What would have happened when the Concorde's low-pressure emergency system brought it lower mid-flight?

I'm answering a point in a comment by the OP, rather than answering the question itself directly - but I do think it's totally relevant.  Feel free to vote accordingly :)

This list provides a list of Concorde destinations.  I am assuming that it is complete.  I have not gone through every route but looking down the list suggests that GOOY-SBGL (Dakar to Rio) is the route with the longest ocean crossing.  This list seems to confirm this.

Concorde did not fly the southerly Pacific routes, I guess because it would not be capable of diverting in exactly the situation you ask about.

Suitable diversions on that route would be FHAW (Wideawake on Ascension Island), SBNT (Natal), SBRF (Recife) and SBSV (Salvador).

Using this tool, we can see that GOOY-SBNT is 1870nm and it's all ocean between them.

Using this tool, we can calculate that the mid-point of GOOY-SBNT is at 10° 26′ 47″ N, 026° 29′ 44″ W.  We can also calculate that the midpoint to FHAW is 732nm and the midpoint to SBNT is 587nm.

So a reasonable guess (without access to the original flight plans) is that the maximum distance from a diversion is to SBNT from the midpoint which is 587nm.  Easily done, even at 10,000 feet.

Before the midpoint, I guess they would have returned to GOOY since it is closer than FHAW.  Therefore, I also guess that FHAW would only have been considered if SBNT and GOOY were not available - most unlikely.

I have now found a longer one!  KLAX (Los Angeles) to PHNL (Honolulu).  This one's easy.  The Great Circle mapper shows us it's 2220nm.  There is nowhere to divert between those two so the new greatest distance is 1110nm.

Concordes' max range was about 3900nm so as long as it was about 60% efficient at 10,000 feet compared to cruise (1110 / ( 3900/2) plus a bit for go-around time), the diversion was no problem.  Although inefficient at lower levels, I doubt it was less than 60%.


How much force is needed to tow an airliner?

Tugs do not need that much horsepower, even the biggest tugs only have around 400bhp. What they do need is lots of torque for push/pull power, lots of weight to give it plenty of inertia, and big grippy tires to transfer the power to the surface.

The T80 in this link is pretty typical, 50-70 tons, 408bhp, and 1500 pound feet of torque. That's more than triple the torque of a hefty pickup.


How is the center ILS used on the 747-400?

It depends on which page you are viewing. There is the NAV RADIO page, and the ALTN NAV RADIO page.

In standard operation (i.e., nothing has failed, more on that in a bit), there are no separate L and R ILS entry lines on the NAV RADIO page (unlike for VOR and ADF).

A single entry, on either CDU, tunes all 3 receivers to that frequency. If FMC 1 and 2 failed, the alternate nav radio page (ALTN NAV RADIO) can be used. And this is where the third CDU comes in.

  If both FMCs fail, ILS receivers can be tuned on the CDU ALTN NAV RADIO page. The left ILS receiver is tuned with the left CDU, the center receiver is tuned with the center CDU, and the right receiver is tuned with the right CDU.

Source: Boeing 747-400 FCOM 11.20.6 (emphasis mine)

Here's the location of the center CDU:

(wikimedia.org)

Note: Normal operation is based on auto tuning, say unlike a 737NG where the frequency is manually selected left and right. With the approach selected, and within range, the plane auto tunes the frequency. The crew can then confirm the identifier on their displays.


What to look for in a flight instructor?

This is an excellent question and at the same time, very broad. Every student and pilot can give you a ton of advice about what qualities the best CFI must have. I will list a few qualities to look for and then guide you to a few resources which can further elaborate the topic.

I presume you are going for Part 61 (14CFR61.159). I also presume that you have selected a flight school or will choose from a few around your.

Once you get to a flight school, normally you will be assigned a CFI by them. They will interview you and you should do the same.

Ask the CFI why they are teaching and what their goals are
Generally speaking, one half of CFIs are doing it for their future career goals (i.e. to get a job in an airline) and others are doing just because they earned the CFI rating and hence are earning money by teaching.
Once you start flying with a CFI, see how they respond to your mistakes
You are a student and are learning something new. There is no way that you will master everything taught just once. (Maybe you can, I'm not just that smart.) Observe how the CFI will notice your mistake, bring it your attention, rectifies it themselves or gives you instructions to do it, and most importantly, how your mistake affects their mood?
Before and after each lesson, notice how they answer your questions and explain to you what you guys will be doing and have done
Some people (like me) would ask a million questions. Often times, you will find teachers/instructors who don't like to be questioned a lot. All your questions are genuine, you just need to see how they are answered.
Ask your pilot friends to guide you, or check with other students at your flight school.
Your friends can give you a very honest feedback. You can benefit from other students too, but if a CFI works for someone else, they may not work for you. You are the one to judge and make the call.

Naturally, you cannot know about a CFI's style unless you take a few lessons with them. That will definitely cost you money. But spending a little money to learn a valuable lesson is not wasting money. It is an investment.

I am not talking about some other details as they are discussed thoroughly in the references below.

Here are some resources which have answered this same question in more detail.

Pilot Tricks
Ask A Flight Instructor
wiki How
AOPA (AOPA has an article about almost everything aviation-related)
About Money
Flying Mag


Who is the owner of the world's only private Boeing 787 Dreamliner?

The registration number of this aircraft is well visible in the video: 2-DEER.
According to Planespotters, this B787 was first leased by Jet Aviation Flight Services from 2014 to 2016. During this time it was registered as N28MS.
In 2016, the plane was bought by Deer Jet, a company owned by HNA and received the registration number 2-DEER. The video was published in 2017. That means 2-DEER was not privately owned, but available and furnished for private charter clients. The video title is a tad misleading.
Deer Jet was trying to sell it for 300 million US$ in 2018 (source).
In February 2020, 2-DEER was spotted still in Deer Jet livery. It appears that they couldn't find a buyer.
The registration number starting with 2- might look unfamiliar to most of us. A company called 2-REG offers these personalised registration marks. Here is an advertising text from www.weareguernsey.com that summarizes it:

2-REG is an ICAO (International Civil Aviation Organisation) registry,
well-recognised around the world for accommodating all aircraft
categories, including commercial aircraft, business jets, helicopters,
and general aviation. In 2015, 2-REG began to issue Aircraft Operating
Certificates (AOCs), and six have been issued so far.
Run by the Dutch company SGI Aviation, 2-REG pays royalties to the
Guernsey government on operating income. The registry has built its
reputation by being extremely responsive and customer-focused,
offering its worldwide coverage coupled with competitive fees, making
it the most successful registry within the aircraft leasing sector.


How much lift is created by a half-sized rotor?

For the hovering rotor, the stationary case, it can be safely assumed that the lift $L$ is a function of the input power $P$, the diameter $D$ of the rotor and the air density $\rho$.

Thus, $L = f(P,D,\rho)$

where $f$ is a function to be determined.

From dimensional analysis, the lift $L$ can be easily derived:

The variables are Lift $L$, dimensions $MLT^{–2}$; Power $P$, dimensions  $ML^2T^{–3}$; Rotor diameter $D$, dimensions $L$ and air density $\rho$, dimensions $ML^{–3}$

The variables form a non-dimensional product $k$

$k = L^a\cdot P^b\cdot D^c\cdot \rho^d$  where $a,b,c,d$ are numbers to be determined.

Let’s form now a parallel product $k^*$ with the dimensions:

$k^* = (MLT^{–2})^a  (ML^2T^{–3})^b  (L)^c (ML^{–3})^d$

Clearly, $k^* = M^0 L^0 T^0$... We now take the exponents for each dimension:

$a  + b + d = 0 \\
a + 2b + c – 3d = 0 \\
–2a – 3b = 0$

We make $a = 1$, since $L$ is the variable we’re going to solve for.

$b = –2/3 \\
d = –1/3 \\
c = –2/3$

Then,

$k = L^a\cdot P^b\cdot D^c\cdot \rho^d \rightarrow  k = L\cdot P^{–2/3}\cdot D^{–2/3}\cdot \rho^{–1/3}$

Solving for $L$

$L = k\cdot P^{2/3}\cdot D^{2/3}\cdot \rho^{1/3}$

where $k$ is a constant

Hence, for rotor diameters $D_1$ and $D_2$, and for the same power and air density, the corresponding lifts $L_1$ and $L_2$ are:

$L_1/L_2 = (D_1/D_2)^{2/3}$

For the case of $D_1 = 13 ft$ and $D_2 = 26 ft$, $L_1/L_2 = (13/26)^{2/3} = 0,63$

In other words, the smaller (13 ft) rotor gives you, for the same power and air density, just 63% of the lift attained with the larger (26 ft) rotor.

That's for the hover. For the climb, you'll need extra power. In order to move 635 kg vertically upwards at 1200 ft/min (6,09 m/s) you would need $635 \cdot 9,8 \cdot 6,09 m/s = 37,9 kW...$


Do FAA endorsements have to use the current language word-for-word?

Here is verbiage from the FAA's AC 61-65G, appendix A, regarding endorsements.

Also, in my view as long as the instructor's endorsement verbiage covers the essential elements in the regulation underlying the actual rquirement(s) that must be met, there are no mandatory words that must be used.  However, should a question arise regarding the action, level of proficiency, or other requirements specified by the regulation the instructor is attesting to, using the recommended language shown in AC 61-61G, appendix A, should eliminate any potential ambiguity.

(emphasis is mine)

  The following examples are recommended sample endorsements for use by authorized
  instructors when endorsing logbooks, or other means found acceptable to the Administrator for
  airmen applying for a knowledge or practical test, or when certifying accomplishm
  ent of
  requirements for pilot operating privileges. Each endorsement must be legible and include the
  instructor’s signature, date of signature, certificated flight instructor (CFI) or certificated ground
  instructor certificate number, and certificate expir
  ation date, if applicable. The purpose of
   this
  advisory circular (AC) is to provide guidance and to encourage standardization among
  instructors.


If the temperature and conditions are right, yes.

Any aircraft which has a heat engine that burns hydrocarbon fuel, which is pretty much any reciprocating or gas turbine engine used in aviation, will emit carbon dioxide and water vapor as byproducts of combustion.  It’s just a byproduct of the chemical reaction to produce heat energy in the engine. And when the temperatures and humidity in the ambient air are low enough and high enough respectively, the water vapor in the exhaust stream will freeze into ice crystals that remain suspended in the atmosphere for a sustained period of time.

