How does turning Errors in the Air Driven Artificial Horizon work?

Rapidly becoming a nonfactor as electronic systems replace vacuum driven gyros:

https://www.flyingmag.com/g00/how-it-works-attitude-and-heading-reference-system?i10c.ua=1&i10c.encReferrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8%3d&i10c.dv=2

How It Works: Attitude and Heading Reference System

Attitude and heading reference systems (AHRS) have been providing heading and attitude information with greater accuracy and reliability than traditional mechanical gyros for years now. But how do these solid-state systems deliver this information, and how do they do so using increasingly smaller and lighter equipment?

Micro Electronics

An AHRS’s key features include micro-electronic mechanical gyros, accelerometers and a magnetometer or flux valve. The micro-electronic mechanical gyros are responsible for capturing motion data as an aircraft moves about all three axes. They do this by using vibrating components. As an aircraft changes direction, these vibrations deviate, and these deviations can be measured and used to calculate directional change data.

Gyro Drift

In order to account for gyro drift, which can produce erroneous data, an AHRS must also rely on accelerometers as well as a magnetometer or flux valve. The former uses gravity to serve as both an initial attitude reference as well as an inflight reference, whereas the latter uses Earth’s magnetic field to provide heading information.

The AHRS aggregates all the information from these different components and conducts complex algorithms and calculations to provide highly reliable attitude and heading data.

Side Note: Previously out of reach for private aircraft owners due to high costs, AHRS prices dropped remarkably as the result of the use and advancement of AHRS technology in the automotive industry. An AHRS today can be as small as a coin.


Is there no warning if landing gear is not retracted during flight?

It's not there because it's like driving with the handbrake on.

  [The flight] was climbing out of Kolkata, however achieved an unusually poor climb rate, was not able to accelerate to normal cruise speeds and leveled off at FL200 after a continuous climb for about 30 minutes (avherald.com).

And because the flight crew should have run the 'after takeoff' checklist, which includes checking that the landing gear is up and locked.

(Source) A typical Airbus A320 checklist.

Related: How much extra drag does landing gear incur?


What's the difference between orientation and position?

Yes there is a distinction, pitch, roll and heading are angles [unit = radian] and latitude, longitude and altitude are linear distances [unit = meter].  Together, these six parameters define the six Degrees of Freedom that define the momentary state of a rigid object with reference to the earth.

All six are defined relative to earth axes. For the linear dimensions this is clear, we just need to define a suitable zero point. For the angles:

Pitch is the nose up/down angle relative to the gravity field of the earth.
Roll is the wingtip up/down angle relative to the gravity field of the earth.
Heading is the angle relative to a suitable earth reference, usually magnetic north or geographical north.

Conversion of aircraft axes into earth axes is a non-trivial matter and the cause of much confusion, for instance in questions comparing lift to weight: lift is always coupled to aircraft axes, weight to earth axes. The axes sets are defined as follows:

Aircraft axes

Origin: Centre of Gravity of aircraft
X-axis: in the symmetry plane of the aircraft, + = forward to the aircraft nose
Y-axis: in the span wise direction of the aircraft, + = to the right wingtip
Z-axis: perpendicular to the XOY-plane, + = down into the floor.

Earth axes

Origin: Centre of Gravity at the start of the response
X-axis: In the horizontal plane (relative to gravity), + = pointing north.
Y-axis: Perpendicular to XOZ-plane, + = pointing east.
Z-axis: Pointing to the centre of the earth = +

Edit

Yes navigation lat/lon is given in [degrees] - the INS sensor ultimately converts displacement into proper navigational definitions of course. But for measuring 3-D aircraft inertial effects the SI system is used, and displacement is internally treated as a linear motion, units [metres].


Do any civilian aircraft use AESA or PESA for weather radar?

Doppler and Electronically Scanned Arrays are different types of technology. Doppler is a method of using radar to determine relative velocity of a radar return. An ESA is a type of radar transceiver. Doppler is useful for detecting precipitation and would probably still be useful on an ESA radar.

Probably the main reason that weather radar has not widely gone to ESA is cost. Especially AESA (Active Electronically Scanned Array) is very expensive. In a military environment, the extra functionality makes up for the high cost. But current weather radar on aircraft works "well enough". The technology has been in use a long time and is well-understood. Advances in signal processing have brought more and more capabilities. There need to be large benefits to justify the expense of developing and certifying a new architecture.

One benefit of ESA radar can be the lack of moving parts. However, a single array would have a limited field of view, where current radars can typically see 180 degrees in front of the aircraft. They could add mechanical steering, but that would be even more expensive to steer something heavier and more delicate than the typical slotted antennas used today.

There's also the issue of military usage. Although many countries have developed ESA radars, there may be some government resistance to exporting that kind of technology.

Although current technology still struggles to detect hazards that lack precipitation such as clear air turbulence, the industry is looking to other technologies such as LIDAR to fill this gap.


How is the direction of the hydraulic fluid changed so that the cylinders and pistons can move backwards and forwards?

The direction of travel is controlled by a directional control valve for a double acting cylinder.

The red line is high pressure from hydraulic pump. when the high pressure fluid is entering the right chamber and push the actuator piston to left.
The low pressure fluid in left chamber (blue line) will leave the actuator and return to reservoir.

If we rotated/move the directional control valve clockwise it will look like the figure below :

The high pressure will enter the left chamber and move the actuator piston to right


How to calculate the vertical profile for a LOC only approach?

The approach shows that the glideslope (if it were working) is a three degree descent angle.   You can calculate your own visual descent point (VDP), since one isn't provided for you, by taking the height above touchdown (600 ft. in this case) and dividing it by 300 ft/NM.  This gives you 2.0 miles from the runway.  Since the chart shows the runway threshold at 0.2 DME, your VDP will be at 2.2 DME.

Assuming that your navigation equipment does not provide a pseudo-glideslope, your best bet is to descend at your normal rate (in a light airplane I would say 800-900 fpm) until you level at 660 ft. (the MDA), then fly to your calculated VDP (2.2 DME) and if you have the required visual cues then descend to the runway knowing that it will be a standard 3 degree descent (300 ft./NM).  If you don't have it at this point, then you can start an early climb and fly the missed approach.

Put another way, first you calculate your VDP:

$$\frac{Height~Above~Touchdown}{Descent~Rate}=VDP~Distance~From~Runway$$
$$\frac{600ft}{300 ft/NM}=2.0NM$$
$$VDP=Runway~Threshold+VDP~Distance~From~Runway$$
$$0.2DME+2.0NM=2.2 DME$$

Then you fly the approach:

Cross HERNY at 2,000 ft.
Descend to minimums (660 ft.) at 800-900 fpm.
Fly to 2.2 DME at 660 ft.

At 2.2 DME, if you see the runway environment, start your descent and land
If you don't see the runway, start your climb and fly the published missed approach


What would happen if I exceeded mach 1 over a regulated area?

It would be a violation of 14 CFR 91.817

  § 91.817 Civil aircraft sonic boom. (a) No person may operate a civil
  aircraft in the United States at a true flight Mach number greater
  than 1 except in compliance with conditions and limitations in an
  authorization to exceed Mach 1 issued to the operator under appendix B
  of this part.

It would be extremely easy to track such an aircraft, and the pilot would be dealt with upon landing.


Why do Russian jets make a squealing sound?

I am by no means an aficionado of Russian fighter aircraft, but I suspect the sound you speak of is caused by intake airflow.

Since Soviet times, their aircraft have ascribed to a design doctrine of being able to fly from damaged or sub-standard airfield surfaces, and incorporate undercarriage & engine intake designs that assume constant presence of engine-killing FOD. They have either a meshed grating, or even an impervious retractable door flap that completely covers the intakes, while having additional doors open on top of the engine intake area to compensate, for ground operations.

At the 3.10 mark in the video, you hear what is probably the No1 engine spooling up, at about 3.35 you hear the No2 (closest to camera) starting to spool up - within a few seconds you will see a series of small doors above the red number "70" open. This is where the engines are drawing their intake air, away from ingestion of gravel, discarded hardware, small animals & the closely-milling, unconcerned ground crew.

I suspect that the restriction/turbulence caused by this slightly torturous air path is causing that high-pitched sound. It could also possibly be compressor bleed air being dumped as a normal part of low engine revs/idling.

At the 9.00 point in the video, you can see the flight intakes completely shut, with the ground intakes open, as it taxies in. Eventually, you even see a ground crewman appear to actually stand in front of the flight intakes while at least one engine is still running.

There is some discussion & a photo on this page

Would it be viable to install a screen in front of jet intakes to prevent them from sucking in birds?

This aspect of airframe design is a common subject of comparisons between US & Soviet/Russian design doctrine.


Handlers are private companies who provide services (for a fee) to pilots and passengers when they fly in and out of an airport.

Depending on the airport, sometimes handlers are required by the local authorities to be used, and other times there are not even any handlers available (a lot of US airports do not have them, for instance).  Often though, they are optional and there to assist crews that are unfamiliar with the procedures at a new airport or who want their assistance as a convenience.

They typically assist with coordinating things like fuel, lavatory service, flight plans, local permits, passenger transportation, catering, coffee/ice/newspapers, etc.  Many times they pay for everything (in the local currency) and provide one consolidated bill for the client to pay.

Note that handlers can be employed by local FBO's (Fixed Based Operators), or they can be part of a larger international company that provides handling services all over the world.  In either case, they are generally coordinating all of the different parties and services needed in order to operate an aircraft in and out of their airport.


How does ATC control / separate Airbus Industrie test flights?

They will be in contact with ATC at all times and ATC can issue a clearance to operate within a defined area or within a specific flight level range, keeping other aircraft out of that area, e.g.

  APP: AIB97XA, cleared for turns and flight level changes in 20NM radius around ABCDE intersection, between FL70 and FL145 at your discretion.

or a bit more standard phraseology:

  APP: AIB97XA, cleared for turns and flight level changes in 20NM radius around ABCDE intersection and maintain block FL70 until FL145.

From what is visible in the French AIP, the TMA airspace of Toulouse has airspace classes D and C from different altitudes up to FL145, also in the area where your mentioned flight happened.

