDIT: please see at the bottom of the answer the update from EASA

Are two people required in cockpit at all times on large commercial aircraft?

No.
From EASA, pag. 101-102: (emphasis mine)

CAT.OP.MPA.210 Crew members at stations
Flight crew members

During take-off and landing each flight crew member required to be on duty in the flight crew compartment shall be at the assigned station.

During all other phases of flight each flight crew member required to be on duty in the flight crew compartment shall remain at the assigned station, unless absence is necessary for the performance of duties in connection with the operation or for physiological needs, provided at least one suitably qualified pilot remains at the controls of the aircraft at all times.

During all phases of flight each flight crew member required to be on duty in the flight crew compartment shall remain alert. If a lack of alertness is encountered, appropriate countermeasures shall be used. If unexpected fatigue is experienced, a controlled rest procedure, organised by the commander, may be used if workload permits. Controlled rest taken in this way shall not be considered to be part of a rest period for purposes of calculating flight time limitations nor used to justify
any extension of the duty period.

Do any airlines enforce such a rule?

As other answers mention, yes.

EDIT: On the 27th March 2015 EASA has issued the following Safety Information Bulletin :

operators are recommended to implement procedures requiring at least two persons authorised in accordance with CAT.GEN.MPA.135 to be in the flight crew compartment at all times, or other equivalent mitigating measures to address risks identified by the operator’s revised assessment.

This still does not mean that 2 people are required, but are recommended.


Yes, a flat rated engine (my familiarity is with gas turbines, but the concept may apply to other engine types), is an engine for which the control system is designed to achieve the same level of thrust (hence the "flat" term), up to a certain OAT, then for higher ambient temperatures, the level of thrust decreases as a function of OAT, normally in a pretty linear fashion. This control system operation gives identical performance over the flat portion of the OAT range even while the engine degrades (until it degrades to the point it hits the EGT limit), making the plane performance predictable. But for higher OATs, it stops the EGT continuing to increase. The temperature at which the thrust starts to decrease is typically 25 or 30 deg C, and can be found in the EASA or FAA engine type certificates (e.g. see section 6 of this EASA one for the CFM56-5). See the graph from this CFM56 document below. So, your understanding was correct.


Galley seal. It works like a cable tie, you can put one end inside a hole on the main body but you can't pull it out without destroying the seal.

The cabin crew will seal the galley carts containing alcohol and other duty-free items before landing and note the seal numbers in their report. This is required by law in a lot of countries.


Why doesn't flightradar show many flights going over China?

From the Flighradar How it works page:

  Flightradar24 relies on volunteers around the world for the majority
  of our coverage

Note it implies:

There are people willing to contribute
These people can afford to buy receptors, gather the data and upload it to Flightradar

About point 1. In case of China how much people are willing to contribute? How many are affraid to do it to a foreign organization and how much are affraid of gettign the wrong attention from government?

About point 2. Most people on China cannot afford to buy such equipment (compared to USA).

It's easy to check point 2 by comparing macro economic statistics (So I doubt I need to link it here).

Point 1 is very speculative so each one should try to figure that by him/herself.

In fact I always wondered Fligth radar will got a poor coverage in third world countries (point 1) while getting near 100% coverage in USA.

Note also the size of aviation community (pilots, enthusiasts, aviation industry workers, etc) in USA is so much bigger tha in other corners of the world.

Edit's in response to Jaydeep comments

Flighradar giving away equipment like that is great, I think Wow!
Note also the note on the same page:

  Exceptions to these requirements can be made to applications from
  unique locations.

So that begs the question if they are actually granting such gifts to China. For the sake of the completion I will ask them.

EDIT     and The Answer is:

So I asked Flightradar about it and they sent me the response below:

  Hello Jean,

  Thank you for contacting Flightradar24.com.

  Your Support reference is 219752.

  Yes, that is correct. We provide this free equipment to anyone in the
  world who has a good location with steady internet and power. The
  reason why you don't see many aircraft in the middle and west of China
  is because of the lack of receivers in these area.

  You make an application and we go from there if it's a good location.
  If we already have receivers in the area then we put the application
  on hold but if its a good location then we provide them with a free
  kit.

  https://www.flightradar24.com/apply-for-receiver
  -- Best Regards, Muazzam  Flightradar24

Straight from the horse's mouth the answer is simple "lack of receivers" what causes that is open to speculation but a quick search for "rural china power grid" and "rural china internet coverage" points out "steady internet and power" can be the problem.


How can I keep my A&P license active without being in aviation?

If you are "not in aviation", then I assume you are not working in/around/on airplanes. You are required to keep currency as per 61.53:

  § 65.83 Recent experience requirements.

  A certificated mechanic may not exercise the privileges of his certificate and rating unless, within the preceding 24 months -

  (a) The Administrator has found that he is able to do that work; or

  (b) He has, for at least 6 months -

  (1) Served as a mechanic under his certificate and rating;

  (2) Technically supervised other mechanics;

  (3) Supervised, in an executive capacity, the maintenance or alteration of aircraft; or

  (4) Been engaged in any combination of paragraph (b) (1), (2), or (3) of this section.

So the only way you can keep your currency (or regain it after you become non-current) without doing anything in Aviation is to demonstrate to the "Administrator" that you are able to do that work. What this entails is not defined in the CFR's, so will be up to your local FSDO.

Otherwise you can take a few hours a week and do mechanic work, for example you may be able to find a flight club and do some fleet maintenance (exchange it for instruction time or something).

tl;dr; You can't keep your license current without working on airplanes or supervising other mechanics. It would be analogous to keeping your pilots license current without ever flying.


Why isn't tungsten used in supersonic aircraft?

While tungsten does have a high melting point (I'm not sure what's the relevance of boiling point here), it has little else to offer for aircraft construction. The main issue of course is weight. One of the main goals of aircraft design is to reduce weight while achieving all the required performance parameters and tungsten is among the heaviest elements around, even beating Uranium.

When you factor in its density, it appears less than ordinary- its specific strength is less than 100 KNm/kg, less than half of Aluminum. Another thing is that tungsten is not exactly an easy material when it comes manufacturability. Even its saving grace, the high melting point (over 3000$^{\circ}$ C) is not very relevant as far as supersonic aircraft are concerned. The temperatures experienced in aircraft anywhere other than engines is well within that limit. For example, the surface temperature of Concorde wouldn't even get to a tenth of it.

Concorde surface temperature; image from erau.edu

Surprisingly, tungsten is indeed used in aerospace industry- at exactly the other end of the speed spectrum. it is used as a counterweight for controls in small aircraft and also as balancing masses in rotorcraft blades.


Pilot passed out in a small GA plane. What can a passenger do?

Best case scenario: You're straight and level, on frequency with some form of human being, there's no immediate danger and you have the know-how to transmit. In that case, that human will provide you with everything they possibly can to help you. Most important thing for you to do is keep the aircraft away from clouds, away from terrain and not panic. You'll probably be in an aircraft that is more-or-less easy to fly in this situation. Most GA aircraft are quite stable and will not be a beast to control.

Once talking to ATC they will tell you to set your transponder to a number. You should find somewhere a 4-digit readout with a knob below/above each digit. Set the number indicated to help ATC identify you easily.

Otherwise, look around you for big landmarks (Mountains, Lakes, even a large Church/Cathedral) as one of the first things ATC will want to do is work out where you are.

That's best case; let's look at some alternatives.

You're out of range of the tuned frequency on the radio, or there is no response:

Tune 121.5MHz, this is the emergency frequency. Someone will be monitoring this channel and be able to give you further advice - if nothing else a local ATC channel to tune. Failing this see if your pilot has a chart handy, he may have drawn his intended route on it - look along that route for anything that looks like a frequency to tune into the radio.

Aircraft is climbing, or descending:

Get the aircraft into safe, level flight. Remember controls work in the opposite sense to what you might expect (probably not if you've ever played any flight simulator). If the engine is roaring reduce power slightly. If you appear to be losing altitude with the nose on the horizon increase power slightly. Do everything with tiny incremental changes. Try not to fiddle too much with controls, only what is necessary.

