What's the difference between Rotation speed vs takeoff speed? My aviation teacher told us to memorize some speed values among other things before our flight training:

$V_R$ = 40 kt
$V_S$ = 39 kt

According to wikipedia:

Vr:
The speed at which the pilot begins to apply control inputs to cause
the aircraft nose to pitch up, after which it will leave the ground.

But I'm somehow confused with the values, since the takeoff speed (according to what I was taught) should be 10-25% greater than Vs, in this case around 43 and 49 kt.
If Vr is the definition mentioned above, which should be takeoff speed? does it have a definition within V speeds? Isn't takeoff speed the speed at which the aircraft leaves the ground?
Thank you

Based on the speeds that you are talking about, it isn't a turbojet definition that you are looking for.  The definition for $V_R$ that you gave is for turbojets.

In small GA airplanes, I teach my students to rotate around $1.3V_{S0}$ which really means to slowly bring the nose up to the takeoff pitch attitude.  Under no circumstances do I want them to yank the airplane off the ground.  If done correctly, the airplane will naturally lift off when it is ready to.


When does root bending moment start to become important? I guess for small aircrafts ,hangliders etc root bending moment is not important at all,because it is relativly easy to achieve sufficient strength ,so their ideal solution will be eliptic..?
Does that mean,small aircrafts dont have any benefits of using bell distribution?
I am also interested what is  root bending moment/wing weight ratio between small aircrafts and big ones,airliners etc?

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


Do turbine engines on multi-engine aircraft rotate in opposite directions to offset torque? I'm not an aviator, I guess I'd call myself an enthusiast. I'm also a physics nut. I've always wondered about this but I equally worried my question posed to a commercial airline crew would land me in the Homeland Security Suites.

On helicopters, torque along the vertical axis is countered by a smaller tail rotor (or a twin main rotor rotating in the opposite direction).

My question is whether the turbines/fans of multi-engine jet aircraft rotate in the same direction. I.e., do both the port engine and the starboard engine rotate uniformly clockwise or counterclockwise?

It seems like if that were the case then maintenance might be easier but it would create some instability along the longitudinal axis of the airframe due to torque and moment arms.

Follow up: I guess, then, that single engine propeller aircraft utilize trim presets to compensate for the longitudinal torque generated by their propeller–correct?

Torque is less of a problem due to the effective roll damping of a wing, but gyro effects and prop wash are important. Gyro effects first became an issue with rotary engines in WW I. A rotary engine has its crankshaft fixed to the airplane, and both the cylinder block and the propeller rotate. This gives better cooling at low speed and produces a flywheel effect, so the engine runs more smoothly. But when you yaw, the gyro effect pitches the aircraft up or down, so any precise maneuvering becomes very hard.

With the increasing engine power in 1916 and 1917, this effect became so severe that geared engines were developed where the cylinders rotate in one direction and the propeller in the opposite direction. As a consequence, the propeller had only half the RPM in air as it had with the cylinder block. This gave great propeller efficiency, but also big propeller diameters, so airplanes with those engines needed a high landing gear. Below is a picture of a Roland D XVI with a Siemens & Halske III counter-rotating rotary engine from 1918 (source). This was an excellent fighter aircraft for its time with almost no gyro coupling.

Today, high power propeller aircraft tend to use identical engines but left- and right-handed gearboxes so the propellers run in both directions. This is less due to gyro effects and mostly to produce benign stall characteristics. The prop wash of a propeller increases the local angle of attack on the wing on one side and decreases it on the other side, so the wing will stall first on the side with bigger angle of attack. If this side is always to the right of the propellers, the aircraft will roll right in a stall. In the WW II period, a number of multi-engined aircraft used left-hand and right-hand turning engines in order to have the prop wash cancel out.

With jets, the rotating inertias are much smaller because the diameters are smaller. But there is one exception: The Bristol-Siddeley Pegasus engine of the Kestrel, Harrier and AV-8B jump jets needs to have the low pressure spool run in opposite direction of the high pressure spool to balance its gyro effects. If that would not be the case, a yawing motion would produce a pitching motion, and vice versa. When you sit on a jet, the thrust of which is equivalent to your weight, tilting this jet fore or aft only slightly will produce a quick shift of your location, so any maneuvering in hover will become extremely hard.

USMC AV-8B Harrier in hover (picture source)


What would the point to point range of the current Virgin Galactic Spaceship 2 launch system be? Many people have suggested that the next step for Virgin Galactic after single point "space tourism" flights begin would be passenger suborbital flights, providing travel times many times faster than even the Concorde.

If they flew up to perhaps 30 miles, instead around 60 miles, much more of the rocket energy could be devoted to moving Spaceship 2 downrange.

If the Knight carrier aircraft flew straight towards the destination, how many miles would it travel before it reached the 50,000 foot drop altitude?

Then, on a flatter trajectory, how much further would Spaceship 2 go? How far could it glide after re-entry?

Not to rush things too much, but a "pilot scale" point to point flight from the Spaceport in New Mexico to California might be a good starting point.  Would it be possible?

This is going to involve a lot of speculation!

I'd guess that White Knight Two will have to fly at approximately airliner speeds once it reaches altitude, otherwise it will stall in the thin air. Total flight time of the combination is expected to be 2.5 hours, which gives a range of about 2500km (if we optimistically assume it does Mach 0.8 the whole time, the initial climb is likely to be much slower)

Spaceship Two is projected to have 6 minutes of freefall and a top speed of 4000 km/h, so that's another 400km. If they thrust at an angle rather than straight up the top speed may be higher but the flight time will be lower, so I think it's a reasonable estimate.

If it starts gliding from 50,000ft (15km) and has a glide ratio of 5:1, it can cover another 75km (so picking a glide ratio out of the air has very little effect on the total)

I doubt anyone will pay $250,000 to fly 3000km at basically the same speed as an airliner.


Why is using opposite rudder and aileron necessary in left turn for coordination? This question goes against everything I've read or heard with the exception of a suggestion from my CFI in my last flight lesson, so I was hoping to get some clarification:

During a left turn into our crosswind leg my instructor informed me that I shouldn't be using so much left rudder, and in fact, might even need to use some right rudder to stay coordinated due to the left turning tendencies of the plane. I could somewhat understand given that I definitely noticed a tendency for the plane to roll more when turning left than right, but still I would think the antidote for that would just be less left rudder, not opposite rudder.

This does not make sense to me. In what situations would I need to do this? I was still able to perform my turns just fine with slight right rudder on my left turns, but I would like to understand this more.

FYI - I'm flying a Piper Cherokee 140 (PA-28-140)

First and foremost you should always be looking at the turn coordinator to see what is going on and applying rudder as necessary.

In your specific case (if we want to discuss the physics), basically what your instructor is saying is that you are using the ailerons to bank (turn) the plane and the rudder to counteract the propeller's yawing moment. The rudder is simply counteracting the Adverse Yaw: the inputs will change depending on how steeply you are banking. If opposite rudder is called for on your ball, then step on it.

Perhaps more importantly, what your instructor is actually stressing is during your crosswind, base and final turns you should really be paying attention to staying coordinated. A great deal of Stall -> Spin -> Crashes happen in the pattern as planes slow down and dirty up, thus it's extremely important in the pattern to watch your speed and your turn coordination.


Are the Boeing MCAS and Airbus Alpha Protection systems the same? I have a little question concerning MCAS from Boeing and Alpha Protection from Airbus.

I think these two systems are the same, if I'm wrong please tell me.

If the two 737 MAX crashed because of the pilots not knowing how to behave when the MCAS behaves wrong, isn't it possible that the same could happen to A321 pilots?

I remember a Lufthansa flight (Airbus) in which the sensors froze and the pilots also didn't know how to behave. They turned the sensor off after talking with the technicians.

No, the two systems are completely different.

The MCAS of the new Boeing 737 MAX was introduced to help the pilots lower the nose in high angle of attack situations by applying down stabilator trim. This was necessary because the engines are mounted further forwards compared to the previous NG models.

Note: We do not know whether or not MCAS caused the recent crash in Ethiopia yet, it is a bit premature to jump to conclusions now!

The Alpha Protection on Airbus aircraft is part of the fly-by-wire control (What is the Alpha protection?) and will limit control inputs from the pilots instead of applying trim. This is very different from how MCAS works.


What is the circular pavement at the end of a runway called? What is the circular pavement at the end of a runway called where aircraft turn 180 degrees to then backtrack? Is the term runway turning bay appropriate for that?

The problem is that there is a special NOTAM at our aerodrome for big aicraft (more than 75 tons of weight) to turn not on the runway but only in this adjacent part, and with maximum radius due to fragile asphault pavement.

It is called the turn pad. This area(pad) is usually located at the thresholds of the runway, where no taxiway exists, so in order for the pilots to make a full-length takeoff, (or taxi to the Apron) they have to backtrack amd make a U-turn on there. Gernerally speaking, these pads exist on small airports. You can see the turn pads at the 2 thresholds of the runway. Skiathos Airport, Greece
Source


How can a CFI renew their certificate with the FAA? I've read that there are several ways a CFI can renew their FAA instructor certificate. What ways are available for a CFI to renew?

14 CFR 61.197 lists renewal requirements for flight instructors.

If your CFI certificate is still valid (unexpired) than you can renew by any one of the following:

Getting a new rating on your CFI certificate or re-taking a practical test for an existing rating on your CFI certificate

  (1) Passing a practical test for—

  (i) One of the ratings listed on the current flight instructor certificate; or

  (ii) An additional flight instructor rating; or

Having had at least 5 students in the last 2 years with an 80% or higher pass rate

  (i) A record of training students showing that, during the preceding 24 calendar months, the flight instructor has endorsed at least 5 students for a practical test for a certificate or rating and at least 80 percent of those students passed that test on the first attempt.