(Source: German NfL 1-251-14 Verfahren Sprechfunk / P. 47)


How do you cope with an asymmetric flap extension?

I'd guess the procedures probably vary considerably by class and type. If the flaps on one side broke or got stuck on the light GA plane I mostly fly, the procedure would be to just set the side you can control to the same as the side you can't control and land with that amount of flaps. You can land it with no flaps; you'll just have to land a little faster than normal and with sub-optimal visibility of the runway (but still plenty to get the plane onto it safely.)

At least in the planes I've flown, it would be nearly impossible for the flaps on both sides to get stuck in different positions (because both sides are mechanically connected to the flap lever,) but even that could be dealt with by using the ailerons to counter the asymmetry of lift.

The other procedure involved is to do a proper pre-flight and make sure your flaps aren't broken, loose, or damaged before you leave the ground. :)


How to calculate CL with the use of MTOW?

For every equation the left and right side should have the the same units.
For example:

$$ Speed  = \frac{distance \:[m]}{time \: [s]}$$

Or in units:

$$[\frac{m}{s}] = \frac{[m]}{[s]} $$

The same so with the lift equation:

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

With units:

$$L [N] = C_L [-] \cdot \frac{1}{2} \: \rho \: \left[ \frac{kg}{m^3} \right] V\left[\frac{m}{s} \right]^2 S [m²]$$

Units only:
$$\require{cancel} [N] = [-] \cdot \left[ \frac{kg}{m^3} \right] \: \left[\frac{m^2}{s^2} \right][ {m^2}] $$
Simplifying:
$$\require{cancel} [N] =  \left[ \frac{kg}{{\cancel{m^3}}} \right] \: \left[\frac{m^\cancel{2}}{s^2} \right][\cancel{ {m^2}}] = \frac{[kg][m]}{[s^2]}$$

Which is correct, link to Wikipedia.

So if you want to use the equation:

$$ L = W $$

Both have to be in $[N]$. You have two options, either have it given to you in Newton, or convert a weight (in $[kg]$) to $[N]$ by using the gravitational acceleration g (in unit $[\frac{m}{s^2}]$ )

I think that the confusion stems from the fact that the unit pound is used in two ways.

for weight called pound (mass)
$$1 [lb] = 0.45359237 [kg]$$
for force called pound (force)
$$1 [\mathbf{lbf}] = 1 [lb] \cdot g
   = 4.44 [N] $$

So if somebody is unspecific and asks what the lift is needed to carry 400 pounds, we don't know if it's way 1. or 2.


Can I fly a UAS that weighs more than 55lbs if I'm on private property?

TL;DR

According to the FAA Part 333 rules, all UA aircraft (> 55 lbs) must register with the FAA with an N-number before flight. As far as I can tell, the rules don't specify zones or altitudes where the regulations aren't in effect, so I think it is highly advisable to register.

My personal rationale

Being safe just in case is far better, at least in my mind, than choosing to avoid registration. I know people in my RC Quadcopter possee that fly sUAS aircraft but don't have Part 107 licenses. I have one, (I would rather be safe than sorry) but I could see how as long as you are careful, flying a small sUAS without a Part 107 license isn't such a terrible option.

In my mind, UA aircraft are an entirely different story, as they are inherently significantly larger than sUAS aircraft, and if something does go wrong, damages would be more severe. The risks (not to mention the responsibility) involved are far more substantial, and I would never consider flying a UA aircraft without a license even if I was only flying on my own property.


What RA will be generated if intruder traffic is at our level in TCAS II?

The TCAS algorithms are specified in RTCA/DO-185B (not freely available).
In case of an encounter at same altitude with a non TCAS equipped aircraft, assuming that neither climb nor descent are inhibited, the TCAS will produce a descent advisory (part 2, sec. 2.2.4.1.2.1.5 - sense selection).
This is a consequence of the somewhat subtle signs used in the specification (<= for descend, > for climb).

A non mode-S intruder will broadcast altitude with a 100ft resolution, and a TCAS equipped aircraft will normally use barometric altitude with 25 ft resolution, so the two aircraft do not need to be at exactly the same altitude - in the worst case, a difference of up to 62 ft will be interpreted as "same altitude".

There are also provisions for climb and/or descent inhibits. In particular descend RAs are inhibited below 1000ft radio altitude.
Climb RAs are inhibited when the aircraft performance are not compatible with a 1500 fpm climb (for example, one engine out). The exact mechanism through which this information is provided to the TCAS computer is aircraft dependent.
In your case of same-altitude encounter, if descend RAs are inhibited, a climb RA will be generated.

EDIT
As requested, more clarification.
A simplified description of RTCA-DO185B initial sense selection follows. This description assumes that the intruder is not TCAS equipped, and that the firmness (confidence in intruder altitude and position) is sufficiently high.
First, choose the direction (climb or descent) that will produce the highest separation at CPA (see below).
If equal, select descent (see 3.52 Noncrossing_Biased_Climb and 3.53 Noncrossing_Biased_Descent).
Denote this direction with D

If a RA in the D direction does not result in a crossing (see below), then issue an RA in the D direction.
Otherwise, if the opposite direction still provides at least ALIM separation, then issue an RA in the direction opposite to D.
Otherwise, issue an RA in the D direction.

Separation: The TCAS algorithm models a RA response as follows:

5 seconds of reaction time (pilot maintains current airspeed and rate-of-climb)
A segment with a constant acceleration of 8 ft/s^2 in the direction of the RA
A final segment at constant rate of climb (usually + or - 1500 fpm).

To select the sense, the TCAS algorithm considers:

Distance from intruder
Time derivative of distance from intruder (closure rate)
Time derivative of the closure rate
Ownship altitude and rate of climb
Intruder altitude and rate of climb

With these 5 parameters, the vertical separation at the CPA (Closest Point of Approach) can be computed.
In this scenario, the relative altitude is zero, and the rate of climb of both intruder and ownship are 0. Due to the symmetry of the model, the separation will be the same for both climb and descent.

Crossing
Crossing is defined as either:

A climb RA, with ownship at least 100 ft below the intruder
A descent RA, with ownship at least 100 ft above the intruder

In this scenario, ownship and intruder altitude are equal, so neither direction will result in a crossing RA.


How does the ICAO VOR separation apply to reciprocal radials?

The mentioned VOR separation does not apply that way.

You commented:

If one aircraft is moving towards the VOR on radial 90 and other is also moving towards the VOR on radial 270, both are maintaining FL360 and first aircraft is 15 NM away from the VOR, are they separated?

Both aircraft in this scenario will be on a head-on collision course.
ICAO Doc 4444 references Annex 2 Appendix 3 for the table of cruising levels. In your scenario both aircraft should not be on the same FL, and should be separated vertically (the east/west or north/south rule depending on the country). (Does ATC direct flights to fly eastbound at odd levels and westbound at even ones?)

The reason for that criteria shown above is because of the 95% containment of the VOR when less than 50 NM away is 4 NM, that is the plane can be left/right of the radial by upwards of 4 NM. To understand that, move both planes closer, still on the same 15° separation, and take into account that they may not be exactly on the radials (loss of lateral separation).
The VOR separation you quoted takes that into account, but not to the full extent, for that reason some states say it should be increased to 30° (from 15°), or make it 35 NM at 15° (not 15 NM). (Twenty-Eighth Eastern Caribbean Working Group Meeting)


While waiting for a delayed outbound flight how can I guess where's the inbound plane?

It's difficult to find out what the inbound aircraft is, unless you are at a small airport and/or the airline you are flying on is only operating a few routes from the airport. When you are at a big airport and/or the airline is operating many routes there, you have no way of telling where your aircraft is. For smaller airports, you can effectively find the inbound aircraft by using the appropriate filters in FR24.

Note that in some cases the aircraft planned for a flight can be changed last minute. This typically happens when aircraft are significantly delayed inbound to their hub / main base and the airline decides to minimise the outbound delay costs by assiging a different aircraft.


Why are my friends flying over Norway, Sweden and Denmark from Manchester to Vancouver?

(gcmap.com)

Above is the shortest route, it's called a great circle route. This is what airlines try to follow as much as possible.

The possibilities:

They've mistaken the icy parts of Greenland and northern Canada for the Scandinavian countries1
They've mistaken the western Scottish fjords for Scandinavian fjords
They need new maps :)

On a great circle route, like a taut thread over a ball, the bearing changes. Roughly it'll be something like this:

Initial heading of NW for 1,000 nautical miles, WNW for another 1,000, then West for 2,700. That's a very rough visualization, because again along the route the heading changes, just like the thread.

The route takes you along the western coast of Scotland, across the Atlantic, passing over Iceland, then Greenland, then Canada, where Vancouver is.

1 Denmark, Norway, and Sweden compose Scandinavia according to the normal definition.


What is the meaning and difference between CTAF, UNICOM and MULTICOM in the US?

From the Pilot/Controller Glossary

  UNICOM− A nongovernment communication facility which may provide airport information at certain airports. Locations and frequencies of UNICOMs are shown on aeronautical charts and publications.

For example, an FBO may have a unicom frequency that they use to provide information to incoming aircraft and provide traffic advisories (not to be confused with instructions), wind directions, weather, and preferred runways. Unicom frequencies have a ground station at the airport in question.

It is important to note that when talking on a Unicom, the person on the ground that you are talking to in the FBO or airport office is not an air traffic controller.

An example of talking on this would go something like:

Pilot: "KXYZ Unicom, N12345 request traffic advisory"
Unicom: "N12345 No traffic in the pattern, winds XX @ YYY, recommend runway ZZ"
Pilot: "KXYZ Traffic, N12345 will be entering the 45 downwind for runway ZZ"

And so on just like a CTAF if the unicom/CTAF are the same, otherwise switch to the CTAF and make announcements.

  MULTICOM− A mobile service not open to public correspondence used to provide communications essential to conduct the activities being performed by
  or directed from private aircraft.

This is an advisory frequency that does not typically have a ground station associated with it. Pilots are to self-coordinate on the Multicom frequency but there is no ground station at the airport for that frequency. Often many small uncontrolled airports will use the same multicom frequency so you can hear traffic at multiple airports while on a mulitcom.

