Can I fly solo when practicing IFR under the hood?

Before going into the FAR AIM, take a second to think about this idea:

You are in your airplane, under the hood, flying along your route or wherever. The only traffic warnings you will get are from your controller, and he does not always see all the VFR traffic on his screen... Not a good idea. Definitely never fly without a safety pilot under the hood in VMC.

Now lets open the FAR AIM:

  §91.109 Flight instruction; Simulated instrument flight and certain
  flight tests

  (c) No person my operate a civil aircraft in simulated instrument
  flight unless -

  (1) The other control seat is occupied by a safety
  pilot who possesses at least a private pilot certificate with category
  and class ratings appropriate to the aircraft being flown.

  (2) The safety pilot has adequate vision forward and to each side of
  the aircraft, or a competent observer in the aircraft adequately
  supplements the vision of the safety pilot; and

  (3) Except in the case of lighter-than-air aircraft, that aircraft is
  equipped with fully functioning dual controls. However, simulated
  instrument flight may be conducted in a single-engine airplane,
  equipped with a single, functioning, throwover control wheel, in place
  of fixed, dual controls of the elevator and ailerons, when—

  (i) The safety pilot has determined that the flight can be conducted
  safely; and

  (ii) The person manipulating the controls has at least a private pilot
  certificate with appropriate category and class ratings.

Getting the important stuff out of there: No person may operate a civil aircraft in simulated instrument flight unless the other control seat is occupied by a safety pilot!

The FAR/AIM part obviously only goes for FAA regions, but I'm assuming that is what you are asking about.

Conclusion: According to logic thinking you should never ever not look out the window in VMC, and the FAA doesn't allow you to either, not even for IFR recency!


Can I legally land an airplane in in Badwater Basin, CA?

https://www.nps.gov/deva/learn/management/rules-and-regulations.htm says you would have to have special permission.

  36 CFR §2.17 – AIRCRAFT and AIR DELIVERY

  (a)(1) The use of aircraft on lands or waters within the park other than at locations designated by special regulations is prohibited.
  Death Valley’s special regulations at 36 CFR 7.26(e) authorizes the
  use of aircraft only at the following locations:

  Death Valley Airport, latitude N 36°27’50”, longitude W 116°52’50”, commonly known as the Furnace Creek Airport.
  Stovepipe Wells Airport, latitude N 36°36’15”, longitude W 117°09’30”.
  The Saline Valley Warm Springs Airfield, latitude N 36° 48.41”, longitude W 117° 46.90”, commonly known as the Chicken Strip, is open
  pending special regulation.

  The landing of aircraft at locations other than those listed above,
  such as for wildlife research, is permitted only under conditions of a
  permit issued by the superintendent.

  Aircraft have a significant potential for impacting park resources and
  human safety. By requiring permits for these activities, the
  superintendent can manage these activities and mitigate negative
  impacts.


Can planes fly without wings but with a horizontal stabiliser?

This is a question about terminology more than aerodynamics. All horizontal surfaces can contribute lift, and also the fuselage does. Take missiles, for example. They create dynamic lift like an aircraft, but only with their fuselage and fins by inclining both against the oncoming flow. Speed compensates for the small area and poor lift efficiency of slender bodies. Since a fuselage is unstable in pitch and yaw, you need to either add fins or something else which creates perpendicular forces at the far end of the fuselage to control it. Like missiles do.

AIM-9L (picture source)

An X-wing will make a horrible model aircraft. But with enough thrust even this design will fly.


Can one ARTCC take over for another ARTCC in an emergency?

Generally speaking, no.

As for the specific situation, New York Oceanic has been closed since midnight UTC:

  DUE TO AN OPERATIONAL EMERGENCY NEW YORK AIR ROUTE TRAFFIC CONTROL CENTER IS DISCONTINUING AIR TRAFFIC SERVICES IN THE NEW YORK OCEANIC FIR UNTIL FURTHER NOTICE.FLIGHTS CHOOSING TO ENTER NEW YORK CENTER AIRSPACE SHOULD EXPECT ONLY ADVISORY SERVICE.
  NOTAM A0249/20 refers.

Most ATS units have contingency procedures in place to dictate what happens if the unit needs to close on short notice, for example during an evacuation. It is quite common to have agreements with adjacent units to help clear the airspace ("clear-the-sky" systems). This is possible if adjacent units have RADAR and radio coverage that overlaps with that of the unit being evacuated. While not able to provide regular service, adjacent units can monitor traffic and make sure everyone gets out of the evacuated airspace safely, after which that piece of airspace is closed.

In order for an adjacent ATS unit to actually take over and provide normal service, several things would be required:

Additional staffing. It might not be possible to just call more people to work, as that would mess up the entire roster in days and weeks to come, seriously affecting the non-evacuated unit.
Additional working positions for the extra staff to actually sit and work, while still maintaining a number of backup positions in case of equipment failure.
Staff must have knowledge of local rules and procedures of the airspace they are taking over, and have valid and current ratings to be allowed to control it. You can't keep your rating current if you don't use it regularily. Just like you can't just take an Airbus-pilot and ask them to fly a Boeing-aircraft because the Boeing crew called in sick.
RADAR coverage must be sufficient. This could be achieved by sharing RADAR-data between facilities, but if one ATS unit needs to evacute, their technicians have probably evacuated too - which means the data cannot be used since there is no one to monitor the status of technical equipment.
Radio coverage must be sufficient (see above)
All telephone lines must be re-routed (which is doable, if the system is set up for it)

What is more likely to happen is that the unit evacuating will move into a contingency facility from where they are able to provide anything from a very limited to full service. Some airports have old control towers that are still being maintained as contingency positions, and area centres might have dedicated backup facilities, or possibly training facilities (simulator positions) that can be switched over to a live environment. Of course, if all the staff that happened to be on shift at the time of evacuation needs to be quarantined due to a contagious disease, you will have a pretty big staffing issue.


Are we at peak speed efficiency for jet airliners at Mach 0.85?

Short answer: Increasing fuel prices would have driven down the most economical speed, but advances in aerodynamics have compensated for that and the maximum cruise Mach number is still at Mach 0.85. But there is a much simpler reason why this Mach 0.85 number seems so immutable.

Please note that we are talking about the maximum cruise Mach number; all airliners will fly more economical at slightly lower Mach numbers between 0.78 and 0.82.

Now we need to define efficiency. For airliners this is haul capacity per time, and can be expressed by the product of payload, range and speed. When none of the three constituents can be changed without making the product more costly to achieve, you have reached the point of best efficiency.

Engine Technology

The biggest change in the last 50 years was in engine technology. Bypass ratios have increased to values close to 10, the turbine inlet temperature is now 300°C higher than in the early jet age, and electronic control has improved especially the off-design performance of engines. This has made it less attractive to increase flight speed, so the optimum cruise Mach would be lower if no other effects had influenced it.

Another effect is the lower fuel consumption. Early designs had to use a high wing chord to pack enough fuel volume for transoceanic flights. The much lower consumption of modern engines has given them ranges which are more than what is needed to reach every point on earth directly. This made it possible to reduce wing area, thickness and mass, and to save some friction drag, helping fuel economy again. The lower thickness helps to make higher cruise Mach numbers possible.

Aerodynamics

Aerodynamics is the second factor. With the A310 supercritical airfoils were introduced, and they shifted the operating Mach number up because now a limited region of supersonic flow on the wing could be tolerated without a significant rise in drag. However, the benefit from that was used to reduce wing sweep, increase airfoil thickness and to attach bigger fuselages to those wings. In the end, the newer airplanes had the same cruise Mach numbers as their predecessors. Something made Mach 0.85 too attractive to abandon.

A second effect of supercritical airfoils is their blunter nose, which helps to reach a higher maximum lift coefficient. This also contributed to reducing wing chord, because now the wing area could be made smaller for the same landing speed.

The Real Reason

Every new airliner needs to compete with the older models. On fuel economy this is no problem, but speed is also important. A higher cruise Mach number allows  shorter times for connections. Now you have to know that the electronic reservation systems would list connections sorted by flight time, shortest first. When a travel agent wanted to book a flight, he or she would rarely look beyond the first screen and pick one of the first flights listed. If a new type made the flight slip down in the listings, it was a non-seller. This is even true in the times of online bookings: The airlines don't make much profit from the bargain hunters in Economy, their target are the business people flying in Business or First Class. And those still order mostly through travel agencies, so the rules have not changed. This is why that Mach 0.85 speed seems to be so firmly set; flying any faster would drive up fuel consumption disproportionally, and even the newest jets will mostly be flown around Mach 0.82 to Mach 0.84.

Making this speed possible is still a struggle for the design engineers, especially when you consider that larger aircraft would need thicker wings for structural efficiency, but need to be fitted with wings thinner than optimal to let marketing claim a cruise speed of Mach 0.85.


What are the missions of high-endurance aircraft?

Historically long duration flights were simply a way to fly further. Before the jet age crossing oceans was a time consuming affair and required what some may consider a "high endurance" aircraft/flight. Keep in mind it took Charles Linbergh in the Spirit of St. Louis 33.5 hours to cross the Atlantic and this was done with no refueling.

On the scientific/record setting front

A variety of airframes have been used for setting world records arguably a stunt in some cases and others with the pursuit of scientific progress. The current flight endurance record is held by  Robert Timm and John Cook at a whopping 64:22:19:05 (thats 64 days, 22 hours, 19 minutes and 5 seconds) in a Cessna 172 of all airplanes quite an endorsement for the endurance of the airframe/engine combo.

Solar Impulse a modern experimental solar aircraft that recently flew around the world regularly flew 15-22 hour legs due to its slow airspeed. In this case the mission effectively required long legs due to the aircrafts performance. This was a purpose built plane.

The Rutan Voyager was another purpose built aircraft that became the first airplane to circumnavigate the globe, non stop and with out refueling remaining aloft for 216 hours 03 minutes and 44 seconds.

On the operational front:

The Air Force operated Boeing VC-25 (often called "Air Force Once") is capable of aerial refueling and could remain aloft for quite some time and is built to be a mobile command center should the need arise for it.

