How do airlines bring spare parts to aircraft stranded outside their main facilities?

In some cases airlines will follow the "what goes around comes around" principle and will loan or sell parts, and consumables like tires, to another operator that is "AOG" (Aircraft On Ground) to the extent they can without jeopardizing their own operation.

What that means is, in an airline's spares inventory it will have a baseline minimum inventory requirement of components to cover its own AOG situations, things like spare actuators, servos, pumps and other odds and ends, called "AOG stock".  If someone on the airport is hard up and approaches you, and you have the part but it's part of your own AOG stock, you won't lend or sell it because of the risk of your own AOG situation arising before you can replace the AOG unit you loaned out or sold.

If it's part of your larger non-AOG spares inventory, and you can afford to part with it temporarily, you might do so, and you may agree to loan it or sell it.  That's if you operate the same airplanes and have similar parts stocks with the same part numbers.  And airlines that operate the same fleets do buy and sell spares from each other, wheeling and dealing from time to time.

What happens probably more often is the stranded operator will have the required parts shipped "AOG" from either its own spares stock, from an OEM's spares stock from the nearest depot (OEMs will normally maintain spares depots at key locations worldwide) or possibly from the supplier of the part itself (both the OEM and the larger parts suppliers will have their own AOG spares support).  Whoever is fastest (or cheapest if time is less critical).  Often if the part is fairly small, and will fit in a Lear or Citation, the airline (or the OEM if it's something under warranty, and the operator is an important customer) will charter a corporate jet to fly the part to where it's needed (this is done a lot in the corporate world).

In the case of that UPS flight, it's more than just the tire replacements; wheel unit fuse plugs, or the wheels themselves, probably had to be replaced and a number of special inspections had to be done, so even if there were tires on the spot, the airplane was probably stuck there overnight anyway.

For the tires, say they were Goodyears. UPS might have had a set shipped from the nearest Goodyear distributor, which is in Dubai, which for an AOG would have probably would have arrived that evening or overnight.  If there was another airline on the field with the same tires, UPS could have tried to buy a set from them, but they'd have to get lucky and find someone with the same PN tires that were surplus to their own AOG needs and willing to give them up.  Or UPS may have just put a set of tires from their own spares on the next UPS flight going to Delhi.  Or they may have had Boeing's AOG spares take care of it.  They probably would have done whatever was fastest under the circumstances at reasonable cost.

There are also 3rd party spares and logistics companies that some airlines contract to handle all that stuff for them, especially if they are smaller.  Like these guys.


What is meant by Manual Tuning of ADF/NDB using BFO?

Manual tuning is like the old style analogue radios with a dial or rolling switch for tuning, similar to old AM/FM radios in your car, etc. Old Automatic Direction Finder (ADF) systems still have a tuning knob that does the same thing.
BFO stands for Beat Frequency Oscillator. There is a bit of electrickery going on, but basically, the ADF radio receiver processes the incoming signal and splits it in two, and just about halves one of those signal's frequencies. These two signals are then layered on top of each other so you can hear them on the headset. You then proceed to tune the radio until you minimise the pulsating sound coming from the headset.
The best analogy of how this works is how a guitarist tunes by ear by comparing two strings. When they pick two strings at the same note, if they aren't in tune there is a pulsing harmonic that doesn't sound nice. When the string is tuned properly, this pulsing goes away. Same concept is happening in your ADF radio with BFO selected.
So in summary, BFO help you tune to the exact NDB frequency using your own ear as a guide.


When must full aircraft registration be used as radio callsign?

The AIM discusses communications with ATC in Chapter 4.

  4−2−3. Contact Procedures a. Initial Contact.
  1. The terms initial contact or initial callup means the first radio call you make to a given facility or the first call to a different
  controller or FSS specialist within a facility. Use the following
  format:

  (a) Name of the facility being called; (b) Your full aircraft
  identification as filed in the flight plan or as discussed in
  paragraph 4−2−4, Aircraft Call Signs; (c) When operating on an airport
  surface, state your position. (d) The type of message to follow or
  your request if it is short; and (e) The word “Over” if required.

  c. Subsequent Contacts and Responses to Callup from a Ground Facility.
  Use the same format as used for the initial contact except you should
  state your message or request with the callup in one transmission.