You typically won’t see this at your average airport or from the average helicopter flying over you as the temperatures simply are not low enough at the altitude the aircraft operates at for contrails to properly form. That being said, see picture below.

Image source: https://koreaaero.tistory.com/40 (in Korean)


In what manner was the Vympel R-73 (AA-11 Archer) a game-changer in comparison with NATO's missiles?

The Russians brought some new ideas to the missile warfare when they mated the Vympel R-73 with Mig-29. The most important of these was the high offset sensor lock mode, which allowed the pilot to 'lock on' to the targer regardless of where the nose was pointed at. According to Peter “Stoini” Steiniger a JG 73 Pilot, who flew Mig-29s in East Germany,

The nice airframe in combination with one weapon was the killer: The Archer in [sensor lock] mode.” Introduced in the mid-1980s, the Archer AA-11 is a very capable heat-seeker with a greater range than the U.S. Sidewinder. “A simple monocular lens in front of my right eye enabled me to slew the seeker head of the missile onto my adversary at high angle off [target].” The Fulcrum’s ability to lock a missile even though its nose was pointed far away from its target “watered many eyes,” ...

The image below shows the missile aiming sight mounted on the helmet of a JG 73 pilot.

Image from airspacemag.com
This off boresignt advantage was not achieved by the western forces till they introduced the AIM-9X missile and the Joint Helmet-mounted Cueing System in 2002.
Aircraft-wise, the Mig-29 was a revelation to the west as the previous Russian designs have not been so sophisticated, so as to speak. The West was concerned enough with Mig-29 to start looking for new fighter ideas. Another important equipment in Mig-29 was the Infra Red Search and Track System (IRSTS), an idea for which the US is just warming up. Most of the exchange pilots, who flew the Mig-29 against the US F-15s and 16s were quite surprised and initial engagements usually went the 29s way, though techniques were later devloped exploting the Mig-29s' weaknesses. From an USAF exchange pilot:

From BVR (beyond visual range), the MiG-29 is totally outclassed by western fighters. Lack of situation awareness and the short range of the AA-10A missile compared to the AMRAAM means the NATO fighter is going to have to be having a really bad day for the Fulcrum pilot to be successful.
In the WVR (within visual range) arena, a skilled MiG-29 pilot can give an [F-15] Eagle or [F-16] Viper driver all he/she wants.


Does the FBW system of a passenger aircraft use differential thrust for yawing?

First, you need to understand what fly-by-wire is. In layman's terms, FBW separates pilot input from direct mechanic actuation over anything. Yes, control surfaces are still moved due to hydraulic work, but such work is not exercised by the crew over the hydraulic lines which means pilots don't need to apply different "strength" levels over the sidestick or any other input mechanism.

That said, the FADEC (Fully automated digital engine control) does not apply differential thrust to control yaw in situations where crosswinds are encountered. Yaw is a rudder-controlled motion. Applying differential thrust would put too much strain on the airframe and wing structure, not to mention that in addition to inducing yaw, differential thrust also induces a roll along the longitudinal axis of the aircraft

The only reason differential thrust would be encountered on an airliner is more closely related to non-normal operations in which an engine is idled or shutdown and in those cases the yaw motion induced by the asymmetric thrust would be countered with rudder input.


Why are US Regional Airline starting wages so low?

Well, the short version is: The airlines pay what they have to pay in a free market.  They can get away with it because pilots are willing to accept it.  Like any other business they are in it to make money and keeping costs down is just as good as making extra money, so they aren't going to volunteer anything extra.

Now, why do pilots do it?  Because of the promise of better things down the road.  It isn't as good as it used to be, but after being at the airlines for a few years, you can make a livable wage and as you get further into your career at a major airline, you still get paid pretty well for a "part time" job.  As I've heard other pilots say before:  It's better than a "real" job!

Other pilots do it just because they love it and can't imagine doing anything else!


How would an aircraft fly PIKES ONE departure procedure of Denver Airport?

Let's treat the "normal" and "lost communication" cases separately.

  Fly assigned heading for RADAR vectors to assigned route. Climb and maintain 10000 or ATC assigned lower altitude. Expect filed altitude 10 minutes after departure.

The essence of this is that on departure, responsibility for navigation rests with the air traffic controllers, not the pilot. The controllers will issue headings and routes to fly in order to keep the aircraft separated from other departures, arrivals, and other traffic. Once clear of traffic, the controller will issue instructions on how and where to rejoin the cleared route. At this point the pilot takes over responsibility for navigation along the cleared route.

Usually, it goes something like this. The departure will be assigned an initial heading, often the runway heading: "runway 17R, fly runway heading, cleared for takeoff." The aircraft flies this assigned heading. The aircraft will then contact the departure controller. The departure controller may continue assigning specific headings in order to separate the aircraft from other departures, arrivals and other traffic. Once clear, the controller has some options. They can clear the aircraft direct to a convenient fix/waypoint or NAVAID on the aircraft's flight plan ("Proceed direct ADANE, resume own navigation") or they can say something like "Fly heading 130, join the Denver 159 radial, resume the departure." It's up to them, but they will issue some kind of instruction that results in the aircraft joining its cleared route.

  LOST COMMUNICATION: If no transmissions are received within one minute after departure, maintain assigned heading until 7000 feet, then climb to filed altitude via direct DEN VOR/DME, thence via assigned transition. If filed altitude is above 10000 feet, cross DEN VOR/DME at or above 11000 feet.

If communication is lost, the pilot should do the following in order once it is realized that communication has been lost.

Fly the last assigned heading until reaching 7,000'.
Turn (back toward the airport and the DEN VOR) and fly to DEN.
Comply with the crossing restriction (make sure you reach 11,000' before getting to DEN if your filed altitude is above 10,000').
At DEN, turn outbound on the appropriate (filed/cleared) transition leg.
Keep climbing to the filed altitude.

It is likely that some short amount of time will pass before it is realized that communication has been lost. The aircraft will travel some distance away from the airport during this time. The aircraft must also continue until it reaches 7,000'. So by the time it would become necessary to "proceed direct DEN," the aircraft will not be "right next to it" and a turn direct DEN is reasonable.

If you departed runway 25, your route might look something like this (not to scale!).


Much like how a gas pedal controls the fuel input of a car's engine, so do the thrust levers on jet-liners. The coasting equivalent is idle thrust. The engine keeps running, but with minimal fuel flow.

The minimum fuel flow is not fixed as it is a function of altitude, airspeed, and temperature. Nowadays it is typically managed by the FADEC, so the pilot (or auto flight system) can pull the levers all the way to idle and not risk flaming out.

Idle thrust in this answer refers to that minimum thrust setting that would not cause a flame-out.

An ideal descent (and its planning) does just that. Descend from cruise all the way to lining up with the runway using idle thrust.

Hitting unexpected headwind, or being asked to slow the rate of descent, would require higher than idle thrust. In the car/slope analogy, that would be the equivalent of changing the slope to a shallower one (planes, unlike cars, need a minimum forward speed).

Most jet engines also supply air for air conditioning and pressurization – it's called bleed air. On a plane like the Concorde that cruised at almost double the altitude of the common jet-liner where the air is even thinner, idling at 55,000 feet or so was not an option because of the impact it would have on the pressurization. The engines needed to run at higher than idle to provide this bleed air.

(Source: ITVV Concorde) In-flight deployment of the Concorde's reversers. Highlighted is the secondary nozzles position indicators – the nozzles double as reverse buckets.

If the Concorde flight crew wanted to increase the rate of descent, they were allowed to deploy the reversers of the inboard engines (#2 and #3) in-flight – this was done from the flight engineer's panel (shown above). This way the thrust is redirected, but the engines keep running at the required RPM for this bleed air. (According to the Type Certificate, this was limited to 4 minutes. That's about 8,000–12,000 feet of descent.)


Why is there such a long displaced threshold on 22R at JFK/KJFK?

Its to maintain proper clearance over the park on approach from the north and avoid trees. They tried to extend the runway in 2013 but were ultimately denied due to minimum altitudes. Its covered in the October 2013 document Runway 4L/22R Improvements John F. Kennedy International Airport

They submitted for

  Relocate the displaced landing (arrival) threshold on Runway 22R 3,316
  feet to the north.

but ultimately...

  Two of the elements, the relocation of the Runway 22R arrival
  threshold 3,316 feet to the north and the relocation of the Runway 4L
  end (departure starting point) 460 feet to the north, would have
  resulted in aircraft being at lower altitudes than existing conditions
  over areas to the north of the runway, including Idlewild Park. The
  lower altitude of aircraft would have resulted in up to 800 trees in
  Idlewild Park becoming obstructions, as defined in FAA Order 8260.3B,
  United States Standard for Terminal Instrument Procedures (TERPS). FAA
  Order 8260.3B specifies the minimum measure of obstacle clearance that
  is considered by the FAA (the Federal authority) to supply a
  satisfactory level of vertical protection for aircraft operating at an
  airport. If the project described in the May 2012 Draft EA were to be
  implemented, up to 800 trees in Idlewild Park would have required
  removal to comply with FAA standards. The project described in the May
  2012 Draft EA has been modified to avoid this impact as explained in
  the following paragraphs.

  In order to minimize the number of trees to be removed from Idlewild
  Park, the Port Authority made the decision to redefine the proposed
  project as described in Section 1.3 of this Revised Draft EA. The Port
  Authority no longer proposes the relocation of the Runway 22R arrival
  threshold 3,316 feet to the north. The arrival threshold on Runway 22R
  would remain in its existing location, which does not result in lower
  landing elevations north of the Airport.


How can one fly a stabilized approach when the final approach path is curved?

Perhaps my thinking is now considered outmoded (retired in 1999), but for me the definition of a stabilized approach doesn't preclude turning, but only that the turning (when necessary) is accomplished at a stabilized rate. The idea was to be setup in landing configuration, at your stabilized final approach speed, sink rate, and power and tracking whatever the approach path is from the FAF down to the landing flare.