The Boeing E-3 Sentry commonly known as AWACS provides aerial radar support and is capable of air to air refueling allowing it to stay aloft for well above its standard 8 hour endurance. I dont know a whole lot about its standard mission so Im not sure it ever flys multi-day missions.

There is a nice list of long range airliners here all of which have considerable endurance (but dont meet your multi-day requirement) and are all built (more or less) for servicing non stop routes from far locations.

Its worth noting that the general civilian use case of and airplane does not really lend to high endurance planes (multi day kinda stuff) in practice. Planes are generally for moving people and cargo in a timely manner and not really for taking off and just loitering for a while. The various militaries of the world simply move their aircraft around on aircraft carriers and launch them closer to where they are needed or fly high speed aircraft from farther away when needed. Airplanes also have the luxury (if permitted by laws and airspace regs) to move directly from point to point greatly reducing the distance traveled to get between locations over other methods of transit, again cutting down on travel time.

Some consider the space shuttle an aircraft and it was capable of multi day missions for the purpose of space exploration, satellite service and delivery and ISS transportation.


Why can Boeing V-22 Osprey carry more cargo internally than externally?

The difference is because when the cargo is inside the aircraft the weight is spread across the cargo compartment floor, whereas when it is carried externally, the weight is concentrated entirely on one or both cargo hooks. The cargo hook attachment points are reinforced, but they still have a weight limit. When the cargo is inside the aircraft the weight limit is the MTOW of the aircraft.


What counts as the wingspan of a tandem-wing aircraft?

Because wetted aspect ratio $b^2/{S_w}$ merely improves on wing aspect ratio as an estimate of efficiency, for $b$ just choose whichever wingspan is largest.  That's good enough to compare one tandem planform to another.
You could get fancy and use a weighted average of the wings' spans, weighted by how much lift each one produces, with those in turn weighted by time spent in climb, cruise, and descent... but that seems against the spirit of a quick estimate provided by two easily measured numbers.


Is the CV-22 / MV-22 Osprey classified as a Helicopter, Plane or Both?

They are classified as Tiltrotors, which is its own category for all the obvious reasons.
If the President were flying in a Marine Osprey, the callsign would be Marine One. If he were in an Air Force Osprey, it'd be Air Force One.


Under what circumstances is the Aircraft 'Stability-Axis' system used in either design or analysis of aircraft?

Body-axis is used to construct the equations of motion and express the aircraft angular velocity and Euler attitudes. By conventional, it is defined such that the x-axis is aligned with the nose and the x-z plane is the plane of symmetry.

Stability-axis, whose x-axis is aligned with the longitudinal incidence of the flow against the body-axis, is used to express aerodynamic data, which are derived from semi-analytical methods (e.g. DATCOM, ESDU), computational methods (e.g. vortex-lattice methods, Navier-Stokes), wind tunnel testing, or full flight data.

Stability-axis is used for aerodynamics because lift and drag are conveniently aligned with the axes. And as the OP alluded to, it is much easier to rotate the aircraft against the wind tunnel balances, than to rotate the flow against the test model.

Wind-axis has its x-axis aligned exactly with the flow velocity vector. It's not really used anywhere. We don't use wind axis because it breaks the x-z symmetry and makes things more complicated than need be. It does not offer any additional benefit than stability-axis.

Image from: https://www.mathematica-journal.com/issue/v8i2/features/codegeneration/contents/html/Links/index_lnk_3.html


How is the emergency exit row handled when there are no passengers aboard eligible to sit in an exit row seat?

In such an extreme case, the row would be unoccupied.

Nothing says that the row has to have people in it; I've had flights with under a dozen passengers, and if everybody had seats up front, the row would be empty, and that's okay.

You can't have unqualified people in the Emergency Exit row -- that's the limitation. Nothing requires the FA's the move qualified people into the row. That typically does happen (and as has been pointed out elsewhere, that row is often desirable due to legroom), but it's okay if the row remains empty.


How did the US get the necessary knowledge to maintain their MiGs?

Its a combination of those. US did have manuals for quite a few of the Migs- Cold war alliances were shifting too frequently to prevent any leak of military technology. As warisboring.com notes:

Because Baghdad re-established its cooperation with London and the United States in late 1963, U.S. intelligence services not only received the opportunity to test-fly MiGs in Iraq, but also received all the related technical and training documentation.

The title page of the English translation of the tactical manual for MiG-21F-13 and MiG-21PF, as prepared by the USAF’s Foreign Technology Division. Notable is the date of issue — Nov. 5, 1965 — meaning that the original document must have been obtained much earlier. Tom Cooper Collection photo; Image from warisboring.com
As the Mig program was established in late 70's US would have had the required documentation for quite a few of the aircraft before that. The rest were done during the project using inputs from US intelligence and pilots themselves writing the flight manuals.
The Soviets sold their aircraft to many countries, the manuals for which could've been obtained from any of them. Also, there are multiple instances of pilot defection with manuals, which provided most of the required technical data for flying, though maintenance would have been difficult. As airforcemag notes:

This led to the second maintenance problem—the lack of instruction manuals  and  tech  data.  US  intelligence supplied  some  of  the  information they  needed  but  not  nearly  enough ...
Parts  were  their  third,  and  maybe biggest, problem. “For things like hydraulic pumps, we would use American components that looked about right,” said Stringer. “But it was only about five to 10 percent replacement. Most of the time we tried to recondition.”


Is an increase in induced drag always caused by an increase in the angle of attack?

At 2:58, the video says "To replace the lift lost by the increased upwash and downwash, the wing must be flown at a higher-angle-of-attack than would otherwise be necessary."

This statement is true no matter what angle-of-attack the wing is "feeling" and no matter how much lift it is making, as long as the amount of lift it is making is not zero.

For example, let's say at a given instant in time, with a given angle-of-attack and airspeed, when the instantaneous flight path is horizontal, the wing would be making Lift equal to Weight if it weren't for the upwash and downwash effect, but because of the upwash and downwash effect, the wing is only making a force equal to 90% of Weight.

Forces are not in balance, and the flight path is curving downward.  In the next instant in time the flight time will no longer be horizontal.  Yet despite the fact that we aren't actually replacing the "missing" lift, it is still true that that "To replace the lift lost by the increased upwash and downwash, the wing must be flown at a higher-angle-of-attack than would otherwise be necessary."  If we were happy to settle for a lift force equal to 90% of weight at that instant in time, and the upwash and downwash effect were not there, we could fly at an even lower angle-of-attack.

More practically, we normally don't want to allow the flight path to curve (accelerate) downward, so we do keep lift close to weight, or very close to it, except during the brief transition (pushover) from a climb to level flight or from level flight to a descent.  The reduction of lift that happens in a steady-state descent (or climb), compared to in level flight, is very small for moderate climb or descent angles.  For more, see a What produces thrust along the line of flight in a glider? and Does lift equal weight in a climb? .

Only if the wing is mounted inside a wind tunnel, where the connection between Lift and Weight is completely severed, does it really make any sense to ask "What happens if we decide not to replace the missing lift?".  In that case, indeed, the upwash/downwash effect does not force the wing to be flown at a higher angle-of-attack than would otherwise be necessary.


How difficult is it to avoid ground loop in practice?

Your simulator gives you a realistic experience: This is normal. What you experience is the gyro effect of the propeller and engine while you change the pitch attitude. When you lift the tail, the axis of rotation is changed and the engine-propeller combination pushed downwards, causing a precession force which acts orthogonally to the plane defined by the down movement and the axis of rotation.

Since the engine is forward of the center of gravity, this precession force is pushing the nose sideways: Left for a propeller which spins clockwise (when observed from the pilot's viewpoint), and vice versa.

The best way to avoid a change in direction is to keep the tail to the ground with the stick aft until you know you are fast enough to lift the tail, and when you lift the tail up, you apply rudder simultaneously. Don't let the tail come up by itself!

I learned this in a Dimona motorglider. Now think of flying a small, light airplane where the propeller is bolted firmly to the heavy engine crankcase, both rotating. The airplane will dive or climb when you change direction! This is what pilots had to endure in the First World War, when they flew aircraft with rotary engines. When engines became more powerful, this became so bad that some aircraft were almost unflyable. See this answer for more.

That crosswind is turning the nose into the wind after lifting the tail should also be no surprise: While the main gear is still on the ground, the plane will weathervane into the wind once the tail is lifted.


Has anyone attempted to recreate the Sack AS-6 (German Saucer-wing)?

I'm not aware of anyone making a replica of the Sack AS-6 (the aircraft was destroyed when the Allies reached the area); however, there are other examples of saucer (circular wing)- like the Rowe UFO, which flies quite happily.

Rowe UFO; image from youtube grab

Then there is also the Vought V-173, whose design is quite similar.

Vought V-173 By Unknown - http://www.flickr.com/photos/sdasmarchives/4822056685/, Public Domain, Link


How Earth's rotation affect flight times?

It does not affect as much as one would think.

The atmosphere moves along with Earth's rotation. An airplane taking off from one place on Earth has to move through the atmosphere which is moving with Earth.

Now you may ask when does it take longer when we travel from Western Europe to Eastern USA, compared to USA to Europe? That depends on Jet Stream:

  Jet streams are fast flowing, narrow air currents found in the atmosphere of ... Earth.

Many air routes take advantage of jet streams, as you can see as follows:

Pilots know about the jet streams and will try to gain benefit of them. Recently, there were some news that a flight from New York to London traveled faster than expected because it was in jet stream (details here and here).

If you want to know why Earth's atmosphere moves with it, please see this.

There is a similar question on Physics.SE.


How much air, by mass, enters an average CFM56 turbofan engine cruising per minute?

The CFM56-5C, the largest CFM56, powers A340. Its thrust is about 145 kN at takeoff. It has an air mass flow of 485 kg/s (source).

CFM56-5C, source.

The Trent XWB (A350 XWB), a larger engine developing 430 kN at takeoff, has an air mass flow of 1,440 kg/s (source).