  4−2−4. Aircraft Call Signs
  2. ATC specialists may initiate abbreviated call signs of other aircraft by using the prefix and the last three digits/letters of the
  aircraft identification after communications are established.…The pilot may use the abbreviated call sign in subsequent contacts with the ATC specialist.

When operating at a non-towered field, many pilots have begun to identify their aircraft by type and color. I’m not sure when this started, but if you listen to popular YouTube flyers like steveo1kinevo, you will notice that when they are flying into non-towered fields, they just give the aircraft type, e.g. Caravan or TBM. From a practical standpoint, it makes a lot of sense. You can’t see the numbers but you can see the type and color. And unless there are lots of white Cessnas in the pattern, it is easy to keep track of who is where. What you want to know in the pattern is where are the other planes and how fast are they going.

Type and color gives you the necessary information. For me at least, it is easier to keep track of type and color than it is to keep track of N numbers.


Can single engine aircraft fly in class A airspace?

Single-Engine aircraft can fly in Class A airspace. Pressurization or oxygen masks are required above 18,000 feet (no cannulas).


How is the F-22's nacelle/engine bay ventilated?

The exact details of the F22 are classified. But the more likely scenario is the engine has a cold bypass air gap between the afterburner inner wall and its exterior shroud. From all the close-up shot of its nozzle, the thrust vectoring nozzle and the emergency arrestment hook fairing is lined with some sort of refractory materials and need no special cooling and the serrated nozzle fairings on either side of the nozzle seem airtight and have no place for a cooling air stream outlet. Plus, we see no scoop on the front of the aircraft as an inlet for engine cooling, and the scoop, should it exist, must be quite large. I say this is the most likely scenario because it's the least heavy and complex solution to engine cooling. And let us do not forget small cavities with a diameter in the range of millimeters is the most effective radar wave reflector/scatterer.

A less likely scenario is the engine is cooled by fuel, just like the avionics, the radar and the AC for the pilot. The fuel is then cooled first by the sheer amount of wing area as a radiator and second by a pair of hidden air-cooled fuel cooler. (I won't tell you where :))


How large and heavy is the B737's built-in stair?

A number of 737s are fitted with forward airstairs (and aft ones too). The Boeing Airplane Planning Document gives the airstairs opening as 0.41 X 1.12m, while the airstairs can be folded to less than 2.5m length. This should give the volume occupied by the airstairs.

Image from Boeing 737 Airplane Characteristics for Airport Planning document.

According to an article in aviationpros, the total system weighs in around 200 lbs:

  Aircraft such as the DC9, MD80, MD90, and 737 aircraft have had a long enough history that many of them were built with the forward passenger air stair assembly. Many aircraft were also converted to non-airstair versions Ñ a 200+ lb. weight savings for the operator.


What's preventing aircraft manufacturers to record every single possible value in FDRs?

I'm not an expert on FDRs, but I do have experience of hardware and software development in a regulated market (medical devices), so might be able to offer some insight.  Here are a few considerations that occur to me:

Development cost:  Adding storage to a FDR isn't like installing new DIMMs in your workstation.  As well as the design work, the changed device must undergo new verification and validation cycles, the supply of the new components needs to be assured, and the manufacturer must continue to support existing products as well as a new one.  The V&V may well include accelerated-life testing and other expensive activities; it's unlikely to be just a few days' work.
Customer demand: Aircraft operators require an FDR that satisfies regulatory requirements; it's a "tick-box item".  Consequently, that's the requirement that aircraft manufacturers demand of their FDR suppliers.  If there's no demand for extra storage (either for an extended loop time or for a greater number of sensor inputs), then there's no money to be made by offering that as a feature.
Interface limits: I don't know enough about FDRs specifically, but the input interfaces may well have a bandwidth limit which precludes providing more readings without providing further connectors (which then has a big impact on development costs; see above).


How can the landing gear fit in the small room in the engine bay on the Tupolev Tu-144?

The Tu-144 uses much smaller wheels than comparably-sized subsonic aircraft. This makes it possible to rotate the gear bogie sideways towards the middle of the aircraft, so it can be stowed vertically inside the wheel well. Your picture already hints at that:  Note that the gear strut is offset inside the wheel well, so it would leave more space on one side for the gear bogie.