This is the typical position/intention reports that you normally make at untowered fields, only you are typically just broadcasting your intentions. Sometimes you may have to work with other incoming aircraft such as reporting each other in sight or telling somebody you'll extend downwind to follow them in, etc.

  COMMON TRAFFIC ADVISORY FREQUENCY (CTAF)− A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications.

Usually CTAF is used as a multicom, but there are cases where it shares the unicom frequency. If the field is towered and in operation, you'll be working with the tower to coordinate your actions. If the field is non-towered or the tower is not in operation, you'll make position reports and work in the frequency just like a multicom.


What was the Trim Problem on the Brabazon's First Flight?

The one thing I have read about this aircraft years ago, is that it had numerous problems in the flight controls, all of them due to the flight controls cables, whose rigging was unstable. I remember having read that it was a  banana (???) effect to the fuselage.I can’t tell  whether it was distortions in the XY plan on in the XZ plan or something else

Reducing the power would it have modified this banana effect?
I can’t tell.


Why do airplanes have to retract landing gear?

In the early days of aviation it was simply easier to have the gear fixed. The landing gear adds drag, but so does a second wing and wire braces. Airplanes generally did not fly very fast or far, so the drag from the landing gear (and that other stuff) was not a big issue. The first design with retractable gear dates to 1911. Since then, retractable gear has been a design decision each airplane must make.

Retracting the gear into the airplane allows for a cleaner form, which reduces drag. However, this is at the expense of added weight. The retract system, which is usually hydraulic, must be added, and the plane must be designed to make room for the gear somewhere at least mostly inside the aircraft. The plane must also be designed to handle situations where some or all of the gear does not extend properly. For planes that need to be fast and/or efficient, retractable gear is worth the reduction in drag.

The additional drag has to be supported by the structure as well. Aircraft with retractable gear will have a maximum speed at which the gear can be extended. Even gear with proper fairings would add significant drag at the speeds airliners fly at. This would be much more critical at supersonic speeds. In these cases the weight of reinforcing the gear could be even higher than the weight of the retracting system.

Particularly smaller general aviation planes tend to not have retractable gear. The retract system adds extra weight and complexity (and therefore cost), which will be fairly significant in a small plane. Fixed gear is simple and can be designed to minimize drag as much as possible. These planes do not typically need to fly fast or have large range, so the added drag is less of an issue. Other small planes do have retractable gear, which will allow for greater speed and range. The PA-32 type shown in Dave's answer was later produced in a retractable gear version as well.


During VMC conditions in terminal airspace (class B), does the pilots have to strictly follow separation standards issued by ATC?

There are several different separation standards which ATC attempts to maintain between aircraft. Note that only one of the standards below needs to be maintained; if one is valid that is sufficient. I'm answering for USA-land as you mention the FAA in your question.
Vertical Separation
Aircraft may be separated vertically. If one aircraft is directly above a point on the earth and is at an altitude of 4000 feet, and another aircraft is directly above the same point at an altitude of 6000 feet, they are separated.
IFR aircraft must be separated from other IFR aircraft by at least 1000 feet. At or above FL290 this increases to 2000 feet if either aircraft is not Reduced Vertical Separation Minima-capable (RVSM), and above FL410 the minimum is 2000 feet no matter what (and sometimes more for certain military or supersonic flights).
Within Class B, Class C and TRSA airspace, IFR aircraft are separated from VFR aircraft by at least 500 feet. This also applies to known VFR aircraft operating in the associated Class C outer area.
Within Class B and TRSA airspace, VFR aircraft are also separated from other VFR aircraft by at least 500 feet. VFR aircraft must receive an explicit clearance into Class B airspace, allowing them to be separated from other VFR aircraft. In the case of a TRSA this only applies to aircraft requesting radar services.
Lateral Radar Separation
Vertical separation is not terribly interesting. Let's instead look at lateral separation, where the two aircraft are at the same altitude, so it would not be good if they were also above the same point on the earth.
The absolute bare-bones basic standard of separation is: Did the planes hit each other? This is a highly undesirable situation. For VFR aircraft operating in Class E/G airspace, this is the only minimum that matters, and pilots will apply it themselves using the "see and avoid" principle: They see other aircraft and maneuver to avoid hitting them. This is also the only separation standard that ATC maintains between two VFR aircraft in Class C/D/E airspace, and in fact separation isn't truly lost until the planes trade paint. (Then it's a bad day for everyone.)
At a slightly higher level there is target resolution. This can be applied between VFR-VFR or VFR-IFR aircraft operating in any type of airspace, except in Class Bravo when one aircraft weighs more than 19,000 lb or is a turbojet. Target resolution means the controller issues instructions, traffic advisories, and safety alerts to ensure that the radar targets on their screen are "resolved," which is to say they do not ever touch each other. There can be some error in the positioning of the targets on the screen but if two aircraft are very near each other the difference between the two errors is likely to be minimal—so if the displayed targets never touch, you can be sure the aircraft themselves certainly don't.
Getting into defined radar separation:

In Class Bravo airspace, VFR aircraft are separated from IFR/VFR aircraft weighing more than 19,000 lb by 1.5 nautical miles.
In the terminal environment (i.e. TRACONs, and enroute facilities at FL230 and below where certain requirements are met) IFR aircraft are separated by 3 NM. This can be reduced to 2.5 NM on final approach, subject to various extra rules and procedures.
If the aircraft is more than the prescribed distance from the radar antenna, or if the system indicates a need, or above FL230, IFR aircraft are separated by 5 NM.
At or above FL600 separation increases to 10 NM between IFR aircraft.

Passing or Diverging Separation
Terminal facilities are authorized to discontinue the use of radar separation and fall back on target resolution if aircraft are on tracks which will never meet (either because one target has passed the projected track of another, or if they are opposite-direction because the two targets have passed each other). Enroute facilities can do this as well but have more onerous rules.
Wake Turbulence Separation
Smaller aircraft operating behind heavier aircraft (defined based on maximum takeoff weight) are afforded increased separation, ranging from 4 to 10 NM instead of 3 or less.
Non-Radar Separation
Almost invariably, using non-radar separation will provide a greater actual distance between aircraft than using radar separation, so it is not usually applied in areas of radar coverage. For myself I don't know much about it, having never applied it.
Lateral
Aircraft may be separated by assigning them to fly on different airways, or different radials or arcs of navigational beacons, or other such procedures.
Longitudinal
Aircraft operating along the same airway, or at the same airport, may be separated based on time and speed.
Visual Separation
Airborne separation may be reduced below the applicable minimum if visual separation is used. Some other form of approved separation must exist before and after the application of visual separation, and visual separation is not allowed above FL180 (i.e. in Class A airspace) or if the leading aircraft is a super weight class.
Pilot-applied visual separation may be used if the pilot of one aircraft reports another aircraft in sight and confirms that they will maneuver to maintain their own separation (i.e. they don't hit). Tower-applied visual separation may be used if the tower controller can see both aircraft and issues instructions to ensure they don't hit.
Visual separation is not prohibited if the weather is below VFR minima (IMC) but will likely have limited usefulness because some other form of approved separation must exist once the pilot or controller loses sight of the aircraft. Some facilities have it written in their local procedures that tower-applied visual separation is assumed to be in effect whenever the weather is better than certain minima.
Runway Separation
Not as relevant to your question but provided for completeness. Runway separation is flight-rules agnostic; the controller will apply it regardless if a flight is VFR, SVFR, or IFR. Based on the category of aircraft (category being defined in relation to engine type and number, and for single-engine propeller planes also weight) and type of operation (arrival-arrival, arrival-departure, departure-arrival, departure-departure) ATC will ensure 3000, 4500, 6000 or "the entire runway's worth" feet between aircraft operating on the same runway. They will also ensure an aircraft or vehicle does not cross a runway another aircraft is operating on.

So to finally answer your question: Pilots do not apply "separation standards" in any type of airspace, except that they are required to avoid hitting other aircraft if they see them in time. Instead, ATC applies separation minima which change based on the type of flight rules, type of aircraft, and airspace in which the aircraft is operating. In order to make sure these separation minima are maintained, pilots are required to comply with ATC clearances and instructions, or else have a really good reason why not.


Is it possible for one runway to have a different TORA in each direction?

Yes.  If you look at the information for London Gatwick as an example, 08R has a TORA of 3159 meters, whereas 26L has a TORA of 3255 meters.

http://www.ead.eurocontrol.int/eadbasic/pamslight-7B4054FA19E6240FA6A62C9356F52804/7FE5QZZF3FXUS/EN/AIP/AD/EG_AD_2_EGKK_en_2018-12-06.pdf


During inverted banking, what happens to heading?

Would a plane in 135° roll be using stick-forward to retain altitude? And thus bank in the direction the wheels are pointing?

Yes and yes.

Let's say you're flying North.  You roll inverted, then lift your left wing 45 degrees above the horizon (this is the wing that pointing East, now that you're upside down).

You'll experience the usual G forces pushing into your head (it hurts), and the plane will start turning to the West.

I once saw a great diagram that explained which controls do what when inverted - it showed the outline of the plane with one cartoon pilot sitting in the normal position, and another "phantom" pilot sitting in the same seat with feet on the rudder pedals, holding an extension of the stick, but with his head pointed the opposite direction - head towards wheels instead of away from wheels.

When the plane's inverted, the "phantom pilot" is upright, and all the controls would behave normally from his point of view.


If there is a misprint on an instrument plate, is a pilot required to comply with it?

The first thing that you should do is check the NOTAM's for the airport (which of course, you should do before you leave on your flight).  Very often, these types of errors have been discovered by someone else and the FAA will have issued a NOTAM to let everyone know.  In this case there is no NOTAM, so we would have had no reason to suspect an issue before we took off.

The main point has already been made.  If you are airborne and there is any reason to suspect that something is wrong, ask ATC for clarification and move on.

If I encountered this situation and couldn't ask for clarification (ie. lost communication) then I would simply select a different approach and fly it.