T/O vs cruise power and fuel consumption

According to this document, the CFM56-5C T/O thrust is 150 kN and the cruise thrust is 40 kN (other sources states 30 kN), 27% of the T/O thrust. Related fuel consumption are 2.3 and 0.5 kg/s, meaning cruise fuel consumption is 22% of the T/O fuel consumption.

Air mass vs fuel mass

For a fuel consumption of 22% of the T/O consumption, it can be assumed relatively safely that the air flow is in proportion, so we can roughly estimate air mass flow in cruise to be about 485 * 0.22 = 107 kg/s. This is supported by figures found online in non authoritative sources, like page 245 of this book:


What is the purpose of having a robotic arm fly a Boeing 737?

The fundamental benefit is that the operator doesn't have to make a lot of adjustments on "legacy" airplanes, they can "simply" install the arm on the existing aircraft that they already have in service.

And this is the main selling point for such a device, they are not marketing it to operators that still have to buy or lease an airliner, but to those that already have one and might want to reduce the number of pilots they have to employ.

Gürkan Çetin notes in the comments that this device is not certified (yet). That's partially the point of such demonstrations, to convince authorities that it can be certified, and to incentivate operators to lobby for their approval.


What is this aircraft, when was it produced and used and what was its role?

It is a Tu-128.

In particular it seems to be the "UT" (training) variant:

Image source

  Full-scale production of the aircraft began in 1966, with 188 Tu-128s built to 1970, that total apparently including the prototype. Ten "Tu-128UT" trainers were built as well, with a new cockpit for a flight instructor fitted into a swollen nose.

Other info on wikipedia

  The Tupolev Tu-28 (NATO reporting name Fiddler) was a long-range interceptor aircraft introduced by the Soviet Union in the 1960s. The official designation was Tu-128, but this designation was less commonly used in the West.

[...]

  The Tu-128's only publicly reported combat operation was the destruction of NATO reconnaissance balloons. The aircraft remained in service until 1990.


Why is “L Fuel Low” illuminating on my Cessna that is full of gas?

Fuel dye has nothing to do with it.
The fuel sender in light airplanes is usually an automotive-style float operated potentiometer, a rotary variable resistor, like a volume knob on a radio.  Inside is an arm, or wiper, that sweeps around a resistive conductor in an arc, providing a variable output voltage for the fuel gauge.  There will be a voltage range for the potentiometer output to the gauge with 28 vdc going in, say, 22 vdc for full, and 4 vdc or less for empty. The low fuel light will be set to come on when the voltage is some margin above that, say, 8 vdc or less or something like that.
Sometimes the resistance element inside the pot is a kind of circular wire coil on a card, sometimes it's a resistive coating on a flat surface.  If part of the resistor is worn to the point where there is an open circuit when the wiper passes the worn spot, the voltage going to the fuel gauge drops to zero, until the arm moves off the worn spot and the voltage is picked up again.
The low fuel light coming on plus the gauge dropping to zero suggests that the voltage signal is dropping out upstream of the fuel gauge and sensing circuit for the low fuel light.  Could be due to a worn spot in the pot as the float moves when fuel sloshes around in the tank, or it could be an intermittent open in the wiring.  If the problem goes away when the fuel level drops to some lower amount where the potentiometer no longer contacts the worn spot, that would tend to confirm that possibility.
If I was the mechanic I'd try to duplicate the fault by sticking something in the tank that can move the float up and down and observe the result.  If everything works normally, it's more likely to be a loose connection somewhere giving an intermittent open circuit. Check wiring, and if ok swap out the level sender and see if the problem goes away.


What's required for the ADS-B to function? A GPS or Mode S Transponder?

ADS-B, Automatic Dependent Surveillance - Broadcast, is a  broadcast of the aircraft's position and other information.

The position is determined by a GPS receiver. It is possible to use another qualified position source, but today it is de facto GPS. Other GNSS (Galileo, GLONASS, Bei-Dou) are other likely candidates in the future, but as far as I know, none have been certified for ADS-B yet.

The broadcast is usually by the Mode S transponder but can also be done by a dedicated transmitter / transceiver in the Mode S format and frequency (1090 MHz).

In the USA below 18 000 ft, in addition to the Mode S based ADS-B, a system based on Universal Access Transceiver  (UAT)  is used. This operates on 978 MHz

A third broadcast system was VDL mode 4, it was never rolled out on large scale.

So ADS-B uses GPS to determine the position and it operates either  on 1090 MHz (a frequency also used by Mode S)  or 978 MHz to broadcast information.


Why might the crew switch off air conditioning in the cabin of a passenger jet during descent?

Systems vary.

Transport aircraft and larger biz aircraft have airpacks handling the AC and at flight idle power settings there is less bleed air, and pressurization is a priority.  The packs simply do not have full power when in a flight idle descent on many aircraft.

The aircraft I routinely fly have separate radial compressor driven refrigerant systems, and have large heat loads from onboard electronics and laser systems.  They have to remain cool, and normally both AC systems are left on until just prior to engine shutoff after taxi.  If it is a hot environment, we use the APU and keep the AC on after engine shutdown.

Once again, the situation is different in different aircraft, and is dependent upon the cooling system, the power plants, the installations and the design and operational goals.

Addendum #1: Some aircraft APUs can provide bleed air for cabin pressurization, but this is not universal.  Also, some aircraft, such as the 787 do not use engine bleed air for pressurization, and rather use electrical compressors.  The flow of pressurized air is rather constant in flight.


Do some aircraft now have "full aircraft" parachutes?

Yes, Ballistic Recovery Systems or Ballistic Parachutes (BRS) are now being implemented in newer aircraft where the manufacturer can provide them or where they are required by law. In Germany, Ultralights are required to have an installed BRS to be deemed airworthy.

  In Europe the sporting (FAI) definition limits the maximum take-off weight to 450 kg (992 lb) (472.5 kg (1,042 lb) if a ballistic parachute is installed) and a maximum stalling speed of 65 km/h (40 mph).

The general idea is to allow the airframe to glide down to the surface and being attached to the airframe, the time saving for pilots to otherwise have to jump out and open their own parachutes (if equipped) is substantial.

The first parachutes were used by Comco in 1982:

  In 1982 Comco Ikarus developed the FRS rocket-launched parachute system for its ultralight and hanglider aircraft.2 In 1998 Cirrus Aircraft provided the first ballistic parachutes as standard equipment on their line of type certified aircraft, the Cirrus SR20.

(Image Source: WikiMedia Commons - Author: NASA)

Here is a Video of the Cirrus Airframe Parachute System in action:

(Image Source: YouTube - Author: AIRBOYD)

An entry on www.aviation-safety.net about the Cirrus parachute system:

  The aircraft experienced a deployment of the Cirrus Airframe Parachute System (CAPS) over west Fayetteville, Arkansas. The airplane came to rest on a roadway shoulder sustaining substantial damage. There was 4 occupants on board, at least two people taken to the nearest hospital with minor injuries, according Police Department.
  The plane started having oil pressure issues immediately after take off.


What is that letter in the top of the tail of that Jumbo?

To identify the aircraft from a distance.. eg if you are driving on the ramp and need to get to SX-OAB and there are several Olympic jumbos parked up, and from where you are you can't read the registration on the fuselage. Not too bad if they're in the same general direction but if some are on your right and some are on your left it may help if you could get a hint from the tail. They only had one letter as OA never had that many widebodies.. I think they never had more than 3 747s at the same time and some A300s. Lufthansa on the other had uses the last two letters. Probably because they had 400s (pax and combis) and 200s at the same time. The pax 400s started at D-ABVA, the 400 combis started D-ABTA and the 200s were D-ABZ(x)(Freighters) or D-ABY(x)(pax).

More airlines put the registration on the nosewheel doors, this saves the ramp staff from trying to get a glimpse of the tail (not easy in bad weather). It is also common to see the last one or two digits/alphabets on the front end, most commonly on the nosewheel doors but also above the cockpit windows or just behind the radome.


What are the take-off parameters for the B-25 Mitchell?

You can find the full POH here, no wind, standard atmosphere, at gross weight you are looking at 3800 ft. of ground roll and 4700 ft to clear a 50 foot obstacle. Take a look at the charts for the other weights as well as other runway surface types.

(source)


What is the difference between SUA (Special Use Airspace) and FUA (Flexible Use Airspace)?

Flexible Use of Airspace is a concept rather than a part of airspace (which SUA is), where the whole airspace is used for both restricted and unrestricted (civil) activities. According to FAA:

• The FAA version of Flexible Use of Airspace (FUA) is called “Joint Use Airspace”
• Although not defined as such, the domestic United States could be labeled as being completely FUA airspace.

The Special Use Airspace (SUA) is a portion of the Flexible Use Airspace (FUA), in which unrelated activities have been restricted:

In accordance with the FUA concept, Special Use Airspace is a defined portion of airspace which may be temporarily reserved for specific activities which require the restriction or segregation of other traffic.

Basically, in a FUA, SUA will be a temporary restriction (rather than a permanent one). Eurocontrol also says the same thing:

The EUROCONTROL Concept of the Flexible Use of Airspace (FUA) is that:
Airspace is no longer designated as purely "civil" or "military" airspace, but considered as one continuum and allocated according to user requirements.
Any necessary airspace segregation is temporary, based on real-time usage within a specific time period.

Related concept is Advanced Flexible Use of Airspace in which SUA is allotted in real time.

An airspace management concept in which airspace is managed as a single entity and in which there are no fixed structures and airspace reservations for special airspace activity are allocated in real time.


Maybe it is one step before the Gladiator: The Gloster Gauntlet. Here the number of wing struts and the landing gear are a better match.

Gloster Gauntlet (picture source)

It must be noted that a lot of experimentation went on with those aircraft. The one in the picture above has guns added on both wings which made the aircraft too heavy and were removed later.

The type in your picture clearly has a different engine with a smaller and deeper NACA cowling - maybe it was used for testing the Bristol Mercury engine of the Gladiator.


Are jet simulators a commercial business or are they owned by airlines?

Both!