Aircraft is heading directly for a cloud/out to the sea/towards a heavily built up area/a big airport:

Turn 180 degrees - don't try to turn too quickly, it should take roughly 30 seconds to 1 minute to complete this turn.

There are courses which are aimed at non-pilots who regularly fly in the right hand seat. Here's some interesting reading:

http://www.avweb.com/news/safety/183023-1.html


Why can APU supply both bleed air and electrical power up to 10.000 feet but bleed air alone up to 17000?

It's a function of the relative demand each service puts on the APU.  You have to remember that bleed is power consumed; you're just taking it in a different form.

As a turboshaft jet engine, the primary limitation on total power is the amount of heat the turbine can take.  When you take bleed from the compressor, the turbine is forced to generate a lot of torque to drive the compressor but it's not getting the mass flow downstream through the burner can and turbine that it would get without any bleed (it's like you were cranking a fan by hand to cool yourself, but some joker put a piece of cardboard between you and the fan to divert most of the air - you're getting some air but you'd be pretty hot and bothered and you just can't do the total work you could do if you were getting all the air).

Since one of its primary functions is to provide hot air to the cabin as opposed to making thrust, a much higher proportion of its mass flow is bled off an APU's compressor compared to a main engine, and is a significant portion of the engine's energy potential. The generator, on the other hand, puts much less demand on the engine.

The result is for the same shaft HP available to drive the generator, the turbine temperatures are much higher when bleed is on, basically because it's doing the job of providing shaft HP and providing compressed air. Hence the 10000 ft limitation when doing both at the same time.

The other altitude limits are based on the effect each service individually has on the APU's temperature limits.  The compressed air service, the bleed, uses most of the APU's power potential and maxes out at 17000 ft, with the generator a distant second and when it's the only service the APU has the HP available to run the generator all the way to 41000 ft.


When the winds aloft are light and variable, what wind direction and speed should I use for flight planning?

Light and variable means there's no meaningful windspeed or direction, so you can just ignore it. For planning purposes, you can simply plan as if the wind was calm.

But, it's very possible that the winds will actually be stronger and more directional than forecast. You should check your actual track and times against what you planned, and adjust your navlog in flight as needed. That's one of the cross-country navigation skills that pilots are expected to learn.


Does the Fokker 70/100 Flight Management Computer really contain the ability to play Pong?

The 'clip' is obviously a fake. Standards for avionics software development and testing are rigorous, with development of flight critical software being done by separate (independent) groups and legally required to be reviewed by another (independent) group.
After that testing is done by another group/person who's certified by the regulatory authority. It is very very difficult and downright dangerous to have this kind of codes in flight critical system software.
Also, as BowlOfRed says, there is a point in the video where the finger (of copilot?) goes behind the screen.

Also, from the clip, it appears that the two 'players' predict each other's moves pretty accurately. I'm not very sure if that's the way it is played, but I doubt it.
Of course, to prove that something is impossible is not possible, but I'm quite certain that the clip is a fake.


Do airplanes have a maximum headwind gust component when landing?

This is quite similar to the linked question but does have some differences. Gust components while reported differently are still part of the crosswind component. In other words a reporting like

  Rwy 03, wind 090/25 gusting 40 kts

Is another way of saying the wind is holding at 25Kts and could be as high as 40Kts at times while you are on approach. In other words you may have a 25kt cross wind on touch down or you may have a 40Kt cross wind. Generally speaking gusts occur in the direction of the wind. In some cases gusty days also come with shifty wind conditions which add for a whole new element of fun.

The maximum gust component is not quoted in the POH because there are to many inconsistent factors that may effect it. The main one being the duration of the gust. A short gust well in excess of your crosswind maximum may be recoverable while long gusts in excess of your crosswind maximum may be unsafe. Strictly speaking a loose limit would look something like

(maximum reported crosswind) + (gust wind * gust time) > cross wind component

but gust time is not reported and thats a lot of trig to crunch on the fly so no limit is typically given. I have landed a Piper Archer in conditions gusting in excess of 40Kts safely but the wind was no more than 20 degrees off the runway.

Eventually you just run out of control surface...

  Example: imagine a GA aircraft with a typical takeoff speed of 60 kts,
  approach speed of 70 kts. Runway is 27, wind is 270 degrees at 20 kts.
  What would be the maximum gust speed along the runway to operate in
  safe conditions?

In this scenario, with the wind down the runway, your maximum gust component is 50Kts. Above that and at your 70kts approach speed you would be moving backwards across the ground making it quite hard to reach the runway and potentially difficult to land the airplane if a gust were to occur at a low altitude. Most trainer aircraft like the one you describe cant do better than ~120Kts so 100Kts is about your gust limit otherwise its going to be hard to get to the runway.

NOTE: Gusty conditions (in my experience) are also generally accompanied by turbulence and in bad cases, wind shear. In many instances all of these factors combined can make an approach unsafe or un-flyable.

There is also an interesting discussion on it here.


How does the load factor vary when the aircraft pitches up/down?

Think not about the rate of pitching but rather about the skyward or earthward curvature in the flight path (trajectory).  This curvature is an acceleration, and requires a force to make it happen.

G-load (i.e. load factor) is essentially just the aerodynamic force generated by the aircraft, divided by weight.

In straight-and-level flight the G-load is +1.

In the case where the aircraft is wings-level and in a level upright pitch attitude (not inverted), we can observe--

If the flight path is curving skyward, the G-load is greater than +1

If the flight path is curving earthward, the G-load is less than +1.  It may even be zero or negative.

This answer could be expanded to consider other flight attitudes.  Think about a loop.  At any instant in time, if the flight path is curving, some force is causing that. The main forces that could be contributing to this curvature are gravity, and the wings' lift force.  Of these two forces, only the latter one determines the G-loading, i.e. the load factor.  In the plane's own reference frame, an "upward" aerodynamic force (towards the canopy) creates a positive G-loading, and a "downward" aerodynamic force (toward the belly) creates a negative G-loading.

Knowing this, you can compute the G-load at any instant, as long as you know the aircraft's attitude in space, velocity, mass, and the radius of curvature of the flight path.

Starting from level upright flight, if you pull back on the stick or yoke, you'll feel heavier.  If you push forward on the stick or yoke, you'll feel lighter.

Note: this answer assumes we are measuring the G-force near the center of pitch rotation of the aircraft.  A pilot seated far forward of the center of pitch rotation will feel a greater increase in G-load when pitching up, and a greater shift toward a negative G-load when pitching down, than if he were seated at the center of pitch rotation.  The same is true of the load factor imposed on any part of the aircraft structure.


How does having multiple ATC towers affect airport operations?

At larger airports it is fairly common to have more than one tower, but it all comes down to how well the tower controllers can see airplanes.  Sometimes they have different towers for ground control frequencies and tower control frequencies, and the position of the tower is optimized for the appropriate task.  For very large airports, they may need towers in different areas of the airport to properly see airplanes at each runway.

As far as practical consequences it doesn't matter much whether they have one or more towers.  At very busy airports they split up the tower/ground controllers/frequencies because one person can only control so many airplanes at a time.  For instance, there may be one controller for the North runway and one for the South runway.  In this case, there could be only one ground controller, or there may be two or even more, depending on the complexity of the ground operations.  With multiple ground frequencies, if you need to taxi from one controlled area to another, the controller that you are talking to will tell you to hold short of a particular point and contact ground on the other frequency.  Once you contact the second controller, they will clear you to continue taxiing.

In short, it is very specific to the local conditions, and they do what they have to in order to properly control the traffic.


How can I calculate the velocity of air drawn by a pusher configured propeller?

Well, the textbooks tell you how to design a subsonic shroud for a turbofan and a propeller, but they usually don't tell you how to design half a shroud for a propeller. Besides, you need to pick a profile for the wing section in the channel also.