For the record, the Jeppesen chart has it coded correctly:

Now, aside from the operational considerations, it is very important to notify the FAA when you find discrepancies like this so that they can be fixed.  Here is a quote from the Aeronautical Chart User's Guide:

  REPORTING CHART DISCREPANCIES

  Your experience as a pilot is valuable
  and your feedback is  important. We make every effort to display
  accurate information  on all FAA charts and publications, so we
  appreciate your input.  Please notify us concerning any requests for
  changes, or potential  discrepancies you see while using our charts
  and related products.

  FAA, AeroNav Products
  SSMC4 Sta. 4503
  1305 East-West Highway
  Silver Spring, MD 20910-3281

  Telephone Toll-Free 1-800-626-3677
  E-mail: 9-AMC-Aerochart@faa.gov

  Mark the chart you are using with the suggested
  changes and  include an explanation of the discrepancy. Mail this
  corrected  chart to the address above and we will send you a
  replacement  right away. Suggestions concerning this guide are also
  welcome.

For the record, I have already emailed the plate with the suggested changes to the email address above (on 24 DEC 2013), and hopefully a NOTAM will be issued soon and an amended approach procedure will follow sometime after.

Update (09 JAN 2014)

I received the following response from the FAA:

  Dear Louis:

  Thank you for reporting the problem

  ...

  Control Number 18335 has been assigned to this issue for tracking
  purposes.  This concern has been closed with the following Response:

  Thank You for your inquiry. A P-NOTAM is being assigned to correct the discrepancy.

  Regards,

Note that the NOTAM hasn't been issued as of yet.

Update 2 (17 JAN 2014)

New NOTAM issued to address the error on the instrument approach procedure:

!FDC 4/3036 ESC IAP DELTA COUNTY, ESCANABA, MI.
   RNAV (GPS) RWY 36, ORIG...
     CHANGE TAA TO READ FROM 274/30 CW 094/30 (NOPT) TO WOKOL
     (IF/IAF) AND FROM 094/30 CW 274/30 TO WOKOL (IF/IAF).
   THIS IS RNAV (GPS) RWY 36, ORIG-A.
   1401171859-PERM

Update 3 (06 MAR 2014):

New, corrected chart issued and the NOTAM was cancelled the next day.


Correct, that optional feature on the 787 relies on the ILS or GLS signals.

  On takeoff, HUD provides lateral guidance for takeoff roll and rejected takeoff using ILS or GLS signals.

(FCOM 4.20.7)

PVD (Para-Visual Display) is a similar instrument (in function) that was available on the 747-400 as an option that relied on the ILS (shown below).

(aerowinx.com) PVD.

Further reading:

Peripheral Vision Displays (nasa.gov).
The crash of Singapore Airlines Flight 006 during a takeoff in LVP conditions.


Please provide some expert commentary to the aborted flight of the German chancellor

Satellite phones would be for passenger use.  Over land, ATC uses VHF/UHF radio, and over sea, ATC uses HF radio or (text-based) satellite data links.

Based solely on the quotes in the question, it sounds like a power distribution panel in the aircraft failed, leaving them with no radios.  There are procedures for aircraft with failed radios to continue flight, but it's a lot of extra work for both the flight crew and ATC.  And who knows what other equipment on the same power panel was affected.

Having a satellite phone available means the crew may be able to contact ATC and arrange a diversion and landing faster and more easily than the usual no-radio (NORDO) procedures allow, but neither ATC nor the crew would want to operate that way for any longer than necessary to land safely.

Also, specific to a Head of State, the protection detail would want to reassure their comrades on the ground that the aircraft hasn't been attacked or hijacked, and they would also prefer any problems be repaired at home by people they've already vetted to reduce the risk of espionage or sabotage.


The wiki quote refers to total pressure at intake and outlet. Total pressure is defined as static pressure $p_s$ and dynamic pressure $p_d$ which for incompressible flow = $\frac{1}{2} \cdot \rho \cdot V^2$.

So the Engine Pressure Ratio is
$$\frac {(p_s + \frac{1}{2} \cdot \rho \cdot V^2)_{exhaust}} {(p_s + \frac{1}{2} \cdot \rho \cdot V^2)_{freeStream}}$$

The turbofan exhaust gas is a mixture of the jet exhaust and the bypass air exhaust.


How does a pilot know if he has headwind, tailwind or crosswind?

With no visual or instrument references you don't know if you have a headwind, tailwind, or crosswind.
You also don't particularly care because you're flying a plane with no way to navigate and therefore have more imperative concerns.

With visual references it's something you can determine with a little thinking and some intentional oversimplification:

Headwinds mean your ground speed is lower than your airspeed.
If your airspeed is 100 miles per hour and you're flying a 25 mile leg it should take you 15 minutes. If it takes you 18 minutes you know you've got a headwind.
Tailwnds mean your gound speed is higher than your airspeed.
If you're flying the same 25 mile leg at 100 miles per hour and it only takes you 12 minutes you have a tailwind.
Crosswinds are a bit more difficult: The easiest way to tell you have a crosswind is if you know what your magnetic heading should be in order to fly toward a given point and you have to point the nose at a different compass heading in order to maintain the desired ground track you have a crosswind.

Note that you almost never have a direct headwind, tailwind, or crosswind, but rather some wind at an angle to your direction of travel which will have both a crosswind component and a headwind/tailwind component. The wind speed and direction can be computed using an E6B flight computer with relatively little effort.

If you have instrument references the problem gets easier:

GPS is the ultimate solution -- it can display your ground speed and ground track, from which you can derive the winds. GPS systems that know your airspeed can even calculate the winds for you so you don't need the E6B anymore (unless the GPS breaks).
VORs provide a magnetic heading reference, which simplifies the crosswind calculation (and largely eliminates the need to do one to figure out your crosswind correction angle: Just keep the needle centered and you have your desired crosswind correction).
It doesn't give you the wind speed and direction without some additional data (how long it takes you to cross some waypoint or fix), because you still need that information in order to determine how much of the wind speed is acting as a headwind, tailwind, or crosswind component.
DME systems can give you your groundspeed. In combination with the VOR this gives you the same information as the GPS and makes determining the wind speed pretty simple.
ADFs can be used for this kind of calculation in the same way as you would for a visual waypoint: If you expect to be flying due north to head toward an ADF beacon and you're flying 010 degrees to keep the pointer needle where you want it then you know you're dealing with some crosswind component.


Let imagine that we put wind indicator on rotating merry-go-around.
Will wind indicator stay perpendicular to the radius of circle,showing
tangential airflow velocity?

Assuming that the indicator has a mass distribution such that the apparent "centrifugal force" from the rotation has no effect on it, and also assuming that the physical length of the wind indicator is trivially small compared to the radius of the circle, then yes, the wind indicator will remain perpendicular to the radius of the circle at the point where it is located, showing  that the "relative wind" is tangent to the circle.
A very lightweight piece of yarn would do essentially the same thing, though there would be a very slight tendency for the apparent "centrifugal force" to displace the free end of the yarn toward the outside of the circle.
However the problem gets more tricky if the length of the wind indicator is not trivially small compared to the radius of the circle.  If the length of the wind indicator is not trivial, this means that the "vane" or fin is located well aft of the weathervane's pivot point.  The relative wind at every point along the circumference of the circle is aligned with the line that is tangent to the circle at that point.  So when the vane streamlines itself to to the relative wind which is tangent to the circle at a point well behind the pivot point of the weathervane, this means that the weathervane is not parallel to a line drawn tangent to the circle at the pivot point of the weathervane.  Rather, the weathervane is skewed with its nose outboard, and its tail inboard, of the line drawn tangent to the circle at the pivot point of the weathervane.
Your intuition is correct that this is why tend to see some sideslip in circling flight, especially in slow-flying aircraft whose linear dimensions are not trivial compared to the radius of turn.  The vertical fin tends to streamline itself to the relative wind, which means that the fuselage tends to be parallel to a line drawn tangent to the circular flight path at a point well aft of the CG.
This effect is illustrated in section 8.10 of the "See How It Flies" website.
In short, in turning flight, the "relative wind" is curved, rather than linear.  It curves to follow the curvature of the flight path.


What is the maximum legal flight time for single pilots under Part 91/135 operations?

Short answer: no limit for private Part 91 operations, otherwise 8 hours.

The only Part 91 regulations I can see on this are in Subpart K - Fractional Ownership Operations. There's too much information to quote here, but see 91.1057, 1059, 1061 and 1062. For a single-pilot operation the basic limit is 8 hours, per 1059(b):

  (b) Except as provided in paragraph (c) of this section, during any 24
  consecutive hours the total flight time of the assigned flight, when
  added to any commercial flying by that flight crewmember, may not
  exceed—

  (1) 8 hours for a flight crew consisting of one pilot;

There's no restriction for typical private GA pilots, apart from 91.13 on careless or reckless operation. Flying while very tired could easily be seen as reckless if it affects the safety of a flight.

As for Part 135, the regulations are in Subpart F—Crewmember Flight Time and Duty Period Limitations and Rest Requirements. Again, there's too much to quote but the basic limit for a single pilot is 8 hours, per 135.267(b):

  (b) Except as provided in paragraph (c) of this section, during any 24
  consecutive hours the total flight time of the assigned flight when
  added to any other commercial flying by that flight crewmember may not
  exceed—

  (1) 8 hours for a flight crew consisting of one pilot;

Your second question about when an additional pilot is required is a bit unclear. A second pilot is usually required because of the type of aircraft or operation, not the length of a flight. But I know very little about Part 135 so I may be wrong; in any case, I think it would probably be better as a separate question.


What are the advantages of a Trimmable Horizontal Stabilizer?

The main advantage is smaller elevator deflection angles. This comes handy in two cases:

When high-lift devices are deployed, the center of pressure on the wing shifts backwards by up to a third of wing chord. Fowler flaps add wing area aft of the trailing edge, and slotted flaps are able to generate high suction peaks. The result is a massive change in trim, and the empennage now has to generate generous downforce. Changing the lift on the empennage by elevator deflection alone will exceed the maximum practicable deflection angle and leave no margin for control. By adjusting the stabilizer incidence, the elevator can be held near its neutral position and has reserves for control.
In transsonic flight the elevator might not always have a linear characteristic. The contour break due to an elevator deflection induces shocks which in turn lead to flow separation which reduces the control effectivity and can even reverse the control characteristic. Since the transition from subsonic to supersonic flight shifts the center of lift backwards, the empennage needs to add downforce when the aircraft accelerates in the transsonic speed range. An elevator deflection might not be able to produce the desired lift change, and only adjusting the stabilizer such that the elevator can be held neutral can restore trim and control effectiveness.