Being a check pilot, chief flight instructor, check airman or flight instructor for a part 121 or 135 operation and active in pilot evaluation during the last 2 years

  (ii) A record showing that, within the preceding 24 calendar months, the flight instructor has served as a company check pilot, chief flight instructor, company check airman, or flight instructor in a part 121 or part 135 operation, or in a position involving the regular evaluation of pilots.

Completing an approved refresher course within the preceding 3 months

  (iii) A graduation certificate showing that, within the preceding 3 calendar months, the person has successfully completed an approved flight instructor refresher course consisting of ground training or flight training, or a combination of both.

Passing a US armed forces military instructor proficiency check in the preceding 12 months.

  (iv) A record showing that, within the preceding 12 months from the month of application, the flight instructor passed an official U.S. Armed Forces military instructor pilot proficiency check.

If you are not actively instructing and just maintaining your certificate the easiest method is the approved refresher course.  There are a few weekend workshops and a online courses that are approved.  The last time I did this method I used an online course and submitted the 8710 via IACRA and completed the whole thing over a weekend and with no physical paperwork.

If your certificate has expired, even if you have completed the above but failed to submit the proper paperwork in time, then you can no longer do this the easy way and have to look at 14 CFR 61.199.  To reinstate an expired certificate you must either pass a practical test for one of your existing CFI ratings or pass a practical test for a new rating for your CFI certificate.


Why is this video of a G36 Bonanza taking off so scary? Why is this video of a G36 Bonanza so 'scary'?

If they had clipped the top of the trees, would it really have brought the plane down? (And even if yes, it looks pretty survivable).

Because those trees will kill them

If you look at this document regarding the Bonanza G36 performance you will note that the lowest stall speed written is 61 kts. 61 kts is 112 kph or 71 mph. We can assume they were going a little bit faster than that but let us say 110 kph / 70 mph.

In that clip, they are just barely keeping airborne. This means the aircraft is extremely sensitive to disruptions. Any loss of power — even partial — or getting knocked back by a collision and thus losing a few knots or upsetting the aerodynamics of the aircraft, is very likely to send it crashing into the trees.

Going 110 kph / 70 mph into a tree is rarely survivable even in a car, and then you have to remember that cars these days are built to withstand crashes while at least keeping the occupants alive, but that assumes crashing into something wide, that distributes the forces over a wide area, and that gives way, like another car. Trees fail that on both accounts.

A G36 does not even come close to any such structural integrity in case of a crash. The cabin will crumple like figurative tin foil, sending the occupants smashing into the trunks of the trees, or throwing them clear of the aircraft only to then smack into other trees or the ground from several meters up and at a high speed. And that is going to be fatal.

Hence, this is scary because if they clip a tree they are very likely to die.


Can a controller be tasked to provide more than one ATC service at a time? During a visit to one of the ATC Facility  I found out that the Aerodrome Controller was also providing procedural approach control service along with aerodrome control service.

Similarly, Area Radar Controller of the same facility was also permitted to assume the responsibility of Procedural (Non Radar) controller (who acts as a backup to the Radar Controller) in the absence of Non Radar controller to provide relief to him.

I find both of these arrangements a violation of safety. I tried to find some reference to support my idea about this in the ICAO DOC 9426 (ATS Planing Manual) and Human factors Training in ATM, but could not find out anything that specifically prevents or allows this particular arrangement.

Can these services be combined? Any reference to the ICAO doc or some regulation would be a great help.

Since you've asked for a document, check ICAO Doc 4444:

  3.1.3.1 Where traffic demand varies significantly on a daily or periodic basis, facilities and procedures should be implemented to vary the number of operational sectors or working positions to meet the prevailing and anticipated demand. Applicable procedures should be contained in local instructions.

The ATS authority can indeed vary the number of working positions based on demand. The local instructions of the airport you visited will contain the details you need.


Am I likely to get permission at a Private Airport? I'm planning a Labor Day flight to a relative's house, and the nearest airport is a Private Airport that looks to be part of a flying community (multiple houses all with hangars directly off the small runway).

I have no experience with private airports.
If I ask nicely in advance, am I likely to get permission to use it?
Or are they likely to be protective of their privacy and airport?

I realize any answer can't apply in all circumstances, but I'm asking if its worth a phone call and conversation? or if I should just go directly to the nearest public airport?

Can't hurt to ask!
I don't know the specifics of the situation, but I would be willing to bet that your chances are better than you think.  If it was one farmer with a grass strip and no accommodations for visiting aircraft you might be out of luck, but from what you describe it doesn't sound like one extra airplane on the ground for a few hours is going to make that much of a difference.
In fact, it might be that Fred (or whoever) will also be visiting friends for Labor Day and might be willing to let you use his ramp.
They can't say yes if you don't ask.


Can light GA aircraft with FDs or couplers use the RVR reduction clause on an ILS? If you are in a modern GA aircraft, you may have a flight director and/or autopilot that can be coupled to your ILS receiver.  (Certainly, this is true of GA glass...)

Some ILS approaches provide a clause (marked by the * on the minimums and in the notes box on the plate shown below) which allows the RVR minimums to be reduced from 2400 to 1800 if you are using a flight director, HUD, or coupled autopilot to fly the approach to the decision altitude.

Does this clause apply to light GA aircraft with the appropriate hardware (say a C172 with a G1000 in it), or is it limited to use by transport category/multi-crew operations?

FAA Order 8400.13C outlines these procedures. Section 7 c outlines the requirements for this procedure. Most of these affect the airport facilities or procedures themselves, and section 5 b outlines the IAP requirements for aircraft:

  Aircraft equipped with an operable FD, or AP with an approach coupler, or HUD which is certified for operation to a minimum of 200 feet HAT are eligible for this operation.

There is also a note under 9 b:

  Single pilot operators are prohibited from using the FD to reduced CAT I landing minimums without accompanying use of an AP with an approach coupler or HUD.

So it would appear that having a FD is not entirely sufficient; a pilot with a FD can use the reduced minimums if they also have one of the following:

AP with approach coupler
HUD
Copilot


PRIM 1 FAULT prior to ETOPS entry, Reroute or Continue? As per the Minimum Equipment List (MEL) you cannot dispatch a plane for ETOPS if it has PRIM 1 FAULT (Flight computer fault) However if this fault appears in flight just prior to entering the ETOPS/EDTO segment should you still continue or fly a non ETOPS/EDTO route? Since the MEL is only referred to prior to flight, I cannot refer to this document to justify not flying the ETOPS route. There is a requirement though for twins that all EDTO significant systems should be operational before conducting an
ETOPS/EDTO flight. I haven’t seen an EDTO specific significant systems list only the general list published by ICAO which includes almost all the systems of the plane. The question is, would PRIM 1 fault, which was considered a NO GO on the ground still be considered an EDTO significant system in flight wherein it would only result to a loss of a pair of spoilers and computer redundancy? I hope somebody here would share their EDTO significant systems list.

Since you are already airborne, the MMEL doesn't come into it. The system was normal when you dispatched.  What applies is the QRH (Quick Reference Handbook).  You should look for that particular message in the QRH in the section on status messages (I assume that fault messages are white status messages in Airbus-land).
If there are any restrictions on ETOPS operations with a fault that comes on while airborne, there will be a notation of some kind to that effect, referenced or attached to that message in the QRH, that you have to divert or take some sort of mitigating action before or after entering ETOPS conditions.  If not, you're good to go.
The MMEL is based on an analysis of risk exposure related to potential follow-on effects following a departure with a degraded system (that is, a second failure of the remaining component of the system in flight that renders the entire system inoperative or operationally compromised).  The risk level prior to departure is higher than the risk level while airborne, because as a general rule, double failures on the same flight are assumed to be extremely improbable.
And, obviously, you should consult with someone in authority at your airline instead of going on the statements of anonymous nobodies on the intertubes...


Why don't planes fly directly to their destination? Here is the flight path for B62554 from PBI (Palm beach) to JFK. This flight almost goes back on itself when off the coast of South Carolina.
I was wondering why this flight takes such a contorted path? Another example is B6242 from Havana to JFK, which similarly diverts out to see when near New Jersey then comes back at an almost 90 degree angle.

There are many reasons why planes don't fly direct to their destination.

Mountains (for smaller piston aircraft)
Traffic capacity and traffic flow considerations for the ATC center
Weather along the route
Preferred airway routings

For an analogy, cars don't drive direct to their destination for the same reasons.  Roads, I would venture to guess, would be preferred routings to your destinaiton.

There would be a traffic jam if everyone wanted to get to the closest airport for the Olympics at the exact same time.  Traffic flow considerations would dictate planes slow down or fly a different routing or wait till there is a time slot for them to land at their destination.


What is the ICAO code and callsign for Amazon Prime planes? Looks like Amazon started flying its own planes to transport goods - check out the announcement here. Apparently they've been flying since at least August 2016, and I just found out about it now, lol.

This is their promo video.

Anyone know what their three letter ICAO code and their callsign is?

Edit: Looks like CNBC confirms that Atlas Air operates flights for Amazon in this crash. There may be others.

As best I can tell, Amazon Air does not hold its own air carrier certificate; they contract with cargo airlines to operate their flights. Per Wikipedia, those contractors are Air Transport International, ABX Air, and Atlas Air. These operators then use their own callsigns.

For example, the aircraft shown in your first link, N1997A ("Amazon One"), is apparently owned  by Titan Aviation, dry leased to Amazon Air, and then operated by a Titan sister company: Atlas Air. The aircraft bears the legend "Operated by Atlas Air Inc" on the paint job. So for the flight it happens to be flying to Charlotte at this moment, it would be identified as GIANT 3581, "Giant" being the codesign for all of Atlas' operations.