There are theoretical equations and heuristic ones for a propeller with not too many blades, but these are not nearly as useful as a run of CFD. The key part is to translate the number of blades and RPM, given pitch, chord, span, wash, and wingtip device into $\Delta p$ across the plane of the propeller. This is better done through simulation and experimenting than working with pen, paper and slide rule.

The roughest of the rough approximation is, of course, assuming $\alpha\approx0$ for each of the blade and $v_\mathrm{i}\approx\frac{1}{2}\cdot\omega\cdot\left(r_a\tan\theta_a+r_b\tan\theta_b\right)$ and assume $v_\mathrm{o}\approx v_\mathrm{i}$, where point $a$ is the point where the blade starts near the rotating axis, and $b$ the wingtip, $\omega$ the angluar velocity of the propeller, $r_{(\cdot)}$ the distance from the rotating axis and $\theta_{(\cdot)}$ the pitch angle.

The pusher configuration means the air hits the engine nacelle before it meets the propeller, and the propeller, therefore, works in disturbed air, if it's got a gas engine it will work also in the pulsing exhaust of the engine.


Why are aerial taxis multirotored, instead of a single rotor?

There are a few main reasons most electric air taxi concepts have multiple rotors.

1) Mechanical simplicity.  Helicopters are controlled by varying the angle of attack of the blades as the rotate, and the mechanical mechanisms to do this (swashplates) are complex and expensive to build and maintain. The thinking is that with electric motors, you can stabilize the vehicle using differential thrust and eliminate the complexity of those systems.  This has implications for vehicle cost.

2) Noise.  One of the main reasons there aren't any helicopter airlines around now (and there used to be) is that helicopters are very noisy.  Noise in rotorcraft is related to a lot of things, but one of the main drivers is blade tip speed.  With more, smaller rotors, you can have lower blade tip speeds for the same disk area, thereby reducing noise.  Whether this has the potential to reduce noise enough to make a significant difference has yet to be conclusively demonstrated, mostly because there's no clear definition of "enough noise reduction".

3) Safety.  Another argument commonly made for eVTOL air taxis is more motors = more safety, because if one motor fails you have lots of others to keep you in the air.  The validity of this argument depends on how much redundancy you have in the rest of your powertrain, but it principle the opportunity for more redundancy offers a pathway to improved reliability.  There are new failure modes introduced by this multitude of rotors and in general these vehicles have no autorotation capability, making a total power failure much higher consequence; all of which needs to be taken into account.

4) It looks cool There's probably more to this argument than it gets credit for.  Most of the investment and momentum behind the air taxi concept is coming from Silicon Valley and not the traditional aerospace players (who, it must be said, are started to get onboard - especially Airbus). This creates pressure to develop a product that looks and feels revolutionary, to raise the billions required for aircraft development.  Public acceptance of these systems will also be an issue, and public opinion in many large cities is pretty anti-helicopter.

From a performance standpoint the big difference between most multirotor concepts and current helicopters is that lots of multirotor concepts are battery-powered (for noise, local emission, and infrastructure flexibility reasons). Batteries are much worse than avgas from a energy/weight standpoint.  A hybrid-electric multirotor would have broadly similar performance to a hybrid-electric helicopter, assuming they had the same disc loading.


Where can I find the exact definition of VFR and IFR?

The Rules of the Air are defined by ICAO and made applicable with few deviations in the ICAO member states.
ICAO Annex 2 Rules of the Air, defines in addition to the general rules, the Visual Flight Rules (VFR) and the Instrument Flight Rules (IFR). Flights shall be in compliance with either of them.

2.2 Compliance with the rules of the air
The operation of an aircraft either in flight or on the movement area of an aerodrome shall be in
compliance with the general rules and, in addition, when in flight,
either with:
a) the visual flight rules; or
b) the instrument flight
rules.

Chapter 5 of Annex 2 contains the Instrument Flight rules.
Chapter 4 of Annex 2 contains the Visual Flight Rules.

4.1 Except when operating as a special VFR flight, VFR flights shall be conducted so that the aircraft is flown in conditions of visibility and distance from clouds equal to or greater than those specified in Table 3-1.

Table 3-1 is summarized below.
+---------------------------+-------------------+---------------------+-----------------------------+
|      Altitude band        |   Airspace class  |  Flight visibility  |     Distance from cloud     |
+---------------------------+-------------------+---------------------+-----------------------------+
| At and above 3 050 m      | A*** B C D E F G  |        8 km         | 1 500 m horizontally        |
| (10 000 ft) AMSL          |                   |                     | 300 m (1 000 ft) vertically |
+---------------------------+-------------------+---------------------+-----------------------------+
| Below 3 050 m (10 000 ft) | A*** B C D E F G  |        5 km         | 1 500 m horizontally        |
| AMSL and above 900 m      |                   |                     | 300 m (1 000 ft) vertically |
| (3 000 ft) AMSL, or above |                   |                     |                             |
| 300 m (1 000 ft) above    |                   |                     |                             |
| terrain, whichever is the |                   |                     |                             |
| higher                    |                   |                     |                             |
+---------------------------+-------------------+---------------------+-----------------------------+
| At and below 900 m        |   A*** B C D E    |        5 km         | 1 500 m horizontally        |
| (3 000 ft) AMSL, or 300 m |                   |                     | 300 m (1 000 ft) vertically |
| (1 000 ft) above terrain, +-------------------+---------------------+-----------------------------+
| whichever is the higher   |        F G        |        5 km**       | Clear of cloud and with the |
|                           |                   |                     | surface in sight            |
+---------------------------+-------------------+---------------------+-----------------------------+
* When the height of the transition altitude is lower than 3 050 m (10 000 ft) AMSL, FL 100 should be
  used in lieu of 10 000 ft.
** When so prescribed by the appropriate ATS authority:
    a) flight visibilities reduced to not less than 1 500 m may be permitted for flights operating:
        1) at speeds that, in the prevailing visibility, will give adequate opportunity to observe
           other traffic or any obstacles in time to avoid collision; or
        2) in circumstances in which the probability of encounters with other traffic would normally
           be low, e.g. in areas of low volume traffic and for aerial work at low levels.
    b) HELICOPTERS may be permitted to operate in less than 1 500 m flight visibility, if manoeuvred
       at a speed that will give adequate opportunity to observe other traffic or any obstacles in
       time to avoid collision.
*** The VMC minima in Class A airspace are included for guidance to pilots and do not imply
    acceptance of VFR flights in Class A airspace

For Air Traffic Management purposes, ICAO Doc 4444 gives more detail of how both types of flights are treated by ATC.

National regulations may deviate from ICAO regulation. If they do deviate, the deviation have to be published in the Aeronautical Information Publication of the country.


What do I do if I wish to move my software from DAL Level A to DAL Level C?

If I wish to downgrade my software's design assurance level (DAL) from Level A to Level C, what do I need to do?

DAL level A software is software which, if it fails, may have "catastrophic" results, defined as "Failure may cause multiple fatalities, usually with loss of airplane."

DAL level C, "Failure significantly reduces the safety margin or significantly increases crew workload. May result in passenger discomfort (or even minor injuries)."

So, to move your software from DAL level A to DAL level C, you'll have to reduce the responsibility of your software.  Your software's operation or failure to operate cannot:

result in passenger major injury or fatality
produce a large negative impact on safety or performance of the aircraft
reduce the ability of the crew to operate the aircraft due to physical distress or higher workload (though significant increases in workload is acceptable at Level C)

At most, your software's operation or failure to operate may:

Significantly reduce safety margins
Significantly increase crew workload
Result in passenger discomfort or minor injury

If you can change your software, or change your customer's use of the software (ie, cannot be used or installed as part of a safety critical control system), then the certifying authorities may allow your software to be certified at Level C.

  What are the benefits and drawbacks of doing this?

There are only 62 objectives that have to be met, and of those only 8 have to be verified by someone independent of the person who implemented the code that falls under that objective. While the number of objectives is only reduced a little (71 vs 62), the number requiring independent verification is cut by over 75% from 33 to 8. This significantly reduces the amount of work required to meet certification requirements, mostly in traceability.

