What exactly are these frequency uses mentioned in the FAA's advisory circular on VHF use?

The FCC is the ultimate authority on radio frequency usage in the US. 47 CFR § 87.5 has the definitions of the aviation services.

  Aviation support station. An aeronautical station used to coordinate aviation services with aircraft and to communicate with
  aircraft engaged in unique or specialized activities. (See subpart K)

Subpark K:

  § 87.319 Scope of service.

  Aviation support stations are used for the following types of
  operations:

  (a) Pilot training;
  (b) Coordination of soaring activities between gliders, tow aircraft
  and land stations;
  (c) Coordination of activities between free balloons or
  lighter-than-air aircraft and ground stations;
  (d) Coordination between aircraft and aviation service organizations
  located on an airport concerning the safe and efficient
  portal-to-portal transit of the aircraft, such as the types of fuel
  and ground services available; and
  (e) Promotion of safety of life and property.

Domestic VHF use is described in § 87.263. In general, these frequencies are used for communicating with aircraft, or between ground stations. There are various restrictions on certain frequencies/ranges, and despite the name, some are allowed for use on international routes.

Back to § 87.5:

  Flight test aircraft station. An aircraft station used in the testing
  of aircraft or their major components.

  Flight test land station. An aeronautical station used in the testing
  of aircraft or their major components.

Flight Inspection is not defined in § 87.5, so it may be the FAA setting these aside for their own use, but these frequencies are used by the FAA for ensuring "the integrity of instrument approaches and airway procedures."


Can a GPS system be used to identify fixes on conventional instrument approaches?

Your reading of AC90-108 is correct. As long as the RNAV equipment is operated and installed in accordance with TSO-C129/-C145/-C146 it can be used as a "suitable RNAV system." (ref: AC90-108, para. 6 a.).

Also, see the AIM, 1-2-3 b. "Types of RNAV Systems that Qualify as a Suitable RNAV System."

Lastly, as far as the requirement for "Dual VOR Receivers" for IZKIP, since you are using a "suitable" (and legal) alternative method by using the GPS database fix location, no additional restriction should apply. Also, it is my understanding that when the subject stepdown fix (identified by a VOR radial) is inside the FAF, as is the case with IZKIP, the dual VOR requirement is for the purpose of presetting the missed approach holding fix.  Again, not an issue if you are using a "suitable RNAV" system for identifying the fixes.


What type of display is used for cockpit displays?

Modern glass cockpits use LCD screens specially designed to be visible in bright sunlight.  Earlier units used cathode ray tubes.

Both the Boeing PFD screen and the Garmin G1000 PFD shown above use LCD screens.


What exactly is an "engine surge" in a jet engine, and what causes it?

The surge is the increase in rpm of a stalled compressor.  The compressor blades are airfoils not unlike propellers and wings. They will stall if airflow is not maintained at the proper angle of attack.

Interruption of airflow in jets can be caused by abrupt maneuvering, ingestion of foreign matter, or excessive application of throttle.  Much has been done to eliminate this issue in modern jets, but the nature of the design still makes it possible. If air flow is interrupted to the compressor, the jet can literally backfire, creating a loud "bang".  A large yellow flame may also be seen coming from the back of the jet as the fuel/air mixture is now excessively rich due to insufficient air.

If the engine is not damaged, it can be re-started the same way we unstall a wing, by re-establishing proper airflow angle of attack.  This is done by lowering pressure BEHIND the compressor.  Throttle is reduced. Provided the engine is not damaged, throttle can be carefully restored.


Modern airliners are designed to be able to withstand the worst (vertical) turbulence. But what about the rarer lateral (horizontal) turbulence?

Yes they are.  FAR 25.427 has the requirements for lateral gust loads.
I don't know if there was FDR information for the BOAC flight, but it may very well have been a similar event to AA Flight 587, the one that lost its vertical fin over NYC when the pilot got on the pedals in reaction to a wake turbulence encounter that induced a large yaw, and made rudder input loads that the fin is not designed to handle.
In that case the fin broke off not because of the gust, but because of the control response.  You will likely be out of phase in the attempt, and your inputs become "doublets"; amplifying inputs that make the yawing worse.  You don't normally touch the rudder pedals on an airliner between departure and landing unless an engine quits; you just let the yaw damper take care of yaw excursions like that and it'll have no problem staying in phase to dampen the motion.  I'll bet that the BOAC incident was that sort of case, where a gust reaction was followed by an input, at high speed.


Why do planes employ vortex generators if the laminar flows exhibit a far lower skin friction drag than turbulent flows?

Laminar flows detach from the surface earlier than turbulent flow does, which means that with everything else constant, a laminar wing stalls at a lower angle of attack, and does so more suddenly and with less warning.

The unsteady nature of a turbulent boundary layer allows it to extract more energy from the freestream (flow which is not slowed down by the wing), thus the boundary layer stays energized and slows down later. This, as you have mentioned, increases drag, so there is a tradeoff between delaying stall and increasing drag.

You'll find VGs on the wings of trainer aircraft,so that they have forgiving stall characteristics...

...STOL/bush aircraft, for lower stall speeds...

and near control surfaces of all kinds of aircraft, to retain control when the control surface itself is in high angle of attack. This also increases their effectiveness so the designers can get away with making them smaller.


Why does a pilot want to hold a Squawk Code when leaving Class B airspace?

The pilot means: I'll be back again, so please don't assign this code to someone else.

Less workload for a pilot going in and out of class-B airspaces, and less hassle for the controllers, so they don't keep assigning a different code to the same plane.

The pilot will switch to the VFR code (1200 in the USA), and then use the one he's written down and used earlier for future passes.


Why do many ram air inlets have this shape?

Those are called NACA inlets or NACA ducts. As wikipedia mentions:

  When properly implemented, a NACA duct allows air to flow into an internal duct, often for cooling purposes, with a minimal disturbance to the flow.

So yes, there is an aerodynamic advantage.
As for the "why", if you're in the mood, you can have a detailed look at the original report (I'm not able to properly summarize it).


Why would my transponder interfere with my ADF?

ADFs and transponders are often right next to each other in the dashboard, it's not the placement that's the issue. The two systems work on different sets of frequencies, so antenna placement shouldn't be an issue. If the ADF is being getting interference from the transponder in ALT mode the most likely issue is that one or the other is malfunctioning, or there is a short in the wiring between the two systems.


What is the difference between "sensitive" and "non-sensitive" altimeters?

All altimeters are "sensitive" to some extent (an "insensitive" altimeter would be one where the internal pressure-sensing mechanism has failed: the pointer wouldn't ever move).

What the FAA calls a "sensitive altimeter" is simply more sensitive than a regular (now often called non-sensitive) one:

Non-Sensitive altimeters have a 1000-foot scale (200-foot tick marks) as their most precise display.
Sensitive altimeters have a 100-foot scale (20-foot tick marks) as their most precise display.

The sensitive altimeter in "glass cockpit" displays go even further, often having 1-foot resolution on a digital read-out.

Let's look at some (analog) examples:

Non-Sensitive Altimeter, not adjustable for barometric pressure

This altimeter is similar to what you'd find on an old Piper Cub: The scale is marked in thousands of feet, with ticks every 200 feet.

This altimeter is not adjustable for "barometric pressure", but it is adjustable: The little knob on the bottom rotates the face of the altimeter. Put field elevation under the needle before you take off and it should be a reasonable approximation of your current altitude for the duration & distance of a typical Piper Cub flight.
These altimeters can only be "set" on the ground, because you need to know your elevation to set the position of the face or needle.

Non-Sensitive Altimeter, adjustable for barometric pressure

These show up from time to time: It's a non-sensitive altimeter (same scale markings we saw above), but it's adjustable for barometric pressure. The Kollsman window on this one is marked in inches of mercury.
When you turn the knob on this altimeter the needle moves and the barometric pressure that corresponds to "zero feet" shows up in the Kollsman window. This makes it easier to read than the previous example, and easier to reset in flight based on radio information: You can set the local barometric pressure (QNH) in the Kollsman window and get your current altitude without having to be on the ground at a known elevation.

Sensitive altimeter, not adjustable for barometric pressure

In this sensitive altimeter you can see that there is a 100 foot scale (large pointer), and a 1000-foot scale (small pointer).

This is a bit of an unusual example: It's a sensitive altimeter that is NOT adjustable for barometric pressure (the knob simply adjusts the position of the pointers, and you set it to field elevation like you would with our first example. It can't be easily reset in flight as you need to know your current altitude to reset the altimeter correctly.

Sensitive Altimeter, adjustable for barometric pressure

This the altimeter most pilots are used to seeing in a "steam gauge" panel: It is a sensitive altimeter (note the 100-foot scale pointer), and it is adjustable for barometric pressure (note the Kollsman window, marked in millibars in this example). This is the type of altimeter required for IFR flight.
This one happens to include 3 pointers (100-foot, 1,000-foot, and 10,000 foot), because it's calibrated to 20,000 feet.

As with most aviation products there is a Technical Standard Order (TSO) behind altimeters which would get into all the specific details of the differences.
For sensitive altimeters it's TSO C10 (I believe C10b is current).
I'm not sure if there's one for a non-sensitive altimeter.


What frame of reference should I use for my Simulink simulation of the F/A-18 Hornet?

It's very prudent of you to be concerned about the axis frames in which different forces/motions are defined. It's a common mistake to ignore the fact that aerodynamic coefficients are normally defined in wind axes.

The standard approach is to calculate Equations of Motions in the body frame; this is how they are usually defined. For this, you'll indeed need a wind-to-body matrix (DCM). This is a simple matrix because it involves only two angles (beta and alpha), and these angles are normally small to be concerned about gimbal lock (the model is probably not defined where they are not small). Then you

Calculate the forces/moments that are defined in wind axes and rotate them to body.
Likewise, calculate forces and other things that are defined in the ground frame, such as gravity and wind per se, and rotate them to body. (It makes sense to use quaternions for that rather than DCM, but this is another matter).
Finally, you'll have forces that are defined directly in the body frame, such as thrust.

Now you can integrate EoM with all the data available in the body frame.

Regarding p, q, r (and such) used in calculation of the aerodynamic forces, these are usually body angular velocities that you can take directly from your EoM. However, you should double check if the aerodynamic model requires something else; this should be explicitly defined. Note that if you do need to rotate angular velocities, you can't use the same DCM but need to use the matrix that preserves the total angular momentum.


