How to determine the traffic avoidance manuver?

In Scenario A there is no obvious answer. You take whatever action is necessary to avoid a collision. If this were a controlled airfield there would be questions raised to the ground controller. If not, similar questions would be directed at the pilot entering a runway without notifying anyone. Even at a completely deserted airfield without any form of station any pilot entering a runway would announce it on a radio beforehand just in case!

Scenario B can be a little more specific, and is a situation that occurs reasonably often at small airfields - less so at large controlled airports. Assuming you've not just busted onto the runway, ignoring traffic on final approach you probably have priority over the approaching aircraft. But if you're a large airliner and/or at a controlled airfield its hugely unlikely you've been cleared to enter the runway to line up if something is on final approach.

If this does happen:

an airliner would follow a missed approach procedure, which would take them well out of the way of the departing aircraft
a light aircraft would perform a similar manoeuvre but commonly known as a "go around". This involves positioning so that the pilot can keep eyes on the departing aircraft, for example flying just to the right of the runway at circuit height.


First of all:

  I have found out that an ISA atmosphere is:
   15 degC temperature 05 degC dewpoint 1013.25 pressure

Not entirely correct. The temperature and pressure are ISA values at mean sea level. These alter with altitude.
Dewpoint is not defined in ISA, as ISA does not contain dust, moisture and water vapor.
ISA-30 atmosphere means temperature deviation from ISA temperature. This means that on a given altitude, temperature is 30 degrees colder than in ISA. Respectively ISA+10 states 10 degrees warmer.

Below is a table of ISA values.

For more physics for calculations, here is a very nice pdf on the matter.


What general aviation operators might hire a low time pilot?

Getting your instructor certificate is your best bet.

Beyond that, there are jobs out there for traffic watch, banner towing, and flying jump planes for skydivers.  Also glider towing and sightseeing.  Ferry flying is possible, although I'd be careful of any place that would hire you with very few hours -- they may be cutting corners & guys with more time look at the operation & say "no thanks."  Not necessarily, but be cautious with anything that looks "too good to be true."

All of these are typically positions that only have a few, or one, or no openings at a time, and those spots are in pretty high demand.  So persistence and personal contact (not just sending a resume) are probably vital to landing one of these jobs.  The place where you're most likely to have more options is flight instructing; obviously that requires the CFI certificate (or equivalent for outside the US).

Good luck!


What equipment does an A320 need in order to operate under RNP 2?

According to ICAO/EASA till 12/2015 Version.
And from Airbus getting to grips with modern navigation.

  Regulatory Authorities have published standards for specific
  airspaces. Provide certification and operational requirements for
  Basic RNAV (RNP-5 Type) and for Precision RNAV (RNP1 Type) within
  European airspace (refer to Annexes 5.1 and 5.2 at the end). FAA Order
  8400.12A addresses RNP-10 operations in oceanic and remote areas (refer to Annex 5.3 at the end). Also RNP AR required equipment is
  specified in several sources and the FCOM manual of airbus. In
  addition for RNP 2 specific terminal and approach operations the
  requirements are specified on the approach charts of airports that implementing it.

Most of the operators/airlines are using the standard required equipment for RNP 1.

  According to FCOM A319/A320/A321 FLEET / PRO-SPO-51 P 8/10 The minimum navigation equipment required to enter RNP 1 airspace is:

  ‐ One FMGC

  ‐ One MCDU

  ‐ One GPS

  ‐ Two IRS

  ‐ One FD in NAV mode

  > ‐ Two NDs (the temporary display of ND information via the PFD/ND
  switch is permitted on one side).

Some helpful information also about RNP 2 you can find also here: http://www2010.icao.int/NACC/documents/meetings/2013/pbn2013/ops7-en.pdf

Moreover Airbus company under PRO-SPO-51 P 5/10 in FCOM refers as RNAV1(2)
so it takes exactly the same equipment for RNP 1.

Let me know if something is different, or if you have different information from another specific-related documentation.


How can jet engines be more efficient than propellers?

Why aren't propellers way larger than they typically are?

There are some "propellers" these days with a 400 foot disk diameter, known as windmills.
But, they are doing their best to extract energy from the airstream and here lies the issue.

"Relative wind" is conveniently used to combine the net direction and force of two aerodynamic effects, but let's look at an old question of:  can a sail boat ever sail faster than than wind?  This is very easy to explain by separating the "wind" components, rather than combining them.  Ice boats can go several times faster than the wind by using wind across the beam as "thrust", and using "wind" from the motion of the boat to create lift.

This is exactly how powered aircraft fly, the ice boat is simply doing it on its side (hence the tiller is the "elevator").

Which brings us to propellers, which can be more accurately described as generating lift than "moving air".  But, as the graph shows, net thrust of props decreases as speed increases because disk drag increases with speed.

Turbojets become more efficient at higher speeds than props because they have much less disk drag subtracting from their thrust.  Even though they are less efficient at producing thrust, their net thrust out put is much more linear over speed as "ram effect" (increasing amount of air available to produce more thrust) and drag cancel each other out, while the propeller falls victim to its own disk drag.


Where does turbine vane and blade cooling air come from?

To build upon a few points in Peter's answer:

This diagram will probably help visualize it (I copied from this question How is the central hub / shaft casing of a two-spool jet engine assembled?):

The seal between the disks is just a labyrinth seal.  Those chambers, however, are pressurized (by similar mechanisms as the cooling air was delivered to the blade). So there is a tiny positive flow of air out of that chambers, which prevents the hot combustion gases from flowing in.  Refering to the diagram, the space in front of the 1st stage disk is pressurized from air coming from the stg 10 compressor through the series of passages colored in orange.  The space between HPT stage 1 and stage 2 is pressurized by air the comes along the inner diameter of the HP rotor, from an impeller between stage 7 & 8 compressor (in blue), and the space aft of the HPT stage 2 is pressurized from air the comes from the stage 4 compressor (by means of pipes on the outside of the engine, light blue color).

Pretty much every cavity/chamber inside the engine is pressurized somehow, to keep air from going in undesired directions.

I don't know exactly how much air is used for cooling. It's on the order of 1% (i.e. I know it's less than 10%, but certainly more than 0.1%)


What will air traffic controllers do when radio contact is lost?

You didn't mention any specific jurisdiction but for the FAA, the expected actions are in the ATC orders. Section 5-2-8 says:

  When you observe a  Code 7600  display, apply the procedures in para
  10−4− 4, Communications Failure

Section 10-4-4 gives general instructions for comms failure, it's too long to quote in full but the first paragraph summarizes it:

  In the event of lost communications with an aircraft under your
  control jurisdiction use all appropriate means available to
  reestablish communications  with the aircraft. These may include, but
  not be limited to, emergency frequencies, NAVAIDs that are equipped
  with voice  capability, FSS,  Aeronautical Radio Incorporated (ARINC),
  etc.

The instructions suggest some specific actions:

Broadcast via NAVAID frequencies
Ask the aircraft to use its transponder or make turns to acknowledge instructions

If comms haven't been reestablished within 5 minutes, ATC is instructed to consider it as suspicious:

  If radio communications have not been (re) established  with the
  aircraft after 5 minutes, consider the aircraft’s or pilot’s activity
  to be suspicious and report it to the FLM/CIC per FAA Order JO 7610.4,
  Chapter 7, Hijacked/Suspicious Aircraft Reporting and Procedures

Section 10-2-5 also says that lost comms are an emergency from the ATC perspective and should be escalated to the ARTCC. If comms aren't restored within 30 minutes then the aircraft is considered overdue, which triggers another set of procedures listed in section 10-3.

As for clearing airspace or whatever, there are no specific instructions in the orders, it just says that:

  When an IFR aircraft experiences two-way radio communications failure,
  air traffic control is based on anticipated pilot actions.

In other words, ATC expects IFR pilots to follow lost comms procedures as per 14 CFR 91.185 and will direct other traffic accordingly.

Finally, one 'routine' lost comms scenario is when ATC can't contact an aircraft because of poor radio coverage. This happens a lot with smaller aircraft (which fly relatively low) operating in remote areas and ATC might ask another aircraft, usually a higher-flying airliner if possible, to contact the first aircraft and relay their call: N12345, this is BigAir 123 with relay from Denver Center.


Why was this helicopter denied entry to Class B airspace?

According to the post at LiveATC, Newark was closed, apparently due to smoke in the tower. With the airport closed, nobody could be granted clearance to take off or land.

Outside of declaring an emergency, there's nothing the pilot(s) could have done to get clearance at Newark other than just waiting.

In an emergency situation like smoke in the tower, there wouldn't be anything published beforehand for the pilots to look up, but otherwise, pilots look at NOTAMS during their flight planning for planned closures or outages. Even in good weather, proper flight planning would also involve an alternate airport, anticipating the possibility that the intended airport might be closed for an emergency like this.

Eight miles south of Newark is Linden Airport, a small uncontrolled field just outside the Class B surface area. If I had passengers in my ship who were trying to fly out of Newark, I would have radioed operations and asked them to send a limo to Linden to pick up my passengers.

[There is one part of the recording that says "[inaudible]". The pilot is announcing his position at the Statue of Liberty, a reporting point for copters landing EWR.]


Did the airfoil choice on the P51D affect its maneuverability?

Yes it did because the stall behaviour of the Mustang, due to the airfoil, was very abrupt and it was much easier to get into an accelerated (high speed) stall pulling high G than it was with an airplane such as a P-38, which had wonderfully benign stall behaviour and could be manhandled all over the sky in relative safety.  At the beginning of a trip in the P-51 this was made worse by the aft fuel tank's effects on CofG which made the stick forces very light so you wanted to avoid radical maneuvering until you burned off the fuselage tank fuel.

The later versions of the P-38 with hydraulic ailerons and dive flaps were just about the best propeller driven aircraft in the sky in 1944, because at high speed they could roll as fast as SE fighters and had the benefits of crazy rate of climb and no engine torque effects, on top of the very gentle stall behaviour.   One reason the Mustang dominated, even though the Lightning's technical bugs were worked out by that time, was the P-51's performance and range was great AND it was only about 2/3rds the unit cost of a P-38.


Should I report my cured mild PTSD in the FAA medical certification application?

