What type of airfoil do low-supersonic aircraft use?

Normally, supersonic fighter wings for which airfoil information is published use a very thin NACA 6-series section with very little camber, such as
Aircraft                root airfoil      tip airfoil
McDonnell Douglas F-15  NACA 64A006.6     NACA 64A203
General Dynamics F-16   NACA 64A204       NACA 64A204
Lockheed-Martin F-22    NACA 64A?05.92    NACA 64A?04.29

This information is from The Incomplete Guide to Airfoil Usage by Dave Lednicer. As you can see, the F-16 uses camber throughout, indicated by the 0.2 design lift coefficient of the airfoil, while the F-15 uses an uncambered root airfoil.
Those airfoils are chosen because flow around them at supersonic flight speed is still heavily influenced by subsonic flow characteristics* as long as wing sweep allows for a subsonic leading edge. This produces nose suction which is very helpful to keep drag down. Delta wing aircraft enhance this nose suction by cambering the outboard leading edge (conical camber).
Common to all supersonic wings is their minimization of wing thickness, because wave drag will grow with the square of thickness. Typical sections use a relative thickness between 4% and 6%. In case of the F15, thickness varies between 6.6% at the root and 3% at the tip.
Supercritical airfoils work best in a narrow Mach and angle of attack range and are used for transsonic designs (flight Mach number between 0.7 and 1.0). Fighter aircraft with their wide variety of speeds and angles of attack will rarely profit from using them. The strongly negative pitching moment of supercritical airfoils (resulting from rear loading) makes them unsuitable for most fighter designs.
Supersonic airfoils are reserved for designs with a supersonic leading edge, like the F-104 or X-15 wings and tail or the XB-70 canard. They are only used if top speed exceeds Mach 2.2 and the sweep necessary for a subsonic leading edge would be too high for decent subsonic performance.

* For those with a severe problem of reading comprehension: Of course the flow over a swept wing is supersonic when the airplane moves at supersonic speed. Only the behavior of the flow is like that at subsonic speed as long as LE sweep is higher than the Mach cone angle.


How does ATC ask a pilot to resume flying a published SID / STAR?

More than likely they give you vectors to fly to get you back on course, or have you proceed directly to the next waypoint. Really depends on where you got turned away and your intended direction of flight afterwards.


The FAA's advisory circular on Airport Foreign Object Debris (FOD) Managament mentions plastic bags and other trash as a type of FOD and says these are the dangers:

  FOD Hazards.   FOD can severely injure airport or  air carrier personnel or damage  equipment.  Types of potential damage include: cutting aircraft tires; being  ingested into engines;  or becoming
  lodged in mechanisms affecting flight  operations.  Personnel injuries
  or even death  can occur when jet blast propels FOD through the
  airport environment at high velocities.

Since you're asking specifically about airborne items, that would mean the most likely dangers from that list are engine ingestion or "becoming lodged in mechanisms affecting flight operations".

The main issue with a plastic bag seems to be that it damages the engine, rather than stopping it entirely. This paper recommends an inspection if any "soft material" (including plastic bags) are ingested:

  Remains on impellers and/or LP diffuser exit ducts confirm a bird or soft material has passed through the Engine and possibly
  contaminated the secondary air system, fuel nozzle and HP turbine vane
  cooling air passages.
  If contamination occurs, hot section components deteriorate rapidly, increasing the cost of refurbishment. Therefore, operators are
  recommended to carry out a hot section inspection (HSI) as soon as
  possible after a bird strike or ingestion of soft material is
  confirmed

As for affecting flight instruments, the main danger is probably that the bag covers the pitot tube, resulting in false airspeed readings. That can be catastrophic if the pilots don't realize what's going on, but many larger aircraft have multiple pitot tubes so it would probably need a lot of plastic bags (or a lot of bad luck) to cause an accident. And a bag stuck on the windscreen could block a pilot's view but if there are two pilots then that shouldn't be critical.

Of course, all of the above applies to airliners. If you fly a light piston single through airborne debris the results could be worse because of the lack of technical (and perhaps crew) redundancy.


What is an example of a system like MCAS?

Irrespective of 737 MAX MCAS, I haven't seen similar decision relying on a single sensor on 777 or on 757.

Similarly I found nothing similar on Airbus 320, 330, 340, 350, or 380. On these Airbuses, 3 sensors are used for critical decisions, thus the faulty sensor is isolated by voting the data. If the 3 sensors are diverging (no 2 sensors giving similar data), the system goes into safe degraded mode, and the pilots are informed by automatic displayed message.


Let's suppose we had to convert a commercial aircraft to an all electric craft tomorrow and use all the available parts, batteries, thrust devices and airframes becoming available, as well as take off and land on conventional runways, with a typical payload etc, would this thing fly?

This amount of specificity makes what would normally be pretty silly into something that can, if only just, work for a question.

The best aviation-specific electric engines are only somewhat heavier per unit weight (but much less powerful in absolute terms) than the best turbine engines, and will make up for it in using bus bars and distribution boards instead of extensive fuel piping, heating and pumps.

You could not simply stack a lot of small electric engines under the wings, as that would ruin the aerodynamics - the wing couldn't produce any lift due to fast jet air flowing under it. It would either have to be an all-custom design, or the engines would have to replace the turbines directly. Such engines are not currently available, but, with superconducting rotors and stators, are potentially achievable within the next decade.

Per calculations done here based on the Breguet equation, a perfect electric airliner will fly up to 10 nmi for each 1% of its weight that is dedicated to the battery. More precisely it's 9.9 nmi at a 0-100% discharge cycle with 100% efficient fans. A more realistic but still optimistic number is 7 nmi, with less than perfect fans and allowing for a 20%-95% cycle that accounts for degradation and emergency reserves.

At takeoff, the A380 can carry up to 254 metric tons of fuel, but that would only leave 44 tons for the payload, supporting up to 400 passengers, and its maximum landing weight would require less than 100 tons of fuel aboard.

Assuming the hypothetical electric 380 is reinforced for a MLW equal to MTOW (575 tons), and counting on savings from general modernization and removing the fuel system to absorb that reinforcement weight, a more realistic battery weight is 230 tons, allowing for a 68-ton payload, supporting the usual 600-passenger capacity. This makes for a 40% battery weight, and thus approximately 280 nmi or 520 km operational range.

So the short answer is: if electric engines with similar power and size to the Trent 900's cores can be produced, the airplane will fly, but its operational range would be just ~500 km, less than 4% of what the current A380 is capable of.

Practically, you would not use an A380 to fly short distances, due to its complexity in ground handling of the two flight decks. There was the Boeing 747SR, built just for the Japanese domestic market, to save on airport slots. The largest plane you'd use has to be something versatile and quick to load and unload, such as the A350 XWB.

But there are short routes for small aircraft 1that are simply begging to be electrified, and if the legacy factor and lack of infrastructure don't interfere, they likely will.


Help in decoding this ATC instruction with landing clearance?

B. After the United 737 lands another aircraft will take the runway and depart prior to American 245 landing.
They may not call out what type/make/airline the departing aircraft is. I’ve heard them say ”Company departing prior to your arrival” if the traffic is the same airline though.

FAA JO Order 7110.65W
3−10−6. ANTICIPATING SEPARATION
a. Landing clearance to succeeding aircraft in a landing sequence need not be withheld if you observe the positions of the aircraft and determine that prescribed runway separation will exist when the aircraft crosses the landing threshold. Issue traffic information to the succeeding aircraft if a preceding arrival has not been previously reported and when traffic will be departing prior to their arrival.


The accessory gearbox is generally driven by the N2 shaft (connecting the high-pressure turbine to the high-pressure compressor) and in turn drives the engine accessories such as generators, hydraulic pumps, oil pumps, etc.  The air turbine starter is also part of this gearbox so during starting the accessory gearbox drives the high-pressure compressor.

This analogous to the serpentine belt on your car, which connects your crankshaft to your cars engine accessories (alternator, water pump, power steering, air conditioning, etc).


Yes, you have to fly the hold.
If you're cleared for the approach, but you're not getting vectors to the final (or one of the other things you mentioned), the approach begins at the Initial Approach Fix (in this case, TFD) and you need to fly the full procedure, which will include the hold.

No, the missed approach point is 1,743 MSL (It's 7.5 DME for a localizer approach)
This is an ILS approach, so you go missed when you arrive at decision altitude and don't have one of the three required elements to descend further:

Visibility
Safe descent to landing
At least one of the required runway environment elements in sight

If you're shooting it as a localizer approach, you go missed when you cross the localizer and the needle flips. at 7.5 DME, a maneuver which is badly illustrated on this chart.  Thanks TomMcW!


What is the fuel burn of the APU on the CRJ900?

It's surprisingly hard to come with that sort of data.  It's hard to come up with a fuel burn number because the fuel burn varies widely, because the loads vary widely, between electrical loads and bleed demand.  However, it's not too hard to come up with a theoretical maximum and estimate from that.
The best way to make an educated guess is to take the baseline HP rating of the Honeywell RE200 APU used in the CRJ7/900, around 325 hp, and work out the fuel burn at maximum power from the typical specific fuel consumption of turboshaft engines, which is somewhere around .5 to .6 lbs/hp/hr.  Say to be conservative, we'll use .6 lbs/hp/hr.
So wide open, the APU will be burning .6 x 325, or just under 200 lbs/hr.  It might get close to that if you are running all of the electrics off the APU gen and both packs.
Normally however, the demands are going to maybe 1/3 to 2/3rds of that.  If it's idle, it might be burning 30-50, and with bleed loads due to running the AC packs, maybe 100-150.
So I think you could use 100-125 lb/hr as a ballpark value when you want to allow for fuel used by the APU while on the ground and providing air conditioning and powering the electrical system. Or if you just want to assume the worst case and go by that, for an hour of sitting on the ground with the APU running everything, you can safely assume it's going to use not more than 200 lb of fuel.


What are the aerodynamic design principles behind the "supersonic" propeller of Luigi Colani's C-309 racing plane?

Looks like the Colani Museum has picked up my question on Twitter and posted a response later with an archive photo of an advertising article:

The English part of the article says about the propellers:

  Since 1976 we have been investigating sharply cambered pusher and tractor propellers which maintain supersonic flow over part of their top surfaces.