For tracking DME arcs, we were taught to find that angle of bank that (given our final approach speed) produced the desired turn rate. We would hold that bank, just as we would hold wings level for a straight final approach path.

If the DME started in increase, steepen the bank a little. If it started to decrease, lessen the bank a little.


How many Inertial Reference Systems are on a commercial aircraft?

The answer is at least two. Although depending on how you view the system, either one, two or three can be a valid answer.

In the past, each IRS (Inertial Reference System) is itself a unit, and manufacturers would put multiple number of this unit in the cockpit. For example, the Boeing 737 has IRS L and IRS R. The pilots can power each unit on or off individually; they can also choose which unit goes to which display (captain side or copilot side). So in the Boeing 737, the answer to your question would be two.

Fast forward to the Boeing 777, the pilots only have one such unit: the ADIRU, or Air Data Inertial Reference Unit. The ADIRU by itself is a fault tolerance unit - within this unit, there are multiple gyroscopes and accelerometers. In the past, when multiple redundant units are provided to the pilots, there were instances where the pilots had trouble identifying the malfunctioning unit or switched to the wrong unit, and the plane crashed. Now there is only one unit, and the redundancy mechanism is auto-managed. So to answer your question for the Boeing 777, the answer could be either one or three.

It should be noted that even GPS has redundancy: there are usually two receivers: GPS L and GPS R. On newer airliners, all the data - GPS L, GPS R, ADIRU, VOR/DME etc. are combined to form a navigation system. Therefore one can say, "In the past there were 2 IRS, which consisted of gyros, on airliners. Nowadays we still have gyros, but we don't call them IRS because they form an integrated system with other elements".


Why tap the brakes on take-off in fixed gear aircraft?

This answer to another question has a link suggesting that the spinning wheels may be sufficiently large gyroscopes to affect handling of the aircraft. That was however on a larger aircraft and higher speed (Lockheed Constellation). I don't know whether that effect would be observable on TB10.


Are two little engines or one big engine more efficient for an ultralight?

Normally you have more power relative to engine mass in the bigger engine. If there is no weight advantage (like in your example), other considerations must be added:

Two engines allow to spread the load out. By placing one on each wing, the fuselage weight can be reduced which in turn reduces the wing root bending moment.
If the engines drive a propeller, asymmetric thrust and gyroscopic effects can be eliminated with two engines if one engine runs clockwise and the other runs counterclockwise.
Two engines need twice the number of controls, fuel lines and instrumentation. This is both a cost and a weight issue.
And the obvious one: If one of two engines fails, you still have the other to keep you flying. However, this is only true if your design is capable of flying with the remaining engine only. Now your rudder authority and minimum thrust requirement must be adequate to keep the aircraft flying with the resulting asymmetric thrust.

Note also that with two engines an engine failure is statistically twice as likely.


What's the difference between 'Go Around' and 'Pull Up'?

Going around is a process, pulling up is an action. When ATC tells you to go around or you say you are going around it means you are initiating a set of actions to abort an approach. Pulling up is a single action, i.e. increasing the angle of attack in order to climb, and would be part of a go-around procedure.

Pull up is a non-standard phrase, in most parts of the world at least, but you might hear it as 'pull up and go around' in Canada. It also might be used in urgent situations to urge a pilot to act to avoid an obstacle or collision.


Why do some aircraft approach the runway with a long detour and others with a short one?

As you can see in this question and its answers, whether an aircraft has to go north or south is decided by ATC, as you also mention.

And, as you have correctly heard, the separation is influenced by the kind of aircraft flying in front of you, particularly during landing, as detailed in this answer.

So, in the end, an aircraft might have to fly further out if they have to put more distance between them and the preceding aircraft, or if there are more aircraft in the queue. ATC will decide in base of the currently available runways, the current amount of traffic, and whether any aircraft has declared any kind of emergency.

Note also that the approach paths for the airport are slightly asymmetrical (left side of page 11 and 12 of the pdf respectively), with ~50km on the south west approach, and ~65km on the north east one.


What are good books to learn basic aerodynamics in plane design?

Beginner

Fundamentals of Aerodynamics by John D. Anderson, Jr.
Introduces the basics of aerodynamics with historical background, the mathematical explanation and some practical applications. In the latest edition,  Computational Fluid Dynamics is also discussed.
Mechanics Of Flight by Warren F. Phillips.
Anderson's book is a good text for understanding the building blocks of fluid dynamics, such as the different types of flow. It is good for understanding how airfoils and wings work, as well as understanding the microscopic flow considerations. Phillips' text also talks plenty about flight dynamics and control, so you can better picture the forces acting on an airplane.
Anderson's and Phillips' make a very good learning pack.

Intermediate

No books found as of yet

Advanced

Fluid Dynamic Lift & Fluid Dynamic Drag both by Hoerner
I wouldn't consider these to be great "learning" textbooks, and the math can get very intensive at times, but these are still go-to reference text, and they are a great resource if you want to start a "deep dive" into aerodynamics and the practical effects of various design decisions. Both books are replete with wind-tunnel testing information and diagrams, as well as the supporting equations to back it all up.

Classics / Older

Aerodynamics for Naval Aviators by H. H. Hurt Jr.
This is a good primer on basic aerodynamics - as the title implies it's primarily aimed at naval aviators, but the material is pretty accessible and much of it is applicable to all fixed-wing aviation. There's even some helicopter stuff in there, though the section is rather thin.
This book is available from a number of publishers. It is also known as NAVAIR 00-80T-80 or NAVWEPS 00-80T-80 and available from the FAA in PDF form.

Additional references

As far as mathematics goes, you can get Stewart's Calculus text. It is a pretty good book with quite satisfactory explanations, and you can get an older edition for almost nothing (make sure you get the full text with both single variable calculus and multivariable calculus sections). Without a basic understanding of calculus it will be difficult for you to get a good grasp of the aerodynamics material.


How does flight control surface authority change with AOA?

Control authority is a function of the local dynamic pressure (the product of air density and speed squared), geometry (the product of control surface area and lever arm), local angle of attack $\alpha$, the angle of deflection $\eta$ and the relative flap chord. Generally, the control surface works fairly linearly in a range between $-15° < \eta < 15°$ for a relative flap chord of 25% rsp. $-25° < \eta < 25°$ for a relative flap chord of 15%. Interpolate for values in between. Note that flap effectiveness is proportional to the square root of the relative flap chord, such that a flap of 15% needs twice the deflection angle to effect the same control authority than a flap of 60% relative chord.

Bigger deflection angles reduce flap authority, and here it becomes complicated, because local flow phenomena can make a big difference, up to control reversal. For a simple model you may just assume that control authority is cut in half for all deflections exceeding the limits mentioned above.

This all is only valid for moderate angles of attack, when forces change linearly with angle of attack changes. Once you approach the lift force limits of the particular control surface, authority suffers. Now it is important to know the local flow field: Elevators fly in the wake of the wing, which in effect reduces the angle of attack changes at the elevator compared to those at the wing. This means that most elevators still have a healthy lift margin when the wing starts to stall. But stall they will, eventually. To give you an idea how a wing performs over the first 180° of angle of attack, see the plot below. A plot for a control surface should look similarly. It is taken from a book which should exhaustively answer all your questions about control surface authority, be it subsonic or supersonic, for all conceivable configurations. It has been written by Sighard Hörner half a century ago and is still the best you will be able to find on this topic.

For an example of an airfoil's flap effectiveness over AoA, see the plot below of the XFOIL calculation for a Wortmann FX71-L-120 symmetric airfoil with a 25% flap at a Reynolds number of 1 Million and with a fixed boundary layer transition at 60% of chord. Note especially the hysteresis close to the maximum and minimum lift angles of attack at higher deflection angles (own work; c$_a$ is the lift coefficient).


%MAC (Percent Mean Aerodynamic Chord) is a mathematical calculation that shows where the center of gravity is over the wing.  The calculations is rather straight forward and the generic formula is the same for all airplanes.  All one has to do is to figure out the numbers and plug them into the formula.

How is %MAC calculated?

Pilots, dispatchers or load masters will calculate the weight and balance with respect to the aircraft datum.  Unfortunately, we need to change where the reference point is from the (datum) to the front of the wing called leading edge mean aerodynamic chord (LEMAC).  There is also a trailing edge mean aerodynamic chord (TEMAC) that is calculated.  TEMAC - LEMAC = Wing width.

LEMAC and TEMAC are easy to calculate for straight wing aircraft.  It is simply the measurement from where the wing starts and ends from the datum.  For swept-wing aircraft it isn't that simple.  As a result, aerodynamic engineers figure out where the average of the LEMAC by averaging the wing root and wing tip.  The same process happens for calculating TEMAC.

%MAC is simply a calculation of how far the CG is from the LEMAC.  If the CG is at the LEMAC, we can say it is at 0% MAC.  CG at TEMAC means the CG is at 100% MAC.

In the picture below, we can eyeball the %MAC to be around 10% MAC.

Here is the generic formula:

$$ \%\mathrm{MAC} = \frac{\mathrm{CG} - \mathrm{LEMAC}}{\mathrm{WingWidth}} \times 100 $$

The formula is great because all the numbers are relatively the same for every airplane.  For example a 13% MAC means that we are most likely at or close to our forward CG limit.  This should instantly give the pilot a sense of how the airplane is going to respond versus a pilot trying to comprehend  what a CG of 2,341.0 inches aft of datum means for that particular aircraft.  The last number can be different for every aircraft type but 13% MAC will be the same.  The only difference is where the forward CG limit is located for that particular aircraft.

A little background, and perhaps an engineer can expand on the thought.  The basic weight and balance formula is $ \mathrm{Weight} (W) \times \mathrm{Arm} (A) = \mathrm{Moment} (M) $.  What may not be obvious is that we can use this formula in figuring out why %MAC is important.

Take a look at the picture above.  There is a moment between CG and CP and another moment between CP and tail down force.  These moments must equalize for the airplane to be in equilibrium.  If the CG moves forward, Moment #1 gets larger and to compensate the tail down force must increase.  We can increase the tail down force with nose up stabilizer trim.  The same analysis can be made when the CG moves aft.

If this is the case, there is a specific pitch trim setting for each %MAC and airspeed combination.  Most jet pilots will set a specific takeoff pitch trim setting for takeoff based on %MAC so that if the pilot loses an engine after $V_1$ the trim will be set for a speed around $V_2$.