But another aircraft in their fleet, N331AZ, is contracted to Air Transport International, and uses the creative callsign "AIR TRANSPORT."

So they don't have an ICAO code or callsign; the companies they hire to operate their flights do.


Why is the ratio of TSFC at altitude vs. sea level different for hi-bypass vs. lo-bypass turbofan engines? I've read up on how the thrust-specific fuel consumption of turbofan/turbine engines increases with altitude, and the Georgia Institute of Technology plot in particular seems to indicate that, for most modern airliners, the TSFC at cruise is 1.6 to 1.7 that of static thrust at sea level.

Now, I've come across this site (courtesy of the Wikipedia page for TSFC) and noted some wide variations with $TSFC_{cruise}$ vs. $TSFC_{0}$.

Some examples (data from the page linked above):

GE CF6-50C2: $\dfrac{TSFC_{cruise}}{TSFC_{0}} = \dfrac{0.630}{0.371} = 1.698$.
P&W PW2040: $\dfrac{0.582}{0.330} = 1.764$.
RR RB.211-535E4-37: $\dfrac{0.598}{0.324} = 1.846$.
P&W JT8D-15A: $\dfrac{0.810}{0.590} = 1.373$.
RR Conway RCo.12 Mk.508: $\dfrac{0.822}{0.726} = 1.132$.
RR Spey RSp.4 Mk.511-5: $\dfrac{0.770}{0.600} = 1.283$.

The upper three examples are high-bypass turbofans, and the lower three are low-bypass.  Notice the big differences in the TSFC ratios.

What causes this difference?

The factor affecting TSFC is speed, not altitude. Altitude is indirectly responsible because the lower density requires a higher flight speed.

Low-bypass engines have a higher exit speed, so the change in speed affects their efficiency less. High-bypass engines double their TSFC between static and Mach 0.8 and only the lower temperature at altitude reduces the difference a bit. If you look at the formula for thermal efficiency in this answer, you see that efficiency drops more over speed for high-bypass engines. Only the much better propulsive efficiency of high-bypass engines makes them overall better for airliners.


Lift distribution on biplanes This Wikipedia page about biplanes says

  in a wing of aspect ratio 6, and a wing separation distance of one chord length, the biplane configuration will only produce about 20 percent more lift than a single wing of the same planform.

My question is, does the wing of  biplane share the lift load 50/50 ?
Secondly, what is the formula for calculating the interference drag of a biplane?

If both wings have the same incidence and the wings are not staggered (= they sit at the same lengthwise location along the fuselage), then yes, their lift is split equally between both.

Most biplanes were (and sometimes still are) single- or two-seaters and in order to give the pilot good forward and upward visibility, the upper wing is shifted forward a bit (positive stagger). This will place it closer to the upwash (flow field ahead of the wing with increased angle of attack) of the bottom wing and in turn place the bottom wing closer to the downwash (flow field past the wing with reduced angle of attack) of the top wing. This effect becomes stronger with increasing angle of attack of the whole biplane, in line with the lift coefficient. With positive stagger, the upper, forward wing carries the majority of the load. How much that is depends obviously on the amount of stagger.

The formula for the interference drag is the Biot-Savart law which describes the effect of one lift-creating object on its surroundings. Since both wings interfere mutually, the solution is not straightforward but needs several steps:

First, the location of a lift-creating vortex and its two trailing vortices is defined. A wing should be split into several sections which all have their own vortex strength. The more sections, the more precise the result will be. For a biplane this needs to be done twice, of course.
Then a number of points where the local flow direction is prescribed must be defined. Whereas the vortex usually is located at the quarter of the wing chord, those points are best placed at three quarters of the wing chord; again spread over the span of the wings. They are called control points.
Now the influence of a particular vortex on a particular control point is described using the Biot-Savart law. After this has been done for all vortices and all control points, those influences define a matrix.
By solving the matrix equation for tangential flow at the control points, the strength of the single vortices in the influence of all other vortices can be calculated.

A more elaborate description of the process can be found in NASA Technical Note D-5335.


Does cargo heat failure require a diversion? What about if there are live animals in cargo? There was a story in the news recently that an Air Canada 787-8, enroute from Tel Aviv (TLV) to Toronto (YYZ), diverted to Frankfurt (FRA) when the pilots discovered a problem with the cargo heat.  There was a live dog in the cargo hold, and the diversion potentially saved it from freezing to death.

The narrative has been that the pilots diverted specifically in order to save the dog.  But I am wondering whether a cargo heat malfunction might require a diversion, as a matter of standard operating procedure, regardless of whether live animals are on board.  After all, even if there are no live animals, there might be other valuable temperature-sensitive cargo.

In general, according to airline policies or procedures, under what circumstances would cargo heat failure warrant a diversion?

Any major airline would be of interest; if you want a specific one, let's say Air Canada.

Does cargo heat failure require diversion? It depends on the cargo being carried.
For your question about pets, then yes.
Council Regulation (EC) No 1/2005 regulates the protection of animals during transport in the EU, which itself is in accordance to IATA Live Animals Regulations. The guidelines based on that EU regulation say:

Commanders, and loadmasters and aircrew under their authority must ensure that the aircraft and equipment are suitable for carriage of the animals concerned in the manner intended. They must ensure that the animals are loaded, carried and unloaded in a way which will protect their welfare.
In particular they must ensure that the animals are accommodated in accordance with the IATA LAR, and that an appropriate environment of air quality and quantity, temperature and pressure is maintained whilst the animals are on the aircraft.

The ability to ventilate and regulate the temperature of an aircraft belly hold varies considerably. The arrangements vary between individual aircraft depending on the make and type, the compartment, and whether or not ‘standard’ or ‘special’ specifications have been fitted.
It is therefore essential that the aircraft operator, who should know the individual features of each of its aircraft, is satisfied that the belly hold to be used can be sufficiently ventilated and maintained at a satisfactory temperature during all stages of the proposed flight. This assessment should take into account the species, number, weight and size, and volume of the animals to be carried, and the heat and moisture that they will produce. Other cargo being carried at the same time will also need to be taken into account.

Even the Minimum Equipment List of aircraft takes that into consideration. For example, the aircraft can be dispatched with an inoperative cargo heater or ventilation fan, but not if there's an animal in that respective cargo hold.
All that confirms the pilot's action in the story you mention.


What is the THS deflection speed? Let's restrict this question to best sellers airliners (A320 and B737). On  this aircrafts, the THS is used for pitch trim. The speed requirements may not be has intense as for elevator as it control a longer term action. I excpect the elevator to act quickly (I imagine less than half a second from full up to full down, several degrees per seconds) but what about the THS? Does this speed change depending on the flight phase? (I see no reason, but I may be mistaken)
This question is restricted to autotrim function (otherwise, I think the speed of pilots hands may be the limiting factor)

For the A320:

Conf 0/1 the rate is 0.3°/s
Conf 1+F/2/3/Full the rate is 0.7°/s

I haven't found any difference for A/P vs Manual flight.

In A319, THS freezes in the following situations:

The pilot enters a manual trim order.
The radio altitude is below 50 ft (100 ft with autopilot engaged).
The load factor goes below 0.5 g.
The aircraft is under high-speed or high-Mach protection.

In A320, THS freezes in the following situations:

The pilot enters a manual trim order.
The radio altitude is below 50 ft (100 ft with autopilot engaged).
The load factor goes below 0.5 g.

There are further conditions under which THS range is limited, let me know if you would like me to expand.

Source: A320 FCOM DSC-27-20


How did this air force plane likely get into the eye of Hurricane Florence? The annotation for this CNN video says

Air Force plane flies into Hurricane Florence
Watch as a US Air Force plane flies into the eye of Hurricane Florence to collect weather data for the National Hurricane Center. Source: CNN

But I can't find any information on what kind of plane this is nor how it safely got into the eye in order to record this.
Would they generally fly through the storm at this altitude, or do they fly above it to reach the eye, then "drop down" into the eye?
The video is also viewable here where the footage is between 00:24 and 00:40.

They fly straight through, as part of their mission to collect meteorological data about the storm, used for forecasting (NOAA's G-IV fleet flies the periphery of storms to collect data used to help predict the path of hurricanes). A typical path:

  We'd begin by making a "figure 4," with the vertical and the horizontal legs crossing at the center of the eye.

This image shows the flight path taken during one observation of Hurricane Patricia in 2015 (from this blog post).

Wikipedia has information about "hurricane hunter" operations, and Google produces many, many results about how these flights work, including videos (even an entire documentary series) and interviews with the crews that fly them. Here's a recent news story featuring an interview with an Aerial Reconnaissance Weather Officer who flew into Hurricane Florence.

The US Air Force's 53rd Weather Reconnaissance Squadron flies the WC-130 (a C-130 variant equipped with meteorological observation equipment and dropsonde deployment capability). Additionally, the National Oceanic and Atmospheric Administration flies a fleet of two WP-3D Orion aircraft (modified P-3 Orions) and one Gulfstream IV, which flies around the periphery of storms to collect weather data.

You can plot their exact flight paths on Google Earth, if you're so inclined.

The Hurricane Hunter Association's site also addresses this question in their FAQ:

  Do you fly over the top of the hurricane? NO!!

  The tops of a big hurricane can be over 50,000 feet high, and our planes could never get
  up there (they can only go up to 30,000 feet). Besides, the weather
  we're interested in is down at the bottom of the storm, where it will
  affect the coastline it hits. For this reason, we fly in as low as
  possible and still be safe. This altitude can be anywhere from 1,000
  feet to 10,000 feet.

They also include an image of their typical "alpha" flight path, typically making four passes through the center of the storm.


Why is a wing tip's front edge tapered? I am beginner and I want to understand the advantage of a tapered wing tip front edge beyond reducing the mass. How does this minimize or effect vortex drag, etc. Can someone help me to visualize this scenario please?
I have captured the screenshot from the video on YouTube.