Tupolev Tu-144 landing gear (picture source). Note the big drums of the wheel brakes: They were needed to stop the aircraft - the engines had no thrust reversers! Inside are stacks of disc brakes to absorb the energy that comes with a landing speed of 270 km/h. Also note the unusual sideways arrangement of the scissors link: This way it did not interfere with the rotated wheel bogie. Next clue: The big hydraulic cylinder on the left was used to pivot the bogie around an axis parallel to the direction of flight.

Picture of a photo from Tu-144 landing gear test, including finger print (picture source). This shows the gear in mid-sequence: The bogie is already rotated and lies sideways, with the gear strut between the wheels. Now the strut pivots forward and up into the wheel well.

Requiring complex motion adds more failure modes: On its 59th flight, the XB-70A suffered a malfunction of the left gear which left the bogie in the upright position. If you want to know how it was supposed to work, watch this video from 14:47 on. The picture below is taken from this video.


Why are aircraft parts built in different places and assembled in one?

You can only hire so many people at one place, and also only find so much land there, so when the whole process no longer fits, there is no other option than start building components at other places and move them to the final assembly place.

In part, it is also historical. Airbus, but to an extent Boeing too, was formed by mergers of smaller companies as building a plane became more complex over time. So the companies got already working facilities with already qualified workers. Closing them down would lose them those workers, and cause quite a bit of bad publicity too (and at least in case of Airbus some political pressure), so they got used for whatever part of the process fits in them.

And some factories simply don't have any unused land around them, so the companies can't grow them even if they want to and have to open new ones instead. This is probably worse in Europe, which is more densely populated, so building a really big factory is basically out of question anywhere.


Is there a 'common courtesy' distance that should be complied with when initiating contact with ATC for class D airspace?

To answer the question in the title, the AIM 4-3-2 says:

When operating at an airport where traffic control is being exercised
by a control tower, pilots are required to maintain two-way radio
contact with the tower while operating within the Class B, Class C,
and Class D surface area unless the tower authorizes otherwise.
Initial callup should be made about 15 miles from the airport.

FWIW, I fly out of a class D and usually call 10 miles out, which gives plenty of time to contact ATC. As always, use some judgement: if the airspace is busy and the radio traffic is heavy then call further out. If it's very quiet then calling closer to the airport should be fine.
All that said, the body of your question is about being directly overhead the field. That seems like an unusual scenario (to me) but there's nothing wrong or problematic about it. I'd just call the tower, tell them where I am and that I intend to land, and let them tell me how and where to join the pattern. I can think of two practical points that might come up:

They might assume you have some sort of emergency, so be ready to tell them you don't (unless of course that is your reason for landing there!)
They might give you instructions to join the pattern that are difficult to comply with because they don't know what you and your aircraft are capable of. Or they might ask you how you'd like to join. Have a plan, be ready to say "unable" if you aren't comfortable with their instructions, and if necessary just tell ATC you need to fly some distance away from the airport to get down to pattern altitude.


How is vibration isolation achieved in helicopters?

There are many techniques.

Passive reduction techniques involve designing the powerplant, transmission, gearbox and particularly the rotor(s) to minimize vibration. Designers carefully arrange all the moving parts to be as closely balanced as possible. They can be mounted using flexible parts and springs to damp vibrations (the same principle behind the shock absorbers in an automobile). The sophistication of helicopter design has evolved over time as engineers learn more about the characteristics of helicopters and how mechanical parts behave. Computer-assisted design has also allowed for huge improvements here as moving parts can be simulated in great detail to optimize each individual part for minimum vibration.

Active systems work by using accelerometers to sense the vibration of the helicopter at certain points in real time. This data is then used to shake a reaction mass back and forth to create vibration opposite to that of the rest of the helicopter. The two opposite vibrations cancel each other out. Effectively, the active system is using electrical power to dump all of the vibration energy in the helicopter into a small mass, so the helicopter stays still while the reaction mass in the active system shakes to absorb the energy. Such systems are already in common use in large transport helicopters and are becoming more prevalent in smaller helicopters as well.


How much of an airline's costs are labor costs?

(Source) Direct Operating Costs

  What percentage of a commercial airline's costs are labor costs?

By labor I believe you mean flight- and cabin-crew, the percentage is roughly 12%.