Some airlines operate simulator facilities. For example, United has a training facility in Denver with a number of simulators. In turn, they rent out training services to others who will pay to use the facilities (more info on their offerings here). They can also provide trainers, cabin crew training, ground school training, and other such services. Many airlines have similar programs. They've even auctioned off simulator time to customers willing to bid frequent flyer miles for the privilege.

When an airline doesn't own and operate the necessary equipment itself (even an airline that runs its own simulators may not have a suitable quantity for every aircraft in its fleet), it can contract for such services from someone else. That someone else might be another airline, a company that provides simulators (example) and may offer other training services like instructors, or a provider affiliated with the manufacturer (example).


Why are the positions of an aircraft's angle-of-attack vanes dependent on airspeed?

It's because the vane isn't weathervaning into the freestream, it's weathervaning into the local flow a few inches away from the skin, and because of the curvature of the nose, this flow changes with body AOA (and therefore speed) with some variation relative to the change in freestream AOA.  The Stall Protection Computer software will have calibration tables derived from development flight testing to compensate for most of this.


Can the 737 Max autopilot be engaged when some sensors have failed?

The following applies to the Boeing 737 NG series, but probably there are no large differences for the MAX series.

The FCOMv2 (4.20.2 Automatic Flight - System Description) mentions only the following systems in the Autopilot Engagement Criteria and the Autopilot Disengagement sections:

  The A/P automatically disengages when any of the following occurs:

  [...]
  either left or right IRS system failure or FAULT light illuminated
  loss of electrical power or a sensor input which prevents proper operation
  of the engaged A/P and mode
  loss of respective hydraulic system pressure.

  Note: Loss of the system A engine-driven hydraulic pump, and a heavy demand
  on system A, may cause A/P A to disengage.

The sensor input is probably what you are asking about because this would affect the instruments as well. In general, if a system only affects one side, the other autopilot should still work. One notable exception would be the IRS, where any IRS failure causes the autopilot to disconnect.

Edit:

The two autopilot systems on the 737 are called A and B, and they are not necessarily linked to Captain and First Officer. Both the Captain and the First Officer can press both engagement buttons on the MCP (marked with 1 in the image from the FCOM below).


Is it legal to install a TACAN receiver on a civilian aircraft?

You can buy and legally use TACAN equipment for GA aircraft from Bendix/King, but the system is expensive (close to US\$100,000), relatively heavy and requires rack-mounting.


Why would an airplane tip backwards during unloading?

A picture is worth a thousand words... Passenger airplanes do not fasten baggage in the belly down, occasionally there can be a concern from the baggage pilling up at the tail (i.e. turbulence). New baggage employees may also have offloaded the aircraft wrong - unloading the front first.

I have been on airplanes where the flight attendants moved passengers from the rear of the airplane to first class because the aircraft was too tail heavy.

Most newer jets have pressure sensors on the gear. This allows the flight computer to show the crew how the aircraft is loaded in real time. The pilot may have received a warning the nose gear was too light or he may have notice the aircraft tipping up.


Can briefly explain the principle behind the inversion on this power required curve?

Power required is drag times speed. In essence, you ask why drag at the same lift and in 10,000 ft is growing either side of the best climb speed at sea level.
As @Kolom rightly points out, the coincidence of best climb speed at sea level being equal to lowest drag speed at 10,000 ft is just that, a coincidence. There is no causal relation.
The power required curve is shifted right due to lower density at 10,000 ft which requires the aircraft to fly faster for the same dynamic pressure. The X-axis of the plot is True Airspeed, so all polar points will shift right as altitude increases. Next, you will also note a small upward shift. This is caused by the lower Reynolds number at higher altitude which increases zero-lift drag at the same indicated speed.
The best rate of climb speed is where the local slopes of the power required and the power available curves match. Then the distance between both power curves  is greatest and leaves the highest specific excess power after the power required for steady flight has been subtracted from the available power. If the curves would be plotted over Indicated Airspeed, they would simply shift slightly up for the power required and down for the power available as density drops with increasing altitude. The author of your book chose to plot them over True Airspeed, so it might seem that the best ROC at sea level has some significance for the drag at 10,000 ft. It hasn't.
Please make sure you read the linked answers, too, because they should help to give more background. I have kept the answer short, so some things are not fully explained. For example, why there is a minimum drag point at all is explained at the target of the first link.


Why is wing anti-ice in transport aircraft not required below -40 degrees Celsius?

That -40 is SAT and in degrees Celsius.

The reason that anti-ice is generally no longer needed below that temperature is because at that point, the air is so dry that there isn't enough moisture left to form frost or ice that will stick to the airframe or engine parts.

Normally, it's engine anti-ice, rather than wing anti-ice, that is still on when you get to the point in the climb that the temperature drops below -40. At least in the 737, the engine anti-ice is kept on continuously while the temperature is below +10 TAT and above -40 SAT and you're in IMC or other visible moisture (i.e. rain, snow, etc), while wing anti-ice is only used "as needed" to remove ice buildups from the wings.

Also of note, the "below -40 is too cold" logic only exists in climb and cruise, not in a descent. The rationale there being, you don't want to miss the transition from the air is no longer "too cold for icing" as you descend, and find out that your motors ARE now accumulating ice, when they start to act sick... that makes your day entirely too interesting!


Why would a plane descend rapidly in uncontrolled manner after a steep turn?

Markus Voelter interviewed Matt Hall for an episode of his omega tau podcast. They discuss this incident in more detail at 1:13:00.

The aircraft experienced a high speed g stall, also called an accelerated stall. Stall is determined by the angle of attack, which is the angle of the airflow hitting the wing. Stall is most often thought of at low speed, because as the plane goes slower, it takes higher angle of attack to provide enough lift, until it reaches the stall angle of attack and stalls. But this can also happen at high speeds in an aircraft performing a high g turn. Much higher lift is required to make the airplane turn, meaning much higher angle of attack is needed. Trying to turn the aircraft too tightly can increase the angle of attack too far, and the airplane stalls at a high speed.

The other factor is that the airplane will tend to roll left due to torque from the engine and P-factor of the propeller. Since the plane was already in a left hand turn, this plus the stall made the airplane roll past 90 degrees and head down towards the water.

Another aggravating factor was the airplane's stability, which is discussed at 1:31:00. The CG was fairly aft, making the plane less stable. The elevators were also over-balanced, meaning they would tend to make the airplane pitch up even further as the airplane pulled more g's. These changes had helped to make the plane a bit faster but were corrected after the incident to make it safer.

On the human factors side, Matt also mentions that he had a head cold at the time, and made the decision to take a phone call right before his flight, meaning he was distracted and not at his best.

Elsewhere in the interview he mentions that when he flies in air shows, he is more conservative in his margin of safety than other pilots might be.

  You don't need the money if you're dead. So it's just a show.


The plane is probably taking off.  The flaps are hard to see but they don't quite look to be extended enough for landing (Looks like flaps 20).  On a 747 they extend to around 45 degrees (flaps 30, but they curve around more than that) for landing and have a huge, unmistakable profile.  Further, we know it's KBFI and we know the plane is on 31L from the photo.  Looking at the area we can deduce... (click for bigger)

...that the plane is about 3500ft into the runway proper, and 4500ft if we count the displaced threshold (and just off the ground) with the face of the southmost Jorgensen Forge building visible in the background (along with the green GA hangars).

At 3500-4000ft into the runway, hovering over the last markers in the TDZ, this seems quite late to be a landing.  It might be a very deep float, but I would expect more precision from an Air Force pilot flying the CINC around.  Air Force One is heavier empty, but probably overall lighter than a loaded 747-200 (and has powerful engines), so a 4000ft takeoff run for a light 747-200/VC-25 is sensible and probably more likely than an extremely late landing.
The flaps are more than minimum for takeoff, but seemingly less than normal for landing. Maybe 31L was running shortened that day?  Entry at B10 onto the displaced threshold would also give them an extra 1000ft - V1 just past the aim point and rotate near the end of the TDZ markers seems sensible enough.

EDIT
After running a series of simulations, it seems difficult for the VC-25 to be able to takeoff from where we see it, even when starting from B10. The VC-25 is 525,000lbs empty.  With only 100,000lbs load (fuel+people) it can takeoff by B5 at flaps 20, but only by lifting off below V2 (no wind).  This has to be a landing (confirmed by the newly discovered set of photos), but it is a very late landing indeed.
It also seems that military aircraft of the United States are exempt from the requirement to execute a missed approach in the case that they can't make the landing within the TDZ by DA/DH (using "normal" maneuvers), so perhaps the pilot just didn't care and bobbled it in anyway.  The plane did touch down in the TDZ, but just barely.


Is it possible for Mig 21 at corner speed to extend the flaps to minimize the turn radius? Or this is not an option?

Not really.
First, the 'legal' reason: the flight manual doesn't offer this method. So you are not supposed to do it.
Second, there is a technical reason: MiG-21 had so called 'floating flaps' (as they call it), which are held down only by hydraulic pressure. The pressure is set such that the air dynamic pressure would retract the flaps as the airspeed rises above certain point even if the pilot forgot to do it, preventing their damage. I can't find the official threshold, but from memory the flaps would fully (or almost fully) retract at 600 km/h. This is a bit more than 330 kt, but anyway this leaves only marginal available extension at the optimum speed. (Full extension limit was around 340 km/h, but we are not talking about full extension in any case).
Now, what if we did it anyway? Floating flaps make calculations uncertain, but we only need to know if flaps would improve things. For that, we need to know if the turn1 is limited purely by the available lift or by something else. This 'someting else' could be thrust, structural load limits or available elevator deflection.
For MiG-21 (and most fighters), elevator becomes limiting only at supersonic speeds, and structural limits at high subsonic speeds (above the optimum turn speeds).
Thrust is important: we can be pretty sure that flaps will increase drag more than they will maximum lift.
Now, I don't want to post a graph for every statement I make, but all the data is taken from the official flight manual for MiG-21bis (the latest major modification of the fighter). I believe it can be easily found in English, at least for the export versions.
At low altitudes, where the turn radius is actually minimal, the data shows that the available load factor significantly increases with thrust (e.g. 2.5G at max military power vs 3.5G full afterburner at M=0.5,2 which is approx. 330 kt), and the turn radius decreases (~1200 m vs 800 m in the same conditions). This confirms that it is thrust that actually limits (the steady state) performance. Thus, flaps will not help. This is a rather typical situation.
However, turn radius keeps decreasing at lower speeds. (At low altitudes. At higher altitudes, it has a minimum at M=0.5 or more). The official data starts at M=0.5, but if I extrapolate a bit, the speed at which it stops being thrust-limited seems to be quite low. There is a chance that we'll get an optimum somewhere between M 0.3 and 0.4, but it will be a very low-energy turn.
Arguably, if we want to out-turn an enemy, we need the maximum turn rate (= minimum turn time), rather than the minimum radius. This optimum is at much higher speeds (around M=0.8-0.9)3, and there it is also mostly thrust-limited. There is no talk of flaps at such speeds anyway.