In contrast, the German translation says:

  Since 1976 we have been investigating strongly forward-swept pusher and tractor propellers.

So this sounds to me like they were simply looking to develop strongly forward-swept propellers with a supercritical airfoil. Aesthetics almost certainly also played a role in the design.


What is the difference between inboard and outboard engines on a Russian IL-18 turboprop?

The inboard cowlings seem to follow a different design structure in order to make room for the landing gear compartment. The air intakes are moved aft on the outboard cowlings.


Is propeller wake turbulence quantifiable based on operating conditions?

As a rule of thumb, use fully turbulent flow at the elevated speed of the propeller wake on all surfaces wetted by it. The speed increase will result in higher friction drag compared to the propeller-free case and results in a drag increase that looks about right.
A very interesting paper on the efficiency of an installed propeller can be found here. By comparing the gliding qualities of a Luscombe 8E with drag in level flight, the authors measured the drag increase of the airframe caused by the propeller wake. A drag increase of 30% from the propeller effect was measured, resulting in an overall propeller efficiency of only 62% when the propeller alone had an efficiency of 81%. The paper cites another result where the installed propeller on a Bellanca showed only 58% efficiency, but the paper is unavailable on the Web.
For pretty pictures you can consult this paper which analyzed the propeller wake - wing interaction on a C-130 J with 6-bladed Dowty propellers using CFD. The picture below is taken from this paper and shows surfaces of the same vorticity.

CDF simulation of propeller-wing interaction. The tip vortices of the single propeller blades can be seen impinging on the wing surface which suggests that local flow speed will vary with the frequency of the propeller wake hitting the wing. Also, the local turbulence is higher on the side of the down-moving blade. However, most of the wing surface shows only a minor increase in local turbulence, judging from the vorticity of the wing wake. Note that the engine air intake - nacelle intersection contributes a wake of its own which technically must be added to the propeller effects.
However, I doubt those details can be accurately subsumed in a simple rule of thumb; therefore I recommend to use a constant, elevated flow speed on all areas wetted by the prop wake.


Is there absolutely any way (hook or crook) to listen to ATC in India, especially Bangalore?

In principle you can listen to ATC of VOBL (Kempegowda International Airport, Bangalore) using a VHF air band radio receiver on the following frequencies:

Tower: 124.35 MHz
Ground: 121.65 MHz
Approach: 121.25 and 127.75 MHz

It is however illegal to own such a receiver in India:

  Prohibition of possession of wireless telegraphy apparatus
  without licence.—Save as provided by section 4, no person shall
  possess wireless telegraphy apparatus except under and in accordance
  with a license issued under this Act.

(The Indian Wireless Telegraphy Act, 1933, emphasis mine)

There used to be coverage of Mumbai ATC on liveATC.net, but according to this thread on pprune.org it was shut down, presumably because it is illegal to pass on ATC transmissions in India.

See also:

Is it illegal for Joe Public to listen to ATC in the UK?


What are the areas of an aircraft that suffers most from G forces?

Basically 3 places on an airplane see very high concentrations of stress in a small area from in-flight G loads.  In this case we'll say a single engine light aircraft.

Wing root spar fittings on a cantilever wing - the bottom in tension and the top in compression. For a high wing airplane with struts, it will be the strut attachments at each end that join the strut to the fuselage and wing.
The roots of the horizontal tail, same except upside down - bottom in compression and top in tension.
Engine mount attachment to the firewall - top mount in tension and the bottom mount in compression.

Those are the points where flight loads from a lot of mass are concentrated at a single point or set of points during high G loading and are where the structural elements will be heaviest.  For most other areas the loads are distributed over more of a large area.


Would it be frowned upon that with a uncommanded nose up, the pilots just do a full loop?

No airliners aren't stressed for loop maneuvers.  The proper action for that kind of extreme pitch attitude is to roll 90 degrees and let the nose fall, then roll level as the horizon is passing.  Of course if you had a nose up stab trim runaway that left you stuck with that pitch tendency (effectively a much lower trim speed), you're back to square one.

You have to slow down to as close as you can get to the trim speed that the nose-up-stuck stab wants to fly at.  You might find that you have enough elevator authority to maintain a level pitch attitude if you get the speed down to a minimum flaps up speed, say 180kt.

Then you can do other things to create a nose down pitching moment, like dropping the gear, and on most airplanes, extending flaps.  That should be enough to remove most or even all of the elevator input required depending on where the stab was when you killed its runaway.  In an extreme case where you've run out of options, you might even try getting passengers to move forward.

In recurrent sim training, a nose up stab runaway was always a more pleasant exercise than a nose down one.  Mostly because slowing down, and gear and flaps helped, and to the extent you had to hold continuous nose down elevator, one of you could brace your knee against the column to help with most of the push force and it was easier to hold it for extended periods.  A nose down stab runway was a much more difficult situation.


Why do delta-wings perform so well on paper airplanes?

Your interpretation of the answer to that question is a bit wrong.

It would be an error to claim that delta wings don't perform well at low speed. Delta wings perform exceptionally well at low speeds.

The correct interpretation is delta wings are not fuel efficient. And this is true at low and high speeds.

There are advantages to delta wings at both high and low speeds. The following list are some of the known advantages:

Improved handling at high Mach numbers due to swept leading edge (note: this is the same advantage as swept wings but with the down side of being draggy when performing manoeuvres - swept wing planes retain much more kinetic energy after a turn).
Intrinsically strong structurally (it's a triangle!) thus can be built much lighter.
Retains quite a lot of rudder effectiveness at low speeds and high angles of attack (this is unintuitive because you'd think the wing would block airflow to the rudder but the strong vortex shedding on the leading edge maintains flow around the rudder).
Have very wide CG range compared to conventional aircraft. This is especially useful in bombers.
Have very benign and gentle stall behaviour. This is especially useful for paper airplanes since it can prolong flight at low speeds (paper airplanes simply dip their noses and regain speed instead of simply diving and crashing).

The major disadvantage is that it is draggy. Thus not fuel efficient. Thus in a business world where profit and cost matters delta wings are not attractive.

For supersonic flights the drag is apparently roughly on par with swept wings. Except, as mentioned above, due to the geometry of the wing it can be built lighter thus save fuel - so it sort of cancels out.

For toy planes, where efficiency is not of great concern (fun and "cool" is more important) delta wings are OK.

Still, if you use the same sheet of paper and built a long, narrow, cambered wing like this:

.. you'll find that the long narrow winged plane flies much further than the delta wing paper airplane given the same launch speed.


In case of a drone strike with an airplane below 400 feet, who is at fault?

The FAA has some rules pending about this, you can read them here but for drones under 55 LBS one of the proposed rules is,

  Must yield right-of-way to other aircraft, manned or unmanned.

and since you bring up class E it should be noted that

  Operations in Class B, C, D and E airspace are
  allowed with the required ATC permission.

if/when this goes through it looks like its the drone operators fault since the plane had the right of way

According to the FAA's website in relation to model aircraft they state that,

  (4) the aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft;

this is pretty much a blanket statement that maned aircraft have the right of way but the FAA handles most things on a case by cases basis so in the end of the day it could go either way.


In a non-symmetric turn, how do the side slip angle and thrust side slip angle affect the equations of motion?

Relying on physics, causing a mass to execute a circular path requires a suitable centripetal force. In an airplane in a banked balanced turn, this comes from the inward component of lift due to the bank angle.

However, if the turn is not properly co-ordinated, there can be additional contributions to the centripetal force from the power plant thrust no longer being directed tangentially and sidethrust on the airframe due to slip.

The extreme case is the flat turn where the wings remain level and the power plant thrust has an inward component due to the sideslip.

That said, apart from an airplane having vectoring thrust, the only reason for a thrust sideslip angle I can think of is that many single airscrew airplanes have built-in sidethrust to counteract engine torque. However there is no requirement for the engine sidethrust angle to equal the slip angle, so in that case the assumption that the two angles are the same cannot be valid.

The thrust line of an airscrew doesn't change with slip. The slip causes asymmetric thrust on the blades which precesses gyroscopically so the airscrew creates a couple which tends to increase the slip angle.


Do aircraft designers gather real data to confirm their design (CFD, wind tunnel) data?

What tools and techniques are used to get real data test to confirm the values that are obtained by computational fluid dynamics (CFD) calculations and wind tunnel testing?

During development wind tunnels and model tests confirm the validity of CFD results.
Usually one prototype is used for stress testing with special rigs which simulate flight loads. This testing will cover the full life of the aircraft, measured in flight hours, and will accelerate ageing by using higher than usual loads.
Once you have a flying article, test flying is used for validating the design. A new design is first flown by a certified test pilot and normally instrumented with telemetry so engineers on the ground can follow what happens during the test flight. While the first flight is done at low speed, successive flights will expand the flight parameters (speed, load factors, rotation rates) until the whole operational envelope has been covered. This is called envelope expansion and will eventually cover stalls, spins, overspeed and flutter conditions. Military aircraft will also test all planned external loads and their separation in flight.

Is this standard procedure for all aircraft before going into production?

Yes, this is the certification process. Unless a design is certified, it may only be used in a limited way. Commercial use of an aircraft requires a certification.


Are jets deliberately excluded from the "Complex airplane" definition?

All jets require a type rating. Therefore you don't need the complex endorsement directly (other than needing it likely for your commercial checkride, which requires a complex aircraft). The historical training progression is: simple prop, complex single engine prop (requiring the complex endorsement), high performance (200 hp+, though this one is sometimes not gotten), light multi-engine props, and then finally moving into heavier turboprops and then jets which require type ratings.

Note, my answer is FAA specific, and other agencies might have different rules/interpretations for this issue.


It is (or was - I'm not sure) relevant because it is limiting:

The touch-down zone RVR is always controlling. If reported and relevant, the mid point and stop end RVR are also
controlling. The minimum RVR value for the mid-point is 125 m or the RVR required for the touch-down zone if less,
and 75 m for the stop-end. For aeroplanes equipped with a roll-out guidance or control system, the minimum RVR
value for the mid-point is 75 m.
Note: “Relevant”, in this context, means that part of the runway used during the high speed phase of the landing down to a speed of
approximately 60 knots.

source: JAR-OPS 1.405 - 1.0.5 (f)
The significance, I suspect, is because it's useful to be able to see where you are going when moving at high speed along the mid section of the runway and in manual control of steering.