The major drawback is that your software cannot be used or incorporated into systems which require a higher level of compliance.

So if your software is designed to control actuators and is currently certified to Level A, you might find that it's being used to control flight surfaces on some planes.

The move to Level C may, in that case, not require any software changes at all.  If you stop performing the full traceability, tests, and meeting objectives with independence at Level A, and only perform those necessary for Level C, then your release under this new system will necessarily only be certified under Level C.  The software can no longer be used to control flight surfaces, but if a new plane comes out with electronically adjustable air nozzles in the passenger compartment, it may be eligible for inclusion there where failure would, at worst, cause passenger discomfort and increase crew workload managing complaints about air vents being misdirected or opened/closed when the opposite is desired.

If your software is an autopilot, though, then it will never be used if it doesn't meet Level A.  In this case, there's no way to change your software or process to a lower level and expect it to be used - the usage of the software defines the level to which it must comply.

In most cases, the usage will drive which level the software must be certified to, and there's no real way (or reason) for you to change your level.  It would cease to be useful software at the wrong level.


What are the other clearance and instructions that must be read back?

Generally speaking, you should read back all clearances, instructions and warnings. You may in some cases not need to read back information, unless it is safety critical (for example QNH).

One of the only instructions I can think of that you do not need to read back is an instruction to report something (report passing 5000 feet, report established, report overhead XYZ). A proper reply to an instruction to report something would be "WILCO". But in all other cases, if ATC directly instructs you to do something, it should be read back.


What is the purpose of the extending wingtip panels on the Su-25?

Those are airbrakes, they allow the aircraft to increase its drag substantially to bleed off excess energy. They are hydraulically operated, and need pressure for both deployment and retraction, i.e. they do not auto-stow, at least on this aircraft.

Airbrakes are a handy feature, especially for a ground attack aircraft like the Su-25 in your picture, as they help both with landing on short airstrips and with dive bombing, a tactic that requires to dive almost vertically on a target to minimize slant errors in targeting. This is made possible by the airbrake, which prevents the aircraft from exceeding its dive speed.

Other aircraft types use or have used airbrakes in the past, mainly to dissipate energy during an approach. Examples include some airliners, most fighters and nearly all gliders.

Fighters are usually optimized for high speeds which are dangerous to land at, and an airbrake enables them to quickly slow down while on final approach, remaining at a comfortable speed until the last moment. They also have some occasional uses in WVR (Within visual Range) combat, but this will be rabidly argued against by the BVR (Beyond Visual Range) and stealth cults.

Gliders also use airbrakes to control their speed on approach and when diving, but also to arrest undesired climbs, when caught in a thermal when they need to descend. Since typically gliders lack a hydraulic or even electric system, their airbrakes are actuated by the pilot's muscles and are more akin to spoilers.

The geometry of an airbrake can vary significantly, but the principle is the same: a large surface extended into the airstream that generates mostly drag. their location on the airframe is a compromise between structural, mechanical and control considerations, i.e., it needs to be strong enough to resist the loads, easy enough to route hydraulic lines or control rods to, and not significantly impact the aircraft's stability.  The examples below are a BAe 146, an F-15, a Slingsby Capstan and a MiG-23:


What do professional pilots keep track of in their pilot log books?

The experience required is simply flying hours on the type or configuration, and flying hours, for pilot logging purposes, is time from engine start to engine shutdown.  If you're flying an airplane with a Hobbs, which usually starts/stops using oil pressure, you can just use the Hobbs value.  If no Hobbs, record the engine start/stop time yourself and use that, or if you forgot to, just use the tachometer hours reading (which is closer to air time, or time airborne) and add a 10th.


Is the "wing area" of a biplane the projected area or the total area?

It's a mixture of both: You add the projected area of both wings, measured separately, without overlap.

The effective (wetted) area is used for friction drag calculations only.


How do the actuator loads (e.g. for the ailerons) vary between different flight phases?

Indeed the hinge moment equation is (with index $_s$ for surface)
$$H_s = C_{h_s} \cdot ½  \rho V^2 \cdot  \delta_s \cdot S_s \cdot \bar{c_s}$$

The moment coefficient $C_{h_s}$ depends on aircraft angle of attack, surface deflection (!) and trim tab deflection, as depicted in the figure below (from this answer). It is not a simple constant linear function due to shading of horizontal tail in the flow of other bits of aircraft structure.

So of course, hinge moment calculation depends on aeroplane configuration and geometry. But as @JanHudec mentions in a comment, the two main variables here are dynamic pressure and surface deflection.

Full surface deflection at cruise speed results in the largest hinge moment. It may also result in structural forces higher than the limit design forces, for instance load factors > 2.5g. It would be safest if the actuator force can never exceed the hinge moment required to reach maximum load factor, which would require making plots of (hinge moment for max. load factor) vs. airspeed, at different c.g. at maximum weight.


On the LAANC map for sUAS operations, why does the permitted ceiling drop to zero southeast of KGFL?

It turns out that the E2 Class-E-to-surface airspace around KGFL has been recently expanded, and the long "arm" projecting to the southwest is a new addition.  KGFL is listed in the current (as of February 2021) version of the FAA's "Airspace Designations and Reporting Points" document, FAA Joint Order 7400.11E.  The airspace change was published in the Federal Register on July 31, 2020, and became effective November 5, 2020.  The old airspace description may be seen on page E-30 of the July 21, 2020 edition of the Airspace Designations and Reporting Points document, J.O. 7400.11E.
One might wonder whether, after the airspace change, the newly-added LAANC grid squares were assigned a zero ceiling to accommodate some unusual feature of the new instrument approaches and departures in the vicinity, while by some oversight no adjustment was made to adjust the ceilings of the previously existing grid squares to accommodate the new approaches and departures.
Close scrutiny of the approach plates suggests that this is unlikely.  Granted, there is some modest amount of relief in the terrain southeast of KGFL. The ridge east of the town of "North Argyle", about 9.6 miles from the airport, tops out at just over 1000' MSL-- let's call it 1100' MSL to be conservative. The airport KGFL is at 328' MSL, so by our conservative estimate the top of the ridge is 772' higher than the airport. This works out to a slope of 66 to 1, or 0.87 degrees above horizontal. Add 400' to the top of the ridge to represent the maximum AGL altitude that the FAA typically grants for sUAS operations, and we have a 43.4 to 1 slope to the airport, or 1.32 degrees above horizontal.  It is difficult to see how permitting sUAS flight beneath this less-than-2-degree-slope would endanger aircraft on the instrument approaches into KGFL. For example, the RNAV (GPS) RWY 30 approach appears to show a Final Approach Fix ERUPE at 2300' MSL just 5 nautical miles from the airport. The Intermediate Fix CATIR is at 4200' MSL, 12 nautical miles from the airport.
Further scrutiny has revealed that the zero ceiling assigned to the new LAANC grid squares southeast of KGFL perfectly fits a pattern, that appears to have little relationship to safety considerations.
The pattern is as follows:  for most or all expansions or other modifications of existing controlled airspace effective 9/10/20 or later, any new squares that have to be added to the LAANC grid have been assigned a ceiling of 0 AGL.
As a result, whenever a significant new "arm" or projection is added to an existing area of controlled airspace, then we can get a pattern like we see at KGFL, where the portion of the new projection that lies outside of any previously existing LAANC grid squares is assigned a ceiling of zero, while the (older) grid squares closer to the airport retain a higher ceiling.
On the other hand, when an existing area of controlled airspace is expanded by a small amount, then we can have a pattern where just a few new LAANC grid squares, seemingly randomly scattered around the periphery of the old airspace, need to be created to accommodate the expanded airspace.  Very often the new airspace just barely impinges into most of these new grid squares.  All of these new grid squares are assigned a ceiling of zero.  This can happen even when the airspace is not actually expanded at all, but rather is simply moved a few hundred feet due to a slight change in the official location of the airport.  It's pretty clear that no safety consideration could possibly be involved in the zero-ceiling assignment in the latter case.
Why this pattern has recently arisen, remains a mystery.  At present it would be hard to say whether it is due to a decision taken at a high level of the FAA, or due to the choices of some particular data entry technician, or due to exigencies of life in the time of Covid-19.  Is there an intention to revisit these cases and correct the arbitrarily low ceiling assignments?  Is there an intention to continue the practice indefinitely?  The FAA sUAS Help Desk has been contacted, and further developments may ensue.
Here are additional specific examples of the pattern described above:1

KDRO -- Durango-La Plata County Airport -- Durango CO -- E2 Class-E-to-surface
Old airspace description page E-72 in FAA Joint Order 7400.11A,new airspace description on page E-68 in Joint Order 7400.11E.  Effective 09/10/20, the official airport location was moved about 130' to the NW, but more significantly, a new "arm" was added to the Class E airspace, projecting 2 miles to the NE, 2 miles in width.  As a result of this new "arm",  7 new squares were added to the LAANC grid, of all which assigned a ceiling of zero.   Note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid squares and the airport.