1 Of course, we are talking about steady turn. If you just want to turn around the quickest way, you are better off doing a chandelle, an unsteady maoeuvre.
2 At H=1 km (3000 ft), weight 7500 kg (fairly low but reasonable), with two missiles.
3 But this optimum is quite shallow, with little difference in the range M=0.6-0.9 at low altitudes. At higher altitudes, the optimum shifts clearly towards M=0.9. But all this only with full afterburner.


What are these numbers visible from the runway at Narita airport?

A good way to answer questions like this is to look at the Aerodrome Chart

As newmanth answered, these are gate numbers.

Using Google Maps, you can also see these numbers painted on the taxiway as a guide to taxiing pilots

If you want to understand airport air-side signage, one document I found useful is CAP 637 Visual Aids Handbook. It is a UK CAA document but I expect most of it applies in other parts of the world.

The CAA refer to stand numbers, as far as I know these are the same as gate numbers. They indicate parking positions for aircraft at airport terminals, these are places that allow for the loading and unloading of passengers.

Airliners arriving at airports will know what gate they have to taxi to, and ATC will provide them with taxiway routes. Airports provide signs so that pilots basically know where to find their allocated gate.


To help you understand this, I feel like we should discuss how Va is determined.

14 CFR 23.337 Limit maneuvering load factors.

  (a) The positive limit maneuvering load factor n may not be less than—

  (1) 2.1 + (24,000 ÷ (W + 10,000)) for normal and commuter category
  airplanes, where W = design maximum takeoff weight, except that n need
  not be more than 3.8;

  (2) 4.4 for utility category airplanes; or

  (3) 6.0 for acrobatic category airplanes.

  (b) The negative limit maneuvering load factor may not be less than—

  (1) 0.4 times the positive load factor for the normal utility and
  commuter categories; or

  (2) 0.5 times the positive load factor for the acrobatic category.

  (c) Maneuvering load factors lower than those specified in this
  section may be used if the airplane has design features that make it
  impossible to exceed these values in flight.

Based on that regulation, the light single-engine aircraft I've flown have a +3.8/-1.52 load factor limit in normal category loading.  The aircraft is designed to structurally handle those load factors up to max gross weight.

A pilot could exceed those limits by making abrupt control inputs or "pulling G's" because by pitching up abruptly, for example, the pilot is increasing the angle of attack and accelerating the aircraft.

At speeds above Va, the wings are capable of producing enough force to damage the structure with positive or negative loading.

This is a V-G diagram (Source)

The curved line represents the load factor at which the aircraft will stall at a given indicated airspeed.

Va is the speed at which the aircraft would reach its maximum positive load factor limit at the same time it would experience an aerodynamic stall.

An angle of attack less than or greater than the critical angle of attack will cause the wing to generate less lift than it would at the critical angle of attack.  Therefore, the stall point is used to determine where the maximum load factor would occur for a given speed.

Maneuvering speed, as you can see by the chart, has no safety buffer above it, which is why Dave's answer has some details about inadvertently increasing speed.

Flying below maneuvering speed would be a better guideline to follow if you feel that there is are hazardous levels of turbulence.

Let's say you are flying well below Va, and you are hit by a strong vertical gust.  The vertical, upward, gust will increase the angle of attack by momentarily changing the relative wind, and therefore increase lift.  If that change in angle of attack exceeds the critical angle of attack, then the aircraft will aerodynamically stall rather than continue to produce greater lift. In that case, the stalled condition would protect the structure of the aircraft by acting as a limit on structure loading.

Now to answer your specific question:

It is unlikely that severe turbulence will come as a surprise during flight in a small single-engine aircraft.  I have never personally experienced turbulence where I felt the need to decrease my speed.

It is a judgement call that needs to be made by the PIC, and I would slow down whenever I am experiencing consistent turbulence that is causing me to physically perceive unusually high G-forces.

If a pilot is in that scenario, there has likely been a poor go/no go decision regarding the flight.  If you need a quantifier, "severe turbulence" would be the classification for which this matters.

I have experienced moderate to severe turbulence in flight, but those were attitude altering gusts; the load factors imposed were not near limits.


Is the main landing gear of a large airplane designed for sideways (crabbed) touchdowns?

The landing gear is indeed designed to cope with crabbed crosswind landings.

The recommendation is to avoid crab on landing however in severe crosswind conditions it is sometimes impossible to decrab completely without introducing excessive bank. Therefore some residual crab has to be allowed.

Airbus recommends less then 5 degrees of residual crab on landing, but aircraft are designed to cope with more.

An exceptional design is found in the B-52, where the main landing gear can rotated to be aligned with the direction of travel to deal with extreme crab angles.


Why don't helicopter change altitude based on variable rotor RPM as opposed to the collective?

As some of the comments have mentioned, one of the major issues in using the rotor speed to adjust for lift instead of the collective is purely the speed of the response, but this is not the only one. Some of the issues that you will run into include

A large rotor blade will have a relatively large amount of inertia, which means that it takes a while to speed up or slow down the blade, and this is going to be prohibitive for safe flight
The rotor itself is attached to the engine via a clutch, which allows the rotor to spin freely if the engine quits. This is a requirement for auto-rotation, but it also means that you can't use the engine speed directly to slow the blade down, you'd have to include some sort of additional brake to slow it down if you want to maintain the ability to auto-rotate
Both piston and turbine engines, unlike an electric motor, have a significantly narrower/smaller range of RPMs that they can function at, with different amounts of power at different RPMs. The engines themselves are also limited in how quickly they can speed up and slow down, which means that even if you could speed up or slow down the rotors themselves rapidly, the engine might not be able to function at the required speed.
As the rotor size increases, so does the speed that the tip of the rotor is traveling at. If the tip of the rotor starts generating shockwaves because it has exceeded the speed of sound, you'll have significantly reduced lift and a large increase in sound volume. The tip of a small rotor isn't going to get anywhere close to super sonic, so this isn't a problem.
The tail rotor itself is mechanically connected to the main rotor, and will need to create different amounts of lift to control the yaw of the helicopter. Since you're probably not going to want to descend or ascend every time you turn left or right, you'll still need a variable pitch for the tail rotor. I already have to adjust the pitch of the tail rotor at various times, and it would add additional complexity to the piloting of the aircraft.
The rotor of a real helicopter is moving a much larger volume of air, and the pilot already has to manage the issues caused by it. For example, if I descend too quickly, I can descend into my own rotor downwash, which will not provide lift. If the wind is blowing in the correct direction, my rotor downwash can be blown into my tail rotor, which will cause a loss of tail rotor effectiveness. Having multiple rotors increases the complexity (and likelihood) of this occurring.

I'm sure there's a number of issues I haven't even thought of that would be difficult or impossible to overcome, but this is just the start. Most of these issues don't exist on a small drone because:

It has electric motors that have a much wider torque curve, and a much faster response time, so they can adjust the speed of the rotors quickly.
The rotors themselves have very little inertia, and their speed can be adjusted quickly.
There are multiple rotors, and no tail rotor, so you don't have the mechanical complexity associated with them.
Because of the significantly smaller amount of air that is being moved by a smaller aircraft, you have significantly less aerodynamic complexity. I don't think you're likely to encounter any issues with settling into your own turbulence, for example.
You can't auto-rotate. In a drone, it doesn't matter as much, since there's no one sitting in it, but as a helicopter pilot, I very much want the ability to autorotate.

This is certainly not a complete list of issues, but are just a small subset of issues that I can think of off the top of my head.


Transport category airplanes, which includes most aircraft in commercial passenger service, must meet the FAA regulations in 14 CFR Part 25. Some relevant excerpts are as follows:

§25.305
The structure must be able to support ultimate loads without failure
§25.307
Structural analysis may be used only if the structure conforms to that for which experience has shown this method to be reliable. In other cases, substantiating tests must be made to load levels that are sufficient to verify structural behavior

Ultimate loads are the absolute maximum loads that a structure must carry without failure. These are loads will be extremely rare and result in permanent damage to the structure, but with the structure still intact the aircraft should still be able to land safely.
The FAA will not certify the design if the manufacturer cannot prove that the structure is capable of meeting these requirements. One option is using computational simulations. Modern analysis techniques are very powerful. However, analysis is useless if you can't show that it is also reliable. Structures like wings are extremely complicated. Once the materials become permanently deformed, the behavior changes and the analysis becomes even more complicated.
So if you can't prove that computational methods will work, you have to do a test of the structure. Fatigue is similarly difficult to predict, so aircraft are generally subjected to multiple lifetimes worth of load cycles with special test rigs to understand how the parts will hold up.
When the Boeing 777 wing was tested, it failed at 4% over the required load. This shows that even the limited analysis capabilities (compared to today) were very accurate, but the only way to find out for sure is to test it. Analysis will always have some amount of error. If the analysis had been a few percent off the wing would have failed the test.
So the analysis for the 777 was shown to be reliable, but only in the case they tested. If a new design differs significantly, this adds some uncertainty into the analysis. Will it still be reliable in the new case? The only way to know for sure is to test it.


What is this plane from WWII (probably French or Allied forces)?