Can the mass flow rate for different power settings be determined?

Yes, it can be done but you need a complicated model with information only the producer has access to. The data in your source are not enough.

You can play around with this a bit https://www.grc.nasa.gov/www/k-12/airplane/ngnsim.html but don't expect overly realistic answers. You have to use the Tunnel Test Mode for off-design performance after entering all the data you have available. And you should pick the "turbofan" engine type.


What is the average weight difference between composite and metal airliners?

(Own work via boeing.com) Overlayed scaled drawings.

Above you see similar sized planes with the same 3-class seating (± 1 seat). The newer-more-composite 787 is 16 tonnes heavier, yet delivers up to 20% fuel saving (route dependent). 3.4 of the 16 tonnes are the newer and bigger engines. And the rest is primarily bigger wings (which can be built bigger more easily thanks to composites).

The aim is building bigger wings, not losing weight. The other main goal is the reduced maintenance cost (better fatigue tolerance, no rust, etc.)

Boeing says:

  The result is an airframe comprising nearly half carbon fiber reinforced plastic and other composites. This approach offers weight savings on average of 20 percent compared to more conventional aluminum designs.

Based on that quotation, the answer is -20% (given the same wing, etc.). Also note the 787 also saves weight from the no-bleed architecture, yet as the above shows, it's not a lighter plane than the one it replaces. (No-bleed also improves engine fuel efficiency, not just weight.)


What effect does downwash have on the horizontal stabilizer

First, the downwash extends over a wide height, so moving the tail up or down will change the local downwash angle only a little (first order approximation: By the cosine of the elevation angle at which the tail is positioned).

Next, downwash at the tail is a good thing: Since the downwash angle increases with angle of attack, the angle of attack range at the tail is smaller by the downwash effect than it is for the wing. This keeps the tail in a narrower band of angles and allows it to still stay firmly in the linear range when the wing is about to leave it (which happens when the wing stalls).

What you don't want to happen is that the wing wake hits the tail. The wake contains the wing's boundary layer and produces an undesirable drop in dynamic pressure at the tail. Initially, tails were moved up to avoid the wing wake impinging on the tail (think MiG-15 or F-101 Voodoo), but that only shifted the eventual point where the wing would blanket the tail to higher angles of attack. With the reduction in aspect ratio and the increase in wing sweep made possible by more powerful engines, the upper angle of attack limit went up and the tail could not be moved up enough. Therefore, all modern designs try to put the tail as low as practical and even add some anhedral. Here the limit is of course a tail strike, so you might get the impression that the tail is in line with the wing. At practical angles of attack it isn't.


How to calculate the fuel flow using the thrust specific fuel consumption?

As Peter Kämpf said, the units should be in kg per N per second/hour.
In your case assuming it's a typo, and assuming the formula is $\text{C}_\text{T}$ = 0.7 kg/h per Newton.

Then in static condition,

Fuel flow $= 12 \cdot 10^3 \cdot 0.7 \cdot \frac{1}{60} \frac{kg}{s}$

gives 140 kg of fuel per second. Seems correct.

As a side note TSFC is not a fixed value but a variable of velocity as well. So have to make sure this CT is for static condition.


What is the wording on outline of Wright Flyer on FAA pilot license?

"Without question, flight is represented by countless heroes who have stirred greatness in others. It was a dream that had been waiting to be realized for thousands of years, and chased by countless visionaries, scholars and brave souls. But even as the mass of collected knowledge came to a crucial turning point, it was not until the ingenuity of the Wright Brothers that the puzzle of powered flight was solved. Discovery requires deep understanding, constant interpretation of knowledge and unbridled persistence."

It is part of a speech given by Marion Blakey on December 17, 2002 at the Air and Space Museum for the Centennial of Flight Kick-Off event. Unfortunately I can't find the full text of the speech (for free at least, it is part of a book you can buy for \$5 used, or \$108 new). Marion Blakey was the 15th FAA Administrator from 2002 to 2007.


What happened with the balloons of project Excelsior?

In general, those kinds of balloons cannot be reused. There was a concern, I don't know if it was a Manhigh flight, where one balloon had burst when strong winds bounced it on the ground, and the spare was used on another day. But the weather was iffy, and if that flight had to be scrubbed they couldn't reuse it once they had started inflating it, and they didn't have another on hand, so that could have delayed the entire project. Used balloons were sometimes given to farmers, who used them to cover hay. I don't know specifically what happened to the Excelsior balloons, but I presume they made it to the ground since the gondola was recovered and reused. Ground control could operate the valves in addition to receiving data, and they had a man on the team who could predict the landing site. But there is no reason they would have kept them.

If you want to read about that in more detail, you might look for the book The Pre-Astronauts: Manned Ballooning on the Threshold of Space, by Craig Ryan.


What were to happen if deicing fluid went in to the jet-engine?

Deicing fluid is inhaled by jet engines nearly every time the truck is called out. The question is how much deice can the engines tolerate?

Turbine engines can accept a rather staggering amount of water, to the point that testing them becomes an exercise in water handling instead of engine handling. The fire department can empty their trucks into an idling engine and not affect it.

Deice does contain various flammable liquids, but the overall mixture is not flammable - rather dangerous although fire would be a quick way to clear the ice.

So, unless you find a way to empty the truck into the engine in less than a few seconds it's simply not an issue.


In what conditions do airline pilots favor crabbing over de-crabbing for crosswind landings?

First, I would say that the question should be between Crab technique vs sideslip technique. What the wikipedia article describes as De-crab technique is simply a quick transition from crabbing to a momentary sideslip as the wheels touch down. Generally, landing while crabbed is bad form, regardless of type or size of aircraft due to the side load on the landing gear at touchdown.

I was taught that side slip technique (where you fly with the down wind wing slightly elevated and use rudder to keep fuselage and wheels lined up with the centerline) is preferred because you don't have to do any last second adjustments right before touchdown. If you do this correctly, the turning tendency of the aircraft is mostly cancelled out by the cross wind component. Also, if you do this right, you touch down with upwind mains first, then downwind mains.

However, I was also taught that side slip makes passengers feel uncomfortable, and that is why airliners stay in the "crab" until last second.

As to your comment about airliners failing to de-crab, I've seen that too, I argue its just bad technique. Its difficult to properly execute the de-crab, it takes finesse and good timing.


Why do some helicopters have the tail rotor mounted higher than the tailboom?

I've been thinking hard about this question, how to answer it and indeed, whether to answer it or not at all since the question itself is a good one but borders on "too broad".

The answer from aeroalias is good but doesn't offer any "whys". Tail rotor design is also a fiendishly complex subject and, like most things in aviation, is the result of many compromises and inter-dependencies.

As an example of how complex it is, there are two helicopter dynamics "bibles" by Ray Prouty and Walter Wagtendonk. Neither of them fully explain tail rotors and indeed, Prouty often says "for reasons I don't understand". If Prouty doesn't understand something, then you are on a safe bet to say that the majority of helicopter pilots don't understand it either. You need a Physics PhD to design helicopters, you don't need a PhD to fly one.

So this is from the understanding of a pilot without the PhD. I will leave out any mention of which way the main rotor rotates and on which side the tail rotor is mounted since it will needlessly complicate the already complex. I am also assuming a generic "standard" helicopter with a single main rotor and both vertical and horizontal stabilisers. Of course, there are designs that deviate from this but to cover all scenarios would need a book, not an answer on SE.

I'm deliberately ignoring a bunch of other dependencies such as "is the advancing blade of the tail rotor at the front or the rear?"; "is it a tractor or pusher tail rotor?"; the interactions between the main rotor down-wash and vortexes and wind and what happens in high yaw rate situations (fast pedal turns) and sideways flight. Yes, tail rotor design is probably the most complex subject in helicopter dynamics.

As you know, the tail rotor counters the torque applied to the fuselage by the rotation of the main rotor. Since the tail rotor generates lift in the horizontal axis, it also produces a force which will move the helicopter across the ground (tail rotor drift).

To offset this, the rotor disc is rigged such that it tilts in the direction of this movement to introduce a horizontal component of lift which opposes the tail rotor drift and keeps the helicopter steady in the hover. If not rigged to do this with the cyclic neutral, then the pilot will subconsciously hold a little lateral cyclic to hold a steady hover. It's subconscious because you do not hold attitude and position by positioning the cyclic. You position the cyclic to hold attitude and position.

So we now have two horizontal thrust components, one from the main rotor and one from the tail rotor. Now all forces act around the centre of gravity, and it is from there that all accelerations to the aircraft to move it are measured. Therefore, if the centres of these two forces are not inline with respect to the CoG, i.e. the same vertical distance from the CoG, then a rolling "couple" is created between them and the fuselage will roll until the opposing forces are equal and opposite. This is why many helicopters hover with one skid low.

As the aircraft moves into cruise flight, the vertical stabiliser increasingly offsets the main rotor torque so the power required by the tail rotor and the angle of attack needed to offset torque reduces, therefore the roll couple force reduces and the deck of the fuselage will roll back towards level. The horizontal stabiliser also generates lift which further counters the roll such that in cruise, you are using little, if any pedal.

This is our main compromise. If the horizontal components of the lift vectors are not aligned with each other, then you accept an uneven deck in the hover. If the design calls for long periods of hovering (police work, search and rescue etc), then your design is likely to be that both centres are aligned and are above the CoG (the main rotor thrust vector must always be above the CoG because of the engine and main rotor gearbox). It is my guess that the Apache has the tail rotor mounted high to align the centres to provide a level and stable deck which makes sense on a gun platform designed to hover for long periods.

If you look at a model where the tail rotor and main rotor vectors are not centred, for example the R22, then they do indeed hover with one skid significantly lower than the other. This also has the effect of adding a couple of feet to the safe hovering height since catching the skid on the ground whilst rotating or moving sideways is almost certainly a generator of Bad Days(TM).

The trade off is that to position that rotor at the top of the fin requires an additional gearbox and drive shaft at the base of the fin adding weight, complexity and maintenance requirements. Not a concern for the Apache; certainly is for the R22.

Why does the Comanche mount the tail rotor so low, at the end of the boom? Well, I'm not privy to the design decisions and I can't find any authoritative references to them so I am using guesses, which I hope are educated guesses.

One design goal of the Comanche which is not present in almost any other helicopter is stealth.