Can the commercial night cross country be done under IFR?

The regulation doesn't specify VFR or IFR, so you may complete that requirement in either.


How many parts does the latest-generation 737 share with the original 737?

The cross section and cabin pressure have remained the same. From what I can tell virtually every part is different. Even parts that might have been able to retain the same shape/loading have gotten improved materials and/or corrosion treatments. I am still looking to see whether any window panels could be common as the holes into which they go have remained the same.

Looking at a couple of generations shows major differences, allowing elimination of whole sections of the aircraft. Wings, tail, engines, pylons, landing gear, fuselage center sections, APU, interior and flight deck have all surely changed.

Originally conceived as a 60 seat jet, the first production model was designed for 100 seats.

The Max10 now goes to 230.

The Max also had major improvements to the the cockpit. Even the throttle levers changed. Here is a photo comparison to the original -100 flight deck.

b737-100

b737-max

NG changes, both structural and cosmetic.

larger wing with new flaps slats
larger tail with improved rudder and elevator
simplified higher capacity landing gear
engines
new AC electrical system
new corrosion resistant materials and treatments throughout the plane
new interior seats, panels, bins, coverings
improved avionics


What do firefighters do on ordinary days?

Calling them "firefighters" is accurate but they can respond to all sorts of incidents, not just fires (in the USA, even outside airports it's common for firefighters to respond to purely medical emergencies). On top of that, there's also training, maintenance and keeping physically fit.

This is from a firefighter at Hobart Airport in Australia:

  The aviation firefighters do more than wait for airplane fires, they
  also attend to other incidents, such as motor vehicle accidents, fuel
  spills, hazardous material incidents and first-aid in the terminal.

  [...]

  "A lot of our working day is routine and there are different types of
  things that we need do every day regarding our equipment, servicing
  all of our equipment, checking it over ...," he said.

And this is from one at Heathrow:

  We don’t really have an average day. We attend to all sorts of
  incidents. We attend to anything that is life-threating at the airport
  or on the roads around it; this could include a heart attack air or
  land-side, a drug mule incident where a passenger has transported
  drugs within their body and has ended up in a serious condition, or a
  car crash that we have to cut a victim out of.

  We all have set duties to do every day and night including practical
  and theoretical training, testing and inspections, and cleaning of
  vehicles and equipment. The crews have to keep physically fit so we
  give them time for physical training and provide facilities to do
  this.


Are intersection takeoffs less common in the USA than in other countries?

US airlines are extremely fuel conscious. They have software that calculates the exact throttle and flap settings required for the exact length of runway available so that they don't burn any more fuel than necessary, and that is all typically computed before they even push back from the gate.

If the pilots know in advance (e g. from the ATIS) that intersection departures are in use, they'll calculate for that. However, if they're already taxiing out to the end and ATC asks if they can accept an intersection departure instead, they'll need time to rerun "the numbers" and reconfigure the aircraft. US ATC has learned from experience that this delay often negates whatever trick they were trying to pull off, so they usually don't bother asking unless there's a really good reason.

Also, unlike light planes, for safety reasons airliners are required to have enough runway available to accelerate to V1 (nearly rotation speed) and then brake to a stop again before the end if they need to abort. This means they'll rarely use more than about half the runway available. This is factored into "the numbers", of course, and is another reason why they need to be checked before accepting an intersection.

As to why intersections seem more common in Australia, perhaps there is some difference in how their airports are designed, or perhaps their ATC is just more willing to do it, or perhaps Qantas pilots are faster at running "the numbers" or have a habit of running all likely options instead of just the expected one.


How are cruise missiles different from ballistic missiles?

A cruise missile is rocket or jet powered and flies to its target within the atmosphere, using lift to stay up. Most have wings, although a few may use lifting body designs. They maneuver using control surfaces on the wings and tail like an airplane. Mission profiles can include big course changes, to evade air defenses, or to hug terrain to stay hidden. They can be launched from fixed ground positions but most are launched from mobile platforms. They tend to have shorter ranges than ballistic missiles.

A ballistic missile is a rocket that powers its way out of the atmosphere and coasts in an arc, re-entering the atmosphere before hitting its target. They have little maneuvering capability, once the boost phase is done it's all down to physics. Some warheads are able to maneuver a bit in re-entry in order to hit a pinpoint target, others are just rocks at that point. The largest ones are launched from fixed positions like missile silos but smaller ones are mobile.


What's parked in Mil Moscow helicopter plant?

Looks like a Mil Mi-6 with the rotor removed (like the adjacent two to the right). Here is the 3-view drawing overlaid:

(Google Earth @ 55°40'04.61" N  37°56'07.62" E)

The tail boom appears to be thicker than it is due to the angle, it'll make sense by taking the satellite's perspective. Note the fatter bottom:

Google Maps measurement; actual aircraft length is 33.18 m (108 ft 10 in).


Can asymmetric thrust occur for Single engine airplane at idle power during stall practice?

The phenomenon you speak of is called P-factor.  It is the result of a non uniform angle of attack for the propeller blades throughout the propeller disk.

A typical piston powered single engine aircraft has a propeller which turns in a clockwise direction as viewed from the cockpit.  In this fashion the propeller blades are ascending to the left of the pilot and descending to the right of the pilot.  During straight and level cruise (high speed) flight where the airplane’s angle of attack (AoA) is minimal the propeller blades on the ascending and descending sides of the propeller disk have approximately the same angle of attack as they rotate causing the thrust force to be uniform over the entire area of the propeller disk.  But as the airplane enters a higher AoA either when maneuvering or maintaining altitude during slow flight, the angle of attack for the propeller blades on the descending side of the propeller disk have a greater angle of attack than do the blades on the ascending side of the disk.  This causes the blades on the descending side to generate more thrust for a given engine speed which results on an uneven thrust loading over the entire propeller disk, resulting in a counter clockwise torque about the airplane’s vertical axis.  P-factor is most pronounced at high engine power settings at the critical AoA for the airplane where the thrust asymmetry is most acute.

P-factor plays an important part during multiengine operations as well.  When an airplane had two or more wing mounted engines all turning in the same direction, there is always one engine such that, if it should fail, the yawing moment generated by the P-factor of the remaining running engine will be the greatest as compared to if the engine which is currently running had failed instead.  This engine is called the critical engine and creates the most difficulty in maintaining directional control should it fail.


How does humidity's effects on density altitude get factored into Takeoff Distance Performance Charts?

Add 10% to your computed takeoff distance if it is too humid.

  Humidity. Humidity is not generally considered a major factor in density altitude computations because the effect of humidity is related to engine power rather than aerodynamic efficiency. At high ambient temperatures, the atmosphere can retain a high water vapor content. For example, at 96°F, the water vapor content of the air can be eight (8) times as great as it is at 42°F. High density altitude and high humidity do not always go hand in hand. If high humidity does exist, however, it is wise to add 10 percent to your computed takeoff distance and anticipate a reduced climb rate.

Source: Density Altitude, FAA, 2008, faasafety.gov

It's worth noting that Airbus makes no mention of humidity in their performance guide, Getting to Grips with Aircraft Performance. So simply follow the FAA's advice, and any correction factors mentioned in your aircraft's flight manual.


What is the correct term for the type of performance chart where curved lines are followed?

The correct term is nomograph or nomogram. Thanks Gerry!
Also, thank you to Peter Kämpf and Dean F. for helping to answer my actual question, instead of the one I asked.


How late can a landing clearance be given?

Short answer: for visual approaches, it is not yet set in EASA regulations, but a draft recommends that the landing clearance be issued somewhere from downwind to short final (dashed line in the diagram below).

The relevant distance I found only applies to radar approaches:

8.9.6.1.7 Clearance to land or any alternative clearance received from the aerodrome controller or, when applicable, the procedural controller should normally be passed to the aircraft before it reaches a distance of 4 km (2 NM) from touchdown.$^1$

As for visual approaches it says:

7.10.1 (...) a landing aircraft will not normally be permitted to cross the runway threshold on its final approach until the preceding departing aircraft has crossed the end of the runway-in-use, or has started a turn, or until all preceding landing aircraft are clear of the runway-in-use.$^2$

Reference: EASA PANS ATM Checklist
$^1$ Transposed from ICAO Doc 4444 as GM3 to AMC2 ATS.TR.160(d)(3)
$^2$ Transposed from ICAO Doc 4444 in various AMCs to ATS.TR.210(c) and ATS.TR.220
A note on EASA regulations: Generally, for air traffic services EASA uses the text of ICAO Doc 4444 as Acceptable Means of Compliance (AMC) to the regulations, hence the transposition here.

A 2017 EASA draft (not yet regulation) discusses where you should ideally receive the landing clearance:

GM5 ATS.TR.210(a)(3) Operation of air traffic control service
DESIGNATED POSITIONS OF AIRCRAFT IN THE AERODROME TRAFFIC AND TAXI CIRCUIT IN RELATION TO AERODROME CONTROL TOWER CLEARANCES
The following positions of aircraft in the traffic and taxi circuits, as shown in Figure 1, are the positions where aircraft normally receive aerodrome control tower clearances. Aircraft should be watched closely as they approach these positions so that proper clearances may be issued without delay. Where practicable, all clearances should be issued without waiting for aircraft to initiate the call.
(...)
— Position 4. Clearance to land is issued here as practicable.
(...)


What is the purpose of wide area multilateration?

Wide Area Multilateration (WAM) is used as an ATC surveillance system. Like Secondary Surveillance Radar (SSR) it is classified as a cooperative independent surveillance system; the aircraft has to cooperate (i.e. an active transponder) but position is determined independent from data sent from the aircraft (unlike e.g. ADS-B).