It's an RAF Coastal Command Vickers Wellington, a maritime patrol variant, with a chin radome for its search radar and the nose turret removed and just greenhouse for observing.  The dark projection on top just above the cowling is a fairing for a Direction Finding loop antenna on the fuselage.  The dark shapes farther back are just dark painted areas.  Here's a shot of a similar one:

If you're sure the picture was taken near Morocco, it was probably doing sub hunting in the Mediterranean and nearby Atlantic.  Likely with 179 Squadron, based at Gibraltar.


Why are the Convair 880's yokes shaped differently from each other?

My guess is that this is a relatively odd situation, where one yoke had already been replaced by a newer one (on the right), whereas the other still is the original.

If you look at the two images below (from Airliners.net), both yokes are the same.

It seems as if the right one has some more controls on the yoke (e.g. for radio settings, trim controls, or something else) and is simply an upgrade to the older model. If the old one still worked, I can imagine an airline waiting for a regular service inspection or overhaul before replacing it, rather than removing parts that are still fit to fly.


How does deploying flaps change the gradient and rate of descent?

Yes you’re viewing it the wrong way.  Deployment of flaps changes all sorts of flight parameters, not just one.  The wing area may increase, the camber and angle of incidence of the wing increase and so the engine thrust line is effectively tilted downwards.  The aspect ratio changes, as does the relative angle of the horizontal stabiliser.  The net result is that the flight efficiency is reduced (i.e. the amount of energy required to maintain height increases) but the stall speed is reduced.  There’s a lot happening and you have to take it all into account.  Typically on approach you’ll want a low airspeed and relatively high rate of descent but without compromising control authority, so the flap layout is designed to provide this.


Why are the positive points in a V-n diagram associated with pitch maneuvers?

Because they are reached when the aircraft flies a pitch maneuver. Let's look at the three points in detail:

Point A: This is where the highest turn rate can be achieved, so it is reached normally in an attempt to change direction. You might argue correctly that this is not a clean pitch-up, but essentially it is. When starting the turn, the aircraft will deflect both aileron and rudder, but once the turn is steady, both will essentially be neutral, except for the small deflection needed to overcome damping effects. What is left is a pitch maneuver akin to a loop with mostly elevator deflection to pull the needed gs.
Point C: This is reached inadvertently when flying into a heavy gust. Aircraft fly straight for most of the time, especially when flying fast, so it is assumed that this happens in straight and steady flight. Here, not even an elevator deflection is needed to reach the envelope point, all you need to do is to fly through exceptionally turbulent weather.
Point D: This is only reached after the pilot screwed up. Certification rules like JAR 23.335 b(4)i explain what the authorities assume: The pilot went into a shallow dive when upsetting the controls, oversped the plane and now tries to slow down by pulling up. This will also most likely occur in symmetric flight only. Or maybe in the initial phase of a dogfight, but then different regulations apply.


So, a SNOWTAM actually has a different format, and your example is just a standard NOTAM in ICAO format.

12/057 NOTAMN  Q) ZBW/QMRXX/IV/NBO/A/000/999/4221N07100W005
  A) KBOS  B) 1912310152  C) 2001010152
  E) 09 FICON 5/5/5 100 PCT WET OBS AT 1912310152.

This decodes into the following:

Series and number:        12/057
Nature of the NOTAM:      New (N in the NOTAMN)

Q) Qualifier line:
   FIR:                   Boston FIR (ZBW)
   NOTAM Code:            Starts with Q and the following four letters:
                          Subject: Runway (MR)
                          Condition: Not Specified / Plain Language (XX)
   Traffic:               NOTAM issued for IFR (I) flights and VFR flights (V)
   Purpose:               NOTAM selected for immediate attention of flight crew members (N),
                          for PIB entry (B), and concerning flight operations (O)
   Scope:                 Aerodrome (A)
   Limits:                FL 000 to FL 999 (000/999)
   Geographical location: 42°21' N 071° 100' W (4221N07100W)
                          Operation radius of the NOTAM: 5 NM (005)

A) Aerodrome:             Boston Logan (KBOS)
B) From:                  01:52 UTC 31 December 2019 (191231 0152)
C) Until:                 01:52 UTC 01 January 2020 (200101 0152)
E) Text of the NOTAM:     Runway 09 Field Condition
                          Braking action 5/5/5 (good for each third of the runway),
                          Runway is 100% wet
                          Observed at 0152 UTC on 31 December 2019

We could dig into the ICAO documents to find the official guidance, but different countries implement it differently sometimes anyway.  Here's a good document that I found which breaks down the different codes.


Is is possible to land a midsize commercial plane on an Ford Class aircraft carrier?

A Classic 737's maximum landing weight is about 114,000# for a -300, less for a -500, more for a -400.  But that is max. Down to "almost empty" gas tanks, knock another 8 or 10,000# off of that. Less than full pax/cargo load, several more thousand pounds off.
With a stiff breeze, say 20 knots, plus the carrier at max speed, you have maybe 50 knots of headwind. With that sort of headwind, can you stop a mid- to light-weight 737 in 1000' using full flaps, max reverse, and max brakes?
I don't have the charts with me, but I suspect you totally could, and in fact it wouldn't even be all that close. No margin for error if equipment fails, but if everything works right, those jets can stop quite well. And 50 knots on the beak is a LOT of headwind... "groundspeed" over the deck would be like 60 or 70 knots, and you can lose that in a lot less than 1000'.
I've flown C-130's and 737's, and the rate of descent on an assault landing in the Herk is nothing the 737 couldn't handle.
So... carrier landing... good to go?
Not so sure.  Compared to carrier aircraft, the 737 wingspan in WIDE -- even for the "little" -500.  That limits where you can plan your rollout so that you don't have an unacceptably high risk of clipping the island. Without playing with scale drawings of a 737 and the Ford's deck, I couldn't even guess if or how the geometry would or wouldn't work out.
Alternate plan that is probably no more risky for the passengers and might be a LOT safer for the carrier: ditch your (nearly out of fuel) jet close to the carrier, and have the carrier's helos and the small boats of the battle group pull the survivors off the wings or out of the water. With calm water, you get a "Sully" scenario (except with wings filled mostly with air, rather than jet fuel... Better buoyancy). In rough water, the risks go up. Way up.
But in that sort of weather, the deck landing gets lots more risky as well.
I suspect the deck landing would neither be allowed nor requested, but not for reasons of stopping performance.


How to handle vacuum and turn coordinator failure in IMC?

This isn't exactly your scenario but at my last instrument checkride the DPE asked me how I would descend from VFR-on-top through a solid cloud layer following complete electrical and vacuum failure (in a C172 or something similar). No avionics meant no help from ATC (vectors, or even a PAR approach) and we also assumed that I had no tablet, phone or other external systems that could help me.

The question came at the end of a discussion about aircraft systems and failures and the DPE didn't expect me to have a ready answer because it isn't something you train for. But he suggested this procedure:

Set up the aircraft on an east or west heading to minimize compass turning errors
Use the rudder only to fly a constant heading on the compass; once you have the aircraft going straight, do not move your feet again
Set power and trim for a stable descent at a little above Va and a little less than your usual descent rate, e.g. 300fpm
Sit back, cross your arms and wait to break out. Resist the temptation to touch the ailerons or power.

His reasoning was that by avoiding using the ailerons and power you can avoid going into a graveyard spiral quickly. You may still do it, but you'll do it a lot more gradually and hopefully by that point you'll have broken out anyway. I've never tried it myself, but I'll have to do it sometime with a safety pilot.

In real life, if you can't get to VMC easily then a tablet app with a portable AHRS unit would be a good backup. Although personally, if I ever lost the complete panel my first thought would be to get to VMC, not to shoot an approach. I suspect that for most people, landing in a field is likely to be the much better choice. But like all 'what if' scenarios, it depends.


Do I have to take science in high school to become a pilot?

There are no specific high school or college academic requirements specified for pilots in the U.S. Code of Federal Regulations.
However, basic knowledge in math and the physical sciences is important, and will greatly improve your understanding of subjects that are taught in ground school so that you can successfully pass required written and oral exams.
Furthermore, to be competitive as a professional pilot a college degree definitely helps, and you will likely need some minimum science credits both to get in, and to graduate.  Don't skimp on your education!


What's the purpose of "over G" penalties in Red Bull Air Race?

It's a safety rule to protect the limits of the airframe and the pilot.

See the video (also on youtube) from this Red Bull Air Race page which explains the rules. The G-limit is discussed from 3:30.

The following is a quote from the relevant section of the video.

  Maximum load factor, that is how much G's is the pilot pulling. That has
  issues [...] the structure of the
  airplane is designed to withstand a certain amount of G. We need to
  ascertain, to check, that the pilot isn't exceeding that amount of G,
  so we monitor that very carefully. A thousand times a second we're
  monitoring the G inputs that the pilot is putting on the airplane. So
  if you exceed the maximum G's then DNF (Did Not Finish)


How to become pilot in India with lack of money

Airlines in most countries (outside of US and Canada) usually offer ab initio pilot programs, meaning they will train a pilot with no experience. Training will be paid for in the form of a loan which will be deducted from your future salary.

However there are some caveats. First, if you fail, you will be responsible for paying off the loan. There is no guarantee you will pass or be offered a job.

Second, these programs are highly competitive. Most programs require a college degree simply due to the number of applicants. Even then, you will have to be high in your class and be the best in all of their tests. I understand typical numbers at European airlines are 1 accepted out of 1,000 applicants.

Some people will suggest the military. Keep in mind that military pilot positions are often equally competitive. In the US, you must have a four year college degree to become a military pilot as well. I believe India is similar to the US as somebody after secondary education may apply to obtain a degree in a military academy, though that is highly competitive in itself.

Therefore, the best way may be to save money and/or get loans and gain your licenses yourself.


Are gliders susceptible to bird strikes?

Gliders, as every other aircraft, are susceptible to bird strikes. This is a detached glider's tail after hitting a 10 kg vulture:

  The  accident  was  caused  when  the  crew  lost  control  of  the  airplane  following  the  loss
  of a part of the tail assembly after the vertical stabilizer on the airplane struck a griffon
  vulture head-on.