Rotor blades make great RADAR targets, especially the tail rotor. It's relatively short blades rotating at high speed and stuck way out there in the open provide a lot of strong RADAR returns. There's not much you can do about the main rotor except in the blade profiles and materials (the details of which I expect are classified) but by mounting the tail rotor closer to the main body at the end of the boom and in a fenestron, those RADAR returns will be significantly reduced.

The tail rotor air flows are also going to help to disturb and cool down the engine exhausts by blowing them sideways and mixing them more quickly with the cooler ambient atmosphere. If you look closely, you'll see that the tail rotor is mounted directly aft of the exhausts. I am further guessing that the tail rotor gearboxes are good sources of heat so removing one (by mounting the tail rotor low) also contributes to stealthiness. The added benefit of mounting in a fenestron is to protect the tail rotor from tree strikes and so on, always a concern in nap of the Earth flying.

Because that tail rotor is mounted so low, there is a strong rolling couple and indeed, the Comanche flew very much skid low.

(Source)

To reduce this tendency, the tail rotor is canted (all this from memory) by about 20 degrees which reduces the horizontal thrust vector component and produces around 1000 lbs of lift through the vertical component which offsets the tail low tendency produced by having the TR below the CoG. That high dual horizontal stabiliser is also going to produce lift to keep the tail up in the cruise as the TR power reduces.

From Peter Kämpf:

  The 20° canting of the whole vertical also removes a powerful RADAR reflector. Flying low, a perfectly vertical tail would return horizontally oriented radiation, while the 20° angle lets one side reflect RADAR energy into the ground and the other into space.

There is a lot more to all this but as I say, it really needs a book to start to fully address all the factors but hopefully, this answer walks through the main lines of thought.


How does a turboprop engine keep running during thrust reversal?

The prop is not blowing air away from the intake, atleast in that region. In modern propellers, the twist of the blades is such that the blade angle is smaller at the tip compared to the root.

Airfoil section in propeller blade; image from FAA Pilot's Handbook

Now, if reverse thrust is applied, the outer regions of the propeller is in the negative angle of attack, producing reverse thrust. However, the case is different in the root region, which won't have a negative angle, thus not blowing air 'away'. The net result is that the compressor can quite easily handle the reverse thrust condition.

Propeller angles in various flight regimes; image from pilotsofamerica.com

Another thing is that the reverse thrust is quite small compared to that of the forward flight and the speed is also quite small. modern compressors don't have much problem in this regard.

For comparison, consider the turboshaft engines in the helicopters in rearward flight- they can handle a much greater range of speeds in that condition. As an extreme case, consider the Russian aircraft doing tailslide- even the turbofan engines cope up with that, albeit in a much limited manner.


Does a safety pilot for a PPL practicing under the hood in VFR conditions need a current medical?

As explained in AC 68-1A, a safety pilot requires a current medical:

  A pilot acting as a safety pilot per part 91, § 91.109(c), however,
  would be a required pilot flightcrew member by regulation rather than
  a passenger. Section 91.109(c) provides that no person may operate a
  civil aircraft in simulated instrument flight unless the other control
  seat is occupied by a safety pilot who possesses at least a private
  pilot certificate with category and class ratings appropriate to the
  aircraft being flown. Because a safety pilot is a required pilot
  flightcrew member, the safety pilot is required to hold a valid and
  appropriate medical certificate in accordance with § 61.3(a).

For information on a safety pilot using BasicMed see this question.

By the way, by definition a safety pilot is only required in VMC. In IMC you're in actual instrument conditions; see this question.


Yes, 500 and 1 is 500 ft ceiling and 1 mile visibility.


Are aviation accident investigation reports always made public?

Unless there is some risk of national security to releasing a public report of the accident, the reports are released. You can search the public ones (almost all are public) at the BEA website. The same applies for the other aviation accident and incident reports and you can find the available reports on the websites of the group that has jurisdiction over the accident/incident; NTSB for the US, AAIB for the UK, and many other ones.


Does Part 135 duty time begin at the start of a part 91 owner flight which occurred immediately before?

Absolutely, 135.267 (d) requires you to have 10 hours of rest within the 24 hour period preceding the completion of every 135 flight, and if the 91 flight is for the same company then it is not considered rest. Duty time starts when you are required to do anything for the company, and for a typical flight it starts when you arrive at the airport.

For more information on rest, see this question and answer.


Why aren't any jet fuels heavier than Jet A/A-1/JP-8 in common use?

As @john K said, fuel needs to be liquid at cruising altitude. The less volatile a hydrocarbon is at a temperature, the quicker it will stop flowing as the temperature drops.

Additionally, the plane is not necessarily landing in the same hot climate it is taking off from. You need a fuel that is stable across the range of temperatures experienced while operating.

This post addresses the specific behavior of different fuels in great depth.


Is using a DERATE for Takeoff actually reducing the power of the engine?

I cant' give you a 737 specific answer, but how DERATE or Flex Thrust is applied generally depends on whether the engine is FADEC or not.
If a non-FADEC, it's just an FMS computed bug target setting on the N1 indicators and you move the thrust levers as required to match N1 to the bug. So it's still the pilot actually setting thrust to a lower computer-provided target than normal (if the airplane has an autothrottle system, it's the autopilot doing that job on behalf of the pilot through thrust lever servos).
If FADEC, where you (or an autothrottle system) just move the thrust levers until they click into a detent of some sort for takeoff and let the FADEC computers directly control the engines to achieve a computed N1 setting, it's the computers controlling the engines in accordance with your thrust rating selection when you ask for TO thrust.  So in that case it's the pilot telling the computers what he/she wants, and the computers do the actual work.


KIBM RNAV (GPS) 10 -- did I find a charting error, or what is the TERPS rationale for this?

This is speculation, but in the absence of an obvious technical reason it's at least possible that this is because category C/D pilots have better lobbyists than category A/B ones.

I found an interesting but somewhat dated (1995) document  called Establishing Visibility Minimums; the author used to chair the ALPA TERPS committee. It says:

  [The TERPS concepts] are a combination of science and politics, with a
  lot of undocumented historical precedence thrown in for good measure

And:

  The political horse-trading that led to the 1976 [TERPS] revision [...]

In other words, we shouldn't necessarily assume that rules and regulations are entirely based on well-defined and documented technical criteria.

The (now outdated) 1976 chart in that document shows a default minimum of 1 mile visibility for all categories (with the single exception of an ILS with DH of 200', which is 3/4) or 1/2 with approach lighting, so a 7/8 minimum is a more recent change. So you could ask, why was this change made? One way would be to find the NPRM or other public records that detail the reasons for the change, but in practice it may be easier to contact the FAA directly and ask them (possibly under the FOIA if the information isn't already public).

One theoretical possibility is that the airline industry successfully lobbied to have 'their' minimums reduced in certain circumstances due to better training, equipment or whatever, and this approach is one of the affected ones. Diverting airline flights is enormously expensive, and the industry has a large incentive to make sure that as many instrument approaches succeed as possible. If lowering the minimums by 1/8 allows even a few flights a day to start an approach that would otherwise be illegal, that could add up to a huge financial saving.

But this is entirely guesswork on my part, I just wanted to make the point that sometimes we look for a technical explanation where the real reason is financial or political. For a definite answer, I would ask the FAA directly.


Are all the Airbus A380's 16 exits designed for everyday use?

None of the 16 exits are hatches. All 16 have identical operation. From the A380 FCOM:

  The aircraft has 16 passenger doors (...) The doors open forward. The opening/locking of the door is performed mechanically by moving the door handle. In normal operation, the door revolves electrically by pressing the OPEN pb, or the CLOSE pb. In emergency operation, the door revolves automatically. In the case of an electrical power loss, the door can be manually operated. There is a flight lock actuator in each door that locks the door handle during the climb and descent phases, in order to prevent inadvertent operation during flight.


A loop is about 3G on the initial pull, declining to maybe half a G over the top, then increasing to 3G on the pull out.  If you go in at the proper entry speed etc and you want to make it reasonably round.  If you release enough back pressure to go even slightly negative over the top, whatever is unsecured falls out (as well as all the crap on the floor coming up into your face, and, if carbureted, the engine quitting momentarily).   All it would take is a little push on the stick while rounding the stop, for whatever reason.

Observers weren't strapped in because they had to be free to move around to do their thing.

So that scene is perfectly plausible.


How much of a plane is replaced over the lifetime of an aircraft?

In the US an aircraft may be allowed to fly indefinitely so long as it continues to meet the requirements of the definition for "Airworthy" in Court Order 8130 (.2e par 9).

  Note: Aircraft operated by government agencies or the military do not
  have to comply with any rules, laws, or regulations - they may operate
  in any manner the agency desires (as long as they are not used for paying passengers). These aircraft are described in FAR 1.1 as "Public Aircraft". Examples: military fighters and transport, firefighting, research, etc.

There are two possible scenarios for replacing a part.

1) Life Limited: The manufacture or FAA through an AD (airworthiness directive) requires a part to be replaced at a certain limit i.e TIS (time in service) - calendar or operating hours, number of operating cycles (i.e. number of landings or pressurization cycles), etc. The manufacture is required to provide a chapter/section of the POH (Pilots Operating Manual) that list all life limited parts.

2) On Condition: Maintenance personal (often during an inspection) find the part 1) inoperative, 2) near or beyond "Service Limits" published by the manufacture, 3) in the discretion of maintenance personal worn and no-longer safe for operation, deemed not airworthy, etc. These parts are repaired or replaced as needed.

In practice many older aircraft have been completely replaced (technically a "repair"). There is no limit on the amount an aircraft can be "replaced".

War birds are one such example. It is legal to salvage an airplane from the ocean floor, use the corroded metal as a template to make new parts and completely assemble an aircraft from new material. The restored aircraft must be identical to the original aircraft and is legally considered the same aircraft ("all" the parts where repaired!).

There are many examples, such as the P-38 "Glacier Girl" being one of the more recent well document examples. It was salvaged after being crushed under 265ft of glacier ice for over 50 years.


Will prior hospitalization for alcohol intoxication prevent the issuance of a first class medical cert.?