I hold both a Sport Pilot License and a Student Pilot certificate. Can I do my BFR in a C-172?

Nope, sorry! If you need a flight review, use an LSA you have been endorsed for.

§61.56(c)(1) states that a flight review must be:

  Accomplished [...] in an aircraft for which that pilot is rated

According to the AOPA (note: this article is specifically targeted at non-Sport pilots):

  Rated is interpreted as category and class [emphasis mine]

And in another article, the AOPA continues:

  Sport pilot certificates will be issued without category/class designation

...and just for the final nail in the coffin, here's the FAA itself (thanks, @Pondlife!), in AC 61-98B:

  A pilot who holds only a sport pilot certificate may only take a flight review in a light sport aircraft for which he or she holds an operational privilege. For example, a sport pilot who holds airplane privileges could not take the flight review in a Cessna 172 since that airplane is not a light sport airplane and he or she does not hold operating privileges for that airplane.

Long story short, this all means that no, a Sport Pilot cannot perform a flight review in a non-LSA type. Because you require specific logbook endorsements in make/model for category/class/speed (an LSA like a Sting S3 vs Airplane Single-Engine Land), you are not rated to fly a Cessna 172, for example. Your solo endorsement isn't a rating, as it isn't part of a certificate - it's an endorsement.

Once you become a Private Pilot, you'll be able to do a flight review in almost any ASEL type, including all LSAs because you're suddenly rated for the Airplane category and Single Engine Land class, with no light-sport-only limitation.

As far as I can tell, your student pilot certificate is actually invalid. It's been superseded by your Sport Pilot certificate and you are now adding privileges to that certificate. As such, it doesn't really matter that you've been endorsed for solo in a 172; you aren't rated to fly one in the same way you are for an LSA.


What are the limitations of using a single shaft between the compressor and turbine in a jet engine?

How is this managed when there are several shafts connecting several compressors/turbines?

The different shaft will rotate at different speed from each other, but the relative compressor/turbine pairs will rotate at the same speed.

Expanding a little, in the most complex case that I heard of, there are 3 shafts: High Pressure (HP), Intermediate-Pressure (IP) and Low Pressure (LP)

Image source

HP turbine and HP compressor will rotate at the same speed, but this is not necessarily equal (in fact is highly likely that it will be different, otherwise there would not be the need for different shafts) to the speed of the IP compressor/turbine couple. And this will be different also from the speed of the LP turbine/fan couple.

  Are reduction boxes needed here or do they, in fact, move at the same speed?

They generally rotate at the same speed. And generally you don't want gear boxes in the central section of your engine. Apart from the maintenance nightmare that they would become, given the rotational speeds and energies involved, they would be extremely heavy, inefficient and would constitute a critical system quite prone to failure.

An exception are the fans, they have enough space and are in front of all the rest of the engine, allowing the housing of a gearbox within their enclosure. You can find a better discussion about this case in this question; keep in mind that here you have 3 compressor stages with only 2 turbine stages, the gearbox was necessary to have a speed differential between fan and IP compressor without requiring 3 turbine stages and an additional shaft. (thanks to @fooot for pointing the PW1000G out)

  Is this a big deal, does it introduce any serious limitation/drawbacks regarding the exiting air power?

As everything in engineering, there are trade-offs. The ideal performance would be obtained via an infinite set of infinitesimally thin turbines/compressors, each rotating at a slightly different speed, but this is not technologically feasible. The engine designers will then settle for a slightly sub-optimal performance, but it will be actually achievable with 1 or 2 (3 in extreme cases) discrete shafts.


Why would a Mode-C transponder report a different altitude than an altimeter/GPS?

It sounds like there was an issue with your altitude encoder

  The transponder depends on an external altitude encoder to provide the
  digitized pressure altitude that the transponder needs for its Mode C
  replies. The encoder is connected the same static air line as the
  altimeter and is wired electrically to the transponder.

  AR-850 The encoder may be either a separate unit ("blind encoder") or
  integrated into the aircraft altimeter ("encoding altimeter").
  Encoding altimeters save space and help ensure that the encoder and
  altimeter agree, but they are fairly expensive.

If you have a blind encoder its possible it can report erroneous information with out affecting other instruments onboard. You should alert your mechanic (or the mechanic that takes are of the aircraft in question) to have this checked.


It is in fact fake but its most likely loosely based on a real plane. The Russian Kalinin K-7 contains a lot of the same design elements.

(source)

It appears that the real plane was also boarded from the landing gear area.

(source)

On a bit of a funny note this article mis-uses the photo you have linked in reference to the Kalinin K-7


Why do cargo airlines frequently choose passenger aircraft rather than aircraft designed specifically for cargo?

Price, commonality, and size choice.

A very large proportion of an aircraft's cost is in design and certification. It's followed by the engines, the avionics, and the fuselage. Not much cost can be removed from an aircraft by removing the passenger-specific elements of design. That is done in freighter versions.

Freighter models like the 747-8F already realize most of the possible savings. Second-hand airliners are cheaper still, and they're not hard to convert. Rip out the interior, install cargo securing systems, and fly.

Commonality with airliners means airliner-derived freighters are easier to service and repair anywhere one needs to. And, as Dohn Joe rightly adds, get pilots for; cargo airlines are both a training ground for passenger pilots and a career path of its own.

Finally, there are more airliner models than freight-only aircraft models, so there's more choice of the right payload and range capability.

This reuse of passenger airliners for freight is a great example of efficiency. Passenger airlines tend to have very high utilization, putting lots of cycles on their airframes and lots of fuel through them, so they care for better fuel efficiency, availability, and passenger experience (or at least their expectations when booking, considering the 9-abreast 787) delivered by newer airframes.

Cargo airlines run looser schedules, because their clients don't care much for their flights leaving on time (air freight is usually offered in 2-5 days), which shifts the optimization focus from fuel efficiency towards capital costs. They are able to use up the rest of the airframe's life in a less-critical job, where the oversight is a bit more forgiving and delays due to lower availability are more acceptable.

The An-225 is special in that it occupies a class above every other freighter in capability. It does the jobs nothing else can, but, until recently, the only airframe built has been able to serve the whole world.


What are the effects of headwind strength on landing?

Are there any specific advantages or drawbacks to a stronger headwind when landing?

A strong headwind right down the runway can appreciably shorten your landing roll, if you want to do that. If you want to clear the runway as soon as conveniently possible, you might be able to take a taxiway closer to touchdown than you otherwise would.

Or, let's say the taxiway that is closest to your gate is 3/4 or more down the runway, so what you might do in a strong headwind would be to not use reverse, or just go into reverse but not bring the power up. What you don't want to do, at least at busy airports, is tie up the runway at a taxi speed.

Some have contended that a strong headwind, with the resulting lower groundspeed, makes for a slightly smoother landing because the tires don't have to spin up as much. I don't have an opinion on that.

A strong headwind can mean that brake temperatures on arrival at the gate will be lower than otherwise, both because of less brake usage on rollout and better ventilation of the brakes while taxiing.

  Are there any specific procedures that kick in when the headwind exceeds a certain number for a certain aircraft?

I've never heard of such specifically for a headwind, or at least I don't remember ever hearing of such.


If you were to fly an ILS in a knife edge would you receve GS and LOC be flipped?

No, the directional part of ILS is located at the ground. (Ground) transmitter creates lobes with specified frequency and modulation to mark the high, low, right and left areas.

LOC and GS signals are distinguished by the carrier frequency, deviation from the optimal approach by relative intensity of 90 Hz and 150 Hz modulation in the signal. These signals provides information about position relative to the airport regardless of airplane attitude.

So flying knife-edge LOC axis of the instrument still shows (correct) horizontal deviation and G/S axis correct vertical deviation.

Of course, display of the instrument is turned 90° together with the whole airplane, so its G/S axis now lines up with the green-blue boundary you see behind your windows (I hope you are not flying such maneuvers in IFR conditions :) ) but it is still the G/S axis and it shows vertical deviation from the optimal glideslope.

Only difference would be that airplane antenna won't match the transmitter polarization (ILS transmitters transmit in horizontal polarization and receiver is likely polarized in the same plane), so you loose some signal intensity and receiver can be more sensitive to reflected signals, therefore reducing maximal working range and possibly increasing probability of spurious signal detection.


The true position of an aircraft in flight can be measured, but the accuracy of any measurement is limited. The actual measured position is the actual true position plus the actual measurement error. Each error of position measurement is 3dimensional. If observed over a long time, the distribution of the errors will have a shape and size that is characteristic for the measurement method.

For GNSS receivers, the measurement of the latitude and longitude measurements depend on each other, while the vertical measurement of altitude does not correlate much with the horizontal measurement. This is why the usual model to describe is a cylinder:

Image source: ESA

The Horizontal Protection Level (HPL) is simply a horizontal cut through the cylinder where the aircraft is located with an acceptable level of probability.
The cross section of a cylinder is a circle, and the radius of this circle is the horizontal performance requirement.

The HPL is just a geometric definition. It is useless without acceptance levels and performance requirements, which are not part of its definition. Those emerge from the performance of an GNSS augmentation system like WAAS for GPS or EGNOS for Galileo, and the requirements for the use in aviation. Here below is a table of GNSS augmentation performance requirements by FAA for different phases of flight:

Image source: ICAO


Could a landing gear jettison mechanism be practical when ditching?

According to at least one source (based on NTSB data) there were 179 registered ditchings of GA aircraft over a period of 8 years, or an average of approx 22 per year. The trend however were going downwards from 30 in the mid-80s to 12-15 ditchings in the mid-90s when the study ended.

In all 22 fatalities were registered, with an 88% overall survival rate but a 92% egress rate. The egress rate is what is important for your question. Discard the long-range ocean-ferry flights and this number rises to 95%.

It's worth mentioning that there numbers are for registered ditchings. Unregistered ditchings are more likely to be successful than not, so the real survival rate is likely to be higher.

According to the report:

  "Where and when you ditch matters more than what you ditch. Examining the fatal accidents, we found that two-thirds of the 22 occurred during the winter in cold or temperate climates and 12 percent are what we call "blue water" ditchings in the open Atlantic or Pacific, done by ferry pilots on extraordinary missions in light singles or twins, or fish spotters operating far from shore."