The swept-back wingtip has been successfully employed by water fowl for many millennia. The use of composite structures has made the three-dimensional shaping of wingtips much easier, and the first airplanes to use increased sweep at the wingtip were indeed composite gliders such as the Schempp-Hirth Discus.

Seagull (left) Schempp-Hirth Discus 2 (right, source)

In the times of metal wings, Dornier introduced their TNT (Tragflügel Neuer Technologie, in English: Wing of new technology) on aircraft like the Do 228, Do 328 and the Dornier ATT flying boat. It used a triangular wingtip with no change in trailing edge sweep, which is easier to manufacture in aluminium.

An Air Alps Dornier 328-110 landing at Fiumicino Airport, Rome, Italy, viewed from Ostia Antica. Picture by Makaristos.

Boeing has now introduced this detail as the "raked wingtip" in the 787 and the 747-8. Compared to a straight wing, a swept wingtip offers some benefits;

Higher sweep lowers the lift curve slope. This helps to reduce the lift contribution (and, consequently, the bending moment!) of the wingtip at high angles of attack. Therefore, raking the wingtip will result in a lower maximum bending moment.
The sweep also shifts the center of pressure of the wingtip backwards, adding a negative torsion moment. This moment lowers the angle of attack over the whole outer wing in gusts and at high load factors, again helping to lower the maximum bending moment at the root.
It allows to combine a near-elliptical circulation distribution over a wide range of angles of attack with good stall characteristics. The lower lift curve slope of the wingtip lets it stall at a higher angle of attack and reduces its lift contribution relative to its area at increasing angle of attack.

In order to prevent the outer wing from stalling first, you want to give it a lower lift coefficient, which can be achieved by locally adding chord over what is required for an elliptical wing planform and a lower local incidence. However, doing so will still add lift proportional to the local chord when the angle of attack is increased. Now the wing will show the ideal elliptic circulation distribution only for one angle of attack. By adding sweep to the outer wing, its lift curve slope is reduced, so its off-design circulation distribution is closer to the elliptic ideal.


What is this weird plane? Can anyone identify the make and model of this aircraft? I'm just really curious.

From what I can tell, it's a Burt Rutan design. I then searched and it appears to be a Rutan Defiant.


How to use airport panel information on sectional chart? In the Chart Supplement, the airport information includes the chart on which the airport is located. It also includes a panel on the chart where the airport is located. How can I use this panel information? Sectional charts don't appear to have panels.

Here is the airport information for San Francisco International:

I understand that San Francisco stands for San Francisco Sectional Chart and H-3B and L-2F are for the IFR charts, but how can I use the 3B and A information?

In addition to @JWalters's answer:
L-2F, 3B is one group, and it refers to the "Enroute Low Chart Number(s) and Panel Identification",$^1$ that is:

L-2F, and
L-3B.

Since you are aware of the L-2F, here's the L-3B:

Source: skyvector.com

$^1$ Interagency Air Committee (IAC) Specifications, IAC 8, faa.gov, § 3.1.5.2.7


What factors govern the placement of a helicopter's tail rotor (left or right)? An image search for 'helicopter' indicates that there isn't a consensus on whether to place the tail rotor to the left or the right of the tail boom, although I'm believe there may be a bias for left.

There never seems to have been a consensus: taking two popular early helicopter designs, the Bell 47 has its rotor on the right; the Hughes 269 on the left.

Bell 47 source

Hughes 269 source

There are many left/right conventions in aviation, e.g. where the pilot sits, which side the passengers exit etc. So the question is, what governs the choice, and would it be beneficial if a 'right' side was generally agreed on?

It's hard to say the design rational used for all helicopter manufacturers. Push vs pull doesn't seem to be very important.

One example is the Bell UH-1 Huey (Left side Pull). When Bell modified the design for civilian use 205, 212, 412, 214, they put the TR on the (RH side Push). When asked about the reasoning for the original Huey/205 change, Bell engineers explained that they found better TR effectiveness with rotation of forward blade climbing, as the interaction with wake and vortices of the main rotor was more favorable in this configuration.

Now look at the AH-1 Cobra Gunship variants. Bell switched sides at least twice. Left on early models, switched to right on later 2 blade models (AH-1W). Back to Left side for the 4 blade AH-1Z. While on opposite sides, the AH-1W and AH-1Z are both forward blade climbing.

Sikorsky? S-76(Left - Climbing) H-60(Right - Climbing) H-53(Left - Climbing). One could speculate that the higher the TR is mounted, the more this rational comes into play.


How useful are the AOA Indexers and indicators for jet pilots and civillians? I dont see them neccessary unless you are landing on a aircraft carrier.

I just don't know a lot about them. I understand what they do but they just dont seem neccessary unless you are landing a jet to an aircraft carrier where every bit of precise information is neccessary.

And now I see them on the Cessna 172SP planes.

Long story short. How important they are for aircraft carrier pilots and Cessna students/pilots?

They’re super useful once you get used to them. No matter your weight, if you fly at the right AOA you’ll have the right stall margin. It is easier to see the indexer than the ASI, for control on approach. It acts like a pitch rate indicator too, if you are rough with the nose, so it helps to smooth out the flying. Responds much faster than the ASI. If you are maneuvering aggressively, it will give you that stall margin too.

Update with nice paper from AIAA Journal of Aircraft:

"Low-Cost Accurate Angle-of-Attack System", Borja Martos and David F. Rogers, Journal of Aircraft 2018 55:2, 660-665

  ...The angle
  of attack for maximum lift-to-drag ratio corresponds to maximum range
  and maximum glide ratio for a piston engine- propeller aircraft.
  Hence, in a fuel critical situation and/or an engine failure
  situation, it is critical that the pilot have accurate access to this
  angle of attack.

  With today’s fuel costs, the Carson cruise [1] angle of attack, which
  represents the most efficient way to fly fast with the least increase
  in fuel consumption, is of significant interest.

  The angle of attack for maximum lift-to-drag ratio does not depend on
  density altitude, weight, or load factor but only on aircraft design
  parameters and aircraft configuration. Similarly, the angles of attack
  for minimum power required and Carson cruise depend only on aircraft
  design parameters and configuration...

  Therefore, a low-cost, accurate, full envelope, easy to flight
  calibrate angle-of-attack system is a transformative technology for
  light general aviation aircraft.


Is the official weather report for an airport in Class D airspace controlling for its Class E surface extension? If the official weather report for an airport for which Class D airspace is designated is showing IMC, is that controlling for a Class E surface extension (designated for that airport)?

For example, if I determine that I have 3 miles flight visibility and at least a 1000 ft. ceiling, can I fly through that Class E surface extension without receiving an SVFR clearance?

The ATC Orders 7-5-1(a)(4) say:

  a. SVFR operations in weather conditions less than basic VFR minima
  are authorized:

  [...]

  Only within the lateral boundaries of Class B, Class C, Class D, or Class E surface areas, below 10,000 feet MSL.
  Only when requested by the pilot.
  On the basis of weather conditions reported at the airport of intended landing/departure.

That means, ATC will issue SVFR clearances - or not - in the class E surface area according to the official airport weather.

The 'twist' here is that ATC can't issue an SVFR clearance anyway unless the pilot requests it. The AIM 4-4-6 simply says that an SVFR clearance is required "when the weather is less than that required for VFR flight". So as far as I can see, if you're in VMC in a class E surface area and you expect to remain in VMC then you aren't required to request SVFR, whatever the reported airport conditions are.

I'm actually not sure what your exact scenario is here (in contact with ATC or not, within 4NM or not, etc.) but in reality I suspect that ATC would say "N12345, the field is IFR, say intentions". If you tell them you're in VMC then they have no way to challenge that but they might hint strongly that you should request SVFR - "N12345, is there anything special you'd like to request?" - because it would clarify the situation for everyone and help keep you safe and legal.


Why is VHF still used? I have a rather easy(?) question. Why is VHF radio still the main communication method between the ATC and pilot?
Is it because there is no better solution at the moment?

Best regards

The reason radios in general are used is covered in this question Why is radio communication still used?

As for why VHF is the band of choice its largely because its assigned for aviation use and the the radio spectrum is not unlimited. Here in the US the FCC regulates which bands are for what, you can find the full list here and you will see that many of them are in use for lots of different things so using a higher (or lower) band for aviation may not be possible as they are likely used for something else.


How should I safeguard my FAA certificate number? The FAA’s Search Airmen Certificate Information reads in part

Personal Information
We do not display your SSN, certificate number, or date of birth. We will display a releasable address in accordance with the Aviation Investment and Reform Act for the 21st Century (PDF). We display medical information based on FAA’s Civil Aerospace Medical Institute (CAMI) medical records. If the medical dates are incorrect, please contact CAMI at (405) 954-4821.

Airmen Certification Frequently Asked Questions contains the same intended exclusions.

Do you display my certificate number on the Internet?
We do not display your SSN, certificate number, or date of birth on the FAA website.

The U.S. Department of Transportation publishes an FAA Privacy Impact Assessment – Airmen/Aircraft Registry Modernization System (RMS) notes that Social Security Numbers were used in the past for certificate numbers, but policy has changed.

Personally Identifiable Information (PII) and RMS
To handle airmen certifications and aircraft registrations, FAA requires PII about airmen and aircraft owners/registrants. With this in mind, RMS may include or collect the following data on airmen and/or aircraft owners and registrants, either for authentication or certification requirements: Name, Date of birth (airmen only), Social security number (airmen only), Driver’s license number, passport number, or government ID number, Physical Description (height, weight, hair and eye color, sex, and citizenship), Address (airmen only), Medical records (airmen only), Certificate number (airmen only). In the past, RMS used an airman’s social security number as the certificate number. FAA is now changing that practice, developing unique certificate numbers not affiliated with social security number. During this change, airmen can request, online or offline, that his or her social security number not appear as a certificate number. For an individual’s PII to be included in RMS, that individual must be associated with an airmen or aircraft certificate or application.