Unfortunately, you have to report it.  It even says so right on the medical application (emphasis added by me):

  18) Medical History - HAVE YOU EVER IN YOUR LIFE BEEN DIAGNOSED WITH, HAD, OR DO YOU PRESENTLY HAVE ANY OF THE FOLLOWING? Answer
  "yes" or "no" for every condition listed below (All "yes" answers
  require a comment. Click Add Comments to add or edit a comment).

  ...

  Mental disorders of any sort: depression, anxiety, etc.

  ...

Based on your own admission, you had it at one point and are now cured.  This means that you have "at some point in your life" been diagnosed with it.

Unfortunately, the FAA takes a very hard line on this kind of thing and it does not surprise me in the least that they are now requiring a battery of expensive tests in order to prove that you are fit to fly.  I don't like it either, but it does keep the people out who "say" that they are cured when they aren't, either because they don't realize it or because they just want to fly anyway.

If it is denied, then you can appeal it, but I would suggest getting good professional help.  As voretaq7 mentioned, AOPA has a very good medical service that helps their members for free.  Membership is pretty inexpensive, and more than worth it just for this service, plus they have many many other benefits as well.

A couple of other questions on the site that may help you:

FAA Class 3 Medical re-examination
Can a private pilot receive recurring training while waiting for a special-issuance medical approval?


I believe you are correct and the terminology they used was incorrect. What possibly is being described is sometimes called "mushing". Some aircraft are capable of having the airspeed bleed off until the elevator is all the way up - it then mushes with a high descent rate to the ground.

I owned a Navion that would do this. If you slowly bleed the airspeed off and add full elevator it will end up with a 500-600fpm wallowing descent and severe buffeting (full aileron may be needed as the wings rock side to side).

Several Piper aircraft are also similar such as the PA-28-140 Cherokee. The Cherokee is known to run out of stabulator during flares and can pancake onto the runway - no damage but an embarrassing hard thump.

I have flown just about all the single engine and small twin engine Cessna's and none of them will do this. They have lots of elevator and are always capable of a nose dropping full stall.

Captain "Sully" Chesley Sullenberger reported he was aware the flight computer of the Airbus A320-214 did this (US Airways Flight 1549, "Miracle on the Hudson") and deliberately held the yoke all the way back and let the aircraft mush onto the Hudson River.


Lapsed Advanced Ground Instructor certificate, can I take a FIRC and and restore my privileges?

First, as the regulation says, you can indeed take an FIRC to restore your privileges.

Second, I couldn't find any FAA clarification on exactly what "employment or activity as a ground instructor" means, but the language is fairly clear: you just have to be able to show that you were providing instruction as a ground instructor. That could be via training records, invoices, employment contracts, written test endorsements etc.

As a general rule, there's no need to look for extra requirements that aren't stated in the regulations.


What should I do after failing the oral portion of my private pilot check ride?

AOPA has a great article about this, and it basically says:

Since you failed the oral, more studying is probably in order.
You will need to receive training in the area(s) of the checkride that you failed from a flight instructor.
Once the flight instructor feels that you are proficient and able to pass the checkride, they will sign your logbook so that you may take it again.
Schedule your checkride again.  If you take it within 60 days, you will only need to test on the areas that you failed.  After 60 days you have to take the entire checkride over again.
Take your Notice of Disapproval (8060-5) with you to the checkride (you didn't burn it did you??)

Like the article says, it isn't the end of the world!  About 20% of first time applicants fail their checkride, but all you have to do is use it as a learning experience and let it make you an even better pilot.

If you have questions about specific subjects, you can also ask questions here and we will be happy to help you out!


Has a micro-burst or wind shear caused fatalities on takeoff?

One (of several) incidents that I remember was Pan Am Flight 759. It encountered windshear after takeoff from New Orleans' Moisant Airport July 9, 1982 and crashed, killing all aboard and several on the ground.


Are bigger and / or heavier aircraft more resistant to crosswind compared to smaller / lighter aircraft?

A constant crosswind affects all aircraft equally. A crosswind gust will however affect a lighter aircraft more than a heavy one due to lower inertia. The acceleration $a$ felt from the gust is

$$ F = m \times a \;\; \Leftrightarrow \;\; a = \frac{F}{m} $$

where $F$ is the force from the gust and $m$ is the total mass of the aircraft. The force is roughly proportional to the area that the wind sees, which scales with the scale factor squared: $ F \sim s^2 $. The mass however is proportional to the volume, which scales with the scale factor cubed: $ m \sim s^3 $. This results in less sideways acceleration from a wind gust for larger aircraft: $ a \sim s^2 / s^3 = 1 / s $. Therefore, there is less need to correct by sharply banking left or right.

Additionally, larger aircraft react to control inputs from the pilots more slowly (for the same reasons), which also makes them look more stable even when the pilots make sudden control inputs.


How can an airplane descend faster than a free-falling roll of toilet paper?

"I think the descent speed of the airplane is not that much"

I think you are wrong.  Airplanes can descend very rapidly when needed.

The airplane is aerodynamic, meaning it slices through the air nicely, whether it is flying straight-and-level, or aiming straight for the ground.  So its free-fall speed is much higher than that of a roll of paper, which will have considerable wind resistance.

In addition, the airplane has a propeller, which adds force.  When in a dive, the airplane has gravity plus the force of the propeller taking down.  But the roll of paper only has gravity.

I expect that in a full dive, the airplane could probably exceed a 10,000 FPM descent, or around 120MPH, which is around the terminal velocity of a skydiver.
(pulling out of a full dive safely is not easy, however).

The roll of paper will obviously and intuitively be slower than a skydiver.
I estimate it to be no more than 2,000 FPM, or about 20 MPH. (and probably a bit less)

  (edit: In the comments, Henning Makholm suggests that a paper roll may only fall at 200 FPM. That is less than 3 MPH, which seems a bit slow to me.   A slow descent rate for a Cessna when approaching an airport is 500 FPM.)

The airplane does not even need to enter a full dive to be faster than the paper. It could probably catch the paper with a nice, gentle 2,500 or 3,000 FPM descent.


It is a British Airco DH9A light bomber.

Some more info: According to an RAF database, this particular aircraft with registration E848 served in RAF No. 27 and No. 30 squadrons. Both of these squadrons flew sorties over India and the Middle East after World War I (hence the additional radiator fitted under the fuselage to operate in warmer climates, well spotted by Peter Kämpf), but I can't find anything more specific about E848 that would place it in either squadron in particular at any specific point in history.


Is it safe to takeoff with some ice and snow on the wings?

It appears that there was a considerable amount of contamination, either snow, ice, frost, or a mix thereof, on the wing when the takeoff roll started, and that is not considered safe under any current standards I'm aware of.

There are markings on the top of the wing for the 737 Next Generation series that define an area where cold-soaked fuel frost is acceptable up to a defined thickness, but the area covered by the contamination in the video extended beyond those markings, so even if it was CSFF (which I doubt, given what's shown late in the video), it was still more than what's allowed.

Late in the video with the aircraft flying, we see that much of the ice is no longer present, which means that it detached from the wing at some point.  If it was dry snow that blew off in the first 10 or 20 knots of the takeoff roll, that's no big deal, but you don't see the ice gone until late in the video -- this isn't simply dry snow.  Plus, you still see significant patches of ice adhering to the wing at the end of the video -- which suggests that it isn't CSFF nor dry snow, but ice.

The current accepted standards of safety in commercial aviation don't permit taking off with any ice adhering to the wing, and from what is shown in the video, it certainly looks like that's what was done here.  (Disclaimer, I'm no expert on watching u-tube videos of ice-covered wings, so there may be more going on here than is apparent on first or second viewing.)  IF that's correct, then I'd have to agree with the title of the video, that this was unsafe.

The standards of safety allow for a lot of margin, so that when mistakes get made they are still likely to be survivable, and it looks like that's how things turned out here.  Things were done wrong but everybody made it out okay.  But... what if one more thing had gone wrong?  What if they'd lost an engine at rotation?  Would the aircraft have been able to climb out with one engine & the wings in this condition?  Or would these guys have been headline news of a crash out of Sarajevo that killed all on board plus how many more on the ground?

No, this looks pretty far out of bounds to me.


Does a glider pilot with a PC canopy need to protect himself from UV radiation?

I assume that you mean polycarbonate by "PC". Polycarbonate plastics block nearly all UV radiation. Here is a typical transmission spectrum:

UV is the light below 400nm. As you can see, the curve shows 0% transmission in that range. In general, the risk of damage by radiation is greatly reduced by elimination of sub-400nm wavelengths.

Nevertheless, high energy visible light from 400-500nm should not be ignored and long exposure to such light can be damaging, especially to the eyes and is implicated in macular degeneration, and I know sailplane pilots with high hours who have suffered macular degeneration.

Also, if you are flying, you know that most pilots spend many hours out on the field waiting to launch or doing other chores, so there is plenty of time when you are not protected by a canopy at all.


Does the aerodynamic center move when flaps and slats are deployed?

The aerodynamic center does not move when plain or camber flaps are used. A plain flap will only change the camber of the wing and, therefore, will only affect its zero-lift pitching moment. Flaps have their own aerodynamic center, and their lift change should be summed up in the flap's aerodynamic center.

Note that the aerodynamic center of the aircraft is used for the lift force change resulting from a change in the angle of attack while the flap aerodynamic center is used for the lift force change from a change in the flap's deflection angle. With flaps deployed, a change in the angle of attack will still cause a lift change which acts on the aircraft's aerodynamic center! Only the constant pitching moment around the aerodynamic center will change with flap deflection, and in order to calculate this moment, assume the lift change from flap deflection to act in the flap aerodynamic center.

The location of the flap aerodynamic center changes with the relative chord of the flap. For a flap approaching a relative chord of 0, the theoretical flap aerodynamic center is at 50% of the wing's chord. With increasing flap chord the flap aerodynamic center moves forward proportionally with the flap's chord increase until it reaches the 25% chord point for a flap of a relative chord of 1 (a full-flying control surface, in other words). See Figure 46a from chapter 5 of Sighard Hörner's Fluid Dynamic Lift for proof.

Flaps which increase the wing's area will of course shift the neutral point in proportion to the change in the wing's chord effected by the flap.

Slats may be viewed like a slat-sized wing followed by a wing-sized flap and an incidence change equal to the slat's deflection angle.


What is the maximum pitch for the Boeing 787 Dreamliner?

30 degrees.