If you want to have a landing gear that can be jettisoned, chances are that it would add quite a bit of complexity and maintenance to address a non-problem. 9 of the 22 fatalities involved an aircraft with retractable landing gear, but the study makes it clear that the status of the landing gear was unknown, so we don't know if or how this affected the statistics.

The problem isn't ditching with or without a landing gear, it's the fact that you're ditching in the first place. And when it happens it most likely does so without you having appropriate survival gear.


What aerodynamic data (drag/lift curves) exists for the L-159 Alca?

From Wikipedia, the aerofoil for the wings is NACA 64A-012. If you would like a full airplane, you would need to plot it in DATCOM. DATCOM is a program that is designed to calculate drag, lift, moment coefficient, etc. on an airplane based on coordinates.

So, here is a link to the polar data I got.

If you want more accurate alpha increase, you need to download X-FOIL and learn to use it (quite a tricky program for certain people).

I am afraid the other data is almost impossible to obtain.


What is the rejected takeoff procedure for a blown tire?

With smaller planes, if you blow a tire on takeoff and have enough runway left to abort, then you should do so. Staying on the ground can be a much better option than a go-around and landing with a flat. Chop that throttle and “fly” the aircraft until it comes to full stop. That said, there will be certain issues to consider based on which wheel is the problem.
On a tricycle gear plane, popping a main will generally cause the plane to pull in that direction, and standing on the brakes aggressively can make it worse. It may require more gentle braking to maintain directional control and avoid going off the side of the runway, and this will, of course, increase stopping distance. If it’s the nose wheel that goes, directional control may be erratic and it might help to hold aft yoke to take some weight off the front gear as you apply brakes. If the plane has differential braking, you might be able to steer the plane with more authority by using stiffer pressure on one brake-side or the other.
If you’re in a taildragger, you may be straight out of luck. Keep those brake inputs punchy, and hopefully you can avoid a ground loop.
Most modern airliners have multiple tires on each landing gear strut, and the tires are designed to handle the load if one of the tires is compromised.
If the pilots know a tire has failed during takeoff at low speed, they will abort the takeoff using a prescribed procedure. At high speed, they will typically take off, perform a go-around, and return to land for a safety inspection.


Once the doors have been opened, it's a pretty clear case: the crime happens on some sovereign soil, and that country is responsible. They are also most likely to get custody of the criminal, which as described in the other answer is a large part of who prosecutes.


Which instruments are assigned to Pilot Flying and Pilot Not Flying in the various flight stages?

The general duties of Pilot Flying (PF) and Pilot Monitoring (PM), also called Pilot Not Flying (PNF), are e.g. outlined in the following section of the Boeing 737 NG FCOMv1 (NP.11.2 Normal Procedures - Introduction, emphasis mine):

  Crew Duties

  Preflight and postflight crew duties are divided between the captain and first
  officer. Phase of flight duties are divided between the Pilot Flying (PF) and the
  Pilot Monitoring (PM.)

  Each crewmember is responsible for moving the controls and switches in their
  area of responsibility:

  the phase of flight areas of responsibility for both normal and non-normal
  procedures are shown in the Area of Responsibility illustrations in this
  section. Typical panel locations are shown
  the preflight and postflight areas of responsibility are defined by the
  "Preflight Procedure - Captain" and "Preflight Procedure - First Officer."

  The captain may direct actions outside of the crewmember’s area of responsibility.

  The general PF phase of flight responsibilities are:

  taxiing
  flight path and airspeed control
  airplane configuration
  navigation.

  The general PM phase of flight responsibilities are:

  checklist reading
  communications
  tasks asked for by the PF
  monitoring taxiing, flight path, airspeed, airplane configuration and
  navigation.

  PF and PM duties may change during a flight. For example, the captain could be
  the PF during taxi but be the PM during takeoff through landing.

So monitoring instruments is primarily the responsibility of the Pilot Monitoring (hence the name). But of course the pilot flying will also monitor instruments like e.g. airspeed indicator when hand flying.

The exact duties for each phase of flight are also outlined in the FCOM, but they are of course aircraft specific. The following is part of the 737 takeoff procedure:

If you are interested in more details, I suggest you try to find an FCOM (Flight Crew Operating Manual) for the aircraft you are interested in online. It should have detailed lists of responisibilities for each phase of flight.


What are these on the F/A-18F's wingtips?

He says:

  Looks like you've got some AIM 9Xs on the wings

Yes, the AIM 9 is a commonly carried short range air-to-air missile, with the 9X being a particular variant.


Are CVR and FDR reset after every flight?

No, they are not reset after each flight, but as commented, the FDR and CVR are on a loop, and just keep recording over the old data. For US registered aircraft, FAA Regulation "14 CFR 91.609" covers flight data recorders and cockpit voice recorders.

It states for flight data recorders:

  (c) 1. No person may operate a U.S. civil registered, multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration... of 10 or more that has been manufactured after October 11, 1991, unless it is equipped with one or more approved flight recorders that .... are capable of retaining no less than 8 hours of aircraft operation.

And:

  (c) 3. All airplanes and rotorcraft subject to (the above)... manufactured on or after April 7, 2010, must ... retain at least the last 25 hours of recorded information...

For cockpit voice recorders:

  (h) 2.  All airplanes required by this section to have a cockpit voice recorder and a flight data recorder, that are manufactured before April 7, 2010, must by April 7, 2012, have a cockpit voice recorder that also ... retains at least the last 2 hours of recorded information ...

There are not "thousands" of parameters.

The CVR must record the following 25.1457 (Cockpit voice recorders):

  (1) Voice communications transmitted from or received in the airplane by radio.
  (2) Voice communications of flight crewmembers on the flight deck.
  (3) Voice communications of flight crewmembers on the flight deck, using the airplane's interphone system.
  (4) Voice or audio signals identifying navigation or approach aids introduced into a headset or speaker.
  (5) Voice communications of flight crewmembers using the passenger loudspeaker system
  (6) all datalink communications

So, probably 6 or so channels.

For the FDR, wikipedia states "There are 88 parameters required as a minimum under current US federal regulations (only 29 were required until 2002), but some systems monitor many more variables."

So, if the flight lasts less than two hours, there will be at least the whole flight on the CVR. But if the flight is longer than two hours, you only have the last two hours.


What is the difference between mist and haze in terms of relative humidity?

The term haze does not say anything about the humidity of the air because it is by definition caused by dry particles, so not by water. If you have mist (or fog), then water droplets are suspended in the air, which usually comes with 100% humidity.
Here is a set of definitions by the UK's Met Office:

Fog
In our meteorological glossary fog is defined as 'obscurity in the surface layers of the atmosphere, which is caused by a suspension of water droplets'.
By international agreement (particularly for aviation purposes) fog is the name given to resulting visibility less than 1 km. However, in forecasts for the public, this generally refers to visibility less than 180 m.
Mist
Mist is defined as 'when there is such obscurity and the associated visibility is equal to or exceeds 1000 m.' Like fog, mist is still the result of the suspension of water droplets, but simply at a lower density.
Mist typically is quicker to dissipate and can rapidly disappear with even slight winds, it's also what you see when you can see your breath on a cold day.
Haze
A third term you might also hear mentioned is haze. This is a slightly different phenomenon which is a suspension of extremely small, dry particles in the air, not water droplets. These particles are invisible to the naked eye, but sufficient to give the air an opalescent appearance.

(metoffice.gov.uk)
Also see: What is the difference between mist and fog?


What are the advantages and disadvantages of a monoplane, biplane and triplane?

One way to look at the differences between them is by looking at the effects of having multiple wings.

Having multiple wings means that the same aircraft can produce more lift for the same wingspan, as they have a greater wing area.

As a result, the biplanes and triplanes have lesser wing loading, which results in shoter to/landing and lower stall speeds.

The shorter wingspan results in reduced roll inertia and roll damping, which results in better roll rates in the bi- and tri- planes. This improved maneuverability was the reason for the surge in triplane designes during WWI.
Due to interference effects, the bi- and tri- planes actually require higher wing area to produce the required lift. Also, the drag is also higher than the monoplane, which gets more pronounced as the speed increases.
The main reason for the use of bi- and tri- planes was that they provided the required strength for the type of airfoils used. As high strength materials became available, this mattered less and the aerodynamic disadvantage of the biplane (and triplane) designs came into fore.

The aerodynamic advantage of the monoplane along with improvements in materials used has made the monoplane the de-facto standard except for certain specialised applications (like low speed aerobatics)


Does deploying flap change the aspect ratio of the wing?

The aspect ratio of a wing is defined as:

$$ \text{AR} \equiv \frac{s^2}{A} , $$

where $s$ is the wingspan and $A$ is the total wing area.

Some types of flaps are not only increasing wing camber, but also the wing area:

  The Fowler, Fairey-Youngman and Gouge types of flap increase the wing area in addition to changing the camber.

(Wikipedia)

Since the wingspan is unchanged, this will decrease the aspect ratio. Other types of flaps, like a plain flap, are not changing the aspect ratio.

You can see the flap types that change the aspect ratio in the following image (modified from Wikimedia):


Before I start, remember that we're talking about statistics of location in the aircraft, within statistics of survival of an accident (95%), which is itself dependent on a statistic of particular type of accident (approx 85% have no fatalities at all), within something which is already a very unlikely event (an aviation accident).

So let us for a moment assume that you're in a semi-survivable accident, ie where there are a mixture of fatalities and survivors - this is already a very unlikely scenario... in the vast majority of accidents either everybody dies (rare), or nobody does (most common).

To give you the straight out answer to your question, in such an accident, the rear of the plane is safest - more passengers have survived plane crashes in those seats than any other. This is due to most accidents being nose-first, so if it's going to be partially survivable your ideal location is near the back: the front of the aircraft essentially acting like a crumple zone. Thus, if an accident is survivable, you are more likely to survive in the back of the aircraft.

Of course, every accident is different - if your aircraft runs off the runway and spins, the back can impact first. Similarly if your aircraft stalls and pitches up. Alternately you could slew sideways into another aircraft in a taxiway etc etc... but in most cases, the impact is more likely to be nose-first, thus the rear is the safest place.