KDLN -- Dillon Airport -- Dillon MT -- E2 Class-E-to-surface -- second attachment
Old airspace description page E-77 in 7400.11A, new airspace description page E-74 in 7400.11E.  Effective 9/10/20, the Class E circle was decreased in radius by 0.9 miles, but a new "arm" was also added, 4.8 miles in width and projecting .7 miles beyond the original radius.   As a result of this new "arm", 8 new squares were added to the LAANC grid, all of which were assigned a ceiling of zero.  Again, note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid squares and the airport.

KCXO -- Conroe-North Houston Regional Airport -- Houston, TX -- Class D --third attachment
Old airspace description page D-125 in 7400.11A, new airspace description page D-125 in 7400.11E.  Effective 9/10/20, the official location of the airport was shifted about 350' to the NNW, and the radius of the Class D circle was increased by .7 miles (about 3700').  As a result of these changes, 27 new  squares were added to the LAANC grid, all of which were assigned a ceiling of zero.  Again, note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid squares and the airport.

KFWS -- Fort Worth Spinks Airport -- Fort Worth, Texas -- Class D --fourth attachment
Old airspace description page D-129 in 7400.11A, new airspace description page D-125 in 7400.11E.  Effective 9/10/20, the official location of the airport was shifted about 85 feet to the west.  As a result of these changes, a single new square was added to the LAANC grid, barely penetrated by the new location of the controlled airspace, with an assigned ceiling of "0" AGL.  Again, note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid square and the airport.

KALN --  St Louis Regional Airport  --Alton/St Louis, IL -- Class D
Old airspace description is on page D-31 in 7400.11E, new airspace description is on this page of the Federal Register.
page D-125 in 7400.11E.  Effective 11/05/20, the Class D airspace was expanded by .2 miles (about 1056 feet), and the center of the circle was shifted about 218' to the southwest due to the change in the official location of the airport.  As a result, there are now 6 anomalous zero-ceiling LAANC grid squares running from the south edge of the airspace clockwise around to the northwest edge of the airspace.  Note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid squares and the airport.

PABE --  Bethel Airport-- Bethel, AK-- Class D
Old airspace description is on page D-3 in 7400.11E, new airspace description is on this page of the Federal Register.
page D-125 in 7400.11E.  Effective 12/31/20, the Class D circle was shifted about 430' to the southeast due to the change in the official location of the airport.  As a result, there are now 3 anomalous zero-ceiling LAANC grid squares at the southeast edge of the airspace.  Note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid squares and the airport.

PASI2 -- Sitka Rocky Gutierrez Airport -- Sitka, AK -- E2 Class-E-to-surface airspace
Old airspace description is on page E-9 in 7400.11E, new airspace description is on this page of the Federal Register.  Effective 11/05/20, the Class-E-to-surface circle was shifted about 150' to the southeast due to the change in the official location of the airport.  As a result, there is now a single anomalous zero-ceiling LAANC grid squares at the ESE edge of the airspace.  Note the presence of grid squares with a 400' ceiling between the new zero-ceiling grid squares and the airport.
Footnotes:

All LAANC screenshots taken on 2-1-21

As of 2-1-21 this link to an on-line portrayal of the aviation sectional chart covering PASI still showed the airspace as it was configured before a recent change that came into effect 11-5-20.  It appears that the 11/5/20 edition of the Juneau sectional chart has not yet actually been made available on-line (see non-working links for Juneau sectional on the FAA's "VFR Raster Charts" page.)  The new configuration of the airspace at PASI, which involves a (nearly circular) E2 Class-E-to-surface area and a single, very large, rectangular E4 Class-E-to-surface extension, may be seen by selecting the appropriate layers on the LAANC map display after entering "PASI" into the search window.  The airspace configuration at PASI therefore is now similar to the airspace configuration at KACV and KTLV, as described in the related ASE question What is the primary reason that the non-towered airports KACV and KTVL have E4 extensions to E2 airspace? .


How to command autopilot to start a fixed rate descent?

Here is what typical autopilot controls look like

Image source: What is a "Flight Director"?

The pilot can set the required altitude, as well as the required vertical speed to get to that altitude. A cruise decent will typically use a shallower descent than an approach descent.


Has there ever been a seaplane with inflatable airbags rather than traditional pontoons?

I would think the stresses would be fairly high and I dont know of any off the bat but there have been helicopters outfitted with them.

(source)

On the drag front, this is only really a problem for smaller sea planes (C172, Caravan etc.). On the large side of things when you want to reduce drag a belly land design is used like in a Grumman G-21 or even as far as the worlds largest airplane the Hughes H-4 Hercules.


How easy is it to pull the ejection handle in a Rafale B?

Believe I remember reading in Scott O'Grady's book that the pull handle in the F-16 required 35lbs of pressure, which he considered to be a lot, but how easy he found it to pull when the time actually came. That I think is the ACES II system, where the Rafale is an MB MK16 one. I would guess the pressures are pretty universal.

There's a little light reading about ejection seats, though no specs on the pull pressure required.  Also has a ton of info. Little clunky to navigate, but good.

As to how a civilian could pull a handle accidentally... I guess throw someone into a jet, pull a half dozen Gs and watch them grab for something. Most tandem aircraft have split ejection "options", for lack of a better term, meaning the RIO/FO/passenger can punch himself out, but leave the pilot inside. Gotta be a hell of a surprise when the back seater disappears like that.

Likewise, I've seen and heard of numerous cases of canopies being blown accidentally without an actual ejection. Had an F-15C I was working on do it one afternoon in FL.


Can a pilot work flight engineer's station?

The pilot cannot just sit down in the flight engineer station.  First there is a different FAA flight engineer certificate that the pilot needs to obtain.  Secondly, the pilot would need to go through the airline's training program for that station.

Granted, a pilot who has flown that airplane before should quickly get those done.


What is the voltage and amps on the transformer rectifier?

What is displayed would be the OUTPUT of the TR.  Those values tell you that (if) the TR is working, and how hard it is working.  If it's supposed to be putting out 12 volts but the actual output is something significantly different, then the TR isn't working correctly.  The amps value tells you how much DC current is being demanded of the TR -- maybe something on the associated bus is consuming too much current (and is thus perhaps the source of smoke that you're trying to eliminate), or another TR in parallel has failed.  The failed TR would show 0 volts & 0 amps, while the operative TR would show normal volts & higher than normal amps.

If you want to know the voltage of the input to the TR, you'd select the generator or bus that is powering the TR to see that.  Voltage is typically a value of a bus, while amps is generally the value of a source, such as a generator, battery, or TR.  The source is putting out however many amps. While you can measure the voltage of a bus coming directly off of an electrical source (so we talk about a generator's or battery's or TR's voltage), you can also measure (and will frequently care more about) the voltage of a bus, independent of what source is powering it right now.  If my Essential DC bus has normal voltage, then the important things on it can be expected to continue operating, regardless of whether the current source for that bus is the #1 TR or the #2 + #3 TR's in parallel or the battery charger or the main battery or the standby battery or whatever else that particular aircraft may have.