A WAM system relies on Time Difference of Arrival (TDoA) measurements to determine the position of aircraft. At least 4 receivers with synchronised timing are needed to calculate the position of a transmitted signal. In practice WAM systems have a redundancy built in to them and are operated with more than 4 receivers. It can operate purely passively but usually the system will interrogate aircraft transponders to ensure a sufficient update rate can be maintained. This is a downside of the system; with its omnidirectional interrogators it is often considered as using much capacity on 1030 MHz, causing an increased transponder load (every incoming interrogation needs to be processed by a transponder, even if it is intended for another aircraft and no reply is to be given).

The system is used as an alternative to secondary radar. The installation of a receiver is much cheaper than a radar, but the life cycle cost of the surveillance system depends also on site renting costs, communication costs and maintenance cost. Maintenance tends to be cheaper (no rotating radar head), but communication is more expensive (more lines). Overall, WAM is a cost effective alternative to SSR.

WAM is able to achieve very high accuracy and high update rates when a sufficient number of sensors are installed. For example, German Air Traffic control DFS operates the Precise Approach Monitoring system in the Frankfurt TMA with 36 receivers and achieves and accuracy better than 25 meters with an update rate of 1 second.

In mountainous terrain, valleys can be covered by installing receivers on mountain peaks, which is much cheaper than covering it all by radars. Austrian Air Traffic Control AUSTROCONTROL operates a nationwide system consisting of 60 receivers.

In terrain that is difficult to access for maintenance or where there is no infrastructure to install radars WAM may also provide a solution. On the North Sea both Dutch (LVNL) and British (NATS) Air Traffic Control operate WAM systems to provide air taffic surveillance services to helicopters operating on the oil platforms. Receivers are installed on oil platforms.

WAM is used around the world, other deployments include for example Afganistan, Australia, Denmark, Ghana, Namibia, USA and many more.

The system can at the same time provide an ADS-B data stream from received ADS-B messages and can add extra security checks by comparing measurements of the data sources.


Is induced drag caused because of the tilt of the wing backwards?

Although your explanation isn't entirely wrong, It isn't necessarily the backward tilt of the wing, but the backward tilt of the aerodynamic force.

I look at it from two different perspectives. The airfoil is designed to accelerate air thus creating the pressure differentials that make the plane fly. The higher pressure areas will try to push the wing toward the lower pressure areas. The overall sum of these forces is called the resultant force.

That resultant force will have an amplitude and a direction or vector associated with it. The goal of designing an airfoil is to orient those forces upward to counteract gravity. So the designer will make the low pressure areas on top of the wing and the high pressure areas on the bottom to make the vector point upward. A perfect airfoil would create a vector pointing directly upward, 180° from the ground and 90° from the direction of travel. In reality, nothing is perfect, so that vector is always pointed backward to some degree. So we break that resultant force into two components. The part we're trying to accomplish, which is 90° from the direction of travel is called lift and the remaining part which is 180° from the direction of travel is called the induced drag since it is induced by the creation of lift. Even a wing producing lift at a 0° angle of attack will still produce a certain amount of induced drag.

Now we come back to your explanation. Although any time a wing is producing lift it will also produce some induced drag, as you increase the angle of attack the vector of the resultant force tilts back with it. Not necessarily at exactly the same rate, but usually not far off. Since we are still defining lift as 90° from the direction of travel and drag as 180° from it, the ratio between the two changes. For every bit of lift produced there is a lot more drag the further you tilt the wing back.

The second way of looking at it is from the inertia point of view. The intent of the wing is to accelerate air downward. Once again, a perfect airfoil would accelerate the air straight down, but in reality it will always accelerate it slightly forward also. And as you tilt the wing backwards you will produce more forward movement and less downward.


What is the top altitude of the class delta KEDC? It looks like it's not depicted on the VFR sectional chart

This looks odd to me.

The supplement (3 Jan 2019) does indicate class D operations:

  AIRSPACE: CLASS D svc 1200–0400Z‡ other times CLASS E.

But the current (August 2018) Airspace Designations and Reporting Points doesn't list class D airspace for it, only class E.  This matches the sectional shown.

When I look at another part-time airport (like Drake Field/FYV), the airspace is listed both as class D and class E as expected, and the height of the class D is given.

Perhaps something needs to be updated?

UPDATE
Yes, looks like the control tower opened at KEDC Feb 2018.  It should eventually be charted.  Until then, NOTAMS...

  KEDC NOTAM:

  !EDC 01/001 EDC AIRSPACE CLASS G SFC AREA CHANGED TO CLASS
  D 1901031200-PERM

And the update section of the supplement.

  8 Nov 2018 No Major Changes.

  3 Jan 2019 Add AUSTIN, TX Class D: That airspace extending upward from the
  surface to and including 3,000 feet MSL within a 4.1-mile radius of
  Austin Executive Airport, excluding the Austin Class C airspace. This
  Class D airspace area is effective during the specific dates and times
  established in advance by a Notice to Airmen. Revise AUSTIN, TX Class
  E: That airspace extending upward from 700 feet above the surface
  within a 14-mile radius of 30º17´55″ N, 97º42´06″W ....

I don't know why the airspace change is marked as Jan 2019 when the tower opened in Feb.


Disclaimer: this answer applies to airlines (operating under 14 CFR 121) but does not encompass all of commercial aviation.

The dispatcher that is working your flight plans the routing and determines the minimum fuel required from takeoff to destination to furthest alternate with additional fuel as required by regulation you operate under.  On top of this, contingency fuel is added which can account for enroute diversions, cruising at a different altitude, un-forecast winds, holding, etc.  The total of this fuel is the "release fuel" and you cannot takeoff below this number.  On top of this, extra fuel will be added for taxi time.

Ultimately, it is the captain's responsibility to decide how much fuel is needed.  For slight increases, airline policy may allow captain's discretion to add fuel.  For larger increases in the fuel order you generally need to call the dispatcher and amend the release -- after convincing the dispatcher you need the fuel.  If you decide you need less fuel (e.g. less contingency fuel) you always need to amend the release so you can legally take off.


Could a plane with an electric turbine engine generate enough lift to provide a electric areodynamic lift and runway to space?

Assuming maximum altitude for the highest blimp is 74,000 feet, and the rail to be angled at 15 degrees, it gives us a rail length of 285,000 feet. The HiSentinel stratospheric airship flew that high, and was able to carry only 36 kg.

The steel rail/rope would weigh roughly 5.5 million kg. Based on steel density and a good sized rope, to withstand the elements. So we'll need 154,000 blimps to carry the rail. That's 1 blimp every 2 meters. Blimps are huge.

While the idea is highly imaginative (good thing), engineering tends to solve problems, not create ones. Would the blimps (if they fit in the sky) power down between launches? Or stay aloft?

You might want to check out the Stargazer:

  [A] Lockheed L-1011 TriStar that was modified to be used as a mother ship launch pad for Pegasus rockets. As of June 2012, 35 rockets have been launched from it.

RE: How much lift could an electric engine powered plane provide if the power source was provided externally?

What you are asking is like having a plane not carry fuel and instead have a long fuel hose attached to a fuel pump on the ground. Ignoring all the problems associated with that, one will help you understand the problem: pumping the fuel.

Pumping electricity over such a long wire / rail will require high voltage / low current (just like power lines). Which means the E-Fan-like plane and all the blimps will need to carry their own super heavy transformers (as I wrote above, one high-altitude blimp lifts 36 kg, which we've already used for lifting the rail).


Do any commercial airline models have a parachute at rear to help in landings?

It is called a drogue parachute and I don't think that any of the present generation large commercial aircraft use them.

That said, a number of older commercial aircraft have used them, a good example being the Sud Caravelle.

Image from eu.airliners.net

There are some issues with using drogue chutes in a commercial airliner, which would limit their effectiveness.

Most commercial airliners have thrust reversers already.
For it to be effective, the parachute has to be quite huge. For example, the Handley Page Victor, which had MTOW in the range of A320, had a drogue chute 48' (or 14.6m) in diameter. The chute would occupy volume and increase weight.
If drogue chutes are used, they have to be packed before every flight, which will increase turnaround times. Another option is to replace them at the end of every deployment, which would increase costs.
Deployment failure/partial deployment/Uncommanded deployment will affect the safety of the flight.
The need to use a drogue chute can limit the crosswind landing of the airliner significantly.
Aircraft dragging a huge chute during taxiing back to the ramp is not a good idea from FoD point of view.


Are there references for the different maneuver configurations?

My CFI initial students fill out worksheets for each maneuver.  They find the numbers that work, and demo the maneuver with those numbers.

My primary students get a similar worksheet, where I have "grayed in" sample numbers.  I demo with these suggested numbers and as the student practices, they are free to change the numbers.  For more advanced primary students, sometimes I will give them suggested numbers which are off, and let them change the numbers to what they find works for them.

Some maneuvers are highly dependent on load / DENALT and will have varying numbers.  I encourage students to adapt the suggestions to something that works for them.  It helps them understand the performance of the plane, and of themselves.

So to answer your question, there may be a CFI out there who has a little notebook which he may share with you.  Probably 25 years ago there was a series of books, which one could buy with V speeds and maneuvers for various planes.  But I have not seen those in a couple of decades.

Finally, there are all kinds of variants.  As an example, I had a CFI applicant once, who right after takeoff reduced the throttle, and flew around the pattern at final approach speed.  Good thing were were at an rural uncontrolled field!  Eventually I convinced him to fly differently for his CFI initial.  But his worksheets would often be quite different than mine.  It took him a while to get chandelles down.

So if you are a student, I would suggest that you work out your estimate of those numbers, and ask the CFI you are working with.  You could even ask him to assist you in finding the correct numbers for your plane (with both of you in it).

Finally, the actual selection of configurations and numbers is colored by the flying style of you, your instructor, or whoever one is trying to emulate.  What is right or wrong is to a large degree subjective.  Most DPEs will let the applicant select the speed they perform a maneuver at, as long as they do it safely, and consistently.  In other words, while I might think my answer is the right one, there are many others which will work.


What is TOGA LK in Airbus 320? How to come out of TOGA LK?