Also statistically, being near to a door but not next to a window gives the "optimum" chance of survival - more people survive in such locations. This is due to ease of evacuation (being near the aisle and the exit), and without being whacked in the head by a crumpling fuselage.

So if you're going on purely "increasing your chances", a non-window seat near the rear door is the best possible place to be in an accident... other than on the ground, having missed your plane.

The thing to remember, though, is that (referring to modern aviation)

Accident rates work out as roughly 1-per-1 million flights
Around 85-87% of aviation accidents involve no fatalities (so fatal accidents are around 15-per-100 million flights)
Even if you're in a crash where someone dies, Aviation accidents with fatalities have a fatality rate of somewhere between 5% and 25% (which is to say, even if we only look at accidents where one or more people do die, 75-95% of people in those accidents survive).

So that gives you a 1/4th to 1/20th of a chance of a 3/20th of a chance of a 1 in a million chance of becoming a statistic in my next post on this subject. So that would take you somewhere between 20 and 100 million flights before you die.

You have a 1-in-100-million chance of being in a fatal accident, and even then you a 75-95% chance of surviving it anyway.

So in short, if it's going to get you it will, if it's not it won't. By the time you've survived enough accidents for it to be anything more then sheer atrocious luck that you die at all, you'd already have developed a healthy fear of flying and have gathered enough air miles to take a taxi....


In RTCA DO-260B, what were the reasons GVA was added ? Is it a replacement for something?

The philosophy behind the the quality indicators is that the ADS-B transmitting system sends the data it has, as well as information about the quality of that data. The receiving systems can then decide, based on the quality indicators, whether the data is good enough for their intended application.

The reason that more find grained quality indicators were developed in subsequent ADS-B versions had mainly to do with two factors:

new insights in the type of ADS-B applications were being developed
better performance and quality information delivered by GPS receivers

Note: at the time of DO-260 development, GPS had Selective Availability (SA) still turned on. This deliberately degraded the accuracy of the civilian GPS signal. This meant that both in the horizontal and the vertical plane the accuracy was very poor compared to current levels.

The big difference between version 0 (DO-260) and version 1 (DO-260A) was the split between accuracy (95% error under nominal conditions) and integrity (protection against non-nominal performance).

DO-260B then split the quality indicators between the horizontal and vertical component (hence the introduction of Geometric Vertical Accuracy (GVA)), added a finer grained resolution to horizontal position integrity and distinguished between between measurement integrity and avionics faults (the concept of system design assurance (SDA)).

GVA is intended for ADS-B applications that depend on the accuracy of the geometric vertical position. One such application is RVSM compliance monitoring using ADS-B. They compare the reported flight level to the geometric height from ADS-B, using an meteo model to compensate for the non-standard pressure distribution in the atmosphere. GVA helps to assess whether a potential mismatch between geometric and pressure altitude is caused by the baro altitude system, the meteo model or the GPS receiver.

The representation in your question shows a cylinder with hard boundaries to represent HFOM and VFOM. Whilst the numbers indeed define clear boundaries, it is important to understand that these are the statistical 95% level of the position errors, as estimated by the GPS receiver. This means that

position errors may occur that are outside of the cylinder (5% of the cases, if the estimate is correct)
the estimate may be (and usually is) wrong. Receivers tend to be conservative in estimating the position error magnitude.

Disclosure: I was involved in the international combined Working Group 51 / Special Committee 186 that wrote the ADS-B standards, however I joined at the time when the work on DO-260B was almost finished. At this moment I not involved anymore in ADS-B standardisation and implementation.


Can throttle control be considered as a primary flight control?

14 CFR 23.673 - Primary flight controls defines primary flight controls as:

  Primary flight controls are those used by the pilot for the immediate control of pitch, roll, and yaw.

While a throttle could be used to effect changes in aircraft attitude (depending on configuration and other factors), the effect could hardly be called immediate/direct. So, throttle could hardly be called a primary flight control; and as @Ron pointed out, there are gliders.

Note: I'm aware that aircraft have been controlled solely using throttle. But it is an exception rather than the norm.


What aircraft looks like a cross between a Cessna and a glider?

As you describe it, a motorglider would fit the bill. There are several types around, the most popular being the Grob 109 and the Hoffman Dimona.

Grob G-109 (picture source)

[Hoffmann H36 Dimona (picture source)

Other possibilities include the Valentin Taifun (the only one with a tricycle landing gear) or the Scheibe SF 36. All of those are of composite construction, but there are also earlier types with wooden wings and a steel tube fuselage, like the Scheibe SF 25 "Falke".

While a Cessna is a high wing plane, all motor gliders are low wing (well, except for this one here). Would a cross between a Piper and a glider describe what you saw even better?


Would FAR 91.227, or any other regulation, forbid use of ADS-B-out in an unregistered ultralight?

It looks like using ADS-B without any identifier would be contrary to 47 CFR 87.107(a), which requires all aircraft transmitters (with some exceptions, which don't include ADS-B) to include an identification, usually the registration.

§87.107   Station identification.
(a) Aircraft station. Identify by one of the following means:
(1) Aircraft radio station call sign.
(2) The type of aircraft followed by the characters of the
registration marking (“N” number) of the aircraft, omitting the prefix
letter “N.”
[...]
(3) The FAA assigned radiotelephony designator of the aircraft
operating organization followed by the flight identification number.
(4) An aircraft identification approved by the FAA for use by aircraft
stations participating in an organized flying activity of short
duration.

14 CFR 91.227 does allow for a "TSO-C154c self-assigned temporary 24-bit address" rather than the actual N-number but that part doesn't apply to ultralights anyway. It appears to be a reference to 87.107(a)(4) above.
Transponders are exempt from the requirement to broadcast identification, per 47 CFR 87.107(d).
Based on all that, and unless there's an FAA regulation about it (I couldn't find one), I'd say that a transponder is allowed on an ultralight (if you can operate it within the weight limit) but ADS-B is not.


What does it cost to get an ATP certificate from scratch?

The cost from 0 to ATP can be highly variable.  An easier number to quantify is 0 - Commercial/CFI.

Even the cost of 0 - Comm/CFI can vary, but there are a few accelerated programs that offer this.  One service (I'm not advertising, so I'm not naming them) offers a program that lasts 150 days and costs $65,000* + checkride expenses.  You start with nothing and end up with single/multi commercial, an instrument rating and your CFI/MEI/II along with 100 hours multi-engine time.  This particular program (and others like it probably) hires their instructors from within, so there is a possibility for multi-instruction -- but you won't be making much money for it.

The cost of commercial to ATP is harder to nail down because of the possibilities that open up post-commercial.

On the high end, you could just rent or buy time to ATP mins, but that could cost a fortune.
On the low end you could work to ATP mins and make some money.

A good way to make money with a fresh commercial/cfi ticket is to instruct. There are also jobs like banner towing or pipeline/powerline patrol you could do, but you probably still need to build time beyond commercial mins to be competitive for those jobs.  You also mention cropdusting, but keep in mind many of those ops are turbine powered ag-cats and you won't be competitive there with a fresh commercial ticket.

*You can do it cheaper but I'm giving these numbers because a fast but expensive program may appeal to a career changer.


Why are hexa airfoils used on rockets despite having more drag that diamond airfoils?

A rocket stabilized by fins alone needs a certain amount of lift at the rear to ensure that if it is disturbed from a nose-first attitude, it returns and damps out the resulting oscillation.  Adding mass at the rear of the rocket increases the amount of lift (hence fin area) required, as well as increasing the inertia factor that counters damping.

If a diamond fine provides little if any more lift, but weighs more (as it most likely does) than a flat-sided hexagonal section, it's probably a net negative in this compromise.  The added mass makes it harder to damp oscillation, and requires more area, which adds more mass.  Drag, on the other hand, helps a little (since it's near the rear of the vehicle, it tends to pull the tail behind the nose).

End result, for a rocket, it's likely that both on a lift/mass basis, and in consideration of drag, the flat-faced hexagonal fin shape is superior for overall performance.


How should we think of 'layers' of air flow?

To understand what a boundary layer is think about air moving above a flat plate. Before the plate and very far from it the air has everywhere the same speed and direction. However, directly on the plate its speed is zero: molecules directly on the plate do not move at all.

Between the plate surface where the air isn't moving and some distance from it where the air has a constant speed, there is a zone where the air changes its speed a lot. We call this zone boundary layer.

There isn't really any clear and distinct boundary delimiting it. That's why we have many definitions for its thickness. The dashed line in the image below is probably the 99% boundary layer thickness.

Generally we give a name to a layer when the physical effects and properties of the fluid in this concrete zone can be differentiated from the rest of the flow. Most of them are on fluid boundaries (body surfaces, places were fluids get gaseous,...) but you can have them inside a fluid too (shock waves).

For example, instead of looking at the velocity you could look at the temperature of a fluid flowing around a very hot body and define a temperature boundary layer.

Some known layers are:

Laminar boundary layer
Turbulent boundary layer
Blasius boundary layer
Stokes boundary layer
Ekman layer
Shock layer
Knudsen layer
Merged layer


When approaching a stall, is the first priority to apply power or lower nose?

The instinct drilled into a pilot's head from the beginning as the primary response is "lower the nose" to lower AOA.  If you learn in a glider, that's the only option, so it's easy to drill the instinct into peoples' heads (one reason that glider training before power is so good for pilot skills later).  In a power plane, it's lower the nose and add as much power as you need, but lower the nose must be the first instinctive action.  How much to lower the nose depends...

In a non FBW jet (FBW is another story, the computers taking care of things on your behalf whether you want them to or not), the stall training you get for low altitude stalls (you don't get to an actual stall - you start from stick shaker onset) is lower the nose but not too much, add thrust to maximum, and regulate the pitch attitude to stay just above stick shaker onset (just above the speed tape's "barber pole", the red broken band that indicates the stall region) and if flaps are at landing setting, call for retraction to go-around flap once you have stopped descending and are accelerating with decent speed margin above shaker.