Possibly, but not necessarily.
First, nobody here is an AME, and a message board is the wrong format, if any of us were, to ascertain all the relevant facts.
Second, you'll need to put that hospitalization on the form you fill out for the exam. To omit it would be a criminal offense, so don't do that.
There are at least two things the AME will consider about what happened. First, is there any lasting damage from that incident? Second, does this indicate enough of an issue with alcohol that it has to go to OKC for their consideration? Both of those questions turn on the specific facts of your case. If both are "no" then your chance of losing the medical may be pretty low. Otherwise... it's all about how your case stacks up with the FAA rules and procedures.
Your best answer may be to consult with one AME to whom you are NOT applying for the medical, and get his expert opinion. Then, with that knowledge, apply (or don't) to your AME for the Class 1.
But please don't substitute internet forum opinions for professional medical advice from an actual doctor.


Why do cabin crew also man check-in desks?

It probably depends on the airline and airport, because on the flights I have been on, the checking-in is managed by "check-in staff" who are not flight attendants. Larger airlines do the arrangement that I just describe while smaller ones might manage everything with the flight crew.


Do hot air balloon pilots file flight plans?

As a balloon pilot: no we do not.  We do fly regularly in classes G, D, and E and will occasionally wander into class C; but it is very frowned upon...and you better have an aircraft radio or at least call the tower to let them know you are there.   Of course balloons always have right-of-way so if you see us get out of the way; we can't control where we're going.


What are these five indicators at the front of the 737 passenger cabin?

This is the forward Master Call Light Panel installed in the ceiling of the cabin. A second one is located aft. These panels exist on all large aircraft for the cabin crew members to be alerted without staying at their seats.

The number and color of lights vary according to customer requested options for the cabin. Some lights may be duplicated to indicate which side of the cabin is affected (e.g. for the passenger call). These panels are not required by regulation, it's to facilitate the work of cabin crew members.

For the B737

The non customized panel of a B737 looks like this:

Source: Boeing 737 FAM

The lights illuminates and chimes are played:

Pink, HI-LO chime: A crew member dialed the forward station number on the cabin interphone handset.
Blue, HI chime: A passenger pressed the ATTENDANT CALL switch on the Passenger Service Unit.
Amber, HI chime: A passenger in the lavatory pressed the ATTENDANT CALL button.

The white portions are not used, there is no light here.

Source: Boeing 737 NG Flight Attendant Manual (D6-27370-6/7/8/900-FAM).

For the B787

Green, HI-LO chime: Cabin crew call.
Green flashing, HI-LO chime three times: All call.
Pink, HI-LO chime: Flight deck call.
Blue, HI chime: Passenger call.
Amber, HI chime: Lavatory call.
Amber flashing, HI-LO continuous chime: Lavatory smoke.
Amber flashing, HI continuous chime: Crew rest smoke.
Red: Sterile flight deck (pilots mustn't be disturbed except for safety matters, and attendants must expedite operational activities leaving commercial activities for later).

Source

No doubt in a few years, attendants will receive these indications directly on individual portable devices with more details.

Airbus has its own similar colors and chimes, see:

What does a blue light by the toilet sign mean?


Are pets/animals in the cargo hold monitored inflight for any sudden medical condition?

To the best of my knowledge, no modern (i.e. currently used in regular commercial service in statistically significant numbers) commercial passenger aircraft have access from the main passenger cabin to the cargo hold, so there is no way for the cabin/flight-deck crew to check on the critters below, even if they wanted to. My knowledge, however, is incomplete, as was pointed out in the comments, the 747-100 & -200 (and likely the -400) do have access from the passenger cabin to the forward cargo hold. The flight crew were notified when animals were stowed there, however, a long-serving 747 pilot indicated having never checked in on said animals.

Large and/or high-value animals such as elephants, giraffes, etc. are shipped as cargo via specialist transport companies where arrangements to have them tended in flight are common and accounted for (hat tip to Simon). I doubt you'll see someone pulling up to the departures gate at LGA with an elephant in a crate and wheel him up to the curb-side check-in gate.

As a personal anecdote: When I flew from JFK/KJFK to TLV/LLBG in the mid-80s we took our 2 dogs since we were moving there for a period. We got to walk the dogs on the tarmac just before they were loaded in their crates and put in the hold (747, probably -200) at JFK, but there was no mention of anyone checking on them mid-flight.

Fun fact (for me): We also got to walk the dogs at TLV just prior to our return flight, and that walk ended up taking about an hour as we got to watch them jack up a wheel on a 747 to change a flat tire pre-flight. (Yes, security was much different then. Even in Israel at the height of their occupation of southern Lebanon.)


How does vertical separation work above FL400?

For flights above FL410, 2000 feet of separation is used. Which makes all flight levels odd numbered, →410, ←430, →450, ←470, →490, ←510, ...
So for each direction as indicated above by arrows, it'll be 4000 feet.
The 2000 feet separation is because the higher up you go the less accurate an altimeter becomes, so it's for safe separation.
Even/odd is just an indication of direction in this case, which can be north/south or east/west, as explained here: Does ATC direct flights to fly eastbound at odd levels and westbound at even ones?

(Image source) Before RVSM came along, flights above FL290 were also separated by 2000 feet, compared to 1000 feet below FL290.

Between 1997 and 2005 RVSM was implemented in all of Europe, North Africa, Southeast Asia and North America, South America, and over the North Atlantic, South Atlantic, and Pacific Oceans.
[Between 2007 and 2011 China and Russia implemented RVSM.]

RVSM in essence is a reduction from 2000 to 1000 between FL290 and FL410 as long as the aircraft shows that its altimeters maintain their accuracy—among other things such as an operative autopilot.

Related:

Does ATC direct flights to fly eastbound at odd levels and westbound at even ones?
What is the maximum altitude of barometric altimeters?
Is it legal to fly in RVSM airspace with an inoperative autopilot?


How much power does the APU generate in a Boeing 737-300?

You are getting the APU mixed up with the RAT:

The Auxiliary Power Unit (APU) is an engine powered generator, either a gas turbine or a piston engine. APUs deliver enough power to start engines, power cabin lights,  cockpit instruments and radios, and in some cases power hydraulics. Often the APU can only be run at lower altitudes where the air is thicker
A Ram Air Turbine (RAT) is a small, automatically deployed propellor run generator which is lowered into the airflow if there is a loss of power. The RAT generates enough power for the most critical systems only, and is designed to give pilots enough electricity to glide until the APU can be started

Often the APU runs from the same fuel supply as the engines, so if the airplane runs out of fuel the APU is unavailable, so the RAT is all they'd have.


To what extent have political (race, gender, social class) attitudes been implicated as human factors in the cockpit?

There are numerous accident reports that state cultural issues as contributing factors, especially respect for elders / superiours / social class in Asian countries leading to poor "Crew Resource Management" - typically the co-pilot failing to challenge the captain.

The first examples that come to mind are:

https://en.wikipedia.org/wiki/Korean_Air_Cargo_Flight_8509 - According to the Mayday episode, the captain was of a higher social class than the co-pilot.
https://en.wikipedia.org/wiki/Korean_Air_Flight_801
https://en.wikipedia.org/wiki/Air_China_Flight_129


One of the suggested communication strategies for uncontrolled airports is to announce the type of aircraft and color. e.g. “Brown and white Cherokee entering downwind”.

Rather than using your initials, which like the tail number, don‘t really give any information, why not use your color or some distinguishing feature. e.g “Red tricycle ultralight” or “Blue weight-shift ultralight”.

Anyone out there would have a better chance of knowing what to look for and seeing and avoiding you.


Tripping the boundary layer refers to the action of artificially transitioning a laminar boundary layer into a turbulent one. It can happen intentionally (via turbulator) or unintentionally (via imperfect aero-smoothness, such as rivets, bolts, counter-sinks). At the point of boundary layer tripping, the surface protrusion destabilizes the laminar boundary layer and causes the transition to occur earlier than via natural Tollmien-Schlichting instability.

The following is an example of a turbulator tape. It is attached spanwise along the surface of the wing (facing flat against the surface) at the desired chord-wise location where the laminar-turbulent transition is to take place:

Since turbulent boundary layer has higher skin-friction drag than a laminar one of the same Reynolds number, unintentional boundary layer tripping is undesired. That's why wing surfaces must be made flush and smooth. At the same time, since a turbulent boundary layer is much better at resisting flow separation than a laminar boundary layer, tripping the boundary layer can be used to improve stability & control at high angle of attack at the expense of increased skin-friction drag.


What systems, in the cabin ceiling, when damaged could cause the masks to deploy?

The scenario where ALL the masks drop, which the article somewhat implies but doesn't outright say, sounds fanciful to me.  A cork striking an individual mask unit might cause that individual unit to drop its masks (so if the unit was for one side of a 3/3 seating arrangement, the 4 masks it contains would all drop), but the masks in Boeing airplanes at least are electrically activated, so physical damage to the cabin ceiling seems unlikely to cause a mass deployment.

Now, if the cork happened to hit the switch in the COCKPIT, then perhaps all the masks could deploy then.  Normally the masks drop only when the system senses a cabin altitude in the range of 15,000' MSL, but there is a switch the pilot can use to drop the masks if you get the rapid depressurization up high and the automatic system failed.  Typically this switch is safety wired shut for obvious reasons, but if some operator didn't use safety wire and the cork hit the switch JUST RIGHT, then this scenario might work.  (We're talking a one-in-a-million shot here, but it might be possible.)

There are stories of hard landing sometimes dropping one or a few rows of masks -- this happens when the latch on the container isn't quite as secure as it is supposed to be, and as long as nobody reaches up & activates the flow of O2, it's a pretty simple maintenance procedure to repack and restow the masks.  (If somebody DOES pull down & activate the O2, then the oxygen generator canister for that unit has to be replaced, and that's a more lengthy process -- especially if the generator isn't on hand at that airport!)  So a physical shock from a flying champagne cork being enough to drop the masks from ONE unit isn't too far fetched, but unless you're talking about a really old design where the signal to all units went out mechanically instead of electrically, I have a hard time believing this scenario. (Please note, I'm not claiming that even in the oldest designs a mechanical linkage connecting all the units would necessarily be present -- just that modern designs are NOT mechanical until you get to the latch on an individual unit.)

And noting that the plane isn't allowed to fly with masks hanging sounds right... but 7 hours just for repacking one unit seems rather lengthy.  I'd suspect that the paper took the facts of ONE unit deploying, and artfully crafted it to sound like lots or all of the masks dropped.  Sensational writing?


What are the definitions of elevator angle of attack and critical angle of attack?

Angle of Attack is the angle between the chord line of the airfoil and the relative wind. The elevator is also a "wing" in the effect that it is an airfoil.