Will a non-certified GPS source work the same in ADS-B mandated airspace?

It may work. It may not work. Nobody knows. If you use a non-certify equipment when you are required to use the certified one you are breaking the law. Nobody can be sure your equipment will work as required but everybody are sure you are breaking the law.

Don't do it. You are endangering your life and others.


Do pressure altimeters take into account differences in temperature?

You can't just adjust the QNH setting to compensate. The temperature adjustment is not linear. The error increases with altitude, so when the altimeter is set for QNH the error at field level is zero. But it increases the higher you go. It's not just everything being X number of feet higher or lower.

In your question you say "the aircraft's pressure altitude is lower than true altitude in winter." That's backwards. The actual altitude is actually lower than what is indicated by the pressure alt. This can run the risk of colliding with terrain if the pilot doesn't adjust. In fact, exceptionally hot weather causes an error also, but in the opposite direction. The reason this doesn't need to be compensated is because the actual altitude will be higher than indicated so it doesn't create a danger of hitting terrain.

From answers to another question an aircraft with an FMS can be set to automatically adjust.

The problem seems to be in who's responsible for making the adjustment (ATC or pilot) and being clear on whether the altitude announced is adjusted or not. According to the answer from wbeard52, in the US the FAA has established a list of airports with cold weather procedures that require the pilot to do the compensation and announce the corrected alt to the controller. According to Sami's answer, in the EU the controller makes the corrections under radar coverage, and the pilot makes the correction without. It would appear from your question that in Korea they have decided to have you make the corrections as controller.


Would it be possible to use a magnetron beneath glider plane to generate its own thermals?

This would not be feasible.  First of all electromagnetic radiation emitted by magnetrons would heat up the water vapor in the air and not necessarily the air itself.  Molecules must have a dipole for EM heating to work.  Second it is not just the heat, what really creates the lift is the moving air upwards.  If you heat the air underneath the airplane that doesn't mean you will make the air move.  Thermals are typically less effective when close to the ground.  Thirdly, finding thermals on your own is part of the sport.  I think that generating your own thermal would defeat the concept of the sport.

Also gliders don't have to completely rely on thermals to stay up.  Ridge Lift and Wave Lift can be used in mountainous areas where the lift is generated by a moderate wind slamming perpendicular to a mountain ridge forcing the air up.


How does an airplane owner correct an airplane misidentification showing up on FlightAware?

For the sake of it:
contact flightaware directly
https://flightaware.com/about/contact/


Is it true pilots in a smaller aircraft have the option of using the right or left door as rudder, to offset the actual rudder if failed?

In reality, in a strongly- deflected stuck-rudder situation, the pilot would be best advised to forget about the doors and just land the plane, selecting a runway with a strong crosswind component if at all possible.  After all, when landing with a strong crosswind, it's not that uncommon to hold the rudder at close to full deflection in the "downwind" direction.  If no crosswind runway is available, the pilot will just have to land the plane going a bit sideways-- no problem if the aircraft happens to have tricycle gear, like most do these days.

Obviously, in a stuck-rudder situation, steering corrections must be accomplished entirely via bank angle changes via the ailerons.  Keeping the rate of change of aileron deflection (and bank angle) low will help smooth things out.


Is the shear centre of a wing the same as its aerodynamic centre?

No. These are very different things.

The shear centre (SC) is a purely mechanical (structural) feature of the wing design. It is a point along the chord such that application of force - no matter what force - causes the wing only to bend but not twist.

Unlike the aerodynamic centre (AC) and centre of pressure (CP), it makes no sense to talk about a single integral point for the whole aircraft. An SC can be found for each cross-section of the wing, and it is the chordwise relation of the SC to CP and CM (centre of mass) of the section that is important to aircraft designers.

Designers can control where the SC will be. If we could make the SC match the point of application of the integral force at this section, we wouldn't need much of the torsional rigidity, and could make the wing lighter.

Unfortunately, this is not practically possible. First and foremost, the CP, the integral point of application of the aerodynamic force in flight, moves forward and backward depending on the angle of attack (AoA). This is just the nature of aerodynamics.

Typically, for a straight wing CP will be behind SC for small angles of attack and ahead of it for large angles. This is rather unfortunate, because this means that at a high G load (esp. at moderate speeds), or in an updraft, the wing will twist to an even higher AoA. This positive twist at the max load (typically 1.5 × rated load) is often one of the critical design cases, so in practice we want SC closer to the forward-most CP location. A clever application of SC can make the wing twist negatively and dampen its own oscillations.

CM of the wing section is nearly always behind the SC. In normal flight, static aerodynamic loads prevail over weight of the wing itself, so this doesn't matter much. However, when we start analysing aeroelastic modes, CM location becomes important. To avoid flutter, a common solution is to move CM closer to SC by installing some dead mass at the leading edge. This often proves to be easier and lighter than increasing torsional stiffness. If we can, we would install some useful mass there, such as an engine.

I didn't talk about AC yet. This is because it has nothing to do here. AC is a very theoretical point introduced for convenience of stability analysis. Any force can be broken into a moment and another force, and we just split lift such that part of it acts at CM, and part at another point. Because CP normally moves linearly with AoA, we can make it such that all changes to lift due to AoA 'kind of' happen at a fixed location. But in reality, of course, lift just increases and moves forward with AoA. The structure and aerodynamics have no idea about our mental exercise.

It is perhaps this fixed location of AC that lets it be confused with SC, which is also fixed. But they have nothing to do with each other. Structural engineers don't need to know about AC at all (they just need to ensure the aircraft CM is in a certain range they are told), whereas flight dynamicists hardly ever talk about CP but always use AC as the reference point (along with CM).


Could a quadrotor use a main gas powered rotor with small electric rotors for attitude control?

Early versions of Sikorsky's VS-300 helicopter prototype used something similar to what you're describing, as his first attempts had three rotors on the tail boom, one vertical rotor for anti-torque and yaw, and two horizontal rotors for pitch and roll.

Of course, if you're already using large main rotors, you might find, as Sikorsky found, that cyclic pitch control works even better and eliminates the need for the two horizontal rotors.


How can I reduce the Short Period frequency of a Pitch Hold Auto-Pilot while maintaining stability?

You seem to have too high an alpha feedback. For intuitive understanding, alpha feedback mainly increases the pitch stiffness, analogous to increasing the static margin; pitch rate feedback mainly increases the pitch damping. For your purpose, you would need to significantly reduce the alpha feedback.

For example, with your provided state space model,

$$\dot{x}=Ax+Bu$$

using a linear feedback,

$$u=Kx$$

where

$$K=\begin{bmatrix}0 & 0.5 & 0.25 & 0 \end{bmatrix}$$

satisfies your damping ratio requirements. SP frequency is 3.9 rad/s, SP damping is 0.53, Phugoid frequency is 0.023 rad/s, Phugoid damping is 0.14.


What is the definition of "geometric pitch angle" for a propeller?

From a variety of online sources (e.g. 1 and 2), the geometric pitch angle is simply the incidence angle between blade reference chord and the plane of rotation.

This makes sense from the definition of blade pitch, which is the distance that a point on the prop would move forward in one rotation, if it's gripping in a solid medium. The conversion from pitch to pitch angle, therefore, has nothing to do with aerodynamics (i.e. lift) and is geometric only.


Why are Russian cockpit panels painted in turquoise?

According to Cold War Air Museum:

  ...the color chosen by Soviet designers helps to reduce stress and
  maintain a pilot's effectiveness on long missions.

  ... the scientists found out that this color keeps pilots awake and
  not getting tired by the black or grey of a cockpit panel, especially
  under terms and condition of long range flights or under heavy work
  load.

This URL contains a color guide for cockpits.