TOGA LK (TOGA thrust locked) is displayed on the FMA after an activation of the ALPHA FLOOR protection when the activation conditions are no longer fulfilled (A FLOOR is displayed during the ALPHA FLOOR condition). The idea is that the thrust does not automatically reduce again after ALPHA FLOOR because this could result in a situation where the speed decreases again. The procedure to get out of TOGA LK is described in the FCTM (Flight Crew Training Manual):

ALPHA FLOOR
When the aircraft’s angle-of-attack goes beyond the ALPHA FLOOR threshold, this
means that the aircraft has decelerated significantly (below ALPHA PROT speed):
A/THR activates automatically and orders TOGA thrust, regardless of the thrust lever
position.
The example below illustrates that:

The aircraft is in descent with the thrust levers manually set to IDLE.
The aircraft decelerates, during manual flight with the FD off, as indicated on the FMA.

When the speed decreases, so that the angle-of-attack reaches the ALPHA FLOOR
threshold, A/THR activates and orders TOGA thrust, despite the fact that the thrust
levers are at IDLE.
When the aircraft accelerates again, the angle-of-attack drops below the ALPHA
FLOOR threshold. TOGA thrust is maintained or locked. This enables the flight crew
to reduce thrust, as necessary. TOGA LK appears on the FMA to indicate that TOGA
thrust is locked. The desired thrust can only be recovered by setting A/THR to off,
with the instinctive disconnect pushbutton.
ALPHA floor is available, when the flight controls are in NORMAL LAW, from liftoff
to 100 ft RA at landing. It is inhibited in some cases of engine failure.

(Airbus A320 FCTM - Operational Philosophy - AP / FD / ATHR, emphasis mine)
The TOGA LK state is not necessarily linked to a Windshear, but since ALPHA FLOOR is part of the Windshear escape strategy, it can certainly appear in this context. The FCTM describes the following strategy to escape a Windshear:

There are three efficient tools to assist the flight crew to escape:

The alpha floor protection
the SRS AP/FD pitch law
The high angle of attack protection

When the alpha floor protection is triggered, the A/THR triggers TOGA on all
engines. The FMA displays A FLOOR, that changes to TOGA LK, when the
aircraft angle-of-attack has decreased. TOGA/LK can only be deselected by
turning the A/THR off.
The SRS pitch mode ensures the best aircraft climb performance. Therefore, the
procedure requests following the SRS pitch bar and possibly full aft stick, in order
to follow the SRS orders and minimize the loss of height.
The high angle-of-attack protection enables the PF to safely pull full aft stick, if
needed, in order to follow the SRS pitch order, or to rapidly counteract a down
movement. This provides maximum lift and minimum drag, by automatically
retracting the speed brakes, if they are extended.

(A320 FCTM - Supplementary Information - Adverse Weather, emphasis mine)


Do planes use autopilot when flying in formation?

Nope, pilots do not use autopilot to fly in formation. An autopilot cannot achieve the precision required for flying formation (e.g. keep the wingtip aligned to that door). Usage of autopilot would also hinder responses when an immediate correction is necessary.

You may refer to the TV episode Jet Stream and Blue Angle training videos on the internet. From the pilot's perspective, the planes are always moving around, though in a confined space. Continuous small adjustment is necessary. From the ground, the small floating cannot be noticed visually because the observer is too far away.

P.S. Based on my 17 years of experience with PC flight simulator, flying in formation in multiplayer is definitely doable, and can become second nature with practice.


Are airliners' pilots trained to safely ditch an aircraft?

This is a very dated answer now, but for what it's worth, prior to my retirement in 1999 from a U.S. airline, we did ditching scenarios in 747-100/200 sims during initial training and then occasionally during recurrent training. Proper execution included being on-speed for your weight, nose attitude at touchdown (5 degrees up as I remember), aircraft configuration (gear up but I don't remember the flap setting), determination of wave direction if possible, and landing parallel to the wave action. It was a relatively easy scenario for the pilots but a busy scenario for the flight engineer. He had to position valves properly at the right time, including making sure the pressurization outflow valves were closed to prevent fuselage flooding.


How do fast-flying aircraft avoid overheating?

To avoid overheating, the usual trick is to select the right material:

The Concorde used a special aluminium alloy, called Hiduminium, which had higher strength at elevated temperatures and allowed the Concorde to cruise at Mach 2.02. Aluminium melts at 660°C.
The MiG-25 used stainless steel instead of aluminium to make its top speed of Mach 3.1 possible (top speed without engine damage was Mach 2.83). Titanium would had been even better, but was expensive and difficult to work with at that time. Stainless steel melts between 1400°C and 1450°C.
The XB-70 used titanium in addition to stainless steel. Its cruise speed was also Mach 3.0. Titanium melts at 1668°C.
The SR-71 used titanium for 85% of its structure to allow a cruising speed of Mach 3.2.
The X-15 was built from Inconel-X, a nickel-chromium alloy which has excellent strength at high temperature (it starts to melt at 1393°C) and allowed it to go up to Mach 6.5.
The Space Shuttle used a ceramic insulation on top of the load-carrying aluminium structure which kept the heat away from the structure during descent. Note that the Shuttle had to be connected to a heat sink to cool the on-board systems after landing.

The next trick is to fly higher up where air is less dense. Lower density does not reduce the air temperature, but it reduces the heat flow so the airframe will settle at a lower temperature. Remember that the eventual heat is the combination of convection, radiation and heat conductivity. Flying high up allows especially the top surface to radiate heat freely into the black of space above.

The hottest aircraft ever was the North American X-15 A-2. For a speed record attempt, the whole aircraft was covered with pink, ablative paint so the process of sublimation would carry some more heat away. To protect the paint from liquid oxygen, a white topcoat was applied also.

X-15 A-2 shortly after being dropped from the B-52 carrier (picture source). Note the small barrel under the lower fin: This was a ramjet which was test-flown on this occasion.

Damage to the ventral stabilizer. The ramjet separated prematurely due to frictional heating (picture source)

A third trick is to fly fast only for a short time. A heat-seeking air to air missile will easily reach Mach 3, but only for less than a minute. To keep the sensor cooled, a pressurized gas (argon or nitrogen) would be expanded (the AIM-9X even uses a stirling cryo-cooler). By heating the structure or using an internal heat sink, the limited heat load can be tolerated, albeit only for a very limited time.


Why do aircraft have two brake pedals instead of one?

In an aircraft the brake pedals control the respective side brakes. This allows for the pilot to turn the aircraft not only with the pivoting nose wheel (if it has one) but also with the brakes. This allows for a very tight turning radius.

(source)

  If each pedals controls different sets of wheels eg the left wheels
  and the right wheels of the main gear, is that not a safety flaw
  rather than measure given that at any point in time,

It is by design to allow for the tight turning. Some smaller aircraft also do not have a steerable nose wheel so differential braking is the only option.

  it is impossible for the pilot to apply an equal amount of pressure to
  the brakes?

Pushing equally on each toe pedal will result in equal brake operation.

  Isn't ABS enough to the point that only one pedal is enough.

The pedals allow for brake steering which a single pedal would prevent. Airplanes also do have ABS but that simply prevents the tires from skidding.

  Finally do both captain and pilot step on the brakes at landing. IF
  not then why have two pedals?

Im not sure, when I fly with an instructor or co-pilot in smaller planes only one person operates the brakes.


What causes the sudden spool-up sound from an F-16 when enabling afterburner?

My first guess based on the sound repeating when the thrust is idled near the end of the video is that's the sound of the actuators of the variable geometry nozzle.

Googling that actually auto-completed it to Great F-16 Actuator Sound (video).

Bonus answers to the bonus questions:

It's a ground test of the engine, making sure it's working fine with no leaks.
The F-16 has a tail-hook like carrier-borne planes, if you look closely a cable is attached to that hook, which itself is attached to the ground. The F-16, F-15, and other land-based fighters have it in case of an emergency, they'd land on a runway with a braking wire across it.


What qualifies for "mass disseminated data" for an abbreviated briefing?

If you look a page or two earlier in the AIM in section 7-1-5(b) the FAA gives two examples:

  b. Standard Briefing. You should request a Standard Briefing any time you are planning a flight and you have not received a previous
  briefing or have not received preliminary information through mass
  dissemination media; for example, TIBS, TWEB (Alaska only), etc.

That's interesting because TIBS was just discontinued (yesterday!) and TWEB is only in Alaska  (weather.gov says it's in other states too but that appears to be out of date according to the FAA's procedures). I have no idea what they include in "etc."

Personally, until I looked into this question I always assumed that "mass disseminated media" meant your local TV station's weather reports :-)


Can military personnel land their own private aircraft at military bases?

As someone already said, 32 CFR 855, Table 1 states:

  Service members, operating their own aircraft, leased aircraft, or other available aircraft for official duty travel (temporary duty, permanent change of station, etc.) or for private, non revenue flights

This of course means you still need to contact base ops for a Prior Permission Required (PPR) of some sort (if required).  If the base has an Aero club, then your logisitcal considerations are much less (most aircraft probably don't want to refuel on JP-8).  The list of Aero Clubs seems to have decreased since I was in though.

The Flight Infomration Handbook will have all the base requirements listed in it.


What factors determine the power curve of a jet engine?

Not a direct answer, but one thing to keep in mind is that thrust has very non-linear dependency on RPM. 70% N1 may mean 20-30% thrust. (And that's static thrust; in flight the difference may be even greater).

I don't have exact figures for AI-25, but for a similar engine I remember the gradient near 100% was around 5 (5% thrust for each 1% N1).

Actually, I have some data for Williams FJ33, which is comparable.

On the ground, it idles at 25% N1, which is only 3% of thrust. For 50% N1, you still have less than 20% of thrust. 60% N1 -> ~28%, and for 98% N1 you have over 100% of static thrust.

By the way, AI-25 on L-39 is 'overrated' compared to Yak-40 and its N1 goes to 107%, if I remember correctly. So it's all not that bad.


Do 'threshold' and 'end of the runway' mean the same thing?

For the simple case, yes.   The threshold will be the end of the runway.  The AIM has a graphic showing standard markings past the a normal threshold.

However, the airport operator may decide that aircraft should not land at the end of the runway.  This may be temporary (perhaps for construction), or permanently (for obstacle clearance or noise abatement).  In such cases the threshold is moved and marked away from the end of the runway.  When permanent, this is called a displaced threshold and will reduce the landing distance available (LDA) to less than the length of the paved runway.