Older airliners from the propeller age had lower wing loadings and less powerful flaps. The center of lift on the wing changed less with flaps, so a fixed stabilizer was sufficient. But once the wing loading goes up to jet levels, and the wing is fitted with slotted fowler flaps, a moveable stabilizer is unavoidable.


How does ATC handle a controller with psychological trauma?

To my knowledge there is no automatic loss of medical clearance following a death in the family. The relevant order is JO 3930.3, current version C. From Chapter 3 Section 1 Medical Status we have the following paragraph:

3. Interim Medical Condition of an ATCS. Illnesses, injuries, or other medical conditions that could affect the employee’s eligibility for medical clearance may occur between periodic examinations.
a. When an ATO Air Traffic management official becomes aware of an ATCS’s absence due to a medical condition, treatment, or drug/alcohol related incident, the Air Traffic management official must promptly inform the FS so that a determination may be made whether the illness or injury affects the ATCSs medical status.
b. An ATCS must report to the FS office the following as soon as he/she becomes aware of the condition, but in any event before performing safety-related duties:

Any assessment or treatment of injuries, illness or other medical conditions by a health professional, except for conditions as noted in Chapter 1 paragraph 9.e,
Any occupationally related injury or illness, and
Any conduct that represents a violation under a DOT or FAA Order such as DOT Order 3910.1 series.

c. Air Traffic management must inform the FS when an ATCS receives medical attention and may request an opinion from the FS regarding the medical status of the ATCS.
d. The FS evaluates available information, obtains additional data if needed, and arranges for examinations or further evaluations as required to make a medical status determination in accordance with this Order.

None of that explicitly accounts for grief but either the controller themselves or management could decide the controller's actions and mental state warrant reporting to the flight surgeon.
There are various ways for a controller to try to deal with grief and loss, for example the FAA contracts with Magellan Health as the agency's Employee Assistance Program provider (I believe up to eight counseling sessions per year are allowed for free), and NATCA (the controllers' union) provides a peer-to-peer service called CISM. The EAP is supposed to be confidential but can pass information to the agency if they suspect the employee has a substance abuse problem.
The collective bargaining agreement provides that up to ten days of annual leave or leave without pay shall be granted (at the discretion of the employee) if there is a death in the employee's family. So you get two weeks off guaranteed, if you want it, but that doesn't really pertain to your medical clearance.
The realistic answer is, if the controller really needs to talk to a therapist or counselor about what they're feeling, they have three options:

Keep it bottled up inside,
Visit an out-of-network therapist, pay out of pocket, and use a fake name if possible, or
Visit an in-network therapist, create an official record of the visit, report it to the flight surgeon (because they'll be really mad if you don't report it and they find out anyway) and hope you can successfully argue to get your medical back after it gets pulled.

If the medical never gets pulled, I don't think there is any additional supervision mandated. But the controller's coworkers will probably keep an eye on them, and if management is on the ball they probably will as well.
If the medical does get pulled, and it takes too long to get it back, the controller will first lose currency and then proficiency on the control positions they've been certified for, depending on how long since they last worked. If they lose currency they will need to re-take a "certification ride" where they control for a decent amount of time while a supervisor is plugged in with them to make sure they still know what they're doing. If they lose proficiency they will probably need to go through their facility's training process again.

In general the likelihood of someone being completely alone in the operational quarters is relatively small, at least at a larger facility like ABQ. Perhaps on the overnight shift there will be just one person in the tower cab and one in the radar room, but generally more than one control position will be open in each area, and higher-up management are generally strict about having a separate supervisory position open as well. (Each operational area needs a supervisor position at all times, but this position doesn't have to be a management supervisor—controllers who are so certified may work the supervisor's desk—and in times of low staffing the supervisor position may be combined with any given control position.)


How are the 737’s elevator and aileron cables attached to their control tabs without impeding the control surfaces’ motion under hydraulic power?

The tabs themselves are not locked -- that lock you mention is upstream: an input lock. Next time you sit next to the wing, watch the aileron as the pilots check the controls and notice how the tab moves opposite (alternatively, and rewindable, you can watch it here).
With the input locked, the tabs are free to move without directly feeding back into the actuators/rods/cables (indirectly though, the elevator tabs serve two different functions depending on the flight regime).

Source: b737.org.uk

Above is a photo for the elevator/tab deflection as seen on ground with the elevator up and tab down. And when unpowered, the elevators droop, and the tabs would be trailing edge up as expected, as seen in the following photo:

Source: wikimedia.org

The mechanism
For the elevators, the cables (from the control column) move the aft control quadrant. From there, no more cables -- a rod moves a differential (floating) lever, which is the input to 1) the hydraulic actuator 2) the manual reversion lever (either/or).
With hydraulic power available, locking pistons lock the manual reversion lever (not the tabs). With loss of hydraulic power, the now unlocked manual reversion lever changes the differential lever's pivot point -- switching the input to the aero tabs.
Here's a drawing from Boeing's manual reversion patent. I colored the differential lever yellow and the manual reversion lever red (locking pistons are shown in another figure), and drew the two pivoting axes:

Source: patents.google.com

This is how with the manual reversion lever locked (hydraulics working), elevator movement would move the tabs in the correct non-impeding opposite direction (rod 34 need not translate), e.g. pull back - elevators up - tabs down. This is also illustrated in Fig. 5 in the patent.

Source: gov.uk/aaib-reports

Above are the rods that move one of the tabs on a 737-700. The ailerons are covered by the same patent (same principle).
But that is not all
At low-speed, triggered by the extension of the TE flaps, a hydraulic/spring mechanism shifts the pivot point of the tabs, which in turn reverses the tabs behavior, making the tabs follow the elevators, e.g. pull back - elevators up - tabs up. This increases the camber giving more control.
The relevant Boeing patent is here; it's an earlier design where each elevator had two tabs, as seen on the 707:

Source: publicdomainpictures.net

On the 707 (and KC-135, etc.), the inboard tabs are the convertible type -- their anti-balance mode is to make the pitch control heavier in cruise; the balance mode is used at low-speed (activated by stabilizer position) to counter the increased air loads on the elevators' top surface when the stabilizer is more nose down. (The 707 pitch/roll is not hydraulically powered.)
When the elevators are pushed down by air loads, the inboard tabs would already be down, keeping the elevators at neutral (no input required), otherwise the stabilizer effectiveness would decrease. And with any input, they would assist -- that's opposite the 737 at low-speed as noted earlier. The mechanism for the convertible function on the 737NG is seen in the following drawing:

Source: slideshare.net

At low-speed and with no hydraulics available for that mechanism, the tabs remain in the balance (assist) function -- move opposite the input, in order to the move the elevators as intended in manual reversion.
Finally, here are the different tab deflections during maintenance testing (elevators are up):

Source: b737.org.uk

To summarize: the lock is for the input (therefore no impeding action), and the tabs on the 737 do a lot behind the scenes.


How often is the cabin air replaced in A320?

Let's do some simplified arithmetic:

The packs airflow in an A320 is 1.2 kg/s per pack in HIGH setting, but let's take the normal setting 1 kg/s, thus 2 kg/s considering both packs
The cabin of an A320 is around 190 m^3
Let's assume the cabin altitude in cruise 8000 ft, i.e. the air density at 20°C is 0.897 kg/m^3
The total airmass of the cabin is then 190×0.897 = 170.43 kg
Assuming that the cabin pressure is constant in cruise (so all the air coming from packs is going out via the outflow valve), in 90 seconds we change the following mass of air: 2 kg/s * 90 s = 180 kg

So 170.43 ~= 180, then 90 seconds is a correct estimation.


Are ICAO and FAA airport signs and markings the same?

Principle

ICAO Airport markings are defined by ICAO in Annex 14 of Chicago Convention, Aerodromes.

ICAO also requires at section 5.8 Notification of differences in the AIP of Doc 8126 Aeronautical Information Services Manual, that differences are explained in the country AIP, Section GEN 1.7 Differences from ICAO Standards, Recommended Practices and Procedures.

US regulations are not entirely compliant with ICAO SARP, and differences exist for airport marking.

Example of ICAO SARP

For the touchdown zone lights, ICAO states in Annex 14, at paragraph 5.3.13.2:

  The lateral  spacing between the innermost lights of a pair of
  barrettes shall be equal to the lateral spacing selected for the
  touchdown zone  marking. The longitudinal spacing between pairs of
  barrettes shall be either 30 m or 60 m.

US example

As US regulations are not fully compliant, the differences are explained in GEN 1.7 of the US AIP, page 129:

  U.S. does not require the lateral spacing of touchdown zone lights
  to be equal to that of touchdown zone marking when runways are less
  that 45 meters wide.

In general

All differences can be found at this location, sorted by ICAO reference and chapter. Differences related to Annex 14 start on page 124 (actually labeled GEN 1.7 81). Listing all of them (15 pages in the AIP) would be too broad for this answer.


What is the most cost effective way of combining an instrument and multi engine check ride?

The cheapest way (I'm talking Canada here) is to do the basic instrument training in the single, then do the multi rating and check ride separately, then the do some practice approaches and emergencies in the twin and multi simulator to prepare for the multi-IFR checkride , and do that.  There's no point in doing an SE check ride.  When I did it some years ago I bit the bullet and did almost of the air time in a Seminole because I was uncomfortable with going into a multi-IFR checkride with maybe only 15 hours in the twin, and the kind of sims available today didn't exist.

Go to a school that has one of those Red Bird motion simulators or equivalent and take maximum advantage of the portion of the training that can be in a sim.  That'll save a ton of money.

Also use MS Flight Sim or Xplane to practice practice practice at home.  It is a very powerful tool if used properly.  By "properly" I man make sure the stuff you practice on your own is being correctly done, and are not reinforcing incorrect stuff.