The objective is to minimize the altitude loss as you recover airspeed.  At shaker onset you still have some margin above the actual stall and if you're close to the ground you don't want to dive, so you just tease the pitch to hold it on the edge of shaker.  You will generally use this procedure for any stick shaker event in denser air, below, say, 10000 or 15000 ft.  As a general rule, you do not make configuration changes with gear and flaps until you have got yourself in a good situation energy wise (not sinking, accelerating - although there may be variations from a/c type to type) because retracting flaps can increase your sink rate and the standard procedure with gear is not to retract until there is a positive climb rate.

At high altitudes, especially above 30000 ft, the stick shaker recovery method is much more aggressive and you are trained to actually push over enough to lose several thousand feet and not be concerned with altitude loss. In the thin air the practice of teasing the pitch to stay just above shaker doesn't work so well, because the air is thin but the inertial mass of the machine is unchanged and that can get you into trouble if you fly it the way you do down low.  You can find yourself back into the shaker/pusher/stall break region if you work the pitch to manage AOA on the edge of shaker the way you would close to the ground.

One of the events that lead to special high altitude stall recovery training during recurrent training was this famous (within the business) Pinnacle Airlines incident with a CRJ200 (quite a harrowing read; I don't think it was mentioned in the report, but the post crash fire was caused when they slid into a back yard garage with a meth lab in it).


What type of microcontrollers are used in large scale UAVs?

Airbus used standard Intel 80186 and Motorola 68010 CPUs with 2.5MiB of memory in the FBW system for A320. Exactly the same chips that were used for computers at the time (around 1985) so they were not expensive and were already tested. Over time they upgraded to newer version of those CPUs. Each computer is composed from two boards with different CPUs, one produces the control output and the other verifies it and shuts the unit down if they disagree. The boards run different standard embedded operating systems and the software was written by two independent teams to minimize risk of the same failure mode in both boards.

Each board only does a little bit of work and the important units have backups. There are 4 units processing the sidestick input, 3 controlling elevator and ailerons, 3 controlling spoilers and elevator trim, IIRC 2 for yaw damper (FAC), 2 for each engine digital control, 1 for each display etc.

The requirements didn't really increase much since then. It is still desired that the tasks are split across many independent boards to minimize effects of one of them failing. So a CPU with few MHz clock rate and few MB of memory would still be able to do the job. But such slow chips are not manufactured anymore, so they are probably using whatever was most common chips few years ago.


How to refute this geometrical method to find MH370?

The picture says that "If [the above facts are] true, the plane can only be at one of two green dot locations." However, it doesn't give any reasoning or evidence to support this claim. So, there's no reason to think that the claim is correct.

You asked if itʼs possible to prove that the method is wrong. Itʼs not possible to prove that the method is wrong, because there is no method here. The picture is merely a collection of facts and unsupported claims.

However, the picture does seem to rely on a particular premise. Specifically, the picture seems to be based on the premise that the departure airport, the Inmarsat satellite, and the crash site must form a right triangle. That premise is false; the locations of airplane crashes are actually not affected by the positions of overhead satellites (or vice versa).


Do tanker aircraft distribute their own fuel?

Both the KC-135 and KC-10 can burn the fuel it carries on board for refueling (the notable exception was the KC-135Q, which carried separate tanks of JP-7 for the SR-71 Blackbird).

Both indeed do have significant fuselage tanks - the KC-10 is notable for being 'dual-mission' capable, meaning it can carry both fuel and cargo, and the KC-10 is also air-refuelable (so a KC-135 can offload extra gas into a KC-10 when their crew rest is up, allowing the KC-10 to stay on station and refuel other planes longer). The maximum fuel load of a KC-10 is 356,000 pounds. This is over 7 full loads of gas for a B-52 (B-52G and H could carry 308,000lbs of fuel, so 365,000 capacity of KC-10 would potentially fully fuel a B-52 one time, with enough fuel left to get the KC-10 home. Of course the B-52 would never be completely empty in the air so the KC-10 would not need to offload the full 308,000lbs), or 30 full loads for an F-16 with external tanks, and the maximum fuel load of a KC-135 is 200,000 pounds, or over 4 full loads of gas for a B-52.

As for how much of the fuselage is taken up by fuel tanks, you can look at cutaways of the KC-135 and KC-10 (unfortunately the captions for the KC-10 are in a foreign language, as I could not find a high-enough resolution one in English). In both cases, the fuel tanks are in the lower half of the fuselage - the reason the KC-10 has a cargo mission as well is because it is a larger aircraft and has a much higher gross weight. The KC-135's cargo space is much smaller, and as such is not used for transporting large items. This technical document for the KC-10 also gives volume of each tank (called Fuel Cells):

Forward Fuselage - 8,250 gallons in 3 sections, 6' deep
Aft Fuselage - 9,870 gallons in 4 sections, 6' deep

You are correct that it is a struggle getting them airborne when fully loaded - several of the KC-135 pilots I have talked to have taken until the very end of 10,000 foot plus runways to get airborne, and one of the KC-10 pilots I know said they would occasionally take off with less than a full load then take on fuel from a KC-135 to make it easier.

Page 3-45 of this technical manual has a chart for calculating minimum runway for a particular speed - for example, a sea level takeoff at 30 degrees (Celsius) at Max takeoff weight would require about a 13,500 foot runway.


What is maximum displacement for aircraft engine?

There is no standard.  Even for a single plane and a single engine, there will be literally hundreds of different possible displacements depending on the condition. The engine manufacturer will split these into several categories.

First would be static versus dynamic loads. Static loads are the loads (or displacements) caused by gravity, thrust load, maneuvers or wind.  Dynamic loads are transient events caused by rotor unbalance, bird impacts, blade loss, etc.

The second category is the severity of the load.  There are several levels here.  First is a fatigue load.  The engine will experience this level of load (or displacement) on virtually every flight.  Therefore, all parts must be able to withstand this load and not have a fatigue failure.  The second level is a "limit" load.  This would be experienced by the engine say once every 4000 or 5000 flights.  E.g. a very rapid maneuver or a particularly hard landing. For this level, fatigue is not a concern, because the engine won't experience it very often.  Just have to make sure no parts yield.  Final level is "ultimate" load.  This is the highest load that will ever be experienced by any engine in the lifetime of the entire fleet (e.g. a fan blade out condition).  Yielding may be allowed here, as long as nothing breaks.

Depending on what you are looking for, the answers could vary between 0.001 inch and several inches. I'm not sure that you will be able to find exact values, as the airframer and engine manufacturers will regard this as proprietary information.


Where can I find the turn radius on the ground for the Piper Seminole?

33.0 ft From pivot point to wingtip, it is in the POH page 1-2


When does a passenger plane leave the cruising phase?

The distinction when you cross from one phase to another is somewhat arbitrary.  However, you can slice this multiple ways depending on your goal:  The approach phase could be considered to start at the first point of a published STAR, (Standard Arrival) the initial approach fix of a published instrument approach procedure, when the pilot descends below the class A airspace, i.e. <18,000' MSL, or the first ATC assigned vector off the filed route.  (Or some radius as you suggested...)

If you really want to dig into this my recommendation is to go to a local pilot shop and purchase a set of Approach Plates/STARS and a high altitude IFR chart for the area you are interested in.  You will likely need help interpreting them if you are unfamiliar with these publications.

If you then have a specific question on your airport of interest there are plenty of experienced people here who are willing to help, but a full education on high altitude IFR enroute and terminal arrival procedures is beyond the scope of this forum.

In lieu of that, if you don't want to take that kind of time to learn something foreign but have a specific airport you are interested in analyzing, please let me know.  I have a full set of United States procedures loaded in my iPad EFB and would be happy to post a screenshot with an interpretive description of where I might consider the approach phase to begin for a specific airfield/runway combination.

There are many many different arrival procedures nation wide, into airports of varying levels of traffic congestion.  Without a better understanding of your actual goal the question as stated is almost to broad to answer, especially for someone who is admittedly "not too deep into aviation".  Good luck with your project.


How does an organization decide to evacuate planes (e.g. in a hurricane)?

This can be dependent on a few things. For larger organizations like airlines resources may not be an issue (they generally have pilots needed to move the planes). For smaller organizations it may come down to a few factors. First off do you have the people needed to move the planes (and how will you get them back home). Do you have anywhere to put the planes provided you do move them, you will need tie downs else where not to mention its going to cost you to store them elsewhere. On that note, can you foot the bill for such a move (not only the planes but the fuel, pilot housing or return trip etc...). If you want to see some of the damage and thought process for smaller planes check out this thread on the recent hurricane.

Often airlines will cancel inbound flights in advance of a hurricane so there will be fewer airplanes turning around at a potentially effected airport anyway. For the planes parked there (for what ever reason) they may they may simply move planes out of the airport,

  Airlines are moving some planes to hangars while flying other planes
  out of the area entirely until the storm is over.

FWIW commercial airframes are fairly transient by nature anyway, so as long as its not the location of a hub city the planes are in and out anyway.

While they have access to way more resources it looks like the Airforce moves planes appropriately.

As to what conditions lead to this decision its hard to say and ultimately up to the operator in question. Generally I would think they would err on the side of caution. But from a purely economical standpoint (potential damage aside) its may be more cost effective to move the planes and use them elsewhere than have them sit on the ground anyway (since the airports will be closed).


How can I pay for flight school in the UK?

There are specialist firms providing loans for aviation training, however it is unlikely that you will be able to get a loan of the amount you would need for an integrated course without some form of security.

The security usually takes one of two forms.  The first is a charge on a property (belonging to you or your parents).  The other is an airline agreeing to act as a guarantor/sponsor, however this doesn't appear to apply in this case as this particular scheme states it is fully self-funded.

If you cannot raise the financing for this particular scheme, you can apply to other schemes that provide some sponsorship or underwrite the loan as they become available.  Naturally there tends to be more competition for these schemes.  Some are targeted towards under-represented potential pilots, such as the Amy Johnson initiative by Easyjet, where they will guarantee/underwrite the loan for a limited number of female trainees.

It is also possible to undertake modular training, where the cost can be closer to £50,000.  There are a number of organisations that can provide funding towards some of the costs, particularly for young pilots.  These include The Honourable Company of Air Pilots, The Air League and The Royal Aeroclub Trust.

Before spending significant sums on training, it is advisable to get a class one medical, to avoid possible disappointment after spending significant sums of money that cannot be recovered.