What are the dimensions of an approach plate plan view in nautical miles?

FYI, what you're trying to do is called "georeferencing."

The scale for each plate is whatever is required to fit in all the relevant information without wasting space. Therefore, to properly geo-reference each plate, you will need to identify at least two points (e.g. CUTIS and CFVGK in this case), look up their lat/long in the published tables, and calculate the scale from there.

Note that some charts (more commonly SIDs and STARs than IAPs) are explicitly marked "NOT TO SCALE", which means this tactic can't work at all. And even some charts that are mostly to scale may have a few elements that aren't, usually transition fixes or navaids, marked by a double zigzag.


Where to find general A320 E&E Compartment Information?

The term E&E is used only in Boeings aircraft. For Airbus try to Google "avionics compartment" as this is the correct term.

This specific data you Will find in wiring diagram manual and schematic diagram manual, sadly due the complexity of the systems you won't find only one file for all systems.


Are there any planes that have ramjet or scramjet engines?

Scramjets
There's only a couple flying examples. The early Soviet-born Kholod, the HyShot series, and the recent ISRO ATV all flew small scramjet engines, although none were designed for net thrust. By far the most [publicly] successful vehicles have been the X-43A and the X-51. Both were fully controllable, independent flight vehicles (rather than just engines hanging from rockets) that produced net thrust.
The NASA X-43A hypersonic research vehicle was dropped from a B-52, then boosted by a modified Pegasus booster, and briefly flew at Mach 9.6 with a hydrogen-fueled scramjet.

Credit: NASA

Credit: NASA
The Boeing X-51 Waverider hypersonic research vehicle was also dropped from a B-52, then boosted by a modified ATACMS (an Army surface-to-surface missile), and then flew at Mach 7 with a JP-7-fueled scramjet.

Credit: USAF
The DARPA Falcon program aimed to produce a hypersonic plane that could takeoff and land under its own power using a turbine-based combined cycle (TBCC) propulsion system (NASA TBCC overivew on NTRS). Two early designs, HTV-1 and HTV-2, were unpowered hypersonic gliders, the latter was launched by ICBMs (basically reentry vehicles, like the X-41 they were probably derived from). But the next two designs, HTV-3X Blackswift (YouTube) and the final Hypersonic Cruise Vehicle (HCV) (YouTube), would have been the first reusable, hypersonic CTOL aircraft. HCV would have been able to carry a few thousands pounds of payload (eg bombs, flight test equipment, cameras) very quickly across great distances. The [HTV-3X and HCV] program was eventually canceled, but other work continues on hypersonic weapons and vehicles.

Credit: DARPA
SR-72. Lockheed Martin is developing the SR-72, an unmanned Mach 6+ ISR (recon) platform. It's meant to fly completely under its own power using TBCC, taking off with turbines and transitioning to ramjet and finally scramjet operation. A key innovation was bridging the speed gap between where turbojets stop working well and where ramjets start working well, but LM declined to elaborate how they achieved that. Their design apparently builds upon their work on the Falcon program (see above). They said they'd fly a single-engined demo before moving to the twin-engined, full-scale vehicle.

Credit: Lockheed Martin
Other ambitious unflown designs include the LLNL Hypersoar and the X-30 National Aerospace Plane. Both were large (100-200 tonnes MTOW), hypersonic, intercontinental vehicles. The SSTO-capable X-30 could launch payloads to LEO as well as serve intercontinental passenger routes. Hypersoar was also envisioned to carry passengers in one variant, perform TSTO in another, and also perform global strike/recon in yet another.

X-30 NASP. Credit: Chad Slattery

Hypersoar. Source: FAS.
Ramjets
The Republic XF-103 Thunderwarrior was essentially an early attempt at TBCC in a manned interceptor. It was a very innovative design (Mach 3-5, no canopy, periscope, crew capsule, huge radar, and internal bays for 6 large missiles, precursors to the AIM-54) but never flew.

Source. Unknown.

Source with lots of great background.
There's a variety of ramjet powered missiles
Notable examples include...
... the Bomarc. Credit: Boeing.

... the GQM-163 Coyote, a notable supersonic, sea-skimming target. Credit: DR Kirk.

... the massive P-700 Granit Source and its relatives, the P-800 Oniks and the BrahMos.

... the RIM-8 Talos SAM. Credit: USN.

... and the Sea Dart, the Moskit, the Hughes/Raytheon AIM-152 (and related ACIMD), the Triple Target Terminator, and a bunch others. Some are antiship missiles (various trajectories), some are SAMs, and some are air to air missiles. All were rocket-boosted before the ramjet took over.
Obviously the most "terrifying" was the Supersonic Low Altitude Missile of Project Pluto fame, a nuclear-armed, nuclear-powered ramjet for the 100,000 mi cruise missile. Air was blown directly through the reactor, directly heating it for thrust. Its unshielded reactor would have propelled it to Mach 3+ at sea-level and irradiated targets below it before crashing into a final target, irradiating that as well. They successfully tested two engines before the program was cancelled in favor of ballistic missiles.
Here's a fun USAF-Convair vid from 1959 explaining the concept:

Credit: USG


Does a request for passengers to open vents indicate pressurization issues or equipment failure?

I have occasionally asked passengers to do the same thing.
I have also asked for window shades to be lowered.

The reason is usually because the APU was not working and the ground air conditioning was not doing a good job or was unavailable.

Without the APU the aircraft's airconditioning can not work and engine starting relies on a ground air source to provide air pressure to spin the engines for start up.

When using ground air for starting, the ground air conditioning  is disconnected first and it takes very little time for the cabin to become uncomfortably warm.


Who do I call to pick up my IFR Clearance at KBKL?

When there is no separate Clearance Delivery frequency, just call on the ground control frequency to get your clearance.

Separate Clearance Delivery frequencies are only needed at busy airports to relieve radio congestion and work load.

Even at a "busy" airport sometimes you will see(hear) one controller work both Ground and Clnc Del when the workload is low.


How much fuel does the A380 use for taxiing before takeoff?

Fuel burn
To be meaningful it's best to compare it. It is approximately 4 times what an A320 needs. So if both planes are fully booked, then in theory each passenger should pay the same for the taxi fuel -- it would become an issue though when the A380 has a low load factor.

Taxi Fuel is 1 170 lb for an average taxi duration of 12 min.

While for 12 minutes an A320 needs 300 lb.
Cost
As of 20 April 2018, it would cost Emirates -- the largest A380 operator -- about \$360 for a 12 min taxi in Dubai (less than a dollar per passenger).
But Dubai is a busy airport and as such the taxi duration can exceed 12 minutes. For example Emirates 203 from a few days ago had a taxi time of 30 minutes. Operating a large airplane at a busy airport has its costs.

References:

Airbus FCOMs for the A320 and A380
IATA fuel monitor (jet fuel cost varies by region).


Does ETOPS apply to Part 125 operations?

Reviewing FAR Part 125, I concur with the last sentence in the question "It would appear that ETOPS wouldn't apply to Part 125 operated aircraft."

Since there are no references associated with ETOPs contained in the regulation, ETOP's criteria, limitations, operating specifications, etc. do not apply when conducting "operations" in aircraft under Part 125.


Why was the P-51 Mustang not adopted by the U.S. Navy?

The biggest driver behind the use of the P-51 Mustang in naval operations was the need for B-29 escorts while bombing Japan. No naval fighter at the time had the range to accompany the B-29's so the P-51D was selected to determine if it could be a suitable carrier operator.

The test project was named "Project Seahorse", and one aircraft was selected and specially modified to cope with carrier landings.

Navy Concept Image in Livery (Image Source)

The modifications included:

"Fin Fillet Extension" which enhanced low-speed operation.
Tail hook (for obvious reasons)
Catapult hook
High pressure tires
Higher pressure in the shock absorbers
Reinforced airframe

The modified P-51D started testing in September of 1944 under test pilot Robert Elder. The tests were carried out at Mustin Field in Phillidelphia on a modified runway fitted with a catapult and arresting cables. Throughout September 1944 to October 1944, 150 launches and recoveries were made on this modified runway. One big concern was that the aircraft would need to land around 90mph and the stall speed was 82mph, not much of a margin.

In late October 1944 the next stage of testing started, carrier landings/launches at sea. Lt. Elder made all the carrier landings at 85mph and was pleased with its handling characteristics, but there were issues:

Stall speed margin was extremely low, too low for safety
Rudder control at low speed and high angles of attack was inadequate
Landing attitude had to be very carefully controlled to avoid airframe damage
Go-arounds required slow throttle advancement. The extreme power of the Packard/Merlin engine meant that a high-power fast throttle advancement could put the aircraft into a roll or snap-roll. At low speeds this would prove a fatal mistake.

Only 25 launches/recoveries were made in the suitability trials and Lt. Elder did not believe that the Mustang had a place in carrier operations.

It was a moot point anyway. By early 1945 Okinawa and Iwo Jima were won by the allied forces. Each island had airfields that were taken over and provided a close base of operations for aerial attacks on Japan. In August 1945 Japan announced its surrender and it was official September 2, 1945. The P-51 wasn't required to be used from a naval platform anymore.

The project wasn't forgotten though. North American presented the NAA-133 based on the P-51H, which was a carrier operations "Mustang". It didn't go any further than the design stage though. In 1947 a P-51H was acquired to test new catapult equipment. Either way the war was over by that time and we didn't have to put any more effort into modifying the aircraft for carrier operations.

Here is my main source


Does TC holder of aircraft need to be notified by the PART 21 DOH that they are making a major mod STC to their product?

I was many years at an OEM, in tech support engineering, and I'm not aware of any requirement to notify the OEM when someone applies for an STC.  You have to remember that many STCs are for airplanes who's manufacturers disappeared long ago, so you really can't make that a basic requirement.  It's possible however, that the FAA may request OEM input like an NTO for a proposed change on a case by case basis, depending on the scope of the mod, and if OEM cooperation is not forthcoming, it could stymie the STC project.

Certainly there is no requirement for the OEM to support an STC for continuing airworthiness, except perhaps where an STC causes an incident or incidents that generate activity toward an Airworthiness Directive and the OEM's Airworthiness Engineering Department has to get involved.  Operators use to come to us for help with issues on a subsystem installed under an STC, and we'd tell them sorry, we have nothing to do with it.