Boeing aircraft, including the 787, have a Pitch Limit Indicator (PLI) in the flight display that tells the pilot how far the wing's angle of attack (AOA) is from stall.

  the PLI also is limited to 30 deg of pitch attitude, regardless of AOA.

But it depends on aircraft configuration

  During takeoff climb, there is no single target AOA to fly that will guarantee certified takeoff performance. Takeoff-climb AOA will vary with such factors as airplane gross weight, thrust, altitude, flap setting, and CG. Takeoff-climb speeds (hence, AOA) are limited by stall speed, tail clearance, and minimum control speeds. The higher speed and greater thrust of an all-engine takeoff reduce the AOA significantly relative to an engine-out takeoff at the engine-out climb speed (V2 ).

From Boeing Aero No.12

At Farnborough 2014, pilots Neville and Bryan were pulling stunts that would get airline pilots fired. Most airlines limit pitch to 20 degrees (or in a few cases 25) from what I've read.

  They kicked off the demonstration with a spectacularly steep takeoff, pitching the plane up just shy of 30 degrees.

I'd guess they flew just inside what Boeing consider unsafe for those conditions.

  Boeing won’t reveal ... just how steeply it can take off

From Wired - "terrifying" (my emphasis).

I think we can be reasonably confident that no production 787 will ever, after take-off, initially climb at greater than 30 degrees.

Flight envelopes

The way I understand it, asking about the "maximum" of anything for an aircraft is less useful than understanding the flight envelope. This is because the maximum depends very greatly on the exact situation of the aircraft including things like altitude, weight, speed etc.

Actual flight data from the six Boeing 787 test aircraft.


Straight vs. angled aircraft carrier decks: tradeoffs for rolling takeoff?

Correct, at the weights and speeds of most carrier based jets they would need several lengths of an aircraft carrier to get airborne.  Catapults became required as the airwings transferred to jets in the 1950s and 1960s.
Aircraft are stored in the hangar below decks, and on the sides.  Anywhere there is free space.  Even during simultaneous launch and recovery.  Look at photos and videos, it can get crowded!
Since we aren't building straight deck and angle deck carriers that are otherwise similar, a fair cost comparison cannot really be made.  (Amphibious ships serving VTOL aircraft lack catapults and arresting gear which would account somewhat for their lower cost.)  Propulsion, radar systems, inflation, and many other factors also account for the increased cost of modern carriers over earlier straight deck ships.  And it is not true that you need a nuclear reactor to generate steam for the catapults.  Steam catapults were around for quite some time before the first nuke boat.

ADDENDUM:   There isn’t enough space in the comments section to refute the multiple inaccuracies in Peter Smith’s response to this question, so I will address them here:

All modern US Navy carriers have 4 catapults, 2 at the bow and 2 at the waist.  (This has been consistent for the last 40-50 years)  The “waist” catapults (cats 3 & 4) are so named because they are amidships, and thus cannot be used during landing operations because they foul the landing area.  The photo in his answer shows the two bow catapults.  The one pictured on the right is NOT a waist catapult, it is cat 1.

Simultaneous launch and recovery is possible however.  Generally the launch starts first while the previous cycle is holding overhead, using all 4 catapults for efficiency.  Once they get to a point where most of the next cycle is airborne and the landing area is clear, they will “wrap” the waist catapults and begin recovering the earlier cycle while they finish launching off the bow.

The only caveat is that longer wingspan aircraft like the Tomcat and E2 will foul the landing area if they are on the left bow catapult (cat 2) with their wings spread.  For this reason they will finish launching them from the right bow catapult (cat 1) if recoveries have begun.  This is not a problem with Hornets, and possibly not an issue on the largest of carriers.

There is almost always some overlap where simultaneous launch and recovery occurs during normal cyclic operations.  And during pilot qual/requal, the deck runs continuously.  You will land, fold your wings, taxi to the bow cat, spread your wings and launch again...  It is a continuous stream of simultaneous launch and recovery operations.

It is also definitely not true that aircraft are not parked anywhere but the bow during recovery.  Any spot outside the landing area foul lines is fair game.  It is a very common sight to see aircraft parked on both sides of the landing area on final approach.  But don’t take my word for it, there are lots of videos and photos on line to verify this…

Finally, the arresting cables are not forward of the “aft lift” you show in your photo.  (Elevator 1 or JBD?)  Again, this photo is of the bow only.  The two waist catapults and the landing area are well aft and left of the perspective this photo was taken from.

BTW, the diagram of the angle deck carrier in the question is not an accurate representation of the current class of US Navy fixed wing CVN Carriers.  Below is a good diagram showing the layout of the 4 catapults in relationship to the landing area.


What are the equations to compute takeoff and landing distance?

I did this, using Fortran 90 for the math and Tcl/Tk for the plotting.
There is no single equation; instead there are several cycles of calculation nested inside each other like a Russian matryoshka.
The innermost loop calculates all forces and moments at the point in time at which the calculation stands.
The next layer iteratively trims the airplane so control deflections fit the desired rotation rates.
The outer layer integrates the parameters, moves one timestep ahead and applies new boundary conditions.
For the initial climb there is another iteration to adjust acceleration and climb angle such that the airplane is at 1.3 v$_\text{min}$ when it climbs through 50 ft.
Initially, the airplane is on the ground and drag is smaller than thrust, so a forward acceleration remains. When the preselected rotation speed is reached, the elevator is trimmed for an also predetermined rotation rate and time steps are shortened to minimize the error in finding the liftoff time. The whole process is divided in three parts: Ground roll, rotation and initial climb.
For airplanes with a constant speed propeller I even added another loop inside the force calculation to find the proper propeller beta for the current engine torque and airspeed, but that made the code very slow (it ran initially on a Mac SE/30). For most cases I pre-calculated lookup tables and interpolated a lot.
We used this software to determine the tables in the flight manual of a jet trainer and checked correctness with a few points from flight test. It is easy to set a wind speed in software, it is much harder to precisely find out what the average wind speed was when the test ran. Since my software included all effects like trim drag, gear rolling resistance over speed and ground effect, the results were easily confirmed.
Calculating landing distances wasn't much different, only that the calculation started at 1.3 v$_\text{min}$ and 50 ft.
If you want good results, no single force is constant over speed. If you don't mind such niceties, you can average rsp. linearize the forces and use the integrals in this text.
For a very rough estimation, average thrust and drag and calculate how long the engine needs to add energy to the system until kinetic and potential energy have changed from standstill to 1.3 v$_\text{min}$ and 50 ft and back again. This should be sufficient already to find the effect of wind and air temperature on takeoff and landing performance.


What is pendulous suspension in magnetic compass?

This video covers it pretty simply.  The compass magnets are attached to the bottom of an upside down cone, which is resting on a spike.  The weight of the compass magnets, and the center of gravity of the assembly as a result, is near the bottom of the cone and the "hang point" is up near the top at the tip of the spike.
It's a cone pendulum; basically a lady in a hoop skirt, out on the dance floor (put a couple of bar magnets alongside at at the bottom of the skirt, stick her in a vat of kerosene to dampen the skirt's movements, and there's your compass-lady).
The pendulum arrangement keeps the compass magnets more or less level to the earth even if the spike it's on is tilted (mostly to accommodate changes in pitch attitude with speed and stabilized climbs and descents), within the range of movement of the cone.  Compass units in ships (and very early aircraft compasses) achieve this by having the compass float on water (or some other fluid) within the housing so the compass can stay horizontal while the ship pitches and rolls.
The various turning errors relate to how the pendulum reacts to accelerations and apparent gravity (think of the lady's hoop skirt tilting off vertical as she starts to move, for example), the C of G of the cone being below the hang point, while at the same time having the magnetic alignment forces acting on the magnets. The result is readings that wander in specific directions (acceleration/deceleration and turning errors) if there are any lateral accelerations going on, and while the magnets are rotating, because of the "struggle" going on between the magnetic forces and the inertial forces.  The compass reading is only valid when the inertial forces have gone away, when there is a steady state condition of no turns and constant speed.


Why are some aircraft built in a single country, whereas others are a collaboration of many countries?

Why did Eurofighter need collaboration among four countries?

For production volume.

We are still in an era of relatively low-volume high-value combat aircraft compared to the early years (say pre 1950).

Cost per unit is less if the development costs are spread over a greater number of manufactured units.

Individual European nations each have requirements for relatively small numbers of aircraft. If they each develop and manufacture their own aircraft, costs to each are likely to be higher.

Politically, it is easier to sell a military aircraft to politicians whose countries benefit from the manufacturing.

There are also benefits in sharing development costs.

Given the close economic, political and military ties between European countries, collaboration makes sense.


How does this IMU work and how to convert its output into meaningful information?

Regarding the Specified IMU

The referenced document describes the output protocol.

  SAEJ1939 CAN 29 bit identifier communication output — the standard for the transportation segment — allows more data to be transmitted than an RS-485 output

You would need to use SAE J1939 to decode the actual meaning of the output data. It is possible that Honeywell could provide you more information as part of purchasing the product.

To use this to develop an AHRS solution you would still need pitot & static inputs to derive pressure altitude and airspeed, as you won't be able to get those from the provided sensors.

  acceleration range up to ±6 g, rotation rates up to ±75 deg/s,inclination angles up to ±50 deg and a sensor update rate from 1 Hz to 100 Hz

I think the biggest hurdle you have here is that it will only measure inclination angles up to 50 deg. Aircraft can find themselves in > 50 deg pitch attitudes, which won't be registered by the IMU.

This particular product (Honeywell 6DF-1N6-C2-HWL) seems to be designed for ground vehicle applications rather than aviation.


How likely is it that there is someone knowledgeable about piloting in a flight control room?

The answer depends a lot on the type of plane being flow.  While plenty of air traffic controllers are also pilots on the side, it is highly unlikely that anyone on duty at the time would happen to have a type rating in a large complex turbine aircraft, and/or enough knowledge to talk through checklists.  They may be able to offer very generic advice such as "See the handle that is shaped like a wheel?  Push it down and that will lower the landing gear."

For simpler GA aircraft they might offer some basic assistance on how to control the aircraft, slow down, deploy flaps, etc. but there is a lot of muscle memory and technique honed by hours of practice needed to perform a "good" landing.  Just explaining the exact steps to take over the radio isn't going to be enough, there is a lot more to it.