It is clear that for airmen whose certificate numbers match their SSNs, adhering to best practices and remaining clear of practices to avoid (cf. recommendations from the Social Security Administration) are wise courses of action, primarily to reduce the risk of identity theft and fraud.
To get credit for FAA WINGS training hosted at AOPA’s Air Safety Institute, certificate number is a required field—but also one whose value ASI is careful to note that they do not store and that they pass with some level of encryption protection.
So many legal disclaimers raise red flags. What are the risks of disclosing an FAA airman certificate number? Is all the handwringing due strictly to the fact that some certificate numbers are also Social Security Numbers and nothing else? How should I protect my certificate number, which differs from my SSN?

Note: All quoted passages were retrieved from the linked resources on July 26, 2015.

I guess the question is, what can someone do maliciously if they have your certificate number, and what's the risk of that happening?

My assumption is that they can do nothing - and therefore the risk is zero - because no one uses the number for anything: it isn't needed for medicals, training, TSA approvals, flight reviews, checkrides, renting aircraft, buying insurance etc. People do want to see your certificate (and even take a copy) for various reasons, but no one will accept your certificate number by itself as proof of anything. That's my experience in the part 91 GA world anyway; I have no idea if certificate numbers are more important for airline pilots.

So my guess - and it is a guess - is that this does indeed come from when SSNs were used as certificate numbers. And as a result, unless your certificate number is also your SSN, there's probably no reason to do anything special to try to protect it.


Where does the term 'steam cockpit' come from? Why are traditional style cockpits with gauges called 'steam cockpits'? Do the instruments actually run on steam?

Well, to answer your second question first: no.  No aircraft instruments actually run on steam.  There are lots of safety issues related to generating and using the steam on board an aircraft that are prohibitive.

As far as why they are called steam gauges, take a look at one and compare it to a traditional flight instrument:

They are both round, both have a calibrated scale printed on  them, and both have a needle which points at the current value.  They actually look pretty similar!


Is there a NOTAM code for solar eclipse? Sun eclipses have some noticeable effect (e.g. drop in air temperature). Inspired from Eclipse Flights (xkcd) I'm curious if eclipses are notified as NOTAM or as weather notice. How?

Never seen such notification (but there are also few sun eclipses).

For the solar eclipse of March 20, 2015, I found this example below, seems like it's the opposite of a warning.

  E) A SOLAR ECLIPSE WILL TAKE PLACE ON THE 20TH OF MARCH.
  SPECIAL ROUTES HAVE BEEN DEFINED FOR FLIGHTS PLANNING TO VIEW THE ECLIPSE.
  THE ROUTES ARE DEFINED AS FOLLOWS:

  (...)

  ANY ADDITIONAL REQUESTS FOR A SOLAR ECLIPSE PROFILE SHALL BE SENT TO REYKJAVIK OACC SHIFT MANAGER, SEE CONTACT INFO BELOW. SOLAR ECLIPSE FLIGHTS WILL BE GIVEN PRIORITY DURING THE ECLIPSE.
  OTHER FLIGHTS MAY EXPECT A REROUTE AND OR LEVEL CHANGE FOR SEPARATION PURPOSES.

Regarding the temperature drop, from NASA:

  Because the patch of the shadow travels faster than the speed of sound, weather systems will only be affected very locally directly under the instantaneous footprint of the eclipse. The main effect is in the "radiant heating" component which goes away suddenly at the moment of eclipse and produces a very fast temperature decrease. If the wind is blowing, your body probably exaggerates, by evaporative cooling, how large the actual temperature swing actually is.

Due to the Earth's geometry, the shadow's speed differs from location to location, the slowest equates to Mach 2.2 at 50,000 feet for an F-15 to fly along.

Even for that F-15 in constant complete darkness, every instance is a new darkness. Some sources mention the drop at the surface being 3°C (5°F), but it looks like it's not a thoroughly studied field (impact of solar eclipses on local weather).


How did the 747SR fly from Qatar to London? The following photo on the Boeing 747 Wikipedia article reads:

  Qatar Airways 747SR-81 landing at London Gatwick Airport in 1996.

How did the 747SR manage this flight [on a regular basis]? The only range information I can find for the SR (short range) is from ANA's fleet history, which puts it at 2,590 km. The -SR also had "a 20 percent reduction in fuel capacity."

(gcmap.com) Range of the 747SR plotted from Doha and Cairo.

Out of the ~520 seats, how many seats were empty to make the trip, or were there stops on the way? I thought maybe a Doha-Cairo-London route, but that falls short as well.

This airplane was also seen as far as Bangkok. These probably are not rare trips, i.e., the destinations are likely to have been regularly served.

I was senior cabin crew at Qatar in 1995/96. Flew on the 747 for about 1 year. My first flight was DOH-BKK-MNL Xmas week 1995. 3 pilots, 14 cabin crew and 1 aircraft mechanic, which was the standard crew numbers. We had 57 passengers all the way to MNL as BKK was in a refuelling stop. If I recall there were 20 First Class seats upper deck and 508?+ seat all economy main deck. The configuration never changed from the ex-ANA seating plans. Gatwick was flown both ways via Cairo and was never full each sector. In the period I worked on the 744, Qatar was still a closed country. There were no tourists and our passengers were mainly workers to and from Doha. After BKK started as a drop off port we would have 1-5 transit pax via DOH. Our Bangkok route which was actually to Manila was a refuel stop only at Dhaka. Flight loads were minimal. First we would only ever have 5-10 max pax. Economy I recall ever having over 200 passengers. The 747sr was also used regularly to Khartoum. They were used also around the Gulf on various flights. The 747sp ex Air Mauritius replaced the 747sr for a few months in the DOH to MNL via BKK with Dhaka dropped. I flew the 747sr on a DOH-DXB-DHA-CMB-DOH route, 20+ hour duty.


What are Operations Specifications (OpSpecs)? I had never really heard of OpSpecs until I started a new flying job that was at a Part 135 company.

So for those people who are new to this (or are just interested):

What is an Operation Specification and how does it relate to the actual CFR regulations?
What kinds of things are they used for?
Who uses OpSpecs?
In general terms, how is an OpSpec obtained?

Putting aside the legal definition for someone else, they are a set of rules that an operator (an airline for example) agrees to operate by. The FAA has to approve them. The ops specs can be more restrictive than applicable FAA regulations, but never less restrictive (as I remember). They cover many things, some of which (that I can remember) are:

Type of equipment you're going to operate.
Where you're going to operate.
Extent to which VFR operations will be allowed.
Types of navigation equipment permitted.
Who you can offer your services to.
Crew training required.
Duty and flight time limitations.
Disciplinary protocols to follow.
Flight planning, dispatch, flight following requirements.
Lists of who is who: chief pilot, flight standards director, etc.

There are a lot more areas, but basically it's how you're going to operate your airline. The thing to remember is to give yourself as much leeway as possible. Don't do something stupid like saying that if someone fails an alcohol or drug test that you're simply doing to fire them. Provide for as much VFR operation as you can possibly get the FAA to agree to. Don't saddle yourself with impossible maintenance requirements if you have a mechanical problem in, say, Harare.

Ops specs are best written by someone who has been around the block many times. Write them poorly and you're going to cost yourself a lot of money that you would otherwise not have to spend. If you get a recalcitrant FAA inspector, it's worth fighting it out. Appeal as necessary until you get what you need. Don't be afraid to show up the ignorance of FAA newbies that may have been assigned. Also, remember that the FAA regions are not standardized. It may even be worth considering changing the region where you're technically based to get what you want.


What advantage(s) are there for the HondaJet's engine mount position? The HondaJet has over wing mounted engines as can be seen here:

Image from LuxuryLaunches.com
The advantages v drawbacks of the over wing mount have been discussed here and here. The over wing mount on the HondaJet could take advantage of the Coandă effect, except that they're not in front of the wing, as can be seen (above), but more clearly here:

Sourced from HondaJet.com themselves.
In fact, the placement looks like the typical rear fuselage mount, except they're not mounted to the fuselage. The rear fuselage mount is quite common in the small private/luxury jet market:

Gulfstream G550 hosted by Gulfstream

Learjet 45 image from Aviation-Times.aero
This seems to combine all the disadvantages of an over wing mount with the disadvantages of a rear fuselage mount, and neither of those positions seem to have a huge amount of advantages.
What are the advantages of a high, over/behind wing engine mounting position as seen in the HondaJet?

Probably the reasons are similiar to the reasons which lead to the same mounting on the VFW-Fokker 614.

  This arrangement was used to avoid the structural weight penalties of rear mounted engines and the potential ingestion problems of engines mounted under the wings. This allowed a short and sturdy undercarriage, specially suited for operations from poorly prepared runways.

// Update

The space in the cabin should be the actual reason in this case.

  “I had the idea around 1996,” says Fujino. “The cost of a business jet is very high. To reduce the cost, you have to reduce the size of the aircraft, but then you sacrifice comfort. I wanted to make the aircraft smaller, but not sacrifice the cabin.” Most business jets have the engines mounted on the rear
  fuselage, and moving the structure and systems to support the engines out of the fuselage would maximise space inside the cabin without increasing the size of the aircraft, he believed.

As always, there are pro and cons:

  The problem with an overwing engine is
  that interference between the nacelle and
  wing can accelerate the airflow and cause
  a strong shockwave, reducing the drag
  rise Mach number – the airspeed at which
  shockwaves form and drag begins to rise
  rapidly. Fujino says computational analysis
  and windtunnel testing enabled Honda to
  find a “sweet spot”, an overwing engine
  location that minimises the shockwave.
  The result, he says, is a 5% better lift-to-
  drag ratio – aerodynamic efficiency – in the
  cruise than a rear-engined aircraft.