An OEM that is still in business may, or may not, participate in development of an STC.  One of the difficulties for the STC developer is obtaining engineering Source Control Drawings, which the FAA may require as part of the STC data package.  However, a lot of the time the OEM will want nothing to do with the STC, because it implies (to the OEM's customers) that the OEM will be obligated to help support the mod.

The linked Advisory Circular covers the STC application process and there is no mention of No Technical Objection letters from OEMs or requirements for OEMs to support STCs.  OEMs will sometimes discover STC mods done on their fleet that they had no idea existed until they start to get visibility in service.

STC Application Advisory Circular


How do modern commercial aircraft handle dust storms?

There is an interesting presentation on the impact of dust on aircraft here. And the Flight Safety foundation has a good article that breaks down a lot of aspects here and is worth the read.

It's not just the reduced visibility, but the associated high winds that can be a real danger for aircraft operating in a dust storm.

  Dust storms pose a significant hazard for aviation. Not only do they
  drastically reduce visibility, they also are associated with very
  strong winds that can seriously affect an aircraft in flight. Engines
  can be damaged by ingesting the dust.

But as per your questions directly

  How do modern airliners and her crews deal with a large sandstorm?

They most likely will avoid them as they would any heavy weather activity. The extremely reduced visibility might bring the airport below operational flight minimums, thus making an approach or departure impossible.

  Would a standard weather briefing warn a pilot of the possibility of a
  sandstorm?

One main issue with dust storms is how fast they come up, and this can make them harder to predict than a storm that is rolling across a region.

  It was a typical early summer evening in southern Arizona, U.S., this
  past July 5. At 1751 local time, the Phoenix Sky Harbor International
  Airport was reporting 10 mi (16 km) visibility with winds of 7 kt. But
  all that changed in a matter of minutes.

As for what to do when you find yourself over or in a dust storm check this article out of a firsthand account.


What is the maximum speed of all the stages of a geared bypass tubojet engine?

The maximum rotational speed of turbofan blades follows from compressibility effects, just like those for helicopter rotors and for propellers.

Image source

On most high bypass turbofans the fan tips can get to slightly supersonic speeds. A Rolls Royce engineer at the Singapore Airshow mentioned Mach 1.05 for the fan tips, that is why the blades have swept back tip shapes.

All other stages are designed such that blade tip speed remains subsonic: compressibility effects cause a rise in blade drag before the speed of sound is reached. It then drops again, but:

There is a large region of high drag that needs to be overcome, where torque will be waisted on compressibility for no gain in thrust.
Blade root stress is proportional to rpm squared, and it is best to stay in the subsonic region.

For the blades in all stages of the turbofan, three main design considerations are:

tip speed;
blade mass;
operating temperature.

Image source

Blade rotational speed follows from blade radius and tip speed limit. For the fan, a slow turning long blade is best, since it works just like a rotor or propeller does. The compressor blades become smaller at each stage due to the smaller air volume to be compressed, the turbine blades reverse this trend. Rotational speed of the compressor and turbine stages is chosen such that tip speeds stay below the compressibility drag, as confirmed verbally by a Rolls Royce engineer.

Benefit of the gearing can be seen from the shape of the engine: the low pressure turbine blades have a smaller radius than the fan blades, an un-geared engine would turn the LP turbine too slow. With a geared turbofan, the fan tip speed will stay at around the same tip speed, but the RPM of the LP turbine will be brought to a higher value. Below drag divergence number for the hot exhaust gases.


What is the "on condition" concept of aircraft maintenance?

I'm not a maintenance guy, but you may be mixing 'inspection' and 'maintenance' together here.

An inspection helps you decide if maintenance is needed or not. For example, inspecting the tire tread before every flight, or checking the cylinder compressions every 100hrs. If the inspection shows that the condition of the item is still within acceptable limits, then you don't need any maintenance yet. This is the 'on condition' or 'condition-based' approach, at least as I understand it.

Another approach is to do planned maintenance at fixed time intervals whether it's 'necessary' or not. For example, replacing engine oil every 50hrs, or replacing the entire engine every 2000hrs. In this case it doesn't matter what the item's physical condition is, you perform the maintenance even if everything looks good.

FWIW, some people strongly prefer the 'on condition' approach, especially for piston engines (see this book, for example). But even they probably replace their oil at more or less fixed intervals.

If you want something more official, I found an FAA definition:

  On Condition Item (Oc)

  A primary maintenance process requiring repetitive inspection or test
  to determine the condition of units, systems or portions of structure
  to assure continued serviceability. Corrective action is taken when
  required by item condition as determined by analysis of inspection
  and/or test results.

The key point as I understand it is that you base the decision to do maintenance (or not) on the physical condition of the item.


Something like it is widely used, only not by this name.

Although less elegant and general than Prandtl's paper, the same solution was found 17 years later by R.T. Jones when he optimized the ratio of lift to mass of wings in NACA TN 2249. The figure below is from the concluding page of this report.

However, induced drag is not all. By increasing span, wing surface area is also increased which will increase viscous drag. Therefore, the optimum really is a combination of both; having the least amount of wetted surface for the most net lift (total lift minus wing weight). This is somewhere between an elliptical and a triangular load distribution where size also matters. Small aircraft are closer to the elliptical distribution whereas large aircraft tend more to the triangular one. Negative lift at the tips only happens with extreme span to elliptical span ratios (note the curve for S/S$_\text{e}$ = 1.30). Negative lift as in the bell-shaped lift distribution, however, is a prerequisite for the Horten type of flying wings because it allows to create proverse yaw. If you have a multi-engined aircraft and need to size the vertical surface for the engine-out case, covering adverse yaw will be trivial and there is no need for a true bell-shaped lift distribution.


What button do I push on the instrument panel to activate DME in VOR navigation?

Typically, there isn't a "button" as such, you tune the DME to the frequency of the ground station (or slave it to the NAV radio).

The knob on the right is used to tune a frequency (shown before MHZ) when in "frq" mode, which is usually a VOR/DME. The numbers before NM is your distance to/from the station in Nautical Miles.


Are there "Introductory flights" available to see if I want to pursue training?

Well, to put it bluntly, somebody has to pay for the airplane.  Much like a car, somebody has to pay for the gas and maintenance.  The major difference is that both cost a lot more on an airplane so it is a lot harder to get someone else to pay for it.

However, similar to a car, if you have a friend that owns an airplane they may take you up for a ride and even (legally) let you fly it, but they remain the person in charge and responsible for the safe outcome of the flight.  If you want to try it for free this is probably one of the only ways to do it.

If you are willing to pay for a one-time flight which does not commit you to pay for your entire license, then you can go to almost any place that teaches people how to fly and they will be happy to let you fly with an instructor and charge you only for the time in the airplane and the time with the instructor.  Often they have an "introductory" flight just for this purpose which is discounted for potential students.  This is a relatively small cost in comparison to learning to fly that I highly recommend to anyone before they commit to getting their license.


What is this loose object above the flap fairing?

It’s a neoprene seal which may be a little loose there at the end like that and made to flutter by the flow of the boundary layer air around it.  That’s a common part used sometimes around the edges of enclosures eg flaps, landing gear fairing doors, etc. 1) to prevent scuffing or abrading parts during operation and 2) to seal out boundary layer flow, reducing drag.  You can notify the airline but the problem is benign and will not affect scheduled operations.


Are there any differences between turbofan and turbojet engines besides bypass air?

You are right about the bypass being the same result as a tubofan.
However the word turbofan refers to an extra turning bladed wheel in front of the compressor and larger in diameter it turns slower and moves air past the engine on the outside.


What is the purpose of runway grooving?

The channels help to remove water from the runway. They also provide an area for the water to build up. With out these channels the water runs the risk of forming a thin surface covering the runway which can be very dangerous. As mentioned by john here in the comments this is usually known as hydroplaning and is the same as what happens to a car.

  How does the airport drainage system work?

This is a bit of a guess but I assume they work like any other road drainage system and it will depend on where the airport is located. Here is a very dated report prepared for the DOT on runway drainage that you may find of some interest. Here is the FAA's full paper on designing surface drainage for airports, it's a bit long but should cover what you are looking for.

  Why do airports remove rubber from the runway?

Tires obtain the best friction when they come in direct contact with the runway surface. Excess tire rubber that wears off and sticks to the runway can affect the tire/runway interactions. This wiki article covers the main points pretty well.


What is the speed of a standard airliner during the different phases of the flight?

Ballpark:

At the gate, 0 knots
Taxi, 5-30 knots (usually 10-20)
Takeoff, 150 knots (rough ballpark)
Climbout below 10,000', 250 knots
Climbout above 10,000', 270-320 knots
Climbout above 28,000', Mach .78 (ballpark)
Cruise, Mach .78 (groundspeed ~450 knots +/- wind)
Descent above 28,000', Mach .78
Descent 28k to 10k, 280 knots (up to 330 knots, if ATC requests)
Descent below 10k, 250 knots
Traffic pattern,200 knots
Final approach, 140 knots
Taxi in, 10-30 knots
At the gate, 0 knots

Edit: these are fairly typical 737 numbers; other aircraft will have differences. Regional jets will typically be slower; 747 and 777 will often be faster (especially for takeoff and cruise).


Why is the NAV ADR 1 ECAM caution a NO GO as per the MEL on the A320?

It is to prepare the aircraft for a possible Emergency electrical configuration. I hope you are aware of the fact that in an A320, if the AC BUS 1 and AC BUS 2 were to fail in flight for some reason, the RAT (Ram air turbine) extends which in turn powers an emergency electrical generator. When the aircraft is in emergency electrical configuration, only the very essential systems are powered and the others are shed. Some of the systems that are shed include the ADR 2 and ADR 3, leaving only the ADR 1 functional. The ADR 1 will continue to supply air data to captain's PFD. In this situation, the first officer's displays goes blank and the captain assumes the flying duties, if the first officer was the flying pilot when the failure occurred.