Think about the first time you drove a car with a manual transmission:  Did the person telling you to push in the clutch, shift gears, then let it out smoothly while adding gas help you to do it smoothly, without stalling the engine, jerking, or racing the engine?  Probably not!

About the best they could probably hope for is to help the non-pilot maneuver into a safe airspeed envelope to survive a controlled crash landing at the airfield where emergency services will be on hand to provide immediate help.


Do any airports have a steeper standard approach than London City?

I found the RNAV approach to Steamboat Springs at 7.75°


How many aircraft and pilots can a part 135 cover?

There is no restriction on the number, type of aircraft, or pilots for a "Full 135 Operator."

There are 4 levels of 135 operators:

Single-Pilot Operator
Single Pilot-in-Command
Basic 135 Operator
Full 135 Operator *

Source: http://usac.com/faa/InstructionTwo.asp?Product=Full%20135%20Operator


How does ATC deal with a crew who is not capable of a clear pronunciation?

There is special phraseology snippets that allow information to be transmitted over the frequency with more accuracy, slower, repeated or worded differently.
ATC may also query other company traffic to relay information in another language or they might use the ACARS/CPDLC system to transmit a text message, should both parties be capable.

SAY AGAIN
„Repeat all, or the following part, of your last transmission“

(Source: AIP Germany GEN 3.4)

WORDS TWICE
„Request: Communication is difficult. Please send every word, or group of words, twice.
Information: Since communication is difficult, every word, or group of words, in this message
will be sent twice.“

(Source: AIP Germany GEN 3.4)

SPEAK SLOWER
„Reduce your rate of speech“

(Source: AIP Germany GEN 3.4)


How small can turbojet engines be made whilst remaining fuel efficient, light, cheap, and producing enough thrust to carry a human, gas, and casing?

The figure of merit here is thrust to weight ratio (https://en.m.wikipedia.org/wiki/Thrust-to-weight_ratio)  For a good turbojet, you get about 5:1. So a 100 lb engine could produce about 500 lbf of thrust. Modern High bypass turbofans are significantly more fuel efficient than turbojets, but the thrust to weight ratio is still about 5:1. So calculate how big your human is,  how much gas you want, and divide by 5


How can the Airbus A380 have such a high lift/drag with a relatively low aspect ratio wing?

The aspect ratio of the aircraft is usually kept as high as possible to reduce the induced drag. However, it forms only one part of the total drag acting one the body.

The L/D ratio can be improved by either increasing the (coefficient of) lift or decreasing the (coefficient of) drag.

While no data is available in open sources, it is likely that the wing airfoil was designed for high lift in cruise conditions. Also, the wing has a number of high-lift-devices to increase lift like the flaps, droop nose etc.

For example, in order to improve the L/D ratio during initial takeoff and climb, the A380 incorporated a droop nose device in the inboard leading edge. This improved the lift by around 5%. The figure below shows A380 deploying droops during landing

"A380 F-WWEA LEGT" by User:Keta - Own work. Licensed under CC BY-SA 2.5 via Commons.

The aerodynamic drag on a body is a combination of a large number of components like

Induced Drag
Parasitic Drag
Wave Drag.

The (lift) induced drag is lesser for aircrafts with higher aspect ratio. In designing the A380 however, the limitations of airport operations meant that the wingspan was limited. This resulted in a rather low aspect ratio of 7.8. However, the same effect(of higher aspect ratio) can be achieved using wingtip devices such as winglets. A380 uses wingtip fences to reduce induced drag.

"British Airways Airbus A380-841 F-WWSK PAS 2013 10 Wingtip device" by Julian Herzog. Licensed under CC BY 4.0 via Wikimedia Commons.

As the speed increases, the induced drag reduces and the parasitic drag (of which the form drag is a component) comes to dominate the drag produced.

"Drag Curve 2" by Original uploader was GRAHAMUK at en.wikipedia - Transferred from en.wikipedia; transferred to Commons by User:Sfan00_IMG using CommonsHelper.. Licensed under CC BY-SA 3.0 via Commons.

The major part of the parasitic drag is the form drag, caused by the movement of aircraft through the air. The A380 design reduces this by reducing the control surface areas through the use of Fly by wire system.

This is also achieved by reducing the drag caused refining the aerodynamics of the aircraft, such as by using improved flap track fairings and increased size of the belly fairing.

"Singapore Airlines A380 9V-SKH" by Simon_sees - Singapore Airlines A380 9V-SKH. Licensed under CC BY 2.0 via Wikimedia Commons.

The overall aircraft configuration and not just the individual components were analyzed using CFD, which led to further optimization of the aerodynamics design and reduction of drag by changing the spanwise distribution of camber and twist from root to tip (around 2%).

The airfoil used was most probably optimized for reducing wave (transonic) drag, though no data is available in open literature.

Even though all these improvements were only marginal individually, put together, they have a significant impact on the overall L/D ratio.

One more thing to note is that though the L/D ratio might appear high, the value is actually comparable (and even less than) the aircrafts that enter service after A380. So in a way, there is nothing surprising about the L/D ratio of A380 except that it illustrates the steady progress being made in civil airliner aerodynamic design.


Does shutting down the engine affect the rate of rotation during autorotation?

with the engine disconnected from the main rotor, no torque is being applied to the rotor by the engine so there is no torque reaction trying to rotate the fuselage backwards. In this case, the only torque being applied to the fuselage is the frictional drag in the main rotor bearing, which will be small. If a tail rotor failure occurred and the fuselage began rotating because of this before the engine failure, then the fuselage will remain in rotation after the engine failure and will slowly lose rotational speed as the main rotor bearing friction acts on it.


How to read the Appleman chart to predict contrail formation?

First of all, the Appleman-chart itself:

Source

Now, let's say we want to know if contrails can form at FL340 at my position, a pretty standard cruise flight level. Because flight levels are standard pressure, we can easily look up the pressure, corresponding to the flight level.

100 ............................................ F530
150 ............................................ F450
200 ............................................ F390
250 ............................................ F340
300 ............................................ F300
400 ............................................ F240
500 ............................................ F180
600 ............................................ F140
700 ............................................ F100
850 ............................................ F050

Source

Ok, we've got the pressure, it's 250 hPa.

Now we need the temperature at this flight level. I am using a winds aloft chart for this.

Source

Let's just take a value from what's nearest to my position, -56 degree Celsius in this case.

Now we can look this up on the chart.

Ok, looks like we've got contrails to see. But am I missing something?

I quickly tried to check the result, by looking out of the window. I expected following:

Contrail existing
Very short contrail. I looked up relative humidity for that flight level as well. It's very low, only 3 to 1 percent. And the lower, the humidity, the faster a contrail sublimes and fades away.

Here's the data for the humidity:

-------------------------------------------
PRES   HGHT   TEMP   DWPT   RELH   MIXR
hPa     m      C      C      %    g/kg
-------------------------------------------
258.0   9699  -54.9  -79.3    3   0.00
250.0   9900  -54.3  -80.3    3   0.00
222.0  10665  -52.1  -82.1    2   0.00
200.0  11340  -52.9  -83.9    1   0.00
198.0  11404  -53.0  -84.0    1   0.00
185.0  11839  -53.4  -84.4    1   0.00
150.0  13180  -54.7  -85.7    1   0.00

Source

So, I first looked on flightradar to search a plane I could possibly spot from my position.

Picture from flightradar24.com

UAE72 is at FL390, what is a standard pressure level of 200, so we've got a relative humidity of 1%.

Now the look out of the window:

As we can see, it's exactly as expected.


Can wing sweep decrease total drag force at low-subsonic speeds?

Sweeping back a wing of fixed spar length and area does decrease form drag. However due to both its lower aspect ratio (span/chord) and sideways flow effects, it increases induced drag and decreases lift, so that the net L/D ratio or efficiency of the wing falls.
Whether the absolute amount of drag goes up or down depends on other factors, such as wing loading and angle of incidence. In most situations drag would be higher. Where it is less, other design optimisations such as reduced spar length would offer greater improvement.


What type are these planes that are flying in formation near Culver City, CA?

My (current) guess is that it may be a

Nanchang CJ-6

  The Nanchang CJ-6 is an aircraft designed and built in China for use
  by the People's Liberation Army Air Force (PLAAF) as a basic trainer.

Round nose.
Sufficient number airworthy.
Rectangular wing shape.
Main gear folds inwards and the nosegear backwards which seems to fit when I zoom in your pictures.

and they do airshows:

(source: riversideca.gov)

Coincidentally, the upper-left aircraft #43 also appears in your pictures (first picture, rightmost aircraft). Another below of her below:

update: as Cardinal said above, "This is likely Tiger Squadron, perhaps flying for the Israel Independence Day Festival over Rancho Park in mid May, as detailed on their Facebook page."


Look for the Honeywell Primus 1000 System.

Early systems were 5 tube - an EADI and EHSI for each crew plus an MFD (Nav/Wx display) as shown below:

source: swaviation.com

Later ones were 3 tube - 1 PFD on each side plus the MFD as shown below:

source: airliners.net

The symbol generators are shown in the MMEL as they have reversion capability. The 'tubes' or the actual displays would be listed under section 31 Indicating/Recording Systems but aren't included in the MMEL as they are always required.

Section 34 Navigation does allow for functional portions of the displays to be inop.


Is there any "instrument take-off system"?

While there is not a specific physical system dedicated to instrument departures per se, there are procedures that rely upon instrument flight rules (IFR) navigation equipment that ensure obstacle clearance when departing from an airport in instrument meteorological conditions (IMC).

From the Aeronautical Information Manual 5-2-8.