Where can I find the full report of this controlled F-4 fighter jet impact?

The test was carried out by the Sandia National Laboratories under terms of a contract with the Muto Institute of Structural Mechanics, Inc., of Tokyo. The purpose of the test:

... was to determine the impact force, versus time, due to the impact, of a complete F-4 Phantom — including both engines — onto a massive, essentially rigid reinforced concrete target (3.66 meters thick).

The reports on the tests can be found in these places:

Full-scale aircraft impact test for evaluation of impact forces: Part 1, Test plan, test method, and test results by von Rieseman, W. A. et al.and

Full-scale aircraft impact test for evaluatioin of impact force: Part 2: Analysis of results by K. Muto et. al.

Interestingly, the aircraft used in the tests were flyable. The report notes:

A flyable F4D aircraft was acquired by Sandia. The aircraft was modified slightly in order to support the aircraft at four locations with a special carriage structure. ... the aircraft weighed 12.7 tonnes (with some avionics removed). The impact weight was 19 tonnes, which included ... 4.8 tonnes of water that was added to simulate the fuel weight...
The target consisted of a block of reinforced concrete 7m square and 3.66m thick ... with a combined weight of 469 tonnes.

The aircraft was crashed with the engines and only a few parts removed:

A fully functional F4  was used in the impact test.Only the gears and flaps at the main wings were partly removed and replaced by a carriage structure and sleds.

This can also been in the following mass distribution diagram for the aircraft used in the test.

Image from Full-scale aircraft impact test for evaluation of impact forces: Part 1, Test plan, test method, and test results by von Rieseman, W. A. et al.
Finally, the test was for measuring the impact forces, not the strength of the wall, as stressed by Sandia:

At Sandia, a spokesman, John German, said the point of the test was to move the wall, as a way to measure the impact forces. ... as a preliminary step in building a computer model of such impacts, ...
Mr. German said: "That test was designed to measure the impact force of a fighter jet. But the wall was not being tested. No structure was being tested."


How many checklists are there for a commercial pilot for the entire flight?

Typically, the checklists in normal operations are:

External walk around and preflight
Before start
Before taxi
Before take-off
After take-off
Cruise
Descent
Approach
Landing
Shutdown
Secure

This list is pretty much the same for all aircraft.

Normally, each checklist is only used once at the appropriate time but a wise pilot would re-run a checklist if interrrupted.

For example, you are cleared to start and complete the before start checklist but there is then an unexpected delay before you actually start.  You wait for 30 minutes.  No need to redo the before start checklist because you did it earlier?  No, do it again.  Something might have changed.


Was the foil in older FDRs reused when it ran out, or replaced?

Those older FDR's are known as "foil oscillographic recorders." This technology is similar to the old recording barometers, which were used for, among other things, providing evidence of altitude in glider record-attempt flights. Just as in these barometers, the recording surface was not reusable in those FDR's. When it would run out, it needed to be changed. The FDR's had an indicator which showed how much usable foil was left in terms of hours. The rolls of foil were 200 ft long and ran at 6 inches per hour when the aircraft was operating, about 400 hours' worth. This was an inspection item on the aircraft.

In addition, the foil was made of Inconel, which is known as a "superalloy" that is resistant to very high temperatures. It would be very difficult to remove the tracings of data without specialised equipment, and in reality the tracings removed material from the protective surface coating on the foil. If you recycled it the quality of the data could be impacted by corrosion.

This very cool video illustrates how these FDRs worked.


Why Heading Indicator is not magnetic itself and need magnetic compass?

Compass readings during turns are inaccurate and sometimes display turns when you are heading straight but accelerating. As such you need something that is referenced to the airframe turning itself. This is where the gyro comes in handy. Since it's referenced to the airframe and relatively unaffected over short periods of time it gives you your heading when your compass can not. You can also "time your turns" using the turn coordinator and a stop watch should your heading indicator fail. It should be noted that a timed turn will only work if the turn remains coordinated (no slip or skid) further more most turn coordinators are set up for 2 minute turns.

The errors are as follows

  If on a northerly heading and a turn is made toward east or west, the initial indication of the compass lags or indicates a turn in the
  opposite direction. The lag diminishes as the turn progresses toward
  the east or west where there is no turning error.
  If on a southerly heading and a turn is made toward east or west, the initial indication of the compass needle will indicate a greater
  amount of turn than is actually made. This lead also diminishes as the
  turn progresses toward east or west where there is no turn error.
  If a turn is made to a northerly heading from any direction, the compass indication when approaching northerly heading leads or is
  ahead of the turn. Therefore, the roll out of the turn is made before
  the desired heading is reached. If a turn is made to a southerly
  heading from any direction, the compass indication when approaching
  southerly headings lags behind the turn. Therefore, the roll out is
  made after the desired heading is passed. The amount of lead or lag is
  maximum on north / south headings and depends upon the angle of bank
  used and the latitude of the aircraft.
  When on an east or west heading, no error is apparent while entering a turn to north or south. However, an increase in airspeed
  will cause the compass to indicate a turn toward north. A decrease in
  airspeed will cause the compass to indicate a turn toward south.

The constant need to reset it is related to gyroscopic precession.


No.  Thermal activity in an area can be predicted in a general way based on atmospheric conditions, but not beyond that. The only way to detect thermals in real time is to stumble into them, and/or locate them by the clouds that form their tops.
In any case, the only conditions for which that sort of thing would work would be on one of those lovely soaring days where steady thermal sources and a moderate wind create "cloud streets" where the cumulus clouds line up for you in rows (the cloud being moisture in the air of thermal condensing at the dew point, creating a handy marker for glider pilots - if the air is dry, the thermals are still there but you have no clouds and you can only find them by trolling).
So it could theoretically work -
If: you had that one day of many where the conditions cooperate and you get decent cloud streets, and
If: the thermals were broad in diameter and,
If: your track just happened to match the direction of the cloud streets, and
If: you cruised just below the cloud bases to make it easy to locate them, and
If: you didn't mind the bumps and surges up and down and didn't have passengers that were prone to airsickness.
In those conditions you could push over and reduce power to maintain speed in the thermals when you feel the upward surge entering it, and then do the opposite when out of the thermal when out of it.  You do this automatically anyway when flying on bumpy days, to hold an altitude, although normally it's random as you stumble in and out of lift.
One problem is, between the clouds on the street, the air is sinking, so the period you are in sink cancels out the period you were in lift, to some degree, limiting the benefit pr maybe negating it.
Another problem is you need to slow the airplane down to do this effectively.
Another problem is you have to get good at identifying when you are in lift and in sink and if you have no soaring experience this can be tough.
Now, I do like to take my own homebuilt PL-2 power plane and soar it on good lift days from time to time, by turning it in a "virtual sailplane" by setting power to give a 200 fpm or so sink rate and fly around just above the stall working the lift (the engine is running at about 35-30% power to do this). I call it "power soaring". But I don't do that when going somewhere although I could try to do it cross country if I wanted and was willing to take an hour to go 40 miles.
If you are really serious about saving fuel, forget about trying to exploit thermal lift except as something to do for fun, and where the right opportunity might happen once in a blue moon, and focus on not being in a hurry to get from A to B.
If you aren't in a hurry, you can cruise your airplane at best range speed and power for the maximum MPG (maybe 40-50%), and you can go places in the early morning when the winds are light and the air is smooth, with your engine barely working, and enjoy the scenery sliding by a little bit slower than normal.  Best time to be in the air.
If you're renting however, and paying on a Hobbes meter, the benefit of the fuel saving is going to the airplane's owner, not in your pocket.


Supercharging was mature technology at the start of the war while the turbocharger was something quite new.  The P-38 used the then radical new General Electric turbocharger (along with the B-17 and P-47) which was quite reliable in itself but the system couldn't tolerate back pressure, which is why the turbine wheel is exposed on the Lightning's turbos on top of the booms - that's where the exhaust comes out.

In any case, the Lightning's many bugs included boost system related issues, but this was mostly due to an ineffective intercooler system in the leading edges that didn't drop the air charge temperature enough.  The tetra ethyl lead in the fuel would actually separate out and lower the fuel's octane rating on its way to the cylinders, causing detonation and blown engines.  This wasn't the turbo's fault and was mostly fixed by the K and L models with the big chin scoops for the new intercooler.  I don't believe the turbocharger unit itself was a major maintenance headache for the P-38.

That's the thing about the Lightning.  In its L model form it really was the F-22 of its day.  It could outclimb just about anything.  With the hydraulically boosted ailerons, at high speed it could out roll single engine fighters in spite of the mass of those booms.  With counter-rotating props it had no torque effects with power changes and was jet like as a gun platform. Compressibility problems were mitigated with dive flaps.  All the more amazing as a pre-war design.  Kelly Johnson really was a mega-genius.

But the turbocharger and intercooler system, with yards of ducting, along with two of everything in the booms, made it very complex and expensive airplane compared to say, a Mustang with its Merlin's simple two speed supercharger, so you could say it was questionable whether it was worth it (there is endless speculation on what a Merlin powered P-38 would've been like).  So to answer your question, cost and complexity may have kept a lot of designers from using GE's turbo system, more than reliability.


How to calculate flight time from time at full throttle?

You say mention a 'forward rate' of 9:2. If I get you right, that means L/D = 4,5 The mass of your body, plus electric motor, battery and parachute is probably around 110 kg. Assuming you may glide with an airspeed of 15 m/s at L/D = 4,5, the vertical component of the airspeed is 15/4,5 = 3,33 m/s, and the 'gravitational power' involved is 110 x 9,8 x 3,33 = 3600 W. The conversion efficiency of motor + propeller is probably 0,5, so the electric power needed to fly level at L/D = 4,5 and 15 m/s would be 7200 W. If the capacity of your batteries is 6 x 504 Wh = 3024 WH, then your flight time would be 3024/7200 = 0,42 hours = 25 minutes...

More or less...


Why does this GPS approach say "RADAR REQUIRED"?

The immediate reason seems to be that for RNAV approaches that start at an IF (Intermediate Fix) - not an IAF (Initial Approach Fix) - radar is required per the ATC orders (4-8-1h):

  issue approach clearance [...] only after the aircraft is:

  Established on a heading or course direct to the IF at an angle not greater than 90 degrees, provided the following conditions are met:

  [...]