Did any WWII aircraft only use a turbocharger but not a supercharger? In doing some basic research, I have concluded that all WW II aircraft equipped with turbochargers also used mechanical driven centrifugal superchargers.

These include the P-38, P-47, B-17, B-24, B-29, etc.

Is this correct, and are there any exceptions where the engine lacked a mechanical supercharger and only used the turbocharger for boost?

As is suggested in the original question, the answer appears to be "no".  This website gives some hints as to why a gear-driven supercharger would normally be used in addition to a turbosupercharger: http://www.rwebs.net/avhistory/opsman/geturbo/geturbo.htm

(Though the link may raise more questions than it answers: it doesn't make it obvious why a turbosupercharger usually injects air upstream of the carburetor, or why a gear-driven supercharger usually injects air downstream of the carburetor, or why only the latter prevents issues with valve cooling.)


How can lift be less than thrust that is less than weight? Physics in schools teaches two contradictory and mutually exclusive things:

That the upward lift force on an airplane in flight equal its weight (Lift = Weight = Mass x Gravity). This is based on applying Newtons 2nd law of motion (F = ma) to the airplane in flight.
However, modern commercial airplanes like the Boeing 747–400 can fly with thrust-to-weight ratio as low as 0.3. Here the engine thrust is only 0.3x the weight of the airplane, but this thrust is sufficient to push the airplane forward and generate enough lift to fly.

Therefore the upward force required for lift and flight must be a lot less than 0.3x the weight of the Boeing 747-400 (Lift < Thrust < Weight). Both statements cannot be true. Which is correct?

Your misunderstanding lies in your thought that lift is smaller than thrust, while in fact, lift is much larger than thrust.

The lift is provided by the wings. Their purpose is exactly to create a lift force (upwards force) while requiring relatively little thrust (forwards force). How well they do this is expressed by their lift-to-drag ratio (L/D ratio). A modern airplane can have an L/D of 20 or more. This means that for every newton of thrust, you can lift 20 newtons of weight!

You can think of wings the same way you think of an inclined plane: you need a lot less force to push a car up a gentle hill than up a steep hill. Indeed, if the hill is gentle, most people can push the car up the hill, while most people cannot single-handedly lift a car up. Wings work by pushing air down, and by pushing the air down at a relatively shallow angle (by going forwards real fast), you need less force to go forwards than to lift the plane.

If you want to know more than this 'intuitive' explanation, perhaps I can recommend you this answer of mine. I will present a terse derivation below, with the aim to calculate the L/D (neglection parasitic drag) purely from first principles.

Lift is due to a certain mass flow $\dot{m}$ being given a certain velocity $v$ downwards: $$L=\dot{m}v.$$ This mass flow is due to the wings encountering a certain amount of air; as an approximation, you can think that the airplane only affects a circular 'tube' of air with the diameter equal to its wingspan. The energy per unit of time (power) necessary to impart this downwards momentum equals $$P=\frac{1}{2}\dot{m}v^2.$$

This power is provided by the combination of thrust $T$ and forwards velocity, $$P=Tu.$$ This gives us an expression for the thrust: $$T=\frac{P}{u} = \frac{1}{2}\dot{m}\frac{v^2}{u}.$$ Note that the thrust $T$ equals drag force $D$, so we can now calculate the L/D:

$$\frac{L}{D}=\frac{L}{T} = \frac{\dot{m}v}{\frac{1}{2}\dot{m}\frac{v^2}{u}} = 2\frac{u}{v}. $$

In other words, like I said before, the L/D ratio is exactly how 'shallow' the relative velocity vector of the affected airflow is. It follows that the forwards speed $u$ should be as large as possible to maximize the L/D. However, I only took into account the so-called "lift induced drag" which is purely the horizontal force it takes to create a vertical lift force. In reality, there is also parasitic drag, which scales with $u^2$ and will at some point dominate over the reduction in L/D.


Are the Gulfstream III's ailerons controlled by hydraulically boosted cables? Are the ailerons for a Gulfstream III controlled cables with hydraulic boost? Also, is it possible that an aircraft mechanic could easily access the control to tamper with it?

Yes, the flight control surfaces on the Gulf Stream III are moved by cables with hydraulic assistance.

From a study guide for the type.

  The flight controls on the G III are cable driven with hydraulic boost..  They are powered by both the "Combined" and "Flight" hydraulic systems.  Each of the systems provides 1500 psi to the flight control servo actuators.  When the landing gear or flaps are extended, the combined system pressure increases to 3,000 psi.  If one system fails, the remaining system pressure increases to 3000 psi.  Failure of one hydraulic system therefore, does not result in a loss of control effectiveness.

As to whether a mechanic could interfere with the controls, of course.  But for what purpose?  I am not sure that I understand what you mean by "tamper" but I assume that you mean sabotage. If so, then there are multiple ways to do this but I see no point in speculating as to what someone might do or why.


What is the best extinguishing agent when wheels catch on fire? What extinguishing agent must be used in the event of a fire involving wheels/tires? Why?

You can find some discussion in this thread but what you are looking for is

  Fire Service manual. Volume 2. Fire Service Operations : aircraft

  incidents Home Office - London

  HMSO, 12/99. Crown copyright 1999

  ISBN 0-11-341192-8; 0113411928

  5.4.2 Brake and wheel fires The overheating of brake and wheel assemblies usually follows excessive braking. This can happen on
  landing when a hydraulic failure reduces the ability of the pilot to
  utilise control surfaces (flaps) and he feels the aircraft may over
  run the runway or more often, on an aborted take-off. Quite often
  tyres will burst or, as the aircraft comes to a standstill, ignite by
  transference of heat from the brakes. To avoid metal failure,
  firefighters attending overheated brake and wheel assemblies should
  usually refrain from applying water and allow natural cooling. If
  there is fire however, a fine water fog applied from fore and aft of
  the undercarriage assembly is generally used.


Is it possible to totally override the flight computer on the Airbus A320-family (in simple non-technical terms)? As I know, in the autopilot oriented airplanes like an A321 the plane doesn't let the pilots pitch down when the plane gets an over-speed warning.

So what if the pitot-static system isn't working properly and the plane is stalling but the flight management systems doesn't let the pilots pitch down?

What will happen? Will the plane crash or is there a button on the FMC that disables all the auto management and autopilot functions so the pilots can do whatever they want in an emergency?

How does it work without being too technical so someone like me can understand?

Autopilot vs FMS vs protection
The autopilot does not prevent a nose down, this task is done by the envelope protection, which is a different flight computer.
The FMS is what sends the autopilot commands, i.e., the autopilot is part of the FMS. The pilot interface with the autopilot is the CDU (which is basically a keypad and a screen), and the FCU (the autopilot panel on the glareshield).
When flying, it's either the pilot or the autopilot in control, it can't be both. (There are exceptions but this is to keep it simple.)
The commands of either are sent to a flight control computer, this is where the envelope protection lives.

Like any computer, there is input (stick forward), and output (elevator down).
The envelope protection has an additional input that comes from another computer, the ADIRU, and one of the ADIRU's inputs is the pitot-static system, so it can decide if pitching down is safe or not before sending the output.
If the ADIRU says the plane is over-speeding, the envelope protection will not pitch down.

What happens if the pitot-static is not working properly?

The engineers thought about your question, and decided to have 2 or 3 of each computer and pitot-static system.
The multiple ADIRUs are always chatting, making sure the inputs they get from each pitot-static system is similar. If they notice, by voting, that one of the data sources is not similar to the other two, the ADIRUs will tell the flight control computer, "our data is bad, don't trust it."
The advanced flight control computer will stop sending output and will disconnect the autopilot if it is engaged, then another simpler flight control computer will give more control to the pilots.
The pilots will be shown on their screens that there is an ADIRU issue, and from their training they will know what to do (memory items) to keep the plane from stalling (your example), and then they will run their checklists to make sure the ADIRU that is getting bad data is no longer voting. This is called a degraded fly-by-wire mode, i.e., not all the functions of the envelope protection are working.

The drawing is own work, which is a simplified version of the actual schematic.


As a plane gets slower, why does a certain bank angle make you turn faster? In the video "Maneuvering during Slow Flight" the narrator states that while flying slow the airplane will be less responsive to aileron and other control inputs. He also says that the plane will turn quicker at a certain bank angle than it would if the plane was flying at normal speed. My question is: why does the plane turn quicker when flying at a lower speed?

So basically what I am asking is, as a plane gets slower, why would it start turning faster then it was when in fast flight?

The part of the video I am confused about is at 1:16

Rate of turn is dependent on the following two items:

The horizontal component of lift (centripetal force)
The tangential velocity of the aircraft (true airspeed)

The rate or turn is directly proportional to the horizontal component of lift and inversely proportional to the tangential velocity of the aircraft.

For a given angle of bank, the vertical and horizontal components of lift will be the same, regardless of airspeed in level flight.

Consequently the airplane will experience the same centripetal acceleration, regardless of airspeed.

Since the tangential velocity is slower, any kind of centripetal force will produce a greater rate of turn for a slower flying aircraft as opposed to a faster moving aircraft and this can be shown by the centripetal acceleration equation

$$a_c = \frac{v^2}{r}$$

so both slow flying airplane with a true airspeed $v_s = 100$ knots and fast flying airplane with a true airspeed $v_f = 200$ knots experience the same centripetal acceleration.

$$\dfrac{v_s^2}{r_s} = \dfrac{v_f^2}{r_f} = 4\ \dfrac{v_s^2}{r_f}$$

or, $$\dfrac{1}{r_s} = \dfrac{4}{r_f}$$

Consequently  $r_s < r_f$; in this case $r_f = 4\ r_s$

Since the angular velocity is equal to the tangential speed divided by the radius.

$$\omega = v/r$$

the angular speed of the slower aircraft will be greater than the faster aircraft.

$$\omega_s = v_s/r_s$$

and

$$\omega_f = \dfrac{v_f}{r_f} = \dfrac{2 \  v_s}{4 \ r_s} = \frac{1}{2}w_s$$

So our twice as slow airplane turns twice as fast as the faster one does under these conditions.