  Instrument departure procedures are preplanned instrument
  flight rule (IFR) procedures which provide
  obstruction clearance from the terminal area to the
  appropriate en route structure. There are two types of
  DPs, Obstacle Departure Procedures (ODPs), printed
  either textually or graphically, and Standard Instrument
  Departures (SIDs), always printed graphically.
  All DPs, either textual or graphic may be designed using
  either conventional or RNAV criteria. RNAV
  procedures will have RNAV printed in the title,
  e.g., SHEAD TWO DEPARTURE (RNAV). ODPs
  provide obstruction clearance via the least onerous
  route from the terminal area to the appropriate en
  route structure. ODPs are recommended for obstruction
  clearance and may be flown without ATC
  clearance unless an alternate departure procedure
  (SID or radar vector) has been specifically assigned
  by ATC. Graphic ODPs will have (OBSTACLE)
  printed in the procedure title, e.g., GEYSR THREE DEPARTURE (OBSTACLE), or, CROWN ONE
  DEPARTURE (RNAV) (OBSTACLE). Standard Instrument
  Departures are air traffic control (ATC)
  procedures printed for pilot/controller use in graphic
  form to provide obstruction clearance and a transition
  from the terminal area to the appropriate en route
  structure. SIDs are primarily designed for system enhancement
  and to reduce pilot/controller workload.
  ATC clearance must be received prior to flying a SID.
  All DPs provide the pilot with a way to depart the airport
  and transition to the en route structure safely.
  Pilots operating under 14 CFR Part 91 are strongly
  encouraged to file and fly a DP at night, during marginal
  Visual Meteorological Conditions (VMC) and
  Instrument Meteorological Conditions (IMC), when
  one is available. The following paragraphs will provide
  an overview of the DP program, why DPs are
  developed, what criteria are used, where to find them,
  how they are to be flown, and finally pilot and ATC
  responsibilities.

There are many details involved in actually using these procedures to make safe departures in IMC. The Instrument Procedures Handbook Chapter 1 is an excellent resource for pilots who want to review these procedures, what they provide and how to use them correctly.

Here is an example of an ODP from my home airport, KCRG. There are some very tall towers less than 10 nautical miles from the airport. They are enormous and easy to avoid under visual conditions, but when IMC prevails these procedures are absolutely life-saving with such large obstructions nearby. They are taken from this takeoff minimums document.

Here is an example of a SID. These are always graphically depicted and will usually be found at larger airports. Here are pages 1 and 2 of the full SID.


How can I avoid downdrafts and icing when crossing the Alps in a small airplane?

Yes, a low powered trainer can fly through tall mountains.
 It is not possible to say how often the flight may be made safely as it depends on specific weather conditions across your route of flight.

This is the same as saying a small sailboat, like a sabot, can sail to the Azores.  It is possible, and might even be safe with proper planning and good weather, but you must take care to plan the trip well every time you make it.

The number one concern I would have flying through the Alps (...or Rocky Mountains, or Sierra Nevadas...) is wind, temperature being a very close second.  A low powered trainer is pretty much at the mercy of the wind much above 5,000' and is absolutely helpless above 10,000'.  A very tame downdraft of only a few hundred feet per minute will exceed the plane's best rate of climb and could effortlessly push you into a ridge or, if you're lucky, a valley or canyon from which you may not be able to climb out.  I use the example of the Cessna 150 in Meteor Crater (elevation only 5,700' in Arizona, USA) of what can happen when an under-powered aircraft runs afoul of nature at high density altitudes.  Ice is not really an issue unless you are willing to fly through visible moisture...so...don't fly though clouds, mist, fog, etc.

I earned many of my hours flying through the Rockies in piston aircraft. The vast majority of my time in the Rockies was flying freight in cabin-class Twin Cessnas with turbocharged, geared, high displacement Continental engines and de-ice kits (a capable airplane).  Even in these planes it was common to encounter downdrafts that far exceeded aircraft performance even when using takeoff power and when lightly loaded.  The turboprops that I flew later on would fare better in that they would hold altitude (maybe even climb) at Vy and max power while carrying a load.  A Cessna 150/152, Tomahawk, or anything else with an O-235 will not do well in breezy mountain conditions.  The large mountain ranges in the US are dotted with light plane wreckage due to unfavorable weather and wind conditions.

There are things you can do to more safely traverse high terrain in a low powered plane.  I learned a few of these the hard way...

1.) Learn proper ridge crossing techniques.  There is a well defined "right way" to approach ridges if you have any doubt as to the wind conditions across the ridge.  I provide FAA documentation only because it is what I am most familiar with.

2.) Set very high weather minimums for trips through mountains.  Twice the standard requirements for VFR may be a good start, perhaps even higher.  Adhere to them during your flight.

3.) Identify alternate airports.  Know the status of the alternates (plowed?), the services provided (fuel?), and their local weather forecasts before you depart.  Take time to note distance and direction to the nearest alternates throughout your flight.  The weather can turn quickly and simply turning around and flying home is typically not an option.  Have frequencies and airport diagrams close at hand should you need an alternate.

4.) Have two realistic emergency landing spots picked out at all times.  You don't need have spots that will allow for a complete rollout, just spots that will permit you to dissipate enough energy to survive the impact. I've built the habit to scan sky, then ground, then sky when flying over rough terrain.

Landing in a field and damaging the plane may be wiser than continuing into worsening conditions.  This is a difficult realization to accept, but attempting to fly through worsening visibility, breezy conditions, and any amount of visible precipitation may kill you while landing in a field may just kill the plane.

5.) Universal advice, but particularly relevant here...if forced to land, fly all the way through the crash.  Pilots that fly their planes through a crash survive.  Pilots who become passengers do not.

If this sounds like a lot of work, it is! If this sounds overly dramatic, it isn't.  The low powered trainer was not really designed for this type of flight.  You need to take additional measures to make sure that the conditions along the route conform to the aircraft's rather severe performance limitations.
You also need to accept that the plane you describe may be quickly and thoroughly outclassed by mountain weather, weather that even a moderately more capable aircraft (C172-180hp, Piper Archer, ...) would not have a serious problem with.

This flight is doable can be done safely if planned well and flown in favorable conditions.


Can someone identify this unusual plane at SeaTac airport?

There is a big clue right underneath the "Sea-Tac Airport" decal - it says

  FIRE RESCUE

It can be seen a little better on this image

source: wikimedia commons

It is a rig used for fire and evacuation training.

  A unique tool the department uses is an aircraft mock-up designed for aircraft approach, entry and tactics training on the airfield. The smoke generated is not harmful to the environment and provides a realistic challenge.
  source: https://www.portseattle.org/page/training

The image below appears to show it in use:


What is this runway marking on Kirkwall Airport's runway?

That's the aiming point mark, UK style. The UK AIP GEN 1.7 (2018-8) notes the following reasons for the different marking:

  The shape of the marking means that 1/3rd of it is outside the centre 3rd of the runway and is therefore less prone to rubber contamination.
  The marking is more easily identifiable as it differs from the TDZ markings.
  It provides enhanced visual cues for the angle of approach.

(Source: CAP 637: Visual Aids Handbook, May 2007)


Are there FAA rules about changing an airport name from Municipal to Regional?

In general there are no strict rules on airport names. This would be more of a marketing decision, and it's up to the owners/operators to decide of the expense of the "rebranding" is worth the benefits.

US regulations do cover international airports, and the Secretary of the Treasury designates the official list of airports. Even then, there are plenty of international airports not on this list, and there are even some airports called "international" with no customs facilities or plans to have them in the near future.


Why does the effective alpha/CL increase at wingtip of swept wing?

You are reading the wrong sources.

I've never come across the claim that the lift curve slope of a swept wing increases towards the tip. That might happen in ground effect (when the tips are very close to the ground from the swept wing's incidence), but that effect is very weak, or when the wing tip has noticeably less sweep (crescent wing).

But not on "regular" swept wings in normal operation.

If, however, the intended meaning of your question is to ask why the tips of backward swept wings reach stall conditions earlier than the inner wing: That they do indeed. Read on for an explanation.

What your sources describe is foremost caused by the thickening of the outer boundary layer of backward swept wings. This is compounded by aggressive taper - but this taper effect is very similar in unswept wings, too. Next, when you plot aspect ratio over sweep angle, you will find a boundary above which swept wings develop undesirable stall behavior, so the wing's aspect ratio is another factor (which your sources stay mum about).

To prepare for the interview, I advise you to read some of the answers here, like:

Swept wing layout for maximum lift at transsonic Mach numbers.
Sub- and transsonic flow separation.
Stability of swept wings.
Why the better designs use increased sweep at the tip, precisely to lower the local lift curve slope.

And make sure you follow the links in the linked answers as well if something is unclear.


Does form 337 need to be sent to the FAA prior or after the work has been performed?

The regulations state that any work must be performed in accordance with either approved, acceptable or specified data on a type certified aircraft. An FAA 337 form is used to report Major Repairs or Alterations to either the Airframe, Engine, Propeller or Appliance. So to answer your question, no, you don't have to send in the 337 form before performing the work because it's purpose is to report the work that was already performed. The form has a conformity statement that must be signed, it states:

  "I certify that the repair and/or alteration made to the unit(s) identified in item 5 above and described on the reverse or attachments hereto
  have been made in accordance with the requirements of Part 43 of the U.S. Federal Aviation Regulations and that the information
  furnished herein is true and correct to the best of my knowledge."

You can view the 337 form here:

https://www.faa.gov/documentLibrary/media/Form/Form_337.pdf


How do modern avionics work without vacuum pumps or gyroscopes?

If you haven't already done so, you should have a look at section 7 of the C162 POH. That section gives an overview of all the aircraft's systems and the information is at a good level of detail for a checkride (at least at the private level). The examiner isn't expecting you to explain how a ring laser gyro works, but he probably will expect you to be able to give an explanation like this (from the POH):

  AIR DATA, ATTITUDE AND HEADING REFERENCE SYSTEM (ADAHRS) AND MAGNETOMETER (GRS)

  The ADAHRS provides airplane attitude and flight characteristics
  information to the G300 displays integrated avionics units. The ADAHRS
  unit, located behind the instrument panel, contains accelerometers,
  tilt sensors and rate sensors that replace spinning mass gyros used in
  other airplanes. The magnetometer, located in the tailcone, interfaces
  with the ADAHRS to provide heading information.

  The air data portion of the ADAHARS compiles information from the
  airplane's pitot-static system to calculate pressure altitude,
  airspeed, true airspeed, vertical speed and outside air temperature.
  An outside air temperature probe, mounted on top of the cabin, is
  connected to the ADAHRS.

The G300 Pilot's Guide goes into more detail about the system's components (see Section 1), although it's still at a fairly high level.


What are the aerodynamic differences between the different types of slotted flaps?

The high energy air that passes through the slots prevents boundary layer separation over the top surface of the flap. Though, this increases drag but it improves the stall characteristics of the airfoil. In other words, we can have higher maximum lift coefficient (Cl_max) by having higher maximum angle of attack (alpha_max). So, higher the number of slots higher Cl_max one could reach, there should be a limit. In case of a fixed weight of an aircraft,a higher lift coefficient implies that one can fly at lower speed before it stalls. A comparison between different types of flaps (up to double slotted)can be found in the book Aircraft Design and Performance by Anderson.