The pilots also need to use oxygen in case of smoke, fumes, or fire in the aircraft.  Thus, they need enough oxygen to be able to get down and land in a fire scenario, which is much more than a decompression!

Fire procedures have the crew on 100% oxygen at positive pressure to prevent them from breathing in smoke and fumes, while in a decompression, their masks mix oxygen with cabin air, in much the same way the cabin masks do.  This is also why the cabin masks are not used in smoke/fumes scenarios.


Can ATC tell if aircraft is being flown manually?

No, the air traffic controller cannot see the whether the autopilot is used or not.

However, in the Mode S radar and ADS-B protocols there are messages defined that contain state of the autopilot. Currently there is no requirement that this data is provided by the aircraft, but some aircraft/transponders do provide the information nevertheless. The data is not displayed to the controller though.

In some control centres the aircraft's Mode Control Panel / Flight Control Unit Selected Altitude can be displayed to the air traffic controller. The information can be used to reduce Level Busts.

From observations of the radar track it is difficult to tell. A competent pilot will be able to maintain altitude and heading in such a way that it is difficult to see the difference from an autopilot at the resolution of the ATC display.

There are circumstances where the pilot is required to use the autopilot, especially to keep separation from other aircraft. In Reduced Vertical Separation Minima (RVSM) airspace the vertical separation is 1000 ft between Flight Level 290 and FL410. The aircraft must be flown using the autopilot in this airspace to ensure the flight levels are adhered to strictly.


What aircraft could make non-stop transatlantic flights in 1958?

The first scheduled trans-atlantic air service was made possible with Zeppelins. The LZ-127 started flying the route in 1931, mostly to Lakehurst, NJ, or Pernambuco in Brazil, but was disassembled in 1940.

The first airliner which was able to cover the distance (back then it was Berlin - New York) was the Focke-Wulf 200, which in 1938 needed almost 25 hours East-West and 20 hours on the return leg. With its slow cruise speed, wind made a lot of difference. Sadly, the US did not allow Lufthansa to start the scheduled service it had planned to open in 1939. Lufthansa had opened regular air mail services in 1934 between Europe and South America using flying boats and a relay ship in the middle of the Atlantic. Air France added its transatlantic mail service flying from Africa to South America and back.

The first heavier-than-air transatlantic passenger service opened between New York and Marseille in 1939 on Boeing 314 Clippers operated by Pan Am. It crossed the Atlantic between Foynes, Ireland and Botwood, Newfoundland. A British service, also using flying boats, was in preparation but stopped by the beginning of WW II.

In the 1950s, there were already several options for transatlantic air travel, but none of them non-stop from Chicago: Pan Am, TWA, Trans Canada Airlines (TCA), BOAC (successor of Imperial Airways), and Air France all operated large propeller aircraft which covered the distance with refueling steps, typically in Gander (Newfoundland) and Shannon (Ireland). Typical aircraft were the Douglas DC-4 and DC-6, and the Lockheed 149 Constellation, but also the French Latecoere 631 flying boat was used until 1955. Of these airlines, only Pan Am and BOAC serviced O'Hare in 1957, before the first international terminal opened there in the following year.

Still, the prevailing eastward wind made the East-West crossing hard and required airlines to reduce payload, and only the advent of faster  airliners like the Douglas DC-7 (from 1956) and the Lockheed 1649 Starliner (from 1957) made the transatlantic services more reliable and economical. Beginning with the DC-7C, their range was sufficient to support transatlantic service directly from Chicago O'Hare.

In October 1958 the first transatlantic jet airliner service was opened by BOAC using the de Havilland Comet 4, followed shortly after by Pan Am, operating the Boeing 707 and connecting London with New York (with an occasional refueling stop at Gander on westbound flights). O'Hare could only participate in this progress after its main runway was extended to accommodate large jets in June 1960.

Therefore, the most likely airplanes to fly transatlantic directly from O'Hare would have been the DC-7C (but operated by Pan Am, not TWA), the Lockheed L-1049G and the L-1649, which both were operated by TWA. For the flying time, the 3628 miles from JFK/Idlewild to Paris Orly took 14¼ hours with the DC-7C and 14.83 hours with the Lockheed 1649. So it is fair to assume a flying time of 15½ to 16 hours for the slightly longer distance between Heathrow and O'Hare.

Quote from Wikipedia:

  In January 1958 Pan American scheduled the DC-7C from Orly to Idlewild
  in 14 hr 15 min; TWA scheduled the 1649 in 14 hr 50 min.


Do large airliners have a short-field landing technique?

Other than extra braking and reverse thrust, is there a specific short-field landing technique for large jet airliners?

Never heard of any. The required landing distance is calculated so that the plane can reliably stop (even if reversers fail) and landing at shorter runway is not allowed.

  so the 747s try to land right on the numbers, rather than the usual technique of touching down within the first third of the runway.

The usual technique is to aim for 1,000 ft down the runway and touch down with some flare somewhere around 1,500.

  In discussions about the famous landings at St Maarten, it is sometimes said that part of the reason for the low passes is due to the relatively short runway, so the 747s try to land right on the numbers

Actually the TNCM runway 10 has PAPI and TDZ marking a little beyond the usual 1,000 ft mark at around 1,250 ft. Ourairports says the threshold is displaced 162 ft (but it also says runway 9, so it is likely out of date), but according to the satellite images it is a bit over 300 ft plus some runway end safety area, placing the threshold around 500 ft past the fence and the touch-down zone around 1,750 ft past the fence.

Now the normal glide-slope is around 5%. That means the aircraft is supposed to cross the fence at around 90 ft, on average. That seems about right. Of course you can't expect every aircraft to be positioned precisely within a few feet, so now and then some crosses it at maybe 50 ft. That is not intention, but simply a deviation. But of course the photos of planes flying especially low are more likely to be picked for publishing.

Also, a short field landing normally calls for steep approach which make precise aim for landing spot easier. That would actually place the aircraft higher over the beach. But the glide-slope at TNCM is normal 3° (5%) one, so it is not a steep approach.

  Such a procedure is fine in a Cessna, but in a large passenger jet? I have my doubts.

In large jet it isn't. Air transport has stricter regulations than general aviation because more is at stake and larger aircraft have stricter limits because the higher energies involved mean errors are harder to fix and have more serious consequences.


I can generally only speak for commercial aviation. The reasoning is probably the same or similar for General Aviation, but seeing as that is such a wide and varied field, with a tremendous number of different aircraft, probe types, etc., someone somewhere could probably find some niche corner-case to dispute the reasoning. My guess would be that, generally speaking, in General Aviation, certain probes are most likely only meant to run for a certain period of time. After all, it's not like a Piper Cub is going on an 18-hour non-stop flight to China like a Boeing 777 might. I'm not saying that a probe will fail after 18 hours of being on, just that repetitive use in that way might necessitate a different type of probe with a more robust design.

In commercial aviation, many modern airliners use certain logic to turn pitot heat on or off. With the exception of a manual override switch equipped on some aircraft, to force it off, the pitot heat is generally on during most flight phases and works as such:

On the ground, with engines off, the pitot heat is turned off. On the ground, with engines running, pitot heat is on low. Finally, once the plane takes off, the pitot probes are put into a "high heat" condition and remain that way for the remainder of the flight (unless manually turned off).

The pitot heat is generally monitored with current sensing relays such that if the pitot heat draws excessive current or not enough current, the crew will be alerted to a pitot heat failure.

Why not keep them full hot all the time? For one, that would most likely cause premature failure of the heating element. Another reason is that, on the ground, pitot covers are normally applied to prevent bugs from building homes inside the tubes as well as preventing other debris from entering. The pitot covers will melt and destroy the pitot probes if the covers are left on while heat is applied. This can also be problematic and dangerous if the pitot cover partially melted, wasn't noticed by ground crews, and the drain holes or entry holes were blocked by the melted cover. Finally, and probably most importantly, the pitot probes get extraordinarily hot. Speaking from experience, and from having touched one that had failed in the "full hot" phase, it takes only a brief second to receive excessive burns on one's hand. Most of us that have been around them in our lifetimes have been burned by them, and a savvy mechanic will always approach them with caution!