What's the UX in modern airliner avionics for diversion choices, and does it integrate to autopilot? This question mentions a flight that had to divert, in that case to Iqaluit (YFB).

I was wondering: in modern large airliners, what is the user interface like when diverting? How is the case of "what is the nearest airport/runway we can divert to now?" handled in the avionics displays?

Does the computer system know at all times what the nearest runway or airport is? Does that information appear when needed, or perhaps it's just continually displayed and updated at all times?

Does the system understand subtleties such as which one is best based on your current heading, altitude and so on? Or do pilots just have to quickly look up the nearest one with no special help from the avionics?

Or, is it figured out for each stage, as part of the preflight planning? Do they have it written down as part of a flight plan? Or does the crew have to program in a list of suitable diversion airports along the coming route, and if the worst happens the system will tell you which one (of that set) is nearest now?

In fact, is there just a big red button marked "Divert Now", and the plane immediately changes course to whatever it decides is the nearest and/or best diversion prospect at that moment?

To be clear, I'm talking about how it works in this sort of cockpit:

(To a civilian, most modern airplane controls look like that: touchscreens with some sort of graphical user interface.)

There are a few options for this and it depends on the type of plane you are in, for the most part it looks like the information must at least be proactively navigated to in what ever NAV system you are using.

Every pilot should study their route before hand and identify possible diversions or at least understand where they are. For pilots flying common trans ocean routes there are some pre-arranged diversion airports that the pilot should know.

If you are using some kind of tablet as your source of navigation information (maps) most of the modern apps have a function for this.

If you have some kind of in panel GPS like a Garmin GNS system there is also a page for that very information.

According to this doc FMS systems may have this info as well. For example in the 737

  This extremely useful page takes a couple of minutes to calculate but
  will list the nearest airports in the database in order of DTG.

  Once again, line selection of 1R to 5R will give more useful diversion
  information as shown below.

(source)

You can also program in you alternates

  You can enter up to 5 alternates here, selecting 1R to 5R against any
  entered alternate will show the info below...

(source)

The FMS will compute data to those points from the aircrafts current location.

  All the diversion data is now shown based on you flying direct to this
  alternate from present position (VIA DIRECT). Selecting MISSED APP
  will show the same data but calculated from the missed approach point.
  Selecting nearest airports will give...

(source)

Even the more modern airbus cockpits contain a traditional FMS input or possibly a keyboard and mouse. To my knowledge airlines have not really adopted touch screens yet.

(source)

Some of the smaller panel avionics are starting to incorporate touch screens like Garmins GTN series however some pilots prefer the tactile feel of hard buttons.


Why do some airports not have ICAO codes? This is a follow up to my previous question What do numbers signify in airport codes?

In that case, I was asking why my local airport (Markham Airport) had a number in its code (CNU8). I later learned that the code was not really a code, but a Transport Canada Identifier.

This leads me to my question, Why do some airports not have ICAO codes? At my local airport, there is plenty of glider activity, and a flight school is also located there.

My main thoughts for the airport not having a code comes from the lack of an Air Traffic Control Tower. When declaring a landing, pilots have to do declare it on Traffic, which doesn't have a controller. It looks something like this (based on memory, I'm not a pilot but I hope to be one):

  Markham Traffic, Aircraft Papa Lima landing on the grass strip beside whatever runway

Am I correct in assuming that airports without ICAO codes don't have codes because of the lack of a control tower? Or is there other reasons for this?

There is plenty of information on the Internet on how certain and specific identifiers came to life, however the codes are sometimes not directly assigned by ICAO, but by the member nations.

  ICAO Document 7910 - Location Identifiers contains codes allocated by national governments, on behalf of ICAO, to airports, airfields and other facilities such as ATC and weather stations.

Ultimately, it is the national CAA's or other authorities' decision whether to assign a code and get it validated through ICAO. The decision may be based on political, historical or other reasons, there is no minimum requirements for airports to receive an ICAO code.

  Am I correct in assuming that airports without ICAO codes don't have codes because of the lack of a control tower? Or is there other reasons for this?

The availability of a control tower is not a requirement for ICAO codes, even small uncontrolled fields with grass strips can have an ICAO code, example: EDKW / Werdohl-Küntrop (600m grass / uncontrolled / PPR)


What is the meaning of these slang terms used in ATC? I have heard some slang terms used mainly by ATCs:

follow the black holes
taxi not too deep
how is your ride

What do they actually mean and are there others?

Follow the black holes

I have no idea about this one. I looked at the airport diagrams and arrival/departure procedures for MIA, MCO and ORL and I couldn't see anything that seems like it could be confused with the words "black hole". So, I have two guesses:

It's the code name for a set of local taxi instructions
As you suggested, it's the controller's slang for "the twin-engine aircraft in front of you", i.e. the black holes are the exhausts

I think the second possibility is very unlikely, though. A controller at a major international airport - which implies many pilots with English as a second language - is unlikely to use non-standard phrasing for a critical instruction like which aircraft to follow.

Taxi not too deep

This one is a lot clearer from the updated comment you gave: "CLEARED PUSHBACK, NOT TOO DEEP, THERE IS A TRAFFIC PASSING BEHIND YOU". That's exactly what it sounds like: the aircraft was cleared to push back from the gate, but the ground controller was warning the pilot not to push back too far ("too deep") because of another aircraft passing behind.

How is your ride?

This one is ATC asking a pilot for a PIREP. That could be because another aircraft nearby is in turbulence and trying to find a smoother altitude, so the controller asks other aircraft about the ride at their flight levels. Or, since you heard this in the US, it could be for this reason, from the AIM section 7-1-20:

  FAA air traffic facilities are required to solicit PIREPs when the
  following conditions are reported or forecast: ceilings at or below
  5,000 feet; visibility at or below 5 miles (surface or aloft);
  thunderstorms and related phenomena; icing of light degree or greater;
  turbulence of moderate degree or greater; wind shear and reported or
  forecast volcanic ash clouds.

Are there other examples of slang?

I'm sure there are, although slang in general is discouraged because of the potential for misunderstandings. The FAA has a pilot/controller glossary to make sure that everyone is using the same words and phrases as far as possible (ICAO provides one too), but that doesn't mean that people always stick to it 100% of the time. Ex-military pilots - and controllers - in particular sometimes use some military terminology (e.g. bingo fuel) out of habit (presumably) even though they really shouldn't in a civilian setting.


Could the Perlan II glider be used for nearspace tourism? I asked the same question about the SR-71 Blackbird, and I'm also curious about the Perlan II sailplane which travelled above 70,000 ft, and is planned to be flown to 90,000 ft, if it could be used for nearspace tourism and what some issues might be with that. Its starting location would have to be near a high enough mountain range where it can use enough lift to climb that high, and this is best at certain times of the year I guess. A major advantage would be that this form of nearspace tourism would be 100% environmentally friendly (for those who bother).

No, Perlan II can't be used for tourism.  It has only two seats, and every description of it talks about the crew of two, or the two pilots, or the chief pilot and co-pilot.  Someone who gets certified for the type and carries that much responsibility isn't called a tourist.


Is there an API to retrieve airport departure and arrivals? I am looking for an API to get the arrivals and departures timetable for any airport in real time, like this table on the EuroAirport website:

Are services like FlightAware or FlightStats relevant for me? I am a non-native English speaker so airport-specific language is a bit tough for me, I am not sure I fully understand what those APIs provide.

Edit : paying APIs are okay, I have a budget of around 100€ a month for this project

It appears that Flightaware does have an API (both SOAP and REST) that would satisfy your needs.

Here is the documentation, see "arrived", "departed", "en route", and "scheduled".

Here's a code example from that page that gets data on flights en route to JFK and KSMO (this fits your arrivals criteria no?):

That said, you'll probably want to experiment with the API once you create an account and get a key to see if it meets all of your requirements.


Is there any disadvantage to having the de-icing system on? I was watching Mayday S11E02 about West Caribbean airways flight 708 and the pilots turned off the de-icing system partway through the flight. It's not why it crashed, but I was curious as to if there was any disadvantage to having the de-icing system on.

The wikipedia article already linked in the question says:

  The system uses power from the engines, thus reducing their maximum performance. With the anti-ice system on, the highest altitude at which the overloaded aircraft could fly – without stalling – was reduced to 31,900 feet (9,700 m).

The de-icing system on most turbine aircraft (including MD-82 involved in that accident) uses bleed air from the engines, that is it extracts some air from behind the (low pressure stage of the) compressor. This air is therefore not ejected from the nozzle and not producing thrust, so the thrust is reduced. Or fuel flow rate increased if thrust levers are advanced to compensate, provided the engines are still below their maximum permitted thrust setting. Either way fuel consumption per mile increases.

Compressing air increases it's temperature, so this pressurized air is simply blown through tubes under the critical surfaces. There are other uses of bleed air, mainly pressurization and air-conditioning, but turning on deicing increases it's consumption significantly.

And note that this switching de-icing off and on was part of the accident sequence. It was only because they turned de-icing off that they were able to climb to FL330 in the first place.

It is also often not allowed to use de-icing when outside temperature is higher than some value because the heated surfaces could overheat.