Source:
The same book.


Does the Piper Aztec have flaps and slats and if so what kind?

The Piper Aztec has standard (plain) flaps:

Source: Sky4Buy.com

Another View:

Source: Same as above

The Aztec does not have slats as can be seen in the image from the front of the wing:

Source: NWAviators.com

Here is a close-up view of the wing of the plane in the first two images (damaged, but no slats):

Source: Sky4Buy.com

Other than the flaps (and wings) there are no other high-lift devices installed on a Piper Aztec.


What is the difference between RNAV and RNP?

RNP is a superset of RNAV requirements. It applies and communicates a performance specification for RNAV that may vary by location rather than by equipment.

On board performance monitoring in RNP requires an alert when the system cannot guarantee with sufficient integrity that position meets required accuracy. Required accuracy can vary. A tight approach may require 0.1nm accuracy while 5-10nm over oceans might be acceptable. RNP requires communication of a numeric qualifier for accuracy. RNAV has no such mechanism.

Confusion is understandable as the terms are sometimes used interchangeably. ICAO is arguing with FAA and other countries to rename RNAV approaches as RNP approaches. The ICAO position is more clear, the FAA position supports existing equipment and training. Everyone believes a navigation performance spec needs to be communicated to pilots in charts and equipment, but there is no clear answer as to how to do it at this point.


Normal tendency of helicopter with counter clockwise rotating main rotors (top view) with force trim off and leaving controls?

With a American made helicopter equipped with a CCW rotating rotor, the helicopter will, as it accelerates past 10-15 KIAS, begin to pitch nose up as well as roll to the right.  This is a direct result of Effective Translational Lift (ETL) as well as Transverse Flow Effect.  Airflow through the main rotor disk past these speeds begins to take a more horizontal flow through the rotor disk, increasing lift on the advancing side of the rotor disk resulting in this.  European made helicopters with a CW turning main rotor will have a tendency to still pitch up as ETL becomes effective but will roll left due to gyroscopic precession from a greater lift imbalance on the front of the rotor disk being applied to the right side of the disk.


Can espresso be made at cruising altitude?

The pressure differential between the boiler and the cabin would be very large. I fear that this would result in the espresso machine being compromised.

The pressure in the espresso machine is 9 bars, 14 in a good one. The difference in outside pressure is 0.3 bars. That is comparably tiny value that does not make any practical difference.

  Water would boil at a much lower temperature (198°F / 92°C) resulting in the machinery not working correctly.

Coffee should not be made with boiling water anyway. 198°F / 92°C is sufficient for making coffee.

Besides, if the boiler was pressurized, the water would not boil until way higher temperature (it isn't, but it does not heat the water above boiling point at that pressure).

  A sudden depressurization of the vessel could certainly result in a dangerous pressure differential resulting in explosive decompression.

The pressurized content is water, not vapour, so it would not significantly expand if the machine cracked. After all, its pressure is relieved as part of normal operation (when the coffee drips to the pot) and it does not expand.

And its amount is tiny compared to the total volume of the aircraft anyway. Very tiny, because the pressure is only in the pipe from the pump to the ground coffee.

But that all assumes the coffee machine is espresso, which most of them are not. Usually they will be just filter machines where the water flows by gravity at ambient pressure or perhaps at some pressure, but much lower than in a real espresso machine. I believe some airlines do advertise they serve true espresso though.


Is it legal to bring your own survival gear aboard an airliner?

Yes, it's legal to bring a parachute, if you can fit it within the permitted carry-on limits. It has been done.

No, it's not going to save you. You are not going to be able to jump out of an airliner. Unless your name is D.B.Cooper, and you're hijacking the last flying 727 with a rear exit door, that is. Again.

No, it's not legal to bring a pressurized container onboard a passenger jet. When you want to fly with a pressurized tank (say, a pony or deco bottle for tec diving), you have to unscrew the valve and bring it separately. This is to ensure you can't bring explosives or poisons inside the tank.

Yes, if you could bring an oxygen or nitrox container (less fire hazard than pure O2), combined with a firefighter SCBA, it could improve your odds of survival in the very marginal event of a fire-related accident, in which the plane manages to land intact enough for you to don it.

No, none of these are practical measures. If you want to somewhat improve your odds without impractical means, wear comfortable leather shoes without heels, cotton clothing, and a fanny pack for your papers, so that you're not tempted to reach for your luggage in an emergency.

One specialized item that has been considered for inclusion on airliners as safety equipment is fire hoods. There are portable smoke hoods that can give you a couple minutes' protection for evacuation. They don't include air or oxygen, only a simplistic filter, which is still a solid step above just holding your breath.


What is the difference between Marginal VFR (MVFR) and Special VFR (SVFR)?

Marginal VFR
Straight out of the Aviation Weather Services advisory circular (AC 00-45G with changes 1 and 2):

Marginal Visual Flight Rules (MVFR) indicated on the Weather Depiction
Chart represents ceiling 1,000 to 3,000 feet and/or visibility 3 to 5
statute miles and VFR operations can take place. MVFR areas are
outlined with a solid line, but the area is not shaded. MVFR areas are
typically shaded blue in colorized versions of the chart.

For all regulatory purposes, this has no rule changes from VFR.  I believe the reason it exists is for pilots to more easily identify areas where the weather conditions are approaching IMC.
Special VFR in the US
Special VFR allows a pilot to fly within the lateral boundaries of controlled airspace to the ground with at least 1SM visibility and clear of clouds.
Special VFR is something that can be granted by ATC upon request by a pilot.  It may only be granted within the lateral boundaries of controlled airspace that goes to the ground.
If the special VFR request is being made at night, the pilot and airplane must be IFR legal.
JO 7110.65Y Section Regarding Special VFR
There is no requirement that the weather conditions being reported are below basic VFR.

The Difference
MVFR is an advisory term.
Special VFR is an, on request by pilot only, "required weather minimums" change that may be approved by ATC.
For the purposes of special VFR in the US, here is the FAA regulation. (14 CFR 91.157)


What happens when a turbo-prop is over-torqued?

This short answer is that you could break something if you over torque the engine.  And that's really about all that we can tell you in general terms.  The manufacturer or an engine repair shop could tell you what is most likely to fail for a particular model, but the failure modes won't be consistent from engine to engine.

As far as what to do if you were to over torque one, refer the the aircraft flight manual.  They will have a limitations section, and most airplanes will have "transient" limits in addition to the "normal" limits.  For instance, the limitation could be 100%, with a transient limit of 103% for 10 seconds and 105% for 5 seconds.  If the transient limits are exceeded, then you (or more likely a mechanic on your behalf) would need to refer to the maintenance manual for instructions.  Depending on the severity of the exceedance, it can be anything from simply logging it in the engine logbooks to a complete tear down and overhaul of the engine.

I'll also add that some pilots lean towards pretending that the exceedance never happened, and hope that nobody noticed.  This is not a good idea for several reason, the main one being that something could have been damaged that is not immediately obvious.  Even though things are running correctly now doesn't mean that all is well, and if an inspection is required, it's for a reason.  Another issue is that a lot of modern engines are computer controlled and monitored.  The next time that the computer information is downloaded, maintenance will see the exceedance anyway and if you have flown it since then you could be in even more trouble.

In short, follow the AFM procedures for your airplane.  They are there to help keep you safe!


Why do simultaneous-ops parallel runways need to be so far apart?

The simple answer seems to be for wake turbulence. This FAA document, ORDER JO 7110.308C, seems to say it is for wake turbulence reasons in para. 9:

  The geometry of the approach, as well as the lateral separation between the two approaches and prevailing local meteorological conditions, provide the wake turbulence avoidance necessary for reduced separation dependent approach operations.

Figure 3 shows the aircraft arriving in a staggered fashion, 1 nautical mile diagonal separation with runways 2500 ft apart (parallel runways separated by less than 2,500 feet, also referred to as, Closely Spaced Parallel Runways (CSPR)).  The text also describes how the lead aircraft follow a lower glide path than the following aircraft such that  the lead's wake turbulence isn't a factor for the following aircraft.


Why should jet engine throttles be moved smoothly?

The issue is the possibility of a compressor stall.  The combustion will directly respond to changes in the thrust lever but it takes time for this to spool up the turbine that is connected to the compressor.  If the incoming air from the compressor is not of adequate pressure because it hasn't spooled up enough you risk a compressor surge.  In these engines you need to slowly increase thrust so that the turbine can spool up (and hence the compressor) so the airflow through the engine remains adequate for the engine power.

Modern engines with FADEC systems should not have these issues as the FADEC can enforce rate limits for fuel flow increases or directly calculate the maximum safe fuel flow from observed engine parameters.  Modern engines might also have more sophisticated compressors with variable stators that can help mitigate compressor stalls/surges.


How do I renew my ability to fly after 40 years?

Much has changed in 40 years, including airspace designations, ATC communications, and new regs.  If I were you I would take an online Private Pilot Ground School to learn about all the new changes.  These courses are not too expensive and it well worth the money.

The AOPA does have a Rusty Pilot Seminar as well (link).

Also it might be worthwhile just to sit in the passenger seat of a plane for a while to re-familiarize yourself with how it all works.


Would the wings of a Boeing 787 be snapped off in the same turbulence in which a DC-8 lost an engine and parts of a wing?

It's very likely that the 787 would have less problems with turbulence than the DC-8 did.

The wings of the Boeing 787 are more flexible than the DC-8, and that flexibility will damp the immediate impact of turbulence. More important, the Boeing 787 has a gust alleviation system that reacts to turbulence by counteracting the induced accelerations using the control surfaces.

Note that the aircraft certification standards have changed a lot since the DC-8 was certified. Originally the focus was very much on the maximum g-forces the wing could sustain, but this is not a very good measure for turbulence. The g-forces encountered in turbulence are the result of a combination of the turbulence itself and the aero-elastic response of the aircraft. Using a more flexible wing and gust alleviation systems will result in a much smoother ride (less g-forces) than a traditional very rigid wing.

Currently the certification standards define, in addition to a required g-force, the characteristics of the turbulence that the aircraft has to sustain. For example, see the FAA's regulation for large aircraft, FAR Part 25, Sec 25.341.
This takes into account a range of characteristics of turbulence that can be encountered as well as the dynamic response of the aircraft to that turbulence.