  Can an airline run a low-cost operation without reducing the wages for crew and pilots, or subjecting them to long shifts?

Yes, but they won't make money. What Low Cost Carriers do is save in everything by making sure each expenditure runs more efficiently, so they can offer cheap tickets, which in turn enables them to fill all the seats.

Examples for saving:

Single-type fleet greatly reduces maintenance cost, which is 15% of an airline's operating costs.
Fuel hedging removes the risk of fuel price hikes, but when oil is cheap, it's offset by having to pay more.


It means fog bank from S to NW of the station, although it's not codified.
The remarks section (after RMK) does not always use official codes. In this case, BNK neither appears in the FAA's 7900.5, nor WMO publications.
To quote the 7900.5:

14.18. Remarks (RMK)
(...)
Where plain language is called for, authorized contractions, abbreviations, and symbols should be used to conserve time and space. However, in no case should an essential remark, of which the observer is aware, be omitted for the lack of readily available contractions. In such cases, the only requirement is that the remark be clear. For a detailed list of authorized contractions, see FAA Order 7340.1, Contractions.

By checking 7340.1, BNK doesn't appear on its own or with FG, only in GRBNKS and SNBNK. Since no contraction in 7340.1 was available, the manual entry was made in as clear manner as possible.
For completeness, if the fog bank had affected the station, the proper code that would have been used before RMK would have been BCFG (fog patches). BC is likely derived from the French banc de brouillard (fog bank).


@Roddy is correct. It is an Romanian IAR-80 all right.

"IAR80" by user:Planck -  licensing policy.. Licensed under Public Domain via Commons.

IAR-80 was produced by IAR (Intreprinderea Aeronautică Română), an airplane manufacturer that was the property of the Romanian State until the end of the WWII. The aircraft first flew in 1938 and was in service till 1952.

The model appears to be the IAR 81. The same image can be found here. It was probably taken in the eastern front.


At what distance from magnetic north do pilots start referencing true north for heading?

In Boeing aircraft the default is to select MAG. When the aircraft enters the polar region it will auto switch to TRU. The pilot can also select TRU when outside the polar region.

The polar region is defined as north of 82 deg N latitude or south of 82 deg S latitude. It also includes the region north of 70 deg N between 80 deg W longitude and 130 deg W longitude and the region south of 60 deg S between 120 deg E and 160 deg E longitude.


What is the threshold between high Aspect Ratios and low Aspect Ratios?

The boundary depends on the type of aircraft. Fighter wings will be called high aspect ratio when the same aspect ratio in a glider wing will still be called low.

Generally, values below 5 are low, regardless of aircraft type.

With passenger aircraft, the boundary might be around 8.

Gliders will only have a high aspect ratio if it surpasses 20.

Still, there is no defined boundary and in the end the choice depends on the whims of the author.


Note: Much of this material, and more, is also covered in answers to the question:
Can you fly a light GA airplane into a major hub? (Didn't know that at the time I wrote this answer.)

Landing at higher than normal speed is not recommended.

Tricycle gear airplanes require a nose-high attitude on touchdown in order to ensure the main gear touch down first. The nose gear is not designed to support initial touchdown forces. In many typical small planes, forcing the plane onto the ground at too high a speed will strike the nose wheel first, risking a collapse or prop strike.
At high speed, the control surfaces and wings are still capable of producing significant aerodynamic forces. If you've forced your wheels onto the ground, you may be producing a lot of torque with the elevator, again, risking gear collapse.
Kinetic energy is proportional to the square of your velocity. And crash damage -- both to the airplane and to its passengers -- is proportional to energy. If you do collapse the gear or lose control, you're going to have a lot more energy to dissipate. And if that energy is dissipated by your body, it's going to hurt. A lot.
You might overheat your brakes, causing brake pad/rotor damage or even a fire (I'm aware of at least one instance of a Piper Cherokee catching on fire because the pilot attempted to take off with a half-stuck parking brake.)

It is true that you will sometimes be pressured by controllers at large airports to keep your speed up as much as possible on approach. It's hard for them to sequence you when you're only flying half as fast as the guys in front of and behind you. The important thing to remember is that this is their problem, not yours. There's no FAR that says you must hot dog your airplane in order to fit in with the big boys.