  (b) Radar monitoring is provided to the IF.
  (c) The SIAP must identify the intermediate fix with the letters “IF.”

The RNAV 26 approach that you mentioned does have an IAF, so according to the same rules radar isn't always required for it.

You might now ask, why is radar required for RNAV approaches that start at an IF? Because, it doesn't have an IAF.

The next question is why doesn't it have an IAF? Probably because of higher terrain north of the approach corridor? Or maybe (as per @Jonathan Walter's answer) there is sufficient Radar coverage to vector to the IF, so it doesn't need an IAF.


How does a Delta-3 hinge on a helicopter tail rotor work?

It's because the blade's span-wise axis is "swept" relative to its flapping hinge line, so when it flaps, the sweep angle results in the blade's effective AOA changing somewhat (for the advancing blade, reducing; that's what the feathering part means).

To picture it, imaging you are standing directly in front of the tail rotor disc watching the advancing blade of the plain rotor come over the top or bottom straight toward you.  All you see is its thin leading edge.  If the plain blade flaps left or right, still all you see is the thin leading edge because the blade's axis is perpendicular to the feathering hinge axis.

Now imagine the Delta three rotor blade from the same vantage point, and the hinge flaps left or right. Because the blade's span-wise axis is offset, or  "trailing" the flapping hinge axis, you will be able to see some of the upper or lower surface of the blade from your vantage point when it flaps. To the airstream, this is effectively a slight reduction in AOA ("feathering") compared to the AOA of the unflapped blade as set by the pitch change linkage (or an increase when flapping while retreating).


How are pilots prepared for a go around on a simultaneous converging approach when the "converging chart" is not published?

The reason you don't see similar charts for the north+west operation (i.e. 35 + 27's) as for those that you pointed out for the south+east (i.e. 17 + 09's) operation has to do with the way the runways are set up, and what ATC has to do to clear aircraft for the approaches in the first place.

In the case of the south+east approaches -- i.e. landing to the south on 17 + to the east on 09R -- the runways shown never intersect, so aircraft can be cleared for the respective ILS approaches without regard for the timing involved.... most of the time, they'll each land, roll out normally, and exit the runway, and they never get anywhere near each other -- even if one or both roll out to the end of their respective runways.

In the case that the weather suddenly goes down & they have to go missed, that's when a deconfliction has to happen, and it's handled by creating the missed approach paths to turn as you showed so that separation is maintained.

So far, so good, and you got all of that already, I suspect.

What differs in the case of the north+west operation that you asked about & illustrated in red is that the paths of the two aircraft absolutely will cross, every single time, and probably at very similar altitudes when landing on 35 + 27L/R.  So ATC has to do a lot more when they clear aircraft for these approaches: they compute (with computer assistance) a separation IN TIME at the point when they will each reach the crossing of the runways.  (And, if the speeds change enough that the separation looks like it won't be maintained, they have to send one or the other around... not common; the controllers there can build in plenty of buffer to avoid that scenario.)

Thus, it doesn't matter if the weather goes down & the aircraft have to go missed... they will still reach that crossing point separated in time.  So they can both go missed straight out.

On the south+east scenario, they don't NEED the "separation in time" constraint (which gets applied to EVERY pair of approaches landing north+west), so they just get a "separation in space" via missed approach routing to keep planes apart in the case of simultaneous missed approaches.

And, to consider the follow-on question, "what about a north+east or south+west scenario"... the south+west scenario (17 + 27's) would probably require separation in time just like the north + west scenario would -- the runways cross (and 17 is probably too short to publish LAHSO), so the timing has to keep the planes apart on roll-out. Which would also keep them apart in the event of go-arounds.  And the north+east option probably isn't used, because if the long runways (i.e. 09L/R) are departing east, aircraft landing to the north (on 35) shut down departures from both the 9's, in a way that doesn't happen when departing to the west.  (West departures don't cross the 35/17 centerline the way that east departures do.)  So in lieu of publishing charts to cover that scenario, ATC simply doesn't use simultaneous converging approaches in that configuration.


What is the feasibility of solar powered drones?

Let's take the MQ-9 as an example...

The MQ-9 is powered by a 900 HP Honeywell TPE331-10GD engine. In order to generate 900 HP, it will take 2100 kVA (assuming 3-phase electric AC motor). 2100 kVA is about 1680 kW. That is 1.68 million watts.

Now, the sun delivers (if you could get 100% of the energy sent to Earth) about 4.8kW per square meter (depends on Latitude, which can range from about 6kW to less than 1kW). This would mean you need about 350 square meters of 100% efficient solar panels.

The problem is that the current "world record" for solar efficiency is 46%, let's round up to 50% for easy math sake. So we have to double our solar panel area to 700 square meters.

Now the wingspan of an MQ-9 is 66 feet (about 20 meters), and a length of 36 feet (11 meters). If the MQ-9 was box shaped, it has a surface area of 220 square meters. Lets assume that 20% of that is real "upward facing" surface area so in reality, if you covered the MQ-9 with the most efficient solar panels in the world, you would only generate (220 * .2 * (4.8 * .46)) about 97kW or about 6% of the power actually required to run the aircraft.

This is also assuming that the extra weight of the batteries/wiring/charge controllers don't make the aircraft heavier or require a larger power plant, and assuming that the 3-ph 2100kVA motor is the same weight as the TPE331-10GD.

This gets even worse for quad-copters because they just don't have the surface area, and don't benefit from aerodynamic lift to reduce the amount of power required to fly.

Sources:
USAF MQ-9 Facts
Wikipedia Solar Cell Efficiency


Descend via STAR, after getting crossing restriction previously

The restriction to cross "BHAWK at FL240" is overridden by the controllers latest clearance to "Descend Via FYTTE5 arrival", unless they  include the instruction  descend via "EXCEPT MAINTAIN FL240".
FAA Climb Via/Descend Via Speed Clearances Frequently Asked Questions, page 6, questions 8.
If unsure, you should query ATC though.


Could one see stars from the Concorde in daytime?

Yes, in at least one exceptional circumstance.
The book Racing the Moon’s Shadow with Concorde 001 describes a 1973 scientific flight that remained in the moon's umbra for more than an hour, in daytime.  As stars are quite visible from the ground during a solar eclipse's totality, they would have been even more visible from a 17 km altitude.


Why does the KC-46 use two sensors for MCAS when the 737 Max doesn’t?

According to the article, the KC-46 uses the dual FCC/AoA sensor for computing both FCC channels and comparing the command signals. With two disagreeing signals there is no way to determine which one is correct and the usual remedy is to disengage both, warn the pilot, and engage in the appropriate crew procedure. And that requires training.
The B737MAX was promoted as requiring only very limited differences training relative to the NG, so the setup for the KC-46 could not be copied. The original design of MCAS in the B737MAX also used two transducers for activation - two different types of transducers, both of which had to be over a threshold value, as mentioned in this answer. Original design MCAS only had limited authority of 0.8 deg stabiliser. From the crash report of Lion Air 610, page 204:

MCAS is designed to function only during manual flight (autopilot not
engaged), with the aircraft’s flaps up, at an elevated AOA. As the development of the 737-8 (MAX) progressed, the MCAS function was expanded to low Mach numbers and increased to maximum MCAS command limit of 2.5 of stabilizer movement.

The report states that in the failure analysis, Boeing classified the uncommanded MCAS failure condition as Major (which may not occur more than once in 10$^5$ flying hours), instead of Hazardous (1:10$^7$) or Catastrophic (1:10$^9$) allowing for indeed a single transducer input. Again from the report, page 206:

If the probability of an undesirable failure condition is not below the maximum allowable probability for that category of hazard, redesign of the system should be considered. If the uncommanded MCAS failure condition had been assessed as more severe than Major, the decision to rely on single AOA sensor should have been avoided.

Why all of this was done for the B737, while the KC-46 uses two sensors, is a conglomeration of factors. Two sensors is best. Time pressure for plane delivery, airline customer pressure for limiting differences training, the observation that previous versions of B737s with accumulated flying hours of 250 million had experienced no catastrophic failures due to AoA sensor failure (reference again from the crash report), all led to the perhaps justifiable belief that the one sensor was sufficient. If rapid action was taken by the crew to contain the failure - but the failure could not be reognised in time. Again page 206:

During the single and multiple failure analysis from the air data system worst case scenario of “failure of one AOA followed by erroneous AOA”, Boeing concluded that the effect would be hazardous until the flight crew recognized the problem and took appropriate action to mitigate it. Since the training or the guidance for actions taken in such situation were not provided, the effect category should have remained hazardous.
Since the FCC controlling the MCAS is dependent on a single AOA source, the MCAS contribution to cumulative AOA effects should have been assessed.


Are the current seat belts used in commercial airlines safe enough?

For a proper answer we first need to define what "safe enough" is. If you want a significant reduction in risk over current standards, improving the restraint will not be enough.

Your observation is absolutely correct: The lap belt is the minimum the airlines get away with, and you would be much better protected in some kinds of accident by a proper 5-point harness. But fitting the harness alone will not achieve much: To stay in place in a crash, all seats need to be reinforced, so they can tolerate the increased loads at the shoulder belt attachment points. This will add weight and cut into the profits of airlines, so it will only happen when it is mandated.

Please read this answer for more details. It concerns GA aircraft, but much applies to airliner seats as well. The better the restraints are, the more deceleration load can be survived. Note that the points in the Eiband diagrams shown in this answer are from tests with additional leg, chest and arm restraints. If all you have is a lap belt, you might probably be able to tolerate only half as many gs.

The better alternative to a 5-point harness would be to turn around all seats. This would help most to reduce injuries and improve chances of survival in a crash landing.

Now I have to contradict @FreeMan: While the brace position will put all the load on a small strip around a person's hips and lets the arms flail forward, a properly secured torso can take 10g for a duration of more than a second and up to 40g momentarily without ripping the head off. See below the famous sequence of Dr. John Stapp in a ride on his rocket sled "Sonic wind":

Dr. John Stapp in a deceleration test (picture source)

He clearly had his head bobbing about, but even though he lost dental fillings and suffered hemorrhage in his eyes, the head stayed intact.