Some countries are more susceptible to this kind of accidents than others. In Spain, which has a large population of vultures, I routinely hear about fatal accidents due to bird strikes.


There are a few different things that you can look for, and to some degree it is trial and error as well.  Gliders will have an instrument that measures vertical speed so that they can tell "how good" a thermal is as well (a variometer or a Vertical Speed Indicator(VSI)).

Some of the things to look for:

Color variation on the ground because the difference in the amount of heat absorbed by the ground varies based on the color/composition.  The hotter area will cause the air to rise (hot air rises) and will create a thermal.  I.e. A dark colored area surrounded by a light colored area or vice-versa such as a parking lot with fields around it.
Birds circling in an area because they tend to circle in thermals.
Certain types of cloud formations that can indicate lift.
Other gliders!  :-)
If the wind is blowing across a mountain ridge or other large structure, the wind has nowhere to go but up so is also a good place to look for lift as well.

Here is an example showing how some of the thermals form and how the wind affects them.  Notice also how once the air has been lifted to the point where it cools below the dewpoint that a cloud will form:

Here is another showing how terrain can cause lift:


MIL-STD-1760A is simply the standard that a processor must conform to, and is not an actual model of CPU.
There are actually a lot of independent computers in a military aircraft, each with specific responsibilities. They are usually linked up via networks, typically over MIL-STD-1553 busses for older platforms. The radar has its own processor(s) and architecture(s), as does the flight control module, the fire control module, the navigation system, the munition controllers (sometimes one per weapon station/pylon), the display controller, the mission computer, et cetera. All of these come from different OEMs, and therefore use a variety of hardware. The different subsystems present and their exact functionalities depend on the design and requirements. A subsystem may itself be composed of multiple computers within their own network, independent of the main aircraft networks.
The F-16 uses Raytheon's Modular Mission Computer (MMC) for its mission computer, with the following specs:

The first generation, the MMC3000 relied on MIPS R3500, a 32-bit chip processors with 110,000 transistors and running at 12 MHz. We found this chip on the end of the 1990s HP9000 computers. The computer had 4 MB of memory RAM.
The MMC5000, the second generation of the F-16 computer, still relied on a chip MIPS, a RM5260 who was noticeably faster (with a 133 MHz to 150 MHz clock frequency) and above all it is a 64-bit chip. The memory was more than doubled, with 10 MB available.
The MMC7000 that equips the more modern F-16, including all F-16 Europeans who benefited from the MLU (mid-life Update) modernisation, has always that 10 MB of memory but its RM7000A processor, designed in the early 2000s, works between 300 and 400 MHz.
Source: http://www.4erevolution.com/en/ordinateur-de-bord-f-16/

I highlighted the mission computer because I think of the mission computer/controller/processor (exact terminology depends on the platform) as the brains of a military aircraft. They tend to be the bus controller of the main aircraft network, aggregating inputs from other subsystems and computing/providing information to the pilot to help them carry out their mission.

To the second part of your question, I assume you mean faster or more powerful CPUs when you talk about modern CPUs. Modern here depends on context. CPUs used In aircraft will never need the type of clock speeds or memory capacity you see in consumer computers, for a few reasons. Firstly, there is actually a lot of processing capacity distributed over the various subsystems - the need for a single powerful chip only arises when you demand that a single chip do everything. Secondly, when the requirements of subsystems are as specific as they as in military platforms, the software can be very compact and efficient, unlike consumer software (which require a lot more code for things like architecture adaptors, multi-tasking logic, and thousands of device drivers) - you trade off unnecessary flexibility in return for reliability and efficiency.
The multi-functional displays of military aircraft (and also commercial ones) focus on conveying the necessary information in a clear and concise manner. The rendering requirements are actually quite primitive compared to modern 3D games - it can get by with less processing power than a computer from the 1990s.

EDIT: Elaborated answer, following user3528438's comment.


Since gliders have no engines, they are often permitted to operate under special agreements called Letters of Authorization, which permit them to operate where other aircraft may not. These agreements may permit them to fly VFR in Class A airspace to capture mountain wave lift, through TFRs, through Restricted airspace, depending on the terms of the agreement with the FAA.

In particular, in the airspace you mention near the Capitol, there is a TFR Waiver in force which permits gliders to operate within the Capitol TFRs.  This Waiver supersedes the TFR rules and the associated NOTAMs. Furthermore, it permits gliders to even thermal inside the TFR if necessary for safety of flight.


Is there a practical use of streaming data received from meteorological sensors installed on aircraft?

Yes, such a system would be beneficial to pilots, ATC, and meteorologists.
Pilots are very concerned with meteorological phenomena like icing and turbulence (for safety-of-flight reasons) and winds aloft (for fuel planning purposes). Pilot reports of weather conditions (PIREPs) may be delivered to ATC or Flight Service for local and long-range dissemination. This information helps other pilots avoid dangerous conditions and helps weather forecasters improve their forecasting models. The 7110.65 2–6–2 PIREP Solicitation includes a note:

Routine PIREPs indicating a lack of forecasted weather conditions, for example, a lack of icing or turbulence, are also valuable to aviation weather forecasters and pilots. This is especially true when adverse conditions are expected or forecasted but do not develop or no longer exist.

Live or periodic streaming of sensor information already present on larger airliners (particularly icing status, outside air temperature, and wind velocity, but other sensors could be installed as well) would relieve pilots and controllers of having to discuss routine PIREPs on frequency and could be developed into graphical systems that automatically display hazards. Delta is using vertical accelerometers in some of their aircraft to automatically report turbulence in real time and transmit that information to airborne flights; obviously they see this as a business advantage and are loath to share it, but the system could be expanded.
Whether the costs and complexities of such a system would be worth the real-time and forecasting benefits, I don't know.


With the upgrade of the 737 to the Max model, what major changes are incorporated?

There are of course a lot of tiny changes that Boeing would have done to the aircraft that most of us wouldn't notice, but for brevity I've just included the major changes between the 737NG series and the upcoming 737MAX.

The CFM LEAP-1B engine replaces the current CFM56 engines. Some of the significant improvements in fuel efficiency (15% savings minus drag from larger engine touted by CFM) come from a much higher bypass ratio (from 5.3:1 to approximately 9:1) and materials that can tolerate higher temperatures. Chevrons (saw-toothed tips at the end of the nacelle) have also been included to reduce engine noise on takeoff.
The engine change required changes to the nose landing gear to allow enough clearance from the ground, extending the nose gear by about 8 inches (20cm) and modifying the nose gear bay to allow it to fit into the existing space.
The AT (Advanced Technology) winglets replace the 737NG's blended winglets. The AT winglet incorporates two portions, done to reduce the weight required (compared to a larger blended wingtip) while still reducing block fuel burn by about 1.5%.
Fly-by-wire spoiler system reduces the need for long cabling between the cockpit and the spoiler hydraulic actuators, saving weight, reducing stopping distance by quicker actuation and increasing the accuracy of the controls.
Redesigned tailcone and modifications to elevator to improve aerodynamics, removing the requirement for vortex generators (VGs), which improves predictability and control by making the air turbulent, but as a result increasing drag.


Why do the jet turbines spin while the engines are turned off?

After shutting down they still have momentum. Or like you said, because of Windmilling - freely turning when the wind impacts the compressor blades.

The APU can, but more often than not doesn't, rotate the engines (overly simplified, not to go into unrelated details).


Why is the Beluga chartered out for oddball missions, but not the Dreamlifter?

The 747LCF cannot haul any cargo except Boeing’s own cargo as its type certificate only allows it to carry Boeing’s own cargo.

Whereas A300 Beluga’s type certificate limitation section only refers to Airplane Flight Manual. It may allows to carry other cargo with some conditions met.

—————————

Page 28 of A20WE, type certificate of 747, states

  XIV - 747-400 Large Cargo Freighter (LCF) Major Design Change (Approved June, 2, 2007 ) Transport Category

  Allowable cargo

  These airplanes are not approved for commercial freight hauling operations of material other than that approved per Exemptions 8769, 8769A and 8769B. Only cargo that supports Boeing corporate lines of business is allowed for carriage. All items intended for carriage must conform to the standards found in Document D926U013-44, “747-400 LCF Flammability Acceptance Criteria for Cargo Carriage,” or be accepted by the FAA once a safe method of transport has been established. A summary of all items allowed for carriage is identified in Document D451U742-01, “Allowable Cargo – 747-400 Large Cargo Freighter.” Document D451U742-01 is considered part of the Weight and Balance Manual/Airplane Flight Manual. In addition, a listing of the FAA-approved shipping mechanical equipment (SME) fixtures that are approved for installation on the 747-400 LCF aircraft are contained in the Weight and Balance Control and Loading Manual (Document D043U545-BHC1).


Which compressed air and fluid are generally used by oleos?

I'm sure it varies by aircraft type, but for the C172S nose gear oleo (for example) it's air and hydraulic fluid. The operating handbook says:

  Keep strut filled with MIL-H-5606 hydraulic fluid per filling
  instructions placard, and with no load on the strut, inflate with air
  to 45.0 PSI


Early biplanes did use similar airfoils. Not as extreme as the Eppler 376, but still very thin and highly cambered.
When Otto Lilienthal started his glider experiments, he tried to copy storks. He experimented with different airfoil shapes by using exchangeable ribs on the gliders and by testing model wings on a rotation test stand (Rundlaufapparat). There he discovered that thick airfoils with a blunt nose were actually better than the thin, birdlike airfoils he had used so far. But he didn't believe his own results and continued with birdlike airfoils.

Farman-Voisin biplane, 1907 (picture source).
The same happened with all other airplane designers until 1915, when scientific work started to influence airplane designs. The highly cambered airfoil works very well in a very small range of angles of attack when the local direction of flow is parallel to the local contour of its nose. But while birds can adjust the camber and area of their wings, airplanes of those times could not. In order to combine fast flight with high lift for take-off and landing, the thick airfoil is better.
While birds are small enough to structurally get away with thin wings, the much larger man-carrying airplanes need the thicker wings to accommodate their bending loads without bracing. Scaling laws show that loads grow faster with size than the dimensions do and only thicker wings make the unbraced, cantilever designs necessary for efficient transportation possible.