So, it makes sense to have the probes off, on the ground, with engines not running. Otherwise, commercial aviation has more or less decided that "full hot" in the air, and low heat on the ground with engines running is a design characteristic.


Aircraft emergency oxygen: how hard do I pull on the mask?

When they first fall down they'll be too high to reach your head, pulling on them will release a switch to activate the generator and release enough slack in the line to reach down to your chest comfortably (for children).

Some types are suspended by a cord connected to the switch:

(image source: wikipedia)

Then you will just need to pull until the cord disconnects from the ceiling.


Why did the flight Osaka -> Frankfurt circle above the airport after taking off from Osaka International?

Looking at FlightAware, we see this takeoff for your flight:

Examining some airport charts for KIX, this looks like the standard departure NANKO REVERSAL THREE DEPARTURE from runway 06R.

I guess that the loop is to give the aircraft enough time to climb to 8000 before it reaches NANKO. And, I guess the 8000 feet is for either terrain or noise abatement (notice the climbing loop is entirely over water.)


How do airlines make sure that pilots remain skilled enough to operate aircraft? What quality assurance is there for certified pilots?

Put quite simply for this answer - The Licence a pilot holds is the assurance that the pilot has received the appropriate level of training.

Each country has it's own standards for training, their own requirements, and their own limitations on the operation of that licence. In saying that, MOST countries standards are reasonably in-line in regards to Aeronautical Experience required to sit each flight test.

In Australia, the requirement to sit a Commercial Pilot Licence is a minimum of 200 hours Aeronautical Experience (150 hours if ALL training has been conducted on an Integrated Course, now to be recognized under Part 141). From there, there is a break down of what that 200/150 hours must consist of.

Now, having a Commercial Pilot Licence (again, speaking from an Australian point of view) does not give a pilot the right to sit in the left seat of an Airliner. You need further training such as;

Multi-Engine Command Instrument Rating
Type Endorsement (for the intended aircraft)
Crew Resource Management Training
Dangerous Goods Training
Senior First Aid (Not mandatory, but common)
Company, Emergency, Cyclic and Systems checks (per company)
Air Transport Pilot Licence Theory Exams (in some cases, Airlines may not even look at you if you haven't completed these - In
Australia, it is an unwritten must-have!)

And thats just to sit in as a Co-Pilot..

Captains need years of experience, and a lot more training and check to get into that coveted Left Seat.

So again, to bluntly answer your question, regardless of country, there is law in place that stipulates that Pilots must be appropriately trained to fly airliners.


Is it possible to modify an AV-8B Harrier II to a supersonic aircraft by applying some modification?

There was actually a plan to convert the Harrier into a supersonic aircraft.

The original plan that lead to the development of the Harrier actually had a supersonic variant, the Hawker Siddeley P.1154. The P.1154 was supposed to be a supersonic aircraft using the Bristol Siddeley BS100 engine, which used Plenum Chamber Burning(PCB).

In the BS100 engine, cold bypass and hot core turbine airflows are split between two sets of nozzles, front and rear, like the Rolls Royce Pegasus engine which powered the Harrier. The PCB called for additional fuel and afterburning applied to the front cold air nozzles only, increasing thrust. The PCB increased the thrust from 116 kN to 160 kN.

Source: aeromodelbasic.blogspot.com

However, the P.1154 never saw the light of the day due to various reasons and the subsonic Hawker P.1127 was developed into the AV-8 Harrier.

Later, Hawker and McDonnel Douglas joined to develop the AV-16 concept, basically a plan to double the range and payload of the Harrier. One version of the AV-16 called for supersonic flight too.

Some modifications that were considered in the study for supersonic aircraft were,

A more powerful engine (called Pegasus 15) which used PCB
A bigger fuselage for the bigger engine
A larger 'supercritical' wing
A lengthier, more slender fuselage

This version was called HS.1185, as shown below.

Source: harrier.org.uk

However, in March 1975, Hawker pulled out due to budget cuts and other reasons.

Later, Rolls Royce (ground) tested Plenum Chamber Burning in the Pegasus engine and made some progress in the 1980s. This was supposed to be used in yet another (supersonic) variant of Harrier. One of the versions was the HS. 1205, which had redsigned F-16 type inlets.

Source: harrier.org.uk

However, this also came to nothing and the project was shelved. For a full list, see Harrier site

To answer your question, it would be possible to make the Harrier go supersonic using more powerful engines and modifications to airframe (listed above).


Why do planes have cross-feed switches or circuits?

The fuel system in aircraft generally includes a left and right tank within the corresponding wings. Each tank generally provides fuel to the engines on that wing. The crossfeed valve is used to temporarily connect the two sides of the system. This system allows the shortest route for the fuel and keeps the systems separate, so a leak on one side cannot drain the entire system. The crossfeed valve is generally kept shut for this reason. A couple scenarios illustrate when opening the valve might be necessary.

To keep the plane balanced, both wing tanks should have about the same amount of fuel. However, for various reasons, they could become unbalanced. The crossfeed valve allows fuel to flow from the tank with too much fuel to the tank with less fuel.

Another scenario would be the loss of an engine. In a twin-engine airplane, the remaining engine would need to be able to draw fuel from both wing tanks.

Note: especially in larger aircraft, fuel systems can be much more complicated, with multiple tanks in each wing and also in the fuselage. Fuel transfer also becomes more complicated.

Using the 737 as an example, this is the fuel system control panel with the crossfeed switch in the center. With the crossfeed valve open, turning off the fuel pumps on one tank will cause more fuel to be drawn from the tanks on the other side.


TCAS II - bottom omni-directional antenna

The directionality of a TCAS antenna is ONLY used for positioning the bogey on the TCAS display, it is NOT used for determining time-to-contact. So you're still going to get TAs and RAs from the Omni antenna even if the upper antenna is blanked, but you won't get the display of that traffic.


What flight controls should be used to counter asymmetric yaw?

The details will depend on the exact aircraft type, so I will answer for the Bombardier Dash-8 Q400 as an example.

The autopilot does not have rudder authority on the Dash-8 (source: FCOM Autoflight chapter):

  12.3.7 Autopilot

  The Autopilot (AP) couples the FD commands to the flight control surfaces using pitch and roll servos for automatic control of the aircraft flight path.

If not disengaged, the autopilot would try to maintain heading with roll only.

The yaw damper would not be enough to overcome the yaw asymmetry either:

  12.3.9 Yaw Damper

  The Yaw Damper provides through control of the rudder:

  Damping of the aircraft Dutch Roll mode.
  Turn coordination.

  The Yaw Damper authority is limited to a maximum of ± 4.5 degrees of rudder by mechanical stops. Yaw Damper commands are limited in software as a function of airspeed.

The correct procedure in case of an engine failure would be to hold rudder towards the live engine and then trim the rudder whenever time permits:

(image source: FCOM Flight Controls chapter)

  RUDDER TRIM INDICATOR

  indicates trimmed rudder position

  RUDDER TRIM KNOB (rotary action spring loaded to neutral)
  ROTATE

  trims rudder in desired direction
  first graduation trims slow, second graduation trims fast

The target for the rudder trim should be coordinated flight, i.e. no sideslip indicated on the primary flight display (PFD):

(image source: FCOM Indicating and Recording Systems chapter)

  SLIP/SKID INDICATOR (white)

  the Slip/Skid Indicator shows the lateral acceleration of the aeroplane and is a trapezoid symbol. It turns with the roll pointer
  the maximum deflection indication shows a 0.14 g lateral acceleration. This is equivalent to one and a half the thickness of the upper part of the slip/skid symbol (trapezoid shape)
  the slip skid Indicator is shown to the left when the aeroplane is slipping to the right and to the right when the aeroplane is slipping to the left
  the indicator goes out of view when the aeroplane roll is more than 60 degrees or the related AHRU attitude has malfunctioned