Apart for aerodynamic and structural differences between the DC-8 and the Boeing 787,  better understanding of (mountain wave) turbulence, better weather prediction, better reporting of turbulence by aircrew (simply because there are more flights) and better weather radars on aircraft have reduced the risks of encountering turbulence since the DC-8 era.


How much advance notice does the FAA have to give for a TFR?

The FAA can issue TFR's on short notice, and if you are flying a slow plane or a fast plane far they may very well pop up while you are inflight. While things that cause TFR are often planned in advance like the super bowl there are plenty of last minute things like a wildfire or a quick movement of the President that will force a fast TFR to "pop up". Even the FAA admits they can can be unexpected

  TFRs can pop up unexpectedly, so before any flight, be sure to
  research NOTAMs, check the TFR list online at http://tfr.faa.gov, and
  call Flight Services for updates at 1-800-992-7433.

I can not find any regulations sating the FAA has a minimum amount of notice time they must give.

A pilot flying VFR in an airplane not radio equipped is always at risk of busting one of these. But if you are in a radio equipped aircraft taking flight following or monitoring your local FSS is a good way to be aware of these kinds of events.

This AC covering TFR's does not list a minimum amount of time they must be filed before becoming active.


What indication will appear in case of one of A320 LGCIU is inoperative?

enter link description here

A320 ECAM "WHEEL" page

The answer:
The LGCIUs (landing gear control and interface unit) receive position information from the landing gear, cargo doors, and landing flap systems and process gear and door position, sequencing, control, and gear lever selection.

When one of two LGCIU is inoperative (№6) amber XXXs in the triangle - indicates that one LGCIU has failed.

...
Source: http://www.a320dp.com/A320_DP/landing-gear/sys-12.2.0.html


How is performance downgraded if the windshield is damaged in flight?

The biggest restriction will be the reduced flight speed and cabin pressure which need to be observed with a damaged windshield. No pressurization will restrict the flight altitude to 10,000 ft or less. The crack will not increase drag, but force the pilot to continue flight at a less efficient speed and altitude.

Why high altitude is good for engine efficiency can be found here.

How to find the most efficient flight speed can be read here.

If pieces break off, the aircraft should not continue the flight, but land immediately.

To answer the other questions: Yes, sure, tail-mounted engines are known for ingesting stuff which has broken off from the fuselage. Ice from a leaking lavatory has caused engine damage and the imbalance made the engine shake so hard that it fell off. The whole windshield or substantial fractions of it could have this effect, but I doubt that flakes will damage the engine.

The aerodynamic pressure at the windshields tends to press them into the fuselage. Suction only starts above of the windshield with the curvature of the fuselage contour. However, with cabin pressurization added, the windshield is indeed forced out if it fails. One accident which was caused by using the wrong screws to secure the windshield is BA Flight 5390. The captain was sucked out of the opening left by the window and only his ankles, which got stuck in the flight controls, prevented him from falling out entirely.


Why doesn't Stratolaunch have connected tailplanes like it has connected wings?

There is indeed an Eigenmode possible on the Stratolaunch which does not exist on regular airplanes: If the two fuselages pitch in opposite direction, thereby twisting the center wing. If that happens at the torsional eigenfrequency of the center wing, flutter might be possible.

Stratolaunch in flight (picture source)

Given the pitch damping of the horizontal tails, however, this scenario is rather unlikely. I bet the elevators have plenty of mass balance to avoid this flutter case. Underbalanced, their dynamic response would support flutter, but overbalancing would dampen this flutter mode. Connecting the tails would not make much of a difference and would even reduce pitch damping somewhat in the above mentioned case.

Similar configurations used both, a connection horizontal tail (F-82 Twin Mustang) or individual tails (He-111 Zwilling).

North American F-82 Twin Mustang (image source)

Heinkel 111 Z (image source)


How much extra drag does an external HF antenna incur?

As this film shows with brilliant simpliciy, the drag of a round wire is almost 10 times the drag of the same thickness streamlined shape.

Biplanes use streamline rod for flying and landing wires because of this.  There is enough flying/landing wire on a biplane for it to make a huge difference.

On a long antenna wire however, there really isn't a practical way to streamline it, and even if you did, to keep the streamline contour properly oriented, so you just live with the drag penalty of the wire.

It also helps that the sharply "swept" angle of the wire in the picture to the airflow means the profile presented to the airstream is more of an oval shape than circular, so the drag of the swept wire will be somewhat less than a wire presented to the airstream at 90 degrees.

So in the case of the 737, the wire itself is probably pretty minor factor overall, but I wouldn't be surprised if the wire costs a couple of knots of cruise speed at a given power setting.


What are the criteria that govern the choice between titanium, composites, and more common materials, like aluminum?

Three main criteria: cost, strength-to-weight ratio, and fatigue resistance.

Cost. Of the three, aluminium used to be the clear winner, with composites having made large advances due to improved manufacturing processes. Titanium is the most expensive and is difficult to machine.
Strength-to-weight.

Buckling. Titanium alloys have higher strength-to-weight than aluminium (this answer, more on temperature below), but aluminium is lighter and that gives it an advantage in structures loaded with compression stresses: buckling resistance is a function of cross sectional dimension as well. For the wing upper surface aluminium would be lighter than titanium, despite the lower specific strength. Composites have the highest specific strength of all.
Temperature. The graph in the linked answer also shows the influence of temperature on the specific strength of materials: aluminium is first to drop, and at higher temps titanium is the best next choice, as from the comment by @PeterKämpf.

Fatigue resistance. Titanium alloys, like steel allows, have a fatigue endurance limit. If stresses remain below this limit, the construction can endure an endless number of cycles. Aluminium does not have an endurance limit, and will eventually fail even from small stress amplitude cycles: aluminium constructions require careful monitoring and maintenance for prevention of fatigue failure.

Composites do not have an endurance limit, but fibre orientation and material choice can improve fatigue life.

Image source


Why should one not slip a Cessna 172 with flaps extended?

The basic problem is that sideslip induces a cross flow over the fuselage that can increase the local negative AOA and flow disruptions beyond that already caused by the turbulence and downwash being generated by the flaps.  The stabilizer surface on the "lee" side of this cross flow may get enough flow disruption to be felt in the elevator, maybe accompanied by a bit of pitch bobbing at some extreme condition that maximizes the tail loading, like side slipping at forward C of G with large flap angles.  In spite of its very powerful flaps, the 172's issue is fairly benign (or there would be a prohibition against using slips with flap as opposed to an advisory).

This can be a significantly worse problem with stabilator or all-flying tails that operate at larger negative AOAs than fixed stabilizer tails, as Cessna Cardinal owners are well familiar with.  The Cardinal required slots to be added to the stabilator inboard leading edge to fend off tail root stall during landings, and resulting broken nose gears, during the first year of production, and that was just doing regular landings with maybe a bit of slip due to crosswind (the '68 Cardinal I once owned had the field mod slots added under the "Cardinal Rule" service bulletin - Cessna sent teams out to modify every aircraft pre production cut-in in 1968, somewhere around 500 a/c, and you can slip them with flap all you want).

The stabilator equipped Thorp T-18 homebuilt had to have a flap limitation added due to stabilator stall in sideslip (John Thorp did some testing after an incident in the 60s, discovering that the stabilator could stall with full flap, forward CG and sideslip, causing a nasty pitch over, and advised owners not to use full flap for landing).


Airline safety: what happened between 1959 and 1962?

I believe the answer has something to do with the introduction of the passenger jet airliner, which first came into service in the late 1950s.  Note please that the original poster is asking for information on "commercial jets" whereas the statistics that others have offered have information on commercial planes in general, including prop planes.  I glanced at the statistics for 1959 presented above and there were only two passenger jets (including one KC-135, which you may discount if you like) that crashed.

Compare this to the statistics presented for 1962.  There were six or seven crashes of Boeing and Douglas jet airliners.

To me this means the differences were in all probablility not statistically significant.  We don't have enough "samples" to reach a valid conclusion.

What you can see is a general explosion in the number of people flying.  Jets really introduced the public to flying.


What is the working principle of a Gurney Flap?

Adding the flap to an existing airfoil increases the angle of attack of the airfoil - just draw a straight line from the leading edge to the trailing edge: after adding the flap, the trailing edge has moved down to the tip of flap. The line before and after resemble flat plates at different angles of attack.

The vortex in front of the flap is produced because the flow can't make the sharp right angle turn around the flap, it can't perfectly follow the geometry.

The increase in CLmax should come from an associated increase in effective camber.

Total drag consists of skin friction drag (mostly, for an airfoil that is just "thick") and pressure drag. Maybe the increase in effective camber changes the relative amounts of both, leading to a net decrease of drag.


For the same reason that you don't takeoff with full flaps. Because the climb performance sucks.

Flaps do add lift, but also a lot of drag. A low flap setting often provides more lift than drag, assisting climbout, whereas full flap offers a whole lot of drag, which is desirable when you want to be slow for landing.

But a go-around necessitates gaining height quickly, which will not work with landing flap selected. The usual procedure, at least in light aircraft, is to wait until the vertical speed is neutral or positive before retracting flap. This minimises some of the risks you've raised about aircraft control.

It is often said that a go-around is a period of heavy workload, and managing the flaps and airspeed is not easy. That is why the go-around is a fundamental procedure taught right from the very beginning, and practiced and tested regularly.


Is there a difference between altitude and flight level?

Yes, altitude is below transition level, flight level is above transition altitude.

Altitude is referencing to actual (local) air pressure, while flight level is against standard pressure 2992 / 1013.

The transition altitude is dependent on the location and are definded so both will not mix up.

When climbing through transition altitude, pilots set their QNH to 2992 - and so no longer need to set it to changes due to local weather.

When decending through transition level they set it back to the local QNH - as they are close enough to ground the real altitude (above ground...) is getting important.


Can a private pilot fly commercial-type aircraft?

Your certificate level determines the type of operations you can conduct*, not the type of airplanes you can fly.  The types of airplanes you can fly are determined by your category, class and type ratings.

If you have a Private Pilot certificate with an instrument rating (not sure if this is required, but you'll want it either way) and an airplane multi-engine land category and class and a B777 type rating, then yes, that person can operate the aircraft privately.