  1) Then what is the angle between the chord line of the elevator and relative wind? Because if I am not wrong, by pitching the elevator up, the wing of an aircraft is subjected to the 'angle of attack'.

It's also called "Angle Of Attack". Pitching the elevator up also changes the angle of attack of the elevator. There are such conditions as elevator stall, although much less common than wing stall.

  2) When you say angle of attack exceed critical angle of attack, is it because the elevator is pitched up thus creating wider angle between the chord line and the relative direction of the wind?

The "Critical AoA" is the angle at which the airfoil is generating the most lift.

  [Wikipedia Article on AoA]: The critical angle of attack is the angle of attack which produces maximum lift coefficient. This is also called the "stall angle of attack". Below the critical angle of attack, as the angle of attack increases, the coefficient of lift (Cl) increases. At the same time, above the critical angle of attack, as angle of attack increases, the air begins to flow less smoothly over the upper surface of the airfoil and begins to separate from the upper surface

Usually when you exceed the critical AoA, the air on the upper surface of the airfoil de-laminates and becomes turbulent. This results in a loss of lift (stall).

Source: FlightSimBooks.com

  3)In the Air France 447 accident, the PF kept saying, keeps the wings level. What does it mean? How can the wings be leveled when the angle of attack is so high? Does keeping the wings level means reducing the angle of attack to zero?

I'm not sure what context you are talking about. I've read the transcripts pretty carefully and I don't recall the PF saying to keep the wings level. The Captain said to descend, while the PF was trying to climb. The SIC was pushing the stick forward while the PF was pulling back, causing the wings to remain level (or at a slight climb).

Keeping the wings level (avoiding an un-coordinated turn) in a stall condition is the best way to avoid putting the aircraft into a spin. This is possibly what they meant, although they didn't know that they were in a stall (or if they did, they were not reacting to it appropriately).

Yes, leveling the wings would be making the AoA at zero (zero meaning where the airfoil is developing lift, and depending on the bank angle), but only if there were positive airspeed to make the relative wind parallel with the chord. In the case of AF447, the aircraft was falling out of the sky at a spectacular 15,000 FPM, which means that the relative wind to the airfoil was basically perpendicular. They didn't have the forward airspeed to change the AoA, so they should have lowered the nose to gain airspeed and decrease the AoA.

The important thing to remember is that the pitch angle of the aircraft is not the same as the AoA. You can take an aircraft at zero forward speed and drop it straight down, the pitch angle will be zero but the AoA will be perpendicular.


How can an airplane land if a hail storm damages the windshield?

In the EMB-145 the abnormal procedure for obscured windscreens is to secure items in the cockpit, open the side window and look through its opening.

There are more aircraft that share this procedure.

Here is the QRH procedure for "Impaired or cracked windshield" in the EMB-145:

Associated Windshield Heating .............................. OFF

IF  only the outer layer (glass) is cracked, no action is
    required

IF  inner layer of glass is cracked, proceed as follows:
    Cockpit Door ......................................... CLOSE
    Maximum Altitude ....................... 10,000 FT., OR MEA,
                                             WHICHEVER IS HIGHER
    Pressurization Manual Controller ........ 1 O'CLOCK POSITION

                    Wait 15 Seconds

    Pressurization Mode Selector ........................... MAN
    Cabin Delta-P ........................... SET EQUAL TO 1 PSI

    Note:  Pressurization Manual Controller must be used to set
           and maintain Cabin Delta-P at 1 psi while descending

    Airspeed .................................... BELOW 250 KIAS
    Smoke Goggles .......................................... DON
    In case both windshields are impaired:
    Cabin (below 10,000 ft) ....................... DEPRESSURIZE
    Airspeed ................................. MAXIMUM 140 KIAS,
                                                    MINIMUM Vref

IF  forward view through both wind screens is impossible, secure
    loose objects in cockpit and proceed:

    Note:  Intercommunication will be impossible with window
           removed.

    Direct Vision Window ................................ REMOVE
    Landing must be made looking through the direct vision
    window

                              * * * *


Single engine failure in a light twin after lift-off: what to do?

What you really should learn by heart is the flight speed for best climb with one engine inoperative. Try to trim that immediately and you will win more time to make a decision. The rest is really depending on circumstances: Is there a landing opportunity ahead? Are you high enough to do a 180 and land on the same runway in opposite direction? Or are you high enough (and the aircraft does not lose altitude) that you can fly a pattern and land normally?

Testing the aircraft at altitude with one engine throttled is highly recommended, but be aware that the remaining thrust / drag of the throttled engine might be different from that of the stopped engine.


Are there any incidents caused by rudder failure in Military jets?

There are certainly a large number of incidents/accidents in military jets involving rudders. I've listed a few cases, not necessarily in takeoff/landing.

A Block 25 F-16C suffered structural failure during flutter tests with the AMRAAM missile. The rudder delaminated and tore off, and the pilot managed to land the aircraft.

Source: f-16.net

B-52 vertical stabilizers were prone to failure during operation at low altitudes. While under testing, a B-52H suffered catastrophic failure of vertical stabilizer. The pilots managed to land the aircraft with help from Boeing test engineers.

"Boeing B-52 with no vertical stabilizer" by United States Air Force - USAF. Licensed under Public Domain via Commons.

However, in other cases, the same failure caused fatal crashes.

A USAF investigation blamed rudder failure for the loss of an F-15 near Hawaii in 2008. The investigation concluded that most probably both rudders in the jet failed due to failure of the aileron-rudder interconnect.
F-14 suffered from rudder hardover incidents, one of which lead to loss of the aircraft. Investigations found the reason was due to mechanical failure of a stop plate attached to the hydraulic actuator.


61.113 - is paying your pro rata share limited to the time you are in the plane?

The situation you're describing is a commercial operation. Without a commercial certificate (and a part 135 operation) you may not receive any compensation at all.

The FAA has consistently held that the 61.113's non-compensation exemption in 61.113(c) requires common purpose for the pilot and passengers (Bobertz - 2009, p.2):

  Absent a bona fide common purpose for their travel, reimbursement for the pro rata share of operating expenses constitutes compensation and the flights would be considered a commercial operation for which a part 119 certificate is required.

There is unfortunately not a strict definition of common purpose. However, the basic ground rule is that to fall under 61.113(c), the pilot must have their own reason for making the flight, independent of the passenger's.

The Bobertz interpretation presents an illustrative example: if a pilot wanted to go to a race, they could bring contestants to the race as passengers, and receive compensation. Because the pilot was flying there for the purpose of attending the race, common purpose is established, and pro-rata cost sharing is permitted.

However, if not all of the members of the race team could fit in the plane, the pilot could not share the cost to go back to the origin to make a second trip: there's no independent reason to do so. This crosses the line into a commercial operation, so no compensation is allowed.

Applying these guidelines to your question, the key phrase here is:

  I made all legs of the flight for the sole purpose of entertaining his desire.

There is clearly no common purpose. Therefore, accepting any compensation for the flight, even a pro-rata cost, is compensation in violation of 61.113.


Which aircraft endure the highest Max Q's (aerodynamic pressure)?

First, your example list doesn't distinguish between stationary and instationary trajectories. A reentry vehicle will see the highest dynamic pressure only momentarily at the end of its trip, and aerodynamic heating can be tolerated either by ablative cooling or a decently sized heat sink. All it has to sustain is the dynamic pressure at the tip.

The first samples on your list which need to continuously sustain the given dynamic pressure are the low-altitude attack aircraft B-1B and F-111. Here the dynamic pressure is given by wing loading, aerodynamics and raw thrust to keep the aircraft moving at its maximum speed. Aerodynamic heating comes on top at high altitude, because the stagnation point heat is independent of air density.

Reasons to limit the maximum dynamic pressure are:

gust loads at low altitude. Hitting the same updraft at higher speed will proportionally increase the load factor.
Aeroelastic deformation: Higher dynamic pressure means also higher torsional and bending loads, and the deformed structure might become unstable when the deformation increases the loads which lead to this deformation. Flying at higher dynamic pressure requires a stiffer and heavier structure.

If you look at the flight envelope of the SR-71 (below), it should be obvious that at each altitude only a narrow band of speed was available due to the high wing loading (= high minimum dynamic pressure) and the maximum dynamic pressure (at low altitude) rsp. the aerodynamic heating (at high altitude).

SR-71 flight envelope (picture source)


Are runways booked by airlines to land their planes?

No one can "book" runways. Traffic on a runway is managed by air traffic control, whose job it is to ensure a safe and expeditious flow of air traffic. Generally speaking, a place on the runway is assigned on a first-come first-served basis.

You may want to explore the air traffic control tag to learn more.


Why would some flights use props instead of jets?

I believe this question is answered here and a nice comparison can be found here but the short answer is efficiency. If memory serves jets gain their efficiency at high altitude moving fast and generally over a long distance. If you are going on a short hop turbo props will be more efficient overall. This chart provides a nice outline of the difference in efficiency.

As for large piston pounders I am not sure of the efficiency but I would think the cost of keeping one running is high simply based on their age (no one is really making big piston planes anymore as far as i know). History channel has a nice show "Ice Pilots NWT" about a freight/passenger airline that still runs DC-3's and the general issues they have with them many of which is related to finding parts.

That being said not all airlines had the money to jump right into jets when they came out. Lots of turbo-props are still flown simply because there is no reason to replace them.


What is the difference between leasing and chartering?

Leasing is just a long term rental of the chattel, the airplane itself, where the lessee entity does whatever it wants with the airplane during the period of lease. So you lease an airplane from a leasing company like GE Capital, and do whatever you want with it until the lease is up, then return it.
A charter is a more restrictive and objective-focused contract: it's an agreement to use aircraft for a specific purpose defined in the charter contract.
So if I want an airplane for a year to be at my beck and call to do whatever I wish, I lease it for a year.
If I want an airplane for a specific purpose, like transporting my football team around between cities X, Y  and Z for a month, with no other uses allowed unless specified in the contract, I charter it.
Usually, the charter contract is "turn key" and will include crew and support services, whereas with a lease, the user is only getting the airplane and has to provide all that themselves.
You can also have all-inclusive leases, called "wet leases" that include crews and maintenance, possibly even fuel, built into the lease rate, but you still have freedom to use the plane however you wish, as opposed to a charter where the use of the aircraft is specified in the charter.
An airline might wet lease an airplane when they need a short term replacements for grounded aircraft, especially if the type is different from their fleet.