Why do we use dimensionless expressions in flight mechanics and aerodynamics?

Here is a dimensionful equation: $$L = \frac{\rho}{2}\cdot v^2\cdot \frac{2\cdot\pi\cdot b^2}{1+\sqrt{1+\left(\frac{b^2}{2\cdot S}\right)^2}}\cdot\alpha$$
Note that all ingredients are physical, measurable values. Now here is the same thing again, now in dimensionless form:
$$c_L = \frac{2\cdot\pi\cdot AR}{1+\sqrt{1+\frac{AR^2}{4}}}\cdot\alpha$$
The dimensionless version is independent of speed $v$ and air density $\rho$ and also needs only the aspect ratio $AR$ and the angle of attack $\alpha$ to give a result, while the dimensionful version needs wingspan $b$, wing area $S$ and angle of attack. However, while the dimensionful version yields an actual force, the dimensionless version yields a coefficient which needs to be multiplied with speed, density and wing area again in order to result in a force.

By working in the dimensionless domain, engineers can work on a generalized form of the problem. This was especially helpful in the time before computers: The complex calculation to arrive at a coefficient was needed only once, and computing the dimensionful value from there was trivial.

Also, when comparing between different airplanes, or between wind tunnel models and the real thing, with dimensionless coefficients the numbers will be very similar, which allows much better to error-check results or to make first assumptions on a new design.

However, there are two drawbacks:

You need to know the reference values! It is easy to screw up, e.g. when combining values from the wing and the tail which are referenced to their individual area. While lift can be added right away, the lift coefficients must first be converted to a common reference value.
Sometimes thinking in coefficients can be misleading: Just consider induced drag. If written in dimensionless coefficients like this
$$c_{Di} = \frac{c_L^2}{\pi\cdot AR}$$
you can be forgiven for thinking that induced drag goes down with increasing aspect ratio. But this is wrong! Now the same again with dimensions:
$$D_i = \frac{L^2}{\frac{\rho}{2}\cdot v^2\cdot\pi\cdot b^2}$$
This shows that induced drag at the same speed is inversely related to span loading, the amount of lift created per unit of wing span.


How can I identify a low flying plane at night over Bangalore?

On Nov 12 at about 1845 UTC, which would be about 1215 local on Nov. 13, a Vistara A320, reg. VT-TTM, took off from BLR and did several touch-and-go’s at VOBG then returned to BLR.

On Nov. 10, around the same time, another Vistara A320, reg. VT-HYD, did the same thing. Taking off from BLR, doing touch-and-go’s at VOBG before returning to BLR.

According to this article @pondlife found, VOBG airport is open for pilot training.


What is a metering frequency and why would an airport have it?

Use of a metering controller and frequency at an airport is one strategy used to prevent congestion on ramps and taxiways. When ready for push back from the gate, pilots call metering. The metering controller will typically either give them permission to push with a ground frequency to call when ready for taxi, or they will tell them to monitor a particular ground frequency for permission to push. They may even tell the pilots to stay on the gate and call back after a specified delay. The use of metering allows the airport controllers to manage ramp and taxi space by sequencing aircraft push and taxi.

Metering control can also help manage potential congestion due to ground delays for situations such as poor weather, runway closures, deicing, flow times into particular destination airports or any other situation that increases taxi time or slows down departures.

Some airports uses different strategies such as discrete ramp areas and frequencies to coordinate push back and taxi flow or internal coordination between controllers.


Are crosswind landings performed using autoland or under manual control?

The B777 is limited to a max crosswind component of 25 knots when using Autoland so it is most likely that it was a manual landing in the photo above.

The B777 has a "max demonstrated crosswind component" of 38 knots. Some companies will round this up to 40 knots for a company limit.

The "max demonstrated crosswind component" is not a limit. It just means the aircraft can land with that wind speed, in a crabbed configuration, without damage to the aircraft or landing gear.

Crosswind landings for certification are done in a crabbed configuration. Boeing has demonstrated landings for the B777 with a 38 knot crosswind, so that becomes the Demonstrated Crosswind Component.

If Boeing had tested with winds greater than 38 knots, AND it resulted in damage,  then the B777 would have a 38 knot Crosswind LIMIT.

Of course there was no damage at 38 knots and there is nothing preventing pilots from landing with crosswind components greater than 38 knots.

Since Boeing has not tested or demonstrated crabbed landings ABOVE 38 knots, we don’t know what the actual limit is when damage may occur due to side loading.

So when landing with a crosswind greater than 38 knots, it would be prudent to use a technique that would involve a slip and removal of any crab at touchdown so that excessive side loading is avoided.


Do any airlines publish their policy on CRM / Do Not Pair?

I worked in the industry for 16 years with multiple airlines.

In two of these we had 'do not pair'. Most airlines use computer systems to do their crew planning. In the systems I have used, you can enter against each crew member, others they should not fly with.

The decision as to the use of this laid with Fleet management or Cabin Crew management and was only used in extremist.

In both airlines however, this was not a documented procedure.
Hope this helps.


What do the Airway Letters and the following numbers mean?

RCTP - Taipei, Taiwan Airport
AJENT SID - Standard Instrument Departure leading to the Navigation fix named AJENT
MKG - fly to the MAGONG VOR Navigation beacon
A1 - follow airway A1
ANPOG - until the fix named ANPOG
R200 - follow airway R200
GLN - until the GUANLAN VOR Naviation beacon
W22 - follow airway W22
IDUMA - until the fix named IDUMA
IDUMA STAR - follow the IDUMA Standard Arrival Route
ZGGG - land at Guangzhou Baiyun International Airport

A1, R200 and W22 are airways. They are defined by lists of waypoints. The
waypoints between the first and last used on the airway are omitted and replaced by the airway name, otherwise the flightplan would be extremely long.

As an analogy one could describe a route on the road. For example Frankfurt - Amsterdam could be described as:

FRA - 44 - FRA KRZ - A3 - BORDER - A12 - KNP OUDENRIJN - A2 - KNP AMSTEL- S110 - AMS

Without mentioning all the highway intersections and exits, the route is described in sufficient detail to drive it. The numbers of the highways appear to be somewhat random, but I am sure somebody has thought about how to best assign the numbers.


What are these three indentations on the SBD's wing?

According to "The Dauntless Dive Bomber of World War Two" by Barrett Tillman, they are "letter-box" anti-stall leading edge wing slots added to improve the planes stability when approaching the 78knot stall speed during landings (and take offs, actually.)

The initial versions tended to not be able to build up enough speed during the (catapult-less) take offs from the carriers of WW2, and would simply drop off the front edge of a carrier. Adding the three slots basically fixed (or lowered) the speed of stall.


How high can I fly a model aircraft under 14 CFR 101 rules?

There's no specific altitude restriction for model aircraft anywhere in part 101 (that I can see). Even within 5 miles of an airport you only have to inform the tower, per 101.41(e):

  When flown within 5 miles of an airport, the operator of the aircraft
  provides the airport operator and the airport air traffic control
  tower (when an air traffic facility is located at the airport) with
  prior notice of the operation.

However, practically speaking there is an indirect altitude restriction in 101.1:

  For purposes of this part, a model aircraft is an unmanned aircraft
  that is:

  [...]

  (ii) Flown within visual line of sight of the person operating the
  aircraft

In other words, you have to be able to see the model aircraft and that limits the altitude and distance you can fly it at. It's also worth noting that 101.43 is very broadly written:

  §101.43   Endangering the safety of the National Airspace System.

  No person may operate model aircraft so as to endanger the safety of
  the national airspace system.

Arguably, that also implies you shouldn't fly any higher than you really need to.


Why is Germany not able to read data from the Boeing 737 MAX black boxes?

This news article (in German) includes a mention that the black box was using newer software than the BFU has the capability to read out:

  Das Gerät habe eine neue Software, die an der BFU nicht ausgelesen
  werden könne.


How much does a refueling stop for an Avro RJ85 cost in Bolivia/Colombia?

It's hard to give an exact figure as their are a number of considerations. If we assume that the re-fueling stop is at El Dorado, and the airplane was a BA146 (RJ85 is a variant) then approximate costs might be (in USD):

Landing fee: at about \$6 per thousand kg, and 42,000 kg would be about \$250. Add 5% for a night landing and another 5% for a night departure for about \$280
Handling charges: this is hard to say, estimate $100
Jet Fuel: the BA146 can carry up to 3000 US gallons, assume 1500 as it's a short hop, at \$3.16/gallon that's \$4740

So it would seem that about \$5000 is a good working figure. Keep in mind they wouldn't have used all that fuel to get to their destination, there would have been plenty left and they wouldn't have had to fill up completely on the way back, but the most expensive part of a flight is the climb to cruising altitude, so 2 climbs are more expensive than one. There might also be ATC fees for filing another flight plan, and taxes not listed, I would imagine that wouldn't change the costs that much - the fuel is still the big chunk of the cost.


How can a private pilot prepare for a long cross country flight in an unfamiliar area?

I'm in a similar boat to you and I just did my first XC from KDYL to KDDH a few months ago. Which was the first time I had been to an airport I did not go to during training. It was a lot of fun but here are a few things to consider,

Get the G430 simulator as Ron mentions. You should always familiarize yourself with all systems in an aircraft before flying it. While you don't need to know the IFR capabilities of the 430 you should understand its VFR functions well. This video covers it well.

If you don't already use it, get ForeFlight or some similar app for your phone/tablet. This will provide you all the charts and calculations you need. Most pilots are using something like this these days but often times it's not allowed during training and many new pilots don't yet have it.

Use flight following if you can. If your instructor never went over that ask a local CFI about what it is, how to get it, and why you should basically always use it when you can.

Since it's a new airport for you, watch videos of others landing there to get an idea of what the terrain and airfield looks like.

If you have, or can get access to a simulator, fly the flight in the simulator using the intended aircraft so you have an idea of time, and basic terrain features en route.

Perhaps most importantly, this is no time to push your limits both physically and mechanically. Don't depart with "just enough fuel + minimums". Don't make this a "just above VFR minimum weather flight". You will most likely be flying a contiguous leg longer than you have flown yet, understand the human limitations in a situation like this. Understand that the plane has far more endurance than your body and understand when to say "I won't be making the flight today".

Most importantly, Have FUN!