In the end, all what the lap belt is really good for is to keep you in your seat with negative acceleration due to gusts. This is by far the most common situation when a restraint is needed. The classical brace position (torso over legs, head down) is impossible anyway in economy class due to the ever reducing seat pitch.


Is excess lift or excess power needed for a climb?

As the answers to your original question already explained, you do need extra lift to accelerate upwards. Once the wing is set into a vertical motion, however, lift again exactly equals weight to keep the wing at a constant vertical speed (if we neglect thrust and drag for a moment). No extra lift is needed to maintain that vertical speed. Only when you want to accelerate further up, extra lift is needed.

The increase in potential energy comes indeed from the propeller, because the lift vector of the climbing wing is tilted backwards, adding a horizontal component that needs to be compensated by extra propeller thrust.

Now let's look at your experiment in detail: I assume the wing has some mass, is rotationally locked and slides up and down that pole without friction. If you accelerate the car, at some point its speed will just be right for the wing to create exactly the lift to cancel out its own weight. At this speed the wing will be stable at any position along the pole. If it slides down a little, its angle of attack $\alpha$ will increase and create more lift, stopping the downward motion. The reverse is true for any upward motion. See below for an illustration of the principle. The cyan vector is the vector sum of the flow due to forward motion (blue) and vertical motion (red), and this is what the wing will "notice".

When the car accelerates further, the lift will increase and now become greater than the weight. The wing will accelerate upwards until its vertical speed will reduce its angle of attack by enough to reduce the vertical aerodynamic forces to exactly equal its weight. Now you have the same situation as before, but not at zero vertical speed, but at a positive vertical speed which will make sure that the wing pops out at the top of the pole unless there is some stop. When the wing hits the stop, the vertical motion ceases, the angle of attack increases and the wing will lift up not only itself, but also part of the car's weight.

Note that I now spoke of the vertical components of the aerodynamic forces, not lift. When drag is added, it will add a vertical component when the wing is in motion. Lift is defined as the sum of aerodynamic forces perpendicular to the flow direction at infinity and drag parallel to it. This cumbersome definition makes sure that local distortions in the flow field do not impact the direction of lift and drag. The direction of lift for the climbing wing will point slightly backwards and the direction of drag slightly downwards. This will add some drag component to the sum of the vertical aerodynamic forces, and lift needs to increase to compensate for this. The horizontal component of lift will now add to the drag and the forces on the pole, so more force from the propeller is needed to push the climbing wing through the air. This extra force is needed to increase the potential energy of the wing on its way up. For a descending wing, the reverse is true: Now drag will add some vertical component and lift will be slightly slower. The forward component of lift will now push against the pole, reducing the force the propeller needs to provide. The reduction in potential energy now reduces the horizontal aerodynamic forces.

An airplane is slightly different, because it is free to pitch up or down and the angle of thrust will pitch with it. This will enable the pilot to select the flight path and the amount of lift the wing creates, but again the vertical motion will make sure that any excess lift will translate into increased vertical speed and a lower angle of attack, so the excess lift vanishes. In a climb, thrust needs to be bigger than drag in order to increase the potential energy of the airplane, and now the vertical component of the tilted thrust vector will support some weight, reducing the amount of lift needed to support the weight.


When is a fuel pump needed on GA aircraft?

On a low wing monoplane you'll need a pump all the time. There will be a mechanical pump fitted to the engine for the purpose. On a high-wing monoplane the engine is often gravity feed.

However, during critical phases of flight (specifically take-off and landing) you wouldn't want to have that fail so a second auxiliary electric pump is fitted that the pilot switches on beforehand and can switch off once that phase is over.

The Pilot's Operating Manual will give specific recommendations for use on any given type.


What are the FAA/CS requirements for rubber chocks?

I could not find FAA requirements; however, there is an industry standard: SAE J348 (the details are behind a paywall).

A 1993 flightsafety.org publication emphasizes that chock placement and design are essential, for example:

  The chock’s height is very important and it depends on the size of wheel to be restrained. For heavy transport aircraft, a six-inch (15.2 cm) height for wooden or rubber chocks is effective in general ramp usage. For restraining an aircraft during ground run-up operations, most operators use larger, fabricated steel chocks of greater height, sometimes as much as 12 or 15 inches (30.5 or 38.1 cm).


Could leading-edge dynamic stall occur for a tripped airfoil?

if the airfoil is tripped on the upper surface to make the boundary layer fully turbulent, does that suppress the √leading edge vortex?

I would say no, because supercritical wings that have that LSB problem, and so suffer from leading edge stall, aren't improved by leading edge contamination, like frost coatings or heavy bug accumulations, which can be presumed to destroying laminar flow well forward of the normal transition point.
On the CRJ200, which has a particularly nasty unrecoverable LE stall due to LSB formation at the leading edge, contamination only serves to reduce the stalling AOA to below shaker/pusher onset, without making the stall any more benign, as a number of frost contamination crashes have shown.  The bubble is still there even with the rough surface forward of it, and so the wing still lets go all at once, just at 9 degrees instead of 15.
The LSB formation is particularly bad on supercritical wings because the profile has an odd kind of "corner" or discontinuity in the curvature because of the extra thickness forward, which gives a kind of squared off profile at the LE.


Can a CFI endorse a BFR flight review through real-time video including the flight portion?

It seems to me that your question is simply "can an instructor provide flight training from the ground?", whether it's for a flight review or something else. As far as I can tell, the instructor must be in the aircraft. All emphasis below is mine.
61.1:

Flight training means that training, other than ground training,
received from an authorized instructor in flight in an aircraft.

61.195(g)(1):

(1) A flight instructor must perform all training from in [sic] an
aircraft that complies with the requirements of §91.109 of this
chapter.

The Williams interpretation (2018) talks about instructing from the rear seat (see this somewhat related question) and states that the regulations require the instructor to be seated in a pilot station per 61.195:

Section 61.195 prescribes limitations and qualifications for flight
instructors. As evident from the heading in § 61.195(g), § 61.195(g)
prescribes limitations on the flight instructor's position in an
aircraft and required pilot stations for flight training.
[...]
The regulation would not require two pilot stations for a training flight unless the flight instructor were required to provide flight
training from the one of the pilot stations.

That last statement seems very clear. In any case, the idea of providing flight instruction from the ground doesn't seem realistic, in my opinion. Even with great cameras, will the instructor be able to see your knuckles are white on the yoke from poor trimming technique? How would you do exercises under the hood (if needed)? There are just too many things that would be difficult to do and/or difficult to assess.


Why does an increase of airspeed result in a decrease of angle of attack?

On page 2-10 under the heading "Induced Flow (Downwash)", the book is making the point that if you have a wing moving forward horizontally at some fixed speed relative to the ground and some fixed positive pitch attitude relative to the horizon, and you surround the wing with a descending airmass, the wing's angle-of-attack will be less than if the airmass were not descending.  A rotor blade of a helicopter can be viewed as such a wing, at least at a given instant in time.

The book is using the term "induced flow velocity" specifically to refer to the downward velocity of the airmass caused (induced) by the rotor blades.  I.e., downwash.

The exact sentence you quoted was under the subheading "Out of Ground Effect (OGE)".  Since the ground is no longer acting like a "floor" to impede the downflow of air through the rotor system, you have more downflow than you would in ground effect.

If you were hovering in ground effect and the ground suddenly disappeared, the downflow velocity would increase and the angle-of-attack of rotor blades would decrease.


What is this plane approaching an airport in Asia? (Also, what is the airport?)

The airport is Lukla - Tenzing-Hillary in Nepal.

The aircraft is a Eurocopter AS350 Écureuil helicopter. I found a picture of one that has the same panel layout.


How much impact can be taken when flying in formation?

@Lnafziger is correct that absolutely ZERO contact between aircraft flying in formation is acceptable, with Aerial Refueling (AR) being the sole exception to this -- but in that case the AR equipment is designed to allow for what's going on.

The problem with contact IS the significant risk of damage to the aircraft involved, so the assumption in "assuming no damage is caused, how much impact..." is outside of typical experience.  IF you could assure no damage, then all sorts of things might be possible, but even pretty stoutly built fighter jets still aren't "bumper cars" and shouldn't be treated as such.  Even if a collision didn't cause an immediate structural failure, the risk of damage to the internal structure of the wing/tail/whatever would be enough that the aircraft would have to be taken apart & xray'd (or another non-destructive inspection method) to ensure that there wasn't damage that would later result in structural failure.

The one exception to all of this that I can recall was a technique that the RAF used in WW II to defeat the V-1 "buzz bomb" cruise missiles.  While the Spitfires could shoot them down, the small size of the missile meant that you had to get so close that you were probably flying through a cloud of debris right after you killed it (i.e. the warhead would detonate and the shrapnel might bring down the Spitfire as well).  They discovered that the gyroscopes in the V-1 guidance (i.e. the primitive autopilot) would tumble if they were inverted, so some pilots would fly formation with the V-1 then intentionally make contact with its wing with their own, flipping the buzz bomb onto its back.  At this point, the autopilot lost its bearings and the V-1 went down into (presumably!) empty countryside, crashing far from its London target.

Other than this, formation flight is carefully planned out so as to minimize all risk of contact between the aircraft.  Even in the (very cool!) video of the Blue Angels, you can see that there is always space between the wingtips -- more space for the more dynamic maneuvers, with the least space during a fairly brief and reasonably stable pass.  Remember, these pilots are extremely good & highly experienced in this sort of formation flying, and while there IS oscillation in pitch & roll, the formation is designed so that this can safely go on.  There just isn't much risk there of a force that would move one aircraft directly to the left or right of its position. Turbulence might produce a rolling or pitching motion that could LEAD TO a collision, but the pilots have enough control authority to correct these sorts of forces.

That's why they're able to do what they do, safely.

Fly Navy!


What is the difference between aluminum tape and speed tape?

Speed tape is aluminum tape that is much thicker with stronger adhesive than the aluminum tape you get at Home Depot, that is approved for temporary application on external surfaces of airplanes.