Where is it documented an airport is military?

AFB, MCAS, NAS, CGAS/CGS, and AAF would always be military, yes. BUT the lack of that in the name doesn't mean it's not military... Outside the US especially there's often no such thing to indicate a military base from a civilian field (though AB (for AirBase) is at times used).
How do you know? You're supposed to know where you're going when you're flying, and that includes what's off limits to you.
http://www.post8.org/images/secchart.jpg shows the legend of a sectional (can't inline the image, SO refuses to), which says clearly "All military airports are indicated by abbreviations AFB, NAS, AAF, etc. For complete airport information consult DOD FLIP". So how do you know? The chart tells you by the name of the facility. It also shows a double ring instead of runway icons as indicating military, but on some charts I looked at that appears to not be consistently applied.


Why is there such a low level of automation in the aerospace industry (compared to other industries such as automobile)?

There are two big factors at play here: scale and throughput.

First, automation is very good at repetitive tasks. The Wolfsburg plant produces over 800,000 cars per year. It's taken 25 years to make almost 600 Typhoons. That means yearly production is different by four orders of magnitude. It's a lot easier to justify the cost of buying, installing, and programming a robot to save a human from doing the task 800,000 times in a year than just 25 times. This also means that a robot can completely replace a person with a job at one place on the assembly line doing only a few tasks over and over. On the Typhoon line, even if a person only works one line position, they may have many more tasks all over the airplane.

The scale of the Typhoon is also different. It's easy for a few standard industrial robots to access an entire car chassis. It's much harder to access everything on a fighter jet. Larger robots will be even more expensive. Mobile robots are much harder to use with high accuracy. And where you might be able to have multiple humans doing various tasks in the same area, the whole area would have to be blocked off for safety to allow maybe a couple robots to work there.

There is also the factor of processes. A lot of the assembly work on cars is done with welding, which is fairly simple for a robot to do. The Typhoon is mostly assembled with nuts and bolts, which is a much more complex process for a robot to accomplish.

If you break things down to the component level, the balance changes. Drilling thousands of holes in the various components is often done with robotics and some smaller assembly work can be done as well. It's where all of that is assembled into a large structure that humans become the cheaper option.

This also feeds back into the design process. Cars are designed from the start to be easily assembled robotically, because it's much cheaper that way. Not having to design all assembly processes around robot access allows aircraft designers to make things smaller and lighter, a much larger factor for airplanes than cars.


Looking for an API that can provide the amount of flights bought from point a to point b on daily basis

Not sure you can get the data easily.
IATA developed the NDC standard an API for airlines, which might enable you to check flight bookings between two destinations.
Nonetheless, as with any industry wide standard, it is interpreted in many different ways by the companies implementing it. Hence a pain to develop.

The most simple solution would be to use a set of well defined APIs from an airline ticketing company. Amadeus is one of them and I am almost sure they provide these kind of information.

In both cases, you are looking at quite a high upfront cost (in the thousands).


What would the altimeter indication be through a cold front?

There are two altimeter reading questions here, what happens when:

flying towards the cold front (third paragraph)
flying into the cold front (headline)

According to this University of Illinois web article following things happen:

Flying towards a cold front (or in the article the front is approaching you, but it makes no difference):

pressure drops steadily
temperature is steady

Passing through the front:

pressure reaches minimum, then rises sharply
temperature drops suddenly.

So, to answer both questions, assuming you are flying at relatively low altitude and maintaining it in reference to your altimeter and you do not adjust QNH:

Approaching the cold front you would steadily drift downwards: from high to low, look out below!
Passing through the front you would need to climb to maintain steady altimeter reading: low to high, hello sky!

You see, the question is about what happens to altimeter reading, but since the vertical position of the aircraft is maintained in reference to the altimeter reading, whether it's you or the autopilot flying, the altimeter reading would not change. The vertical position of the aircraft would be instinctively or algorithmically adjusted to keep the reading at a selected value.

What happens at altitude, is (for now) somewhat beyond me (pressure gradients and stuff), so  I dare not answer that scenario here yet.

P.S. a private pilot should not fly through a cold front: it's not a good place for small planes to be in...


What prevents miltiary jets and turbo-props from being refitted with a turbofan?

Anti-submarine and maritime surveillance aircraft (such as the turboprop P-3 Orion) typically fly slower and lower than the 100+ passenger jetliners.

For those speeds and altitudes, a turboprop is more economical. So there is no need that would push such a massive undertaking to retrofit an airplane.

See: Which engine is more efficient between turboprop vs jet?

That aside, let's say you have bought a P-3 Orion and you wish to retrofit it with turbofans.

High-bypass turbofans are wide, ideal position would be under the wings where the current engines are. Since they are big and the current engines are mounted mid-wing, there will be no engine—ground clearance.
Raise the landing gear, this is extremely difficult to accomplish. It's easier to build an entirely new aircraft. If it was easy, Boeing would have done it for the 737 Classic, 737NG, and 737 MAX (three opportunities).
The current engine cowls are an integral part of the wings, so new wings will be needed.
Loss of efficiency with same fuel carrying capacity means degraded range and endurance.
New cockpit instruments and controls will be needed. Almost a complete overhaul for the avionics. Which for the flying equipment (non-military equipment), costs in the neighborhood of 30% of the total aircraft cost (not taking into account the required R&D).
New electrical system, new pneumatic system, etc. Basically any system the current engines power, needs to be re-engineered.

For turbojets (and low-bypass turbofans) it's not easy, but much easier than turboprops. It has been done for the Boeing KC-135 Stratotanker for example (and to the DC-8 on the civilian side). And it's been discussed numerous times for the B-52.

Here since the speeds and altitudes are almost the same, there is now a gain in fuel efficiency (as long as we are not talking about supersonic aircraft).

Before the advent of the commercial jet age, converting a piston airplane to a jet airplane for the purposes of engineering validation was done. Such example from 1950 is the Avro Tudor 8:

(Source: Flight)


How is a "conflict" between aircraft predicted and determined?

It is a bit of a grey area and the answers you'll get will depend also on which field of expertise you are in. I am involved in developing and standardising ATC surveillance systems, here's my take on it.

Loss of separation is the simplest definition of the two and it has regulatory consequences. But even that one is not black and white. How do you determine the exact position of two aircraft? Suppose you have a 5 NM radar separation minimum and a radar that has an accuracy of 0.2 NM. If the two aircraft are flying parallel 5.1 NM apart at the same altitude there is a high probability that at some point the difference in radar measurements is less than 5 NM. Is that a loss of separation? To make it even more complex, radar tracking systems lag in turn detection; while an aircraft has started to turn 15 seconds ago, the tracking system may see that as radar measurement noise and may stubbornly paint a straight track depending on the tuning parameters.

The definition of conflict you quote has little regulatory meaning but has its roots in workload estimation of aircraft traffic controllers. It is also used in conflict detection systems. Short term conflict detection systems predict the path of aircraft by extrapolating the current position into the future using speed and flight plan, usually augmented by the aircraft traffic controller with cleared altitude, speed, heading etc. If within a predefined time window (approx. two minutes) two aircraft are predicted to be below the separation minimum, an alert is raised. The exact method of prediction varies from system to system. Medium term conflict detection is similar, but depends more on the flight plan than on the current speed vector. The longer term the prediction, the higher probability of a missed conflict or a false alert

The big trick is to design a conflict detection system that has a low missed alert rate (otherwise it isn't effective) and a low false alert rate (otherwise it is a nuisance and will be ignored or turned off) at the same time. It is indeed a trade-off of probabilities.


How do CH-47 pilots lower the tail during a pinnacle landing?

A careful balance of nose-up cyclic and decreased collective to stick the aft of the ship firmly in place. Not so much a landing, as flying with the aft gear and ramp planted.


Why are the transition altitudes/levels different around the World?

Flight Levels are easier to work with for ATC and for pilots since everybody will use standard pressure setting. Effectively it means less work load and lower probability of making an error with a safety impact.

Typically the highest terrain elevation plus some margin is used as transition altitude. This gives the highest number of flight levels available.

For example in the Netherlands, being a flat country partly below sea level and the highest obstactle at about 1500 ft, has a transition altitude of 3000 ft for IFR flights and 3500 ft for VFR flights.

There is (was?) an initiative to create a common transition in Europe, but I haven't heard anything about it for a while. Some interesting reference documents were produced:

Towards a Common Transition Altitude - A Flight Deck Perspective

A Common European Transition Altitude  - An ATC Perspective

(both files in PDF format)


What happens when a pilot is incapacitated?

Is there a contingency for such a situation, where one of the pilots leaves the cockpit, the other pilot is incapacitated (for example losing consciousness) while the first pilot is still outside the cockpit and can not reenter the cockpit.

Yes, a keypad on the door will allow the second pilot back into the cockpit. It doesn't help when the pilot outside doesn't know/forgets the code or if the unlock code is denied from inside the cockpit.


Is it legal to rent out an experimental aircraft?

Since you specifically state the question as it relates to E-AB, the reference to 91.319(f) doesn't apply. But 91.319(a) does apply.

From 91.319, the answer is "no".

  §91.319   Aircraft having experimental certificates: Operating
  limitations.

  (a) No person may operate an aircraft that has an experimental
  certificate—

  (1) For other than the purpose for which the certificate was issued;
  or

  (2) Carrying persons or property for compensation or hire.

Your statement that "The aircraft will not be used for hire or compensation but to rent out to a pilot who wants to fly from point A to point B." is where you have erred. The FAA has interpreted that rental (or lease) of an aircraft with or without crew is a commercial operation that is "Carrying persons or property for compensation or hire."

So in the view of the FAA, renting the aircraft is a violation of §91.319 (a)(2).

You should also be aware that you could be violating access rules for your airport by operating a business that doesn't comply with the airport's minimum standards for business. That could get you kicked off the airport.

You also need to consider the conditions of any insurance policy that covers the aircraft.

That said, there's nothing that prohibits you (except possibly insurance) from loaning the aircraft to someone as long as you don't receive any compensation. Just be aware that the FAA interprets the term "Compensation" very broadly; e.g. excess fuel on return of the a/c could be considered compensation.

Final caveat: I'm not an aviation lawyer, so nothing I say should be considered legal advice. Contact the FAA, EAA (since this about E-AB) or an aviation lawyer if you want a more definitive answer.


Can audible warnings be heard from the cabin?