If the aircraft is dispatched with ADR 1 deferred, and if it undergoes an emergency electrical configuration, as soon as the ADR 2 and ADR 3 are shed, all the flight displays will go off, including the captain's side instruments which are supplied by the ADR 1. Then you will have to rely on standby instruments to fly which would not be the most ideal condition to be in an already crippled aircraft. Remember, this configuration will force the aircraft into alternate law. Both auto pilots, autothrust and even the flight directors would not be available.


Why do passenger embark on the left side of an aircraft?

Because the cavewoman who invented the log-canoe was right-handed?

Note: I arrived at this answer by looking at a kind of etymology of the terms starboard & port but that's incidental. The answer to this question happened to be contained in an answer to a rather different question. Some groups of aviators may have dropped the archaic terms while still being subject to a continuation of an archaic habit/convention.

People get on the left side of a jet airplane because Vikings (etc) steered their wooden boats with a steering board (hence starboard?) held in their dominant right-hand.

Since it was inconvenient to have your steering apparatus wedged against a quayside (or earthen bank) they docked at the port along their left side and therefore loaded and unloaded on the left.

Farhan's comment leads you to this answer in English.se which I reproduce here for convenience

Excerpt from trivia on the Navy website:

  Port and starboard Port and starboard are shipboard terms for left and
  right, respectively. Confusing those two could cause a ship wreck. In
  Old England, the starboard was the steering paddle or rudder, and
  ships were always steered from the right side on the back of the
  vessel. Larboard referred to the left side, the side on which the ship
  was loaded. So how did larboard become port? Shouted over the noise of
  the wind and the waves, larboard and starboard sounded too much alike.
  The word port means the opening in the "left" side of the ship from
  which cargo was unloaded. Sailors eventually started using the term to
  refer to that side of the ship. Use of the term "port" was officially
  adopted by the U.S. Navy by General Order, 18 February 1846.

So it's a historical convention, many arbitrary choices are of this sort. Pioneers of a new form of transport adopt the terms (port, startboard) and habits of more ancient forms of transport.

Ironically, since aircraft became able to carry substantial non-human cargo, the cargo entry has moved to the other side to reduce the chances of crushing the human cargo with the non-human cargo. Presumably also because having lots of large holes all in one side may be structurally disadvantageous.


What are the advantages of 3 spool over 2 spool turbofan engines?

There are two advantages;

It's easier to match the compressor rotational speed with the turbine. Typically, the first stages of the compressor want to rotate slower than the turbine is required to rotate. The turbine needs to spin faster to help obtain as much energy from the airstream as possible, but initial stages of compression prefer to spin slower. With 3 spools instead of 2, less compromise is required.
A greater pressure rise per stage can be achieved. This occurs because each compressor in a 3 spool engine (fan, LPC, HPC) will have fewer stages than each compressor in a 2 spool engine (for the same overall pressure ratio). A 5 stage compressor requires less compromise than an 8 stage compressor. The front stages prefer a high airflow to avoid stall, but the back stages can't always swallow the same mass flow, and can cause a backpressure which can lead to stall. Hence, air flow is often bled off in the middle of the compressor, to avoid stall. This is air that has been partly compressed, absorbing work, but isn't available to generate thrust. Hence, it's a parasitic load. So, the compressors in a 3 spool engine are better optimised than in a 2 spool engine, because this situation isn't as severe. Hence, the designer can be a little more aggressive in the pressure rise per stage the compressor achieves, because the compressor is less prone to stall. Thus, a 3 spool engine, in theory, can achieve the same overall pressure ratio, as a 2 spool, with fewer stages. This means, a lighter weight engine.


Are there rules governing the conduct of flight attendants?

The FAA is responsible for safety regulations and standards, not for code of conducts or courtesy regulations for interactions between flight attendants and passengers. Flight attendants are bound to certain behaviour only by their employer and their code of conduct, additionally to any national law that prohibits insulting others or harming them otherwise.


I believe this refers to the cowling design where a mixed flow the fan and gas core streams mix inside the cowling whereas in unmixed streams the fan air excites the cowling without mixing with the gas core exhaust gases.


How does the Blackbird SR-71 pressurize the cockpit at Mach 3?

The SR-71 used the P&W J58, which is full of moving parts, and works very similar to a typical jet engine.  Your assumption that it has no moving parts is wrong.   While the engine RPM did slow down at maximum speed (up to 90%), it never stopped, and always generated enough power for electrical systems, pressurization, hydraulics and any other needs.

While the cockpit was pressurized (but sometimes only to 26,000 ft. pressure-altitude), the two-man flight crew wore full body flight suits for warmth and oxygen.


How to calculate coefficient of drag for a particular shape?

There are essentially only two ways to do this.

First you can build a wind tunnel, run experiments and measure the forces involved.

The second is to run a computer simulation. There is software that will do this, but it is complex professional grade engineering software. Free applications are available, but I can't vouch for their effectiveness. You can search for "computational fluid dynamics software" to find options. Adding "free" to that will find you a few cost-free options.

Be aware that setting up and using this software is a complex task that involves creating a CAD model of your shape. You can definitely do the calculation if you are interested, but it's not a simple or quick task.


What is the difference between iSpec2200 and S1000D specifications?

I've only worked with S1000D, but what I understand is that they share a common origin in ATA Spec100, with some differences being:

iSpec2200

maintains a focus on "legacy", monolithic publications
scope is more limited to aircraft
specification costs money (https://publications.airlines.org/CommerceProductDetail.aspx?Product=274)

S1000D

focuses on modular data, with concepts such as data modules and the CSDB
scope is more generalized to any product (air, land, sea, etc.)
specification is free (http://public.s1000d.org/Downloads/Pages/S1000DDownloads.aspx)


Could aircraft already do a safe auto-takeoff with todays equipment?

With some refinement and programming, the technology is easily there, sure; it just needs a few million dollars of design and certification costs for very little benefit.

The main reason we have autolands is because it saves airlines money, by allowing the plane to land safely in minimal visibility instead of diverting to another airport. Aircraft taking off don't have this problem as they can do it in just about zero visibility. If there is no commercial incentive, the reality is it is not going to happen. Only when pilots are considered surplus to requirements will this ability be developed in earnest.

There could be an argument made that it should be done for safety's sake, but I don't buy it. Pilot errors made on the takeoff run, resulting in an accident are incredibly rare. Maybe an auto takeoff could prevent a few tailstrikes but I can't see much more benefit.

Whenever you introduce something new you have to think long and hard about the ramifications of it. There's a whole discussion to be had on how rejected takeoffs would work - generally speaking, you do not want automation doing something that the pilots aren't expecting. It is sometimes better to take an issue into the air than take the risk of a high-speed RTO even under V1, how will the computer judge that when there are few hard and fast rules for it? Do you trust the human programmers to account for every single scenario? Then there's pilot competency, how do they keep their skills up when they could go months without flying the aircraft? If they are in the habit of delegating their decision making to the computer, will they be able to handle the heat in that career-defining moment when the computer fails and it's all on them?


What's the name and purpose of a barrier raised behind a carrier based jet?

The official name is a Jet Blast Deflector.

As the name suggests, they direct the fast-moving and hot air from the jet engines upwards. This protects the personnel and equipment behind the departing aircraft from getting blown around or damaged from the jet blast. Because of the high temperature of the jet blast, they may have active cooling systems, and must be allowed to cool sufficiently before being used as regular deck again.

To illustrate the risks, see this video, which shows a vehicle being blown away by a 747.

There was also a recent event in Pakistan where a 737 damaged the tarmac (and, as a result, itself) during an engine run-up.

To make a comparison, each engine on a 737-400 can produce up to 22,000 lbf (98 kN) of thrust. The Su-33 in your picture has two engines close together which can each produce 16,750 lbf (74.5 kN) of thrust, or 28,214 lbf (125.5 kN) with afterburner.  That's a total of 56,248 lbf of thrust in afterburner, or 2.5 times the force of one engine on the 737-400. Of course, this does not directly equate to jet blast or temperatures, but it is a good indicator of the forces involved.

To provide a better idea of the jet blast, see this chart (based on the 737-800). At 20 m behind the tail (which is about 20 m behind the engines), the jet blast can reach 300 km/hr at takeoff thrust. For more details about jet blast on the 737 series, see the Boeing documentation.

The CFM56-3 (used on the 737-400) can produce exhaust gas temperature (EGT) of up to 930 C at takeoff. This will mix with the cooler bypass air (and ambient air) to reach cooler temperatures further behind the engine. Military jet engines have a smaller bypass ratio, which means there is less of the cool bypass air in the exhaust to mix with the hot core exhaust.


Why couldn't the DHL611 crew hear the ATC transmissions for the Bashkirian 2937 crew?

It wouldn't matter if they had.

The DHL611 crew had been trained to obey TCAS orders over ATC. This was fairly common, but not universal practice at the time. Their training was unambiguous, and stated that TCAS should be followed over ATC instructions. They had been trained that both aircraft would follow TCAS and avoid the collision, and had no reason to believe that wasn't the case: they didn't even necessarily know that BTC2937 was the aircraft causing their TCAS alert

The crew of BTC2937 hadn't been trained to follow these priorities, or became confused.

From the Wikipedia page about the incident:

  The TCAS Pilot's Guide was ambiguous as to whether or not TCAS advisories should take precedence over ATC instructions.[BFU 14] This ambiguity was replicated in the Tu-154 Flight Operations Manual, which contained contradictory sections. On the one hand, chapter 8.18.3.4 emphasized the role of the ATC and describes the TCAS as an "additional aid",[BFU 15] whilst chapter 8.18.3.2 forbids manoeuvers contrary to the TCAS

Since that accident, it was made official procedure for all flights to follow TCAS, ignoring ATC when a TCAS RA is in effect.


The term 27/10 is the temperature (27°C) and dew point (10°C).
The RF term in the remark section is used to indicate the accumulated rainfall (in this case 0, so no rain):

What is the meaning of the RF group in METAR/SPECI and TTF?
This group reports rainfall in the last ten minutes and accumulated rainfall since 0900 local. For example, RF02.2/024.4 reports that 2.2mm of rainfall has fallen in the 10 minutes prior to the report time; and 24.4mm has fallen since 0900 local.

(Australian Government - Bureau of Meteorology)