He will also need an SIC and he will only be able to collect the pro-rata share of operating expenses from people he carries.  He will also want to be careful in who he lets on his plane to avoid operations that are regulated under 14 CFR 119.

An example of such a pilot is John Travolta, who has a private pilot certificate with the following ratings:

PRIVATE PILOT
  AIRPLANE SINGLE ENGINE LAND
  AIRPLANE MULTIENGINE LAND
  INSTRUMENT AIRPLANE

Type Ratings:
P/B-707 P/B-720 P/CE-500    P/CL-600    P/EA-500S
P/G-1159    P/HS-125    P/LR-JET

Limits:
ENGLISH PROFICIENT.
AUTHORIZED EXPERIMENTAL AIRCRAFT: SO-G2.
B-707 SIC PRIVILEGES ONLY.
CE-500 (VFR ONLY).

* Private pilots may only collect pro-rata operating expenses, Commercial pilots may be paid to act as PIC and ATPs may act as PIC in 14 CFR 121 operations.


When evacuating after a rejected takeoff, what is the minimum distance you should be from the plane and which direction should you run?

First and foremost, you follow the directions of the flight crew and any emergency services you encounter. This takes precedent over anything anyone else tells you. Failing to do so may put your life and the lives of those around you in danger.
That said, lets break this down into the possible sources of danger...
Brakes and Wheels
If you're evacuating from an aircraft there's fair chance the brakes and wheels are extremely hot and possibly overheating. If that's the case there is a danger of them exploding. We have a good answer about how firefighters deal with these, which says to avoid being directly in line with the front or sides of wheels and to prefer being at a 45° angle to them.
Based on this, you should avoid being close to tires in general and ideally keep to a path that puts you at 45° to the wheels until you are at least 80 m away (263 ft). The most important thing is to avoid being directly inline or to the side of the tire.

Engines
The engines are normally shutdown asap after an emergency landing, however they could still be running. If the engine has been shutdown and isn't on fire it should pose no threat to your safety, though for good measure I'd avoid putting myself in line with the turbines (or generally to the side of the engine), because if they break/explode it will not be contained.
If an engine is still running, on an airliner you'd normally avoid evacuating on that side of the aircraft as there is a danger of being sucked into the front of a running engine or being hit with the hot air coming out the rear. Again I'd avoid being to the side of the engine in case of turbine disc failure.

Fire and Smoke
Fire and smoke can be spread by the wind, so as others have said, I'd prefer to be upwind to avoid a lung full of toxic smoke and being in the path of a fire. Though I think this is very much a secondary consideration. I'd be much more worried about the tires.
Explosions
If there is a general explosion on the aircraft debris could fly in any direction so there is no preference for a safe direction to run in this case. For distance I'd suggest an absolute minimum of the 80 m as per the brakes, but why would you want to be closer than necessary to a potential explosion? Keep going and DO NOT stop to take a selfie or video until you come across some emergency services, who should guide you to a safe location.


How come certain airports can have unique rotating beacon colors?

The lighting for private heliports is not regulated by the FAA, but by the individual states. The FAA has an Advisory Circular laying out guidelines for heliports, but it is only a recommendation.

  The  Federal  Aviation  Administration  (FAA)  recommends
  the  specifications
  contained in this AC for all applica
  tions involving development of this natu
  re.  In general, use of this AC
  is not mandatory.

  From FAA AC 150/5345-12F: Specification for Airport and Heliport Beacons

It is only regulatory when the heliport is built using federal funds. In the AC they recommend the white/green/yellow pattern.

Only a couple of states have adopted the FAA guidelines as regulatory.

The state of Pennsylvania incorporates many of the FAA Advisory Circulars in their state law. For example the ground markings and the lighting for the perimeter of the landing and takeoff area for the heliport are required to adhere to the appropriate FAA AC's. But in regards to the beacon it simply states:

  A rotating beacon is recommended to be installed for night operations at public heliports.

  Pa Code § 471, Appendix A, Criteria I, i)

It does not even have that recommendation listed for private heliports.

Although it is not in the FAA Advisory Circular some places list the beacon color code for hospital heliports as white/green/red. I can't find anything authoritative on this but examples are at an aviation wiki, on Quora and on airliners.net.

This company that sells heliport beacons indicates that their beacon is "Available in Hospital Heliport version (not FAA certifiable)." It doesn't indicate, but this is likely a white/green/red version. And since it doesn't adhere to the Advisory Circular it isn't FAA certifiable.


Before a flight, what are the most important things to check in an aircraft (walkaround)?

Many things are checked on a walkaround. The pilot-in-command should do the walkaround, not the co-pilot. The main classes of items are as follows:

structural integrity; the aircraft must be sound and undamaged and ready to fly

sensors; sensors such as antennas and gauges should be undamaged and not have anything blocking them or adhering to them

clean flight surfaces; the control surfaces and flight surfaces must be smooth and clean; for example, the wings must not have ice on them

no leaks; hydraulic fluid, oil, fuel, and other critical liquids should not be leaking out of the aircraft

chocks, control locks and covers removed; all chocks, protective coverings and locks should be removed before flight and stowed

correct tire inflation; wear on the tires should not be excessive and the tires should be inflated properly

fasteners present and correct; all bolts, shims, nuts and other fasteners should be present, undamaged, and correctly installed

hatches and fairings secure; removable inspection plates and any other small doors, fairings and cowlings should be in place and secure.

lights ok; the lights on the aircraft should operate correctly and their lenses should have no cracks or other defects

blades ok; the propeller or turbine blades (as the case may be) should be perfect with no cracks or chips

Overlooking any of these sorts of items can cause (and has caused) serious accidents or incidents in flight or during takeoff and landing.


What is the standard report when pilots exiting and clearing the runway

Nitpick: that would be runway 07, not runway 7

The phraseology is mostly standardised, and in general consists of notifying the relevant unit that you have vacated the runway. At a small, GA airfield with AFIS in the UK the typical communication goes as follows.

  ATCO: G-ABCD Cleared to land Runway 07, wind 240 at 5
  G-ABCD: Cleared to land, Runway 07. G-ABCD
  ... controlled crash ....
  G-ABCD: Runway vacated at Charlie

This becomes a bit more formal at controlled airfields. In the UK, Cap 413 is the radio telephony communications bible. Secion 4.89 "Runway Vacating and Communicating after Landing" is the part you'e interested in. The communications would be more along the lines of (Note: CAP413 uses the name "Kennington" as a fictitious airport)

  Kennington Tower: BIGJET 347, vacate left
  BIGJET 347: Vacate left BIGJET 347
  Kennington Tower: BIGJET 347, when vacated contact Ground 118.350
  BIGJET 347: When vacated Ground 118.350, BIGJET 347
  BIGJET 347: Kennington Ground, BIGJET 347, runway vacated
  Kennington Ground: BIGJET 347, Kennington Ground, taxi to Stand 27 via taxiway Alpha


How does the CFM LEAP-1B engine achieve the same efficiency as the LEAP-1A despite its lower bypass ratio?

Bypass ratio (BPR) alone never tells the whole story.

Take a low BPR engine and add to it a bigger fan, now you have higher BPR. Does that mean better efficiency? No. The reason is simple, by keeping everything the same, the same combustor/turbine do not have the right power/design to turn the now bigger fan at the optimum speed (slow fan).

But if you use a smaller fan on an already high BPR engine, which is the -1B case (approx. 8 inches smaller), then the thrust will be lower, which is indeed the case (approx. 130 vs. 143 kN). Since the combustor and OPR (overall pressure ratio) haven't changed, they can easily drive the now smaller fan at the right speed.

The other benefits the -1B have that may offset the lower BPR are the lighter weight (2 fewer turbine stages), lower duct loses, and the Max's cruise Mach, which is 0.01 faster than the neo – the slightly faster speed means slightly less time burning fuel for the same distance, and also slightly better inlet compression.

The LEAP SFC values aren't public yet. The official statement is:

  The advanced LEAP engine provides a 15 percent improvement in specific fuel consumption (SFC) compared to today's CFM56 engines.

That can also mean compared to the CFM56 of the respective plane, which is different for the A320ceo and 737NG:

  CFM56-5A1
  A320-211/-311
  0.330 lb/lbf hr

  CFM56-7B24
  737-700/-800/-900, 737-700BBJ/-800BBJ2 (option)
  0.370 lb/lbf hr

Source: jet-engine.net

The main reason there has been an increase in BPR in recent times, is because of the higher OPR they've been able to design (powerful small cores). Without OPR, you can't drive big fans at the right speed using small cores.

The slide below by Safran also shows why BPR alone is not the full picture:

(Safran via forum-ae.eu)

Related: Why does the CF6 have a lower bypass ratio than the TF39?


Dangers to the Engine if CHT goes below minimum in flight during descent?

To my knowledge, the problem with running low CHT is mainly related to incomplete combustion, leading possibly to fouling of spark plugs and buildup of carbon and lead (if present in fuel) deposits in combustion chamber. How severe this actually is, I have not studied the subject any further, or looked inside an engine during such a condition ;)
However, from experience I can tell that after a prolonged descent, running the engine cool, the engine usually has some "difficulty" picking up the pace as the descent is stopped and power increased. Some sputtering and hesitation are present sometimes, but after a while the situation is normalized. During training, such descents were advised against, and I would say for a reason.
In extreme cases very low CHT might lead to stalling the engine, as it can no longer support combustion due to lack of heat and possibly the fouled spark plugs I mentioned earlier.


How is d(Cl)/d(alpha)@stall and Cl increment to stall defined in Xrotor?

I interpreted the values as follows:

The angle of attack at which the specified propeller airfoil generates zero lift
The change in lift coefficient per change in $\alpha$ in radians
The same as 2, except that it is this value around the stall angle (it is mostly a safety factor for numerical calculations I think, small but non-zero)
Maximum $C_l$, which is achieved at the theoretical stall angle
Minimum $C_l$, which occurs on the backwards sweep of the propeller
The $C_l$ increment from the last linear part of the $C_l$ polar to the stall point
The $C_d$ at $\alpha=0$
The $C_l$ at $\alpha=0$
Quadratic drag dependence on $C_l$, slope of the $C_d,C_l^2$ curve
The Reynolds number at which these values are obtained
Re scaling exponent as explained in the XRotor documentation
Moment coefficient $C_m$
The critical Mach number.