Heron in flight (picture source). This picture shows nicely that 90% of the area is feathers, so a thick wing becomes impossible for birds.
Birds cannot be hollow inside, except for hollow bones. So they have no choice of using thick wings - they have to work with thin wings and adjust camber and wing area to the flight conditions. Being much larger, airplanes need thick wings for aerodynamic and structural efficiency.


Is there an official record of the pilot with the most logged flight time?

From Wikipedia, the free encyclopedia  John Edward "Ed" Long, Jr

John Edward "Ed" Long, Jr. (1915–July 18, 1999) was an American pilot who is in the Guinness Book of Records for the most flight time by a pilot: over 65,000 hours (more than seven years and four months) at the time of his death.

He began in 1933 at the age of 17, when he took his first and only flying lesson. In September 1989, he broke the previous record, 52,929 hours, set by Max Conrad in 1974. According to his brother, Ed Long's job involved checking power lines, so "most of that was under 200 feet, in a Piper Cub".He died in 1999 at the age of 83.*


What if a commercial airline pilot misses their flight?

Airlines try to maintain some ratio of crews to fleet to provide surplus bodies to cope with this sort of thing.  For Regionals, where the average aircraft hours are around 2500 hrs per year, and each pilot flies somewhere around 800-1000 hrs per year, you need 3 crews per a/c just to meet the baseline operational need.  Add absentee time for vacation requirements and booking off sick, training etc, and you need 4-5 crews per a/c to be able to sure that you can keep each airplane running 2500 hrs/year.

As a result, Regional operators will try to keep about 8-10 pilots on staff per aircraft and if they are below that, problems start to happen.  You can get by somewhat with crews working overtime, but there are limits to that due to regulatory duty limits.  Airlines have a reserve system to organize crews to make sure there are available idle bodies to step in if required.

There is "reserve" and "ready reserve" duty.  Reserve duty is being on-call at or near home and able to report within a reasonable time of being called, like 2 hours.  These are to cover book-offs with advance notice, like a pilot calling in sick 6 hours before.  Ready reserve duty is where the pilot has to go to the airport crew ops office in uniform and basically hang around ready to go on short notice for someone who doesn't show or who calls in at the last minute.

So:

Yes probably, if there isn't a ready reserve pilot on hand.
They'll stick in a guy/gal on ready reserve if they have one.  If not, the flight will get delayed or cancelled.
See above.
Booking off sick or calling in because you had a traffic accident or home crisis isn't a problem.  The problem is failing to call in and leaving people hanging.  You better have a very good reason for not showing up and not calling in.  That would result in some kind of disciplinary ding on your record, getting worse if you do it more than once.  It would depend on an airline's union contract, or if non-union, the management's disciplinary policy.
In a union shop, for a one time thing, probably not if not repeated.  Union shops give you the luxury of having to screw something up several times to really get hammered for things that are not safety related. It'll depend on contract language; but you could get suspended or let go eventually.  In a non-union shop, it could hurt you in terms of promotion, or if you did it more than once you might get let go more readily than at a unionized airline.

Bottom line is, the next worst thing to unsafe pilots are unreliable pilots.

In the Regional airline business especially, the shortage of crews is really starting to bite and airlines are not able to maintain the necessary staffing "fat" as the flow from the bottom thins out and the majors suck up the experienced crews.  Many cancelled flights with Regional operators are due to lack of crews, not mechanical or weather issues.  The 1500 hr "Colgan Rule" requirement in the US has made this that much more severe, but up here in Canada where Regionals can still take 250 hour flight school graduates under special programs where they are groomed in-house, there are still not enough to cope with retirements and flights are being cancelled for lack of crews.

This is all tied to the final stages of the movement of the "baby boom" demographic wave, which is now resulting in a flood of retirements of airline capts born in the mid 50s hitting retirement age, which should finally start to taper off in the next 10 years once the peak of the wave is mowing the lawn at home.  Everybody's vacuuming up pilots from the levels below them, resulting in shortages all the way down the chain.


What's the point of using T-38 to instill flight proficiency in Space Shuttle pilots?

What the T-38 airplane provides NASA is currency and proficiency in high performance aircraft operations in a jet which has many of the same characteristics as the shuttle in this respect ie high wing loading, high approach and landing speeds, similar glide descent ratios.  The White Rocket is a temperamental and challenging little jet to land and will not tolerate sloppiness from her flight crew here.  She requires the pilot to stay well ahead of it while making an approach, plan out and execute small corrections very precisely while maintaining airspeed, glide path and angle of attack.  Maintaining good proficiency in these aspects of high performance aircraft flight and keeping sharp on that high speed mindset comes in handy in an astronaut's line of work.

And T-38s make excellent chase aircraft, capable of keeping up with the shuttle during the final phases of its descent and approach, and can provide an extra set of Mk 01 eyeballs to verify external functioning of systems, eg landing gear, speedbrakes, hydraulic leaks, etc.

Actually, outside of the shuttle sims, landing approach practice was done in a modified Gulfstream II which included a replica of the shuttle flight deck for the left seat guy.  It apparently was remarkably similar to the shuttle in a deadstick landing.


Does a history of social anxiety significantly damage commercial pilot career prospects?

I don't know about the question in your title, but I can answer the question in the body:

  I was wondering if it's important that I disclose this to employers or just lie if asked?

No, you should not lie about your medical history. If you knowingly lie about your medical history, and it subsequently comes out, it could cost you your career - including the tens of thousands of pounds (or euros or dollars) you spent on getting your CPL or ATPL. Even if you have insurance against losing your medical certificate, they almost certainly won't pay out in this case, leaving you with a debt bigger than a student loan and no job to pay it off. It'll also make it much harder to get a medical certificate in future and return to flying status.

Worse yet, if the reason this comes out is because of an accident, you may face a criminal investigation because you flew knowing that your medical certificate was not valid, regardless of whether you think your condition could have contributed. You can't expect your employer (ex-employer) to stand up for you in this case.

Although I have a class 2 medical in the UK, I'm no expert in the medical requirements. It would surprise me if a past mental health condition which doesn't really affect your ability to fly, and which was successfully treated without medication, would stop you getting even a class 1 medical. It would probably just mean more uncomfortable questions in the medical exam, and probably having to get a written opinion from the psychiatrist who treated you. That might cost you some time and cash in the short term, but it's worth it to know it won't come back to haunt you later.


SNLF stands for Supersonic Natural Laminar Flow.

Laminar flow over the wing reduces the friction drag. Achieving this has been the aim of a number of designs, from the laminar flow airfoils of the past to the latest 737 MAX winglet. While it is difficult enough to achieve in subsonic flight, the high wing sweep and Reynolds number in supersonic aircraft make it much more difficult to achieve.

One method of achieving this is to use wings with low sweep (unlike delta wings) and sharp (supersonic leading edges) at the expense of other forms of drag.

Dark colors show the expected laminar flow regions, while the graph shows the pressure gradients. Image from Unconventional Configurations for Effecient Supersonic Flight by I. Kroo

A number of designs have been proposed to this end from reverse delta to the Aerion's design, which looks strikingly similar to F-104 starfighter.

One method of achieving the laminar flow (i.e. extending it chordwise) in supersonic flight is by using laminar flow control (LFC) methods like suction etc. A good example is the use of suction in a F16XL test aircraft by NASA, which produced laminar flow over nearly half of the wing (less than the design value though).

F16XL with porous titanium LFC glove on the left wing, image from NASA report TF-2004-12 DFRC, F-16XL Supersonic Laminar Flow

The problem with LFC is that it increases weight and takes up space in the wing, hardly an advantage in a supersonic aircraft. So, the next thing to do is increase the laminar flow distribution without using any mechanical (or other) aids.

Natural laminar flow means the presence of laminar flow even in the absence of any LFC measures. From NASA F-16XL Supersonic Laminar Flow document:

  Passive laminar flow can be achieved in the wing design process, .... Passive laminar flow can also be created on an existing wing by altering the cross-sectional contour of the lifting surface to change the pressure gradient. Both of these laminar conditions are called natural laminar flow.

SNLF then, is basically laminar flow in supersonic flight without the aid of active boundary layer control methods.

SNLF has been demonstrated in the past (unsurprisingly in F-104), but the tools to analyze it and replicate it in other aircraft were lacking. This seems to the main thrust of the Aerion.

The AS2's wing design has been tested by NASA in a F-15 and the results seem to be encouraging.

SLF flight test on F-15 with NASA Dryden (top). Predicted transition (left)
and infrared image (right) showing extensive natural laminar flow. Mach 1.8, 40,000 ft., Reynolds Number about 10 million. Image from Unconventional Configurations for Effecient Supersonic Flight by I. Kroo

Aerion doesn't say that delta wing is inferior, but it is a simple fact that you can't use a delta wing for supersonic laminar flow. Aerion claims that its design will have 20% less drag than delta wing, but till the aircraft actually flies, we should take its announcements with a large dose of salt.

There are other problems the company has to overcome if the product is to be successful- if the wing is thin (as I expect it to be) and quite small, the aircraft's range appears wildly optimistic. For example, the F-104 had thin wings, but had the fuselage to put the fuel in; something that is very difficult in AS2 unless the passengers agree to carry some. Also, the small wing size may lead to quite high landing speeds.

Planform comparison of AS2 (top) and F-104. Not to scale. AS2 from company website; F-104 from Wikipedia- attributed to Kaboldy.


How would a helicopter deal with auto rotation when it transports a hanging payload?

In theory, with that load, the rotor revs will be higher during the descent, and releasing the load just before flaring will give the pilot more rotor energy to control the aircraft with the collective in the last stage of the landing.

But it would be more prudent, in my opinion, to release the load as soon as possible. After all, in any dead stick landing, the lighter the aircraft, the better...