On the Airbus even with O2 masks, loudspeakers aural alarms level ( normal or abnormal) can’t  be adjusted by the crew, these are such as ground proximity alarms or stall alarm, or engine fire, degradation in autoland or autopilot disconnect, single amber gong, repetitive red gongs, altitude hold deviation, altitude decrements  at flare etc

As these loudspeakers sound levels are not adjustable, and as the cockpit is not sound proof, these aurals  are heard  in the very front rows.


What does METAR show when actual RVR is below the reporting minimum?

If the RVR is less than the minimum value that can be measured , M will precede this value e.g. R24L/M0050.

If measured in ft, then FT will follow. For example: R24L/M0200FT

For greater than can be measured and trends:

  If the RVR is greater than the maximum value that can be measured, P will precede this value e.g. R24L/P1500.
  If RVR trends can be measured then U, D, or N will follow the RVR value to indicate increasing, decreasing or no change respectively.

Source: https://www.skybrary.aero/index.php/Meteorological_Terminal_Air_Report_(METAR)


Anybody with the resources and connections to buy an F-14 could probably find a former Navy CFI to get them up to speed.  Otherwise no, there is no existing course you can simply attend.  There just isn't enough demand to run such a business.


Why don't jetliners maneuver to avoid a bird strike if spotted in time?

If you're low, slow, and heavy (say, early in climb with full passenger and fuel load for a transcontinental or transoceanic leg), just dipping a wing can result in a stall and crash if you lose power while in a more than minimal bank.

The reasoning goes like this: the birds might not hit you.  If they do, it's unlikely you'll lose all engine power.  Even if you do lose all power, if the aircraft is level wings and not maneuvering, you have the most options for a safe landing (return to port, land on a nearby strip, land on flat ground or a road, etc.).

A sharp maneuver at that stage of a flight can itself cause a crash, never mind what will happen if you get a bird strike anyway.


In India, what is the difference between "local flying area" and "airspace"?

A local flying area is airspace that is designated by local air traffic control for general flying not involving circuits and landing. In the US it is something that is loosely referred to as "the practice area." In this area aircraft can perform practice and other maneuvers, and air traffic control will be aware of it and can warn other aircraft to be on the lookout for this. In India it is common for these practice areas to be segregated for flying school aircraft, and medium to heavy aircraft.

To put it another way, all local flying areas are part of a country's airspace, but only a fraction of the airspace is designated as local flying areas. I hope this helps.


Is the twin vs quad engine industry preference really challenged?

Why would Airbus go to the effort of developing the A330 when they could offer the A340? Both have the same airframe and differ mainly in the number of engines. With ETOPS requirements at the time of development (when they were known as TA9 and TA11) being just 2 hours (ETOPS 180 operations were only begun in 1989), the only reason for developing the 4-engined variant was its capability of flying long overwater routes.

The time it takes to check an engine is the same regardless of size, so having only two of them saves time and money. In addition, the higher power reserves of a two-engined aircraft allow for higher climb speeds and enable it to reach the most efficient cruise altitude faster.

Today, most airliner engines are no longer owned by the airlines, but leased from the engine manufacturer. They offer a simple thrust per hour model where the airline knows exactly how much the engine will cost them over time, maintenance included. The only open issue is how long the airliner is grounded due to unforeseen maintenance, and with four engines per aircraft the number of unforeseen snafus is twice that of a twin.

At the same time, the airline is in the best position to judge how expensive a seat-mile in any of their aircraft is. Engine cost can be calculated very precisely, so every airline should have a very clear picture of how expensive their twins and four-engined aircraft are.

There is a small chance that the geared turbofans which are now being introduced will give the A340 an edge over a twin variant. The higher thrust class of large twins makes a geared fan currently impossible, so a four-engined aircraft will have an edge because it can use a more advanced engine.


Why don't modern F-16s incorporate the VISTA thrust vectoring?

Thrust vectoring adds weight, cost and complexity, and the benefit isn't important enough to outweigh that.

Various aircraft have been used to experiment with thrust vectoring, but the list of thrust vectoring fighters in service is fairly short:

F-22
Su-30 (newer variants)
Su-35S
J-20 (fairly new)
Su-57 (very new)

The F-16 was envisioned to be a small, light, and cheap fighter. It has certainly grown heavier and more expensive over the years, but that is still one of the big selling points. Although it worked fine for the VISTA experiments, the limited space, power and cooling on the F-16 is best used for other upgrades, such as better sensors. And the F-16 is still selling fairly well. Lockheed is still getting enough orders that they moved the production line to make room for the F-35 rather than shutting it down.

Even the F-35A, intended to replace the F-16, adds stealth but not thrust vectoring. If you can kill your adversary before they even know you're there, dogfighting ability becomes less important. There's also the reality that US manufacturers build primarily for the US, and for US interests. There might be resistance to exporting an even more maneuverable F-16 when it may already be close in capability to the F-35.


Is joining the air force a good way to become an airline pilot?

Honestly, every U.S. Air Force pilot I know, who wanted to retire to the airlines, got hired on with no problems.  The ex-Air Force pilots I know have all gotten immediately put into the big planes: A380, 747, 767, 787, etc right from the start.  This is because the airlines know that an ex-military pilot has had some of the best training and experience in high pressure situations.

That being said, in the USA it is very hard to become an Air Force pilot.  You have to contract with the Air Force before they even let you know if you can go to pilot training.  That means, if you don't make the cutoff for pilot training, you have to spend at least 4 years in the Air Force.  If you do make it through Air Force pilot training you have to contract for 10 years after you finish flight school, which means about 12 years from your date of commissioning.  This will take a good 16+ years out of your life, including the time spent in college.  However, you will progress from your first flight all the way to potentially flying F-22s in under two years - a rate of progressing you won't see anywhere else.

Bottom line is, if you don't want to join the military then you shouldn't.  By joining the military you are expected to give your life for people you may not know, or even care about.  That aside, there's no point in spending a minimum of 16 years doing something you don't like, or fighting for a cause you don't support just to become an airline pilot.  If you can find a good airline cadet program, or scholarship, you can become a great airline pilot, it will just take a longer time to progress from one aircraft to another.

Just a little tangent.  That being said, I'm currently an AFROTC cadet, and I had no military background.  I love AFROTC, the US Air Force, and the USA.  I'm currently applying for a pilot slot in the U.S. Air Force, but if I don't make it I would be vary happy taking other jobs, too.  The key is to have small, achievable goals that you can take one step at a time.

I wish you the best of luck.


How does the IAS stall speed vary with increasing altitude?

Airplanes do not stall at the same indicated speed or even at the same angle of attack - it all depends on circumstances.

The angle of attack dependency is discussed here. An increased pitch rate can push the stall angle of attack 50% higher than what the stall angle of attack is in stationary conditions.

The next big factor is the Mach number. When increasing the angle of attack, the flow around the airfoil's nose will develop a suction peak. This suction is equivalent to higher local speed, and if the critical speed (when local flow speed equals the local speed of sound) is exceeded, the flow past the suction peak will no longer behave similarly to the flow at the same angle of attack but a lower flight Mach number. Let's just say that the local Mach number in the suction peak has a strong influence on the stall angle of attack, and flying at a higher Mach number lowers the stall angle of attack, sometimes dramatically.

Increasing altitude will raise the flight Mach number in two ways:

The reducing density means you need to speed up to fly at the same dynamic pressure, and
the atmospheric lapse rate decreases the speed of sound in air.

Both effects conspire to reduce the stall angle of attack at 30.000 ft to a value quite a bit below that at sea level. Details depend on the airfoil and specifically on its nose radius and wing loading.

Only very light aircraft will not be affected by the change in Mach number, but even here the stall angle of attack at altitude is lower than at sea level due to the reduction of the flow's Reynolds number with increasing altitude.

In short, the indicated stall speed goes up with increasing altitude for a variety of reasons and does so nonlinearly. The magnitude of the change depends on a multitude of details.


What do the yellow lashes/wings on the B737 PFD indicate?

They display the maximum pitch that can be exercised with the current configuration of the aircraft.

Using data which is measured in modern airliners, a maximum pitch angle can be calculated and displayed to the pilot on the primary display. It is described fully on this page (h/t @mins)

  With airplane aerodynamic specific data and the angle of attack measurement, we can have an effective pitch limit indicator PLI. A pitch limit indicator informs the user about the current difference between $max(\alpha)$ and the current $\alpha$. In many commercial airplane the pitch limit indicator is integrated within the glass cockpit, as shown in Figure 3; with this setup the pilot has a real-time indication of how much can pull on the column.


Why are many runways used just for departures/arrivals?

There are many constraints on runway usage, and sometimes it's not the runways themselves but the protected airspace for approaches that determines what "normal" is - as well as airport design, noise abatement, wind, aircraft type, taxiway configuration, departure routes in use, etc.  It is typically more efficient (= less delay) to run all of one type of operation on a runway: you can launch more departures faster if you're not trying to land other aircraft in between them, so if there is a major departure push on, the tower will try to dedicate at least one runway to departures only.  Same thing for arrivals: landing aircraft need to be spaced further apart if there are departures going out on the same runway, and if a departure can't roll as soon as expected (for example, if the last arrival doesn't clear the runway as quickly as possible), the next arrival may have to go around because the next departure is still sitting on the numbers.  Having said that, unless the airport management puts specific restrictions on runway usage, ATC is free to shuffle the deck any way they see fit and land/depart from any appropriate runway if operational needs require it.  Pilots also have the right to request a specific runway for THEIR operational needs, and ATC will accommodate the request even if it isn't exactly their current plan.

LAX generally lands on the outboard runways because the final approaches are further apart, and taxiing is less complex if the departures go off the inboard runways.  That doesn't mean they never do anything else, but that's kind of the "normal" case.


What's the name of this part of combustion chamber and what is it for?

On depictions of the CFM56 combustion chamber, that's part of the cross-section depiction of the diffuser.


Should you wait to switch to the ground frequency until after crossing a runway?

Remember that active runways are always the jurisdiction of the local (tower) controller. Even if a ground controller tells you to cross a runway, they have to clear it with the local controller next to them. So generally you switch frequencies when you have finished crossing the runway unless told otherwise.

I can tell you this is exactly how it works in Boise, Idaho where there are the parallels 10/28 L/R.

However, if you are unsure of any instructions a controller gives you, the basic rule is: ask. The tower controller won't mind, and will typically appreciate the clarification. Just read back the crossing instruction as normal, then ask.

  Right on E, cross 27 R, contact ground .9, N12345, and should I contact ground on the other side of 27R or immediately?


Where can I find the various operating limitations of the ATR 72-500?

LIMITATIONS

  PAGE : 001 APR 11 EASA APPROVED

  Model : 212 A
  AFM 1

  2.01.01 | INTRODUCTION

  Observance of the limitations contained in this chapter is required by law. When
  operating in accordance with an approved appendix or supplement to
  this manual, the limitations of this basic Airplane Flight Manual
  section apply, except as altered by such an appendix or supplement.

  2.01.02 | KINDS OF OPERATION

  The airplane is certified in the
  Transport Category, JAR 25 and ICAO annex 16 for day and night
  operations, in the following conditions when the appropriate equipment
  and instruments required by the airworthiness and operating
  regulations are approved, installed and in an operable condition :

  VFR and IFR
  Flight in icing conditions.
  Reverse thrust taxi (single or twin engine)

  2.01.03 | MINIMUM FLIGHT CREW

  2 pilots

  2.01.04 | PERFORMANCE CONFIGURATION

  Refer to 6.01.03 for airplane configuration associated with certified
  performances.

  2.01.05 | MAXIMUM OPERATING ALTITUDE

  25000 ft

  2.01.06 | MANEUVERING LIMIT LOAD FACTORS

  Gear and flaps retracted : + 2.5 to -- 1 g
  Gear and/or flaps extended : + 2 to 0 g

  2.01.07 | CONFIGURATION DEVIATION LIST

  Refer to 7.01.02

  2.01.08 | NOISE CHARACTERISTICS

  The aircraft meets the requirements of ICAO annex 16,
  Chapter 4 with no weight restriction. Refer to noise characteristics
  in Appendix 7.01.01 of this manual for noise levels.

  2.01.09 | MAXIMUM NUMBER OF PASSENGER SEATS

  74 as limited by emergency exits
  configuration

  2.02.01 | WEIGHTS

  STRUCTURAL LIMITATIONS

  MAXIMUM WEIGHT KG LB

  RAMP 22970 50640
  TAKE-OFF 22800 50265
  LANDING 22350 49273
  ZERO FUEL 20800 45856

  PERFORMANCE LIMITATIONS

  Maximum take-off weight and maximum landing weight may be reduced by performance
  requirements related to the following (see chapter 6) :

  climb performance (first and second segment, final take-off and en route, approach and landing climb)
  available runway length (take-off and landing)
  tyre limit speed
  brake energy limit, observe BRK TEMP alert for take-off
  obstacle clearance (take-off and en route)
  en route and landing weight

  2.03.01 | AIRSPEEDS

  MAXIMUM OPERATING SPEED VMO / MMO

  This limit must not be intentionally exceeded in any flight regime.

  VMO = 250 kt CAS
  MMO = 0.55

  MAXIMUM DESIGN MANEUVERING SPEED VA

  Full application of roll and yaw controls, as well as maneuvers that involve angles of attack near the stall
  should be confined to speeds below VA.

  VA = 175 kt CAS

  CAUTION: Rapidly alternating large rudder applications in combination with
  large sideslip angles may result in structural failure at any speed.
  MAXIMUM FLAPS EXTENDED OR OPERATING SPEEDS VFE

  FLAPS 15 185 kt CAS
  FLAPS 30 150 kt CAS

  MAXIMUM LANDING GEAR EXTENDED OR OPERATING SPEEDS

  VLE = 185 kt CAS
  VLO
  lowering = 170 kt CAS
  retracting = 160 kt CAS

  2.03.02 | OPERATIONAL PARAMETERS ENVIRONMENTAL ENVELOPE

  Note : Refer
  to 2.04.05 for fuel temperature limitation. TAKE–OFF AND LANDING –
  Tail wind limit : 15 kt – Maximum mean runway slope : ±2 %

  2.04.01 | ENGINES

  PRATT&WHITNEY CANADA PW127F or PW127M or PW127N

  Operating limits with no unscheduled maintenance action required;
  Beyond these limits refer to maintenance manual.

  OPERATING CONDITION TIME LIMIT TQ
  (%) ITT ($^\circ$C) NH (%) NL (%) NP (%) OIL PRESS (PSI) OIL TEMP ($^\circ$C)
  (2)

  RESERVE TAKE OFF 10 mn (6) 100 (1) 800 103.2 104.2 101 55 to 65 0 to 125

  NORMAL TAKE OFF 5 mn 90 (1) (5)
  101.9 101.4 101 55 to 65 0 to 125

  MAXIMUM CONTINUOUS none (7)
  90.9 (1) 800 103.2 104.2 101 55 to 65 0 to 125

  GROUND IDLE 66 mini 40 mini (4)
  -- 40 to 125

  HOTEL MODE 715 55 to 65 125

  TRANSIENT 20 s 120 840 106.4 106.8 106 (3) 40 to 100 5 s 120 20 mn 140

  STARTING 5 s 950 --54 mini

  Value linked to 100 % NP.
  Oil temperature must be maintained above 45$^\circ$C to ensure protection for
  the engine air inlet against ice accumulation.
  Permissible for completion of flight provided TQ does not exceed 75.2 %
  during climb and 73.13 % during cruise.
  Up to 75 % NH only.
  ITT limits depend on outside air temperature. Refer to 2.04 page 2.
  Single engine operation only, beyond 5 mn.
  MCT rating is the max
  power certified for continuous use. In-flight emergencies are the
  only conditions for which MCT use is authorized.

  NOTE : Flight with an
  engine running and the propeller feathered is not permitted

  2.04.02 | PROPELLERS

  TWO HAMILTON STANDARD HS 568 F
   – 1 GROUND OPERATION
  Engine run up must be performed into the wind.  Avoid static operation
  between 41.6 % and 62.5 % NP.  Avoid operation in feather above 66.6 %
  TQ.

  GROUND OR FLIGHT OPERATION  If a propeller is involved in an
  overspeed or in an engine overtorque refer to the propeller
  maintenance manual.

  FLIGHT OPERATION  ATR airplanes are protected
  against a positioning of power levers below the flight idle stop in
  flight by an IDLE GATE device.  It is reminded that any attempt to
  override this protection is prohibited. Such positioning may lead to
  loss of airplane control or may result in an engine overspeed
  condition and consequent loss of engine power.

  04 POWER PLANT 2
  LIMITATIONS PAGE : 001 DEC 96 EASA APPROVED
  --Model : 212 A AFM 4 AUG 07 FEB 05 R JUL 06 SEP 06 R R R

  2.04.03 | OILSYSTEM SPECIFICATION Refer to specification PWA 521 type II.

  2.04.04 | STARTER

  3 starts with a 1 minute 30 seconds maximum combined starter running time followed by 4 minutes OFF.

  2.04.05 | FUELSYSTEM

  Acceptable fuels : Jet A, Jet A1, JP5 and RT, TS1. Use of JP4 and Jet B is prohibited.

  TEMPERATURE

  For flight
  preparation, a minimum fuel temperature must be taken into account to
  ensure adequate relight :

  3 4 o C JET A, JET A1 and RT, TS1.
  2 6 o C for fuel type JP5. •Maximum temperature : 57 o C for fuel types JET A, JET A1, JP 5 and RT, TS1.

  REFUELING

  Maximum pressure 3.5
  bars (50 PSI)

  USABLE FUEL

  The total quantity of fuel usable in each
  tank is : 2500 kg (5510 lbs)

  NOTE :Fuel remaining in the tanks when
  quantity indicators show zero is not usable in flight.

  UNBALANCE

  Maximum fuel unbalance : 730 kg (1609 lbs)

  FEEDING

  Each electrical pump is able to supply one engine in the whole flight envelope.
  One electrical pump and associated jet pump are able to supply both
  engines in the whole flight envelope

  2.05.01 | AIR PRESSURIZATION

  Maximum differential pressure: 6.35 PSI
  Maximum negative differential pressure 0.5 PSI
  Maximum differential pressure for landing 0.35 PSI
  Maximum differential pressure for OVBD VALVE full open selection 1 PSI
  Maximum altitude for one bleed off operation 20000 ft

  2.05.02 | HYDRAULIC SYSTEM

  All hydraulic fluids compliant with technical
  specification : NSA 307110 Compliant fluids are listed in the AMM
  (Chapter20, 20-31-30)

  2.05.03 | LANDING GEAR

  Do not perform pivoting (sharp turns) upon a landing gear with fully braked wheels except in case of emergency.
  In case of ground speed over 165 kt all tires to be replaced.
  Towbarless Towing is prohibited, unless the towbarless towing operations are performed in compliance with the appropriate
  operational requirements (JAR--OPS--1 for Commercial Air
  Transportation) using towbarless towing vehicles that are designed and
  operated to preclude damage to the aeroplane nose wheel steering
  system or which provide a reliable and unmistakable warning when
  damage to the steering system may have occurred. Towbarless towing
  vehicles that are specifically accepted for ATR aircraft are listed in
  ATR Service Letter 72--09--6001.

  2.05.04 | FLAPS

  Holding with any flaps extended is prohibited in icing conditions (except for single engine operations).

  2.05.05 | AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

  Minimum height for autopilot engagement on take off : 100 ft
  NAV mode for VOR approach, using either autopilot or flight director is authorized only if :

  a co--located DME is available, and
  DME HOLD is not selected

  Minimum height for use of either autopilot or flight director :

  Except during take off or executing an approach : 1000 ft
  VS or IAS mode during approach : 160 ft
  CAT 1 APP mode : 160 ft Refer to 7.01.03 for CAT II operation

  2.05.06 | INSTRUMENTS MARKING

  Red arc or radial line : minimum and maximum limits Yellow arc : caution area Green arc : normal area

  2.05.07 | CARGO DOOR OPERATION

  Do not operate cargo door with a lateral wind component of more than 45 kt.

  .../... 05 SYSTEMS 2 LIMITATIONS PAGE : 001 AUG 14 EASA APPROVED
  --Model : 212 A AFM 2

  2.05.08 | ELECTRICAL

  Single DC GEN operation : In flight, if OAT exceeds ISA + 25, flight level must be limited to FL200.

  2.05.09 | MFC

  Take off with two or more failed MFC modules is prohibited

  2.05.10 | COMMUNICATIONS

  Not applicable

  2.05.11 | TCAS

  When installed, Refer to appendix 7.01.0