Why are these rivets on the 777 so visible? Look at this 777 nose:

Source: Airliners.net

It is full of rivets.Why are they so visible on this particular aircraft? Why doesn't the radome have rivets?

At the risk of sounding ridiculous, the purpose of the rivets is to hold the plane together. More specifically, they hold the outer aluminum skin to the structural skeleton of the aircraft:

(That skeleton happens to be made of manilla folders, but the real one is pretty much identical except that it's bigger and made of metal.)

There are also additional rivets around things like the AOA vane, holding doublers in place to stiffen the skin where these instruments penetrate and create additional load.
The radome has no rivets as it is a single molded piece of plastic. It does however have structural stiffeners, which you can see running fore-to-aft in the photo.

You can see the rivets clearly on this particular aircraft because of the paint scheme (all white) and lighting, however if you look closely you can spot them on any 777 nose.
Here's one from an aircraft during assembly, and as the interior has not been installed you can also see the skeleton through the windscreen openings:


What is the function of cross bracing of interplane strut? Pic 1 is the top and lower wing of a biplane called Bloop Ultralight,what is the function of the cross bracing between the interplane struts  as seen in pic 1(I'm not talking about landing and flying wire)?

Is it there to resist wing twist?  If yes, why is it not in between the interplane struts closer to the wing tip since wing twist and torsion is greatest at the wing tip?....as seen in pic 2

The cross bracing is to prevent the upper wing collapsing onto the lower one, the Bloop is an ultralight without the fuselage that the wings are normally attached to.

The two wing struts are in parallel and together with the parallel wings form a shape which must be cross-linked.. The bracing is for defining and retaining the structure and shape of the wings relative to each other, not to compensate for wing twist.

In the OP picture I cannot see any evidence of wing twist, only a constant wing incidence. The bracing wires need to be inboard only where normally the fuselage provides shape definition: in a classic biplane, there is no cross wiring required at the outer struts.


How are STCs granted for similar aircraft? Archer vs Arrow I'm specifically interested in the Garmin GFC 500 autopilot certification, but this question can apply to any STC question.

The GFC 500 is certified for a ton of Archer (PA-28) variants, but no Arrow (PA-28R) variants, and Garmin doesn't seem to have any plans to certify the Arrow. Since the Arrow (201) and Archer (181) are the same airframe, the only difference between them is the engine and the landing gear as far as I can tell. Why would the work put into certifying the PA-28-181 not basically cover also certifying the PA-28R-201?

When getting an STC, do you have to start the entire process from scratch for every variant of every aircraft you're trying to get an STC for?

Having been involved with several FAA STC's for GA and airliners I can pass on my experience. Additional FAA information is available in FAR part 21, 23, 125 and here.

First, transport, airliner's, etc are not held to the same rules. The FAA generally considers the engineering department of aircraft manufactures such as Cessna, Boeing or Aerobus to know what they are doing and pretty much rubber stamps anything they come up with. What they are mostly looking for is performance and operational documentation.

[ For 5yrs I was part of a Boeing team that primarily modified doors such as cargo doors for special purposes. We installed and verified or corrected engineering drawings for the modification and approval process. FYI: when I wasn't doing that, I did the final ramp, taxi and opps check of aircraft before their first flight out of Everett WA.]

GA aircraft STC's are administered by the regional FAA office (FSDO) and the process is highly dependent on the region and personal inspector. (The FAA says it's standardized, but it is not.) For example many float planes are flown all the way to Alaska to get approvals because the Anchorage regional office is experienced and generally more permissive than other offices.

Typically the FAA reviews the applicant against new product standards and expects the applicant to provide the "same as" level of safety found in FAR part 21, 23, and 125. With the new "industry self policing" policy passed last year, all bets are off on how it will be done in the future.

I have seen STC's approved with as little explanation as "performs equal to or better than original equipment..." on high performance Alaska Borer props, vortex generators, lights, antennas, gauges, etc with very little or no other data. In 2000, the Alaska FSDO changed from pencil whipping strobes (i.e. ...it works fine on 3000 other Cessna 172's..), to requiring 3 page form that includes a illumination profile chart to be filled out! The A&P's started a revolt and I don't know what happened, I moved three years later to work for Boeing in Seattle.

EXAMPLE: I assisted an Alaska company in a fuselage battery mount. I took a damaged C-180 and removed the tail surfaces and separated the fuselage aft of the cabin. I then hung a 25"G" horz weight (later 7G vertical) from the battery CG for 5min and took a picture. I certified the test and submitted it and received approval. I then took that approval and resubmitted approval for all applicable aircraft with the same skin thickness (individual W&B was calculated for each installation). It took about 6mo for the first approval and an additional year for about 15 additional aircraft to became STC approved. The company estimated it cost around $20-30k.

It often depends on the whim of you local FSDO. One of the reasons Wichita Kansas is a popular place for manufactures is the FSDO office is notorious for ignoring FAR regs. A good example is one FAR says "...every part large enough to be identified must have a unique part or serial number". Try to find a serial or part number on control columns/sticks, rudder peddles, flaps, wings, ribs, bell-cranks, etc. There are AD's on Cessna parts such as gauges but they don't have a part or serial number! An A&P can't write, I complied with the AD by replacing part "x" with new part "y"! (what some A&P's do is use the parts manual number, but the parts manual is not "approved" data by the administrator.)


How do I calculate aircraft range with these parameters? The parameters are:
MTOW, MLW, MZFW, OEW, maximum fuel weight, fuel flow rate and true airspeed. Measured in lbs and kts. Not given drag so unsure how to apply Breguet equation. Trying to construct a payload range diagram!

If the fuel flow rate and the true airspeed are for the same polar point, the answer is easy. You cannot, however, determine if this is your maximum range because you do not know any other points of the polar.

Your fuel consumption is MTOW - MLW. The flow rate will give you the flight time when you divide the fuel by the flow rate. With the flight time you can calculate the range by multiplying it with the airspeed. Hint: Convert all data into metric first so you don't screw up the calculation.

The maximum range can be done the same way using MTOW - MZFW for the fuel mass. MZFW - OEW will tell you how much payload remains at this point. The only impossible part is the transfer range point - use the maximum range and assume that the aircraft will fly as far with a lower take-off mass as with MTOW.

The Breguet equation will not work in this case.


How long does downwash last? I think most of us know how lift is created. Air is deflected downward because of the shape of an airfoil.

How long does downwash last, is the air going to flow downward forever or will it climb back up to leveled degree? If so how long would it take for the air to get back on its normal flow path, which is not downward?

Like everything else, air will be accelerated either upwards or downwards if a force is applied to it. The aircraft's wing applies a downward force to the air mass thus accelerating it in that direction. However, nothing applies an upward force to that mass of air, so it can be assumed it will not climb back up.
(I am neglecting the formation of vortexes and possible differences in air density)

The velocity of the mass of air will be reduced by friction with and the inertia of the surrounding air until it comes to rest.

What you call the "normal flow path" of the air is it simply being still before an aircraft flies through it.


What qualifications or training allow a test pilot to fly a new aircraft? What makes a test pilot a test pilot? I'd imagine recovery from unusual attitudes is a must, but aerobatic pilots can do that as well. What training does a test pilot go through, that is unique and not taught to general pilots, makes that person a better candidate to test-fly a new aircraft with uncertainty in its aerodynamics?

All commercial or military test pilots attend either a DoD or ABET approved test pilot school.  The military has two said achools: the USAFTPS at Edwards AFB in Muroc, CA and the USNTPS out at NAS Pax River in MD.  There are at least two test pilot schools who train civilian pilots that I know of: The National Test Pilots School in Muroc, CA and Empire Test Pilot School in the UK.

Qualified applicants need to possess at least a commercial pilot's certificate and at least 750 hours TT, plus possess at least a bachelor's degree in engineering, physics, or related technical discipline.  Military programs are very competitive and sought after; TPS slots can pretty much guarantee a job with major aircraft OEMs doing test pilot work after their military service ends.  Outside of the military you will probably need some kind of corporate sponsorship to attend as it is very expensive. The NTPS Masters of Science in Test piloting in an 11-month course costing a whopping $960,000 to attend!

The courses in a TPS are graduate level type classes.  The NTPS curriculum can be found here.

Hollywood portrays test pilots as these outlandish, devil-may-care guys with brass balls and ice water running in their veins, but the truth about most test pilots and flight test work is pretty boring by comparison to the movie image. Test pilots are first good system engineers, second skilled aviators and third calm and collected under pressure. Test flying itself is much more about planning - and planning for contingencies and contingencies for those contingencies  - than the actual flying itself.  Test flying is conducted according to more or less a rigid schedule developed by a flight test department.  A test pilot will fly the aircraft through specific test points and is expected to maneuver the aircraft in a very precise way - precise control inputs, precise altitudes, air speeds, angle of attack, flight maneuvers, etc. In order to collect test data for the flight test team.  The test pilot is also expected to be able to correctly evaluate how the aircraft or systems handled.  Also needed is an ability to accurately describe discrepancies in performance and handling to design engineer teams to correctly determine the root cause of these issues and address these problems correctly.

Safety is also paramount for doing flight test work.  Long gone are the days of strapping your little pink fanny into a crate, pushing it off a cliff and hoping for the best on the way down.  Test plans are thoroughly evaluated prior to flight for risks, mitigating factors and means to minimize those risks - and contingency plans should something go wrong.  I once heard a USN test pilot put it "we try to make the process as boring as possible."  Many test points will be attempted in simulators prior to the actual flight test and test pilots will have flown them many times, complete with conducting emergency procedures there.

Most test pilots don't even do experimental work; often times they are involved with manufacture flight test work.  This is usually involves simply testing all the systems of an existing production sample aircraft.  Other jobs test pilots are involved with are testing of new avionics, weapons, or mission systems aboard existing aircraft as part of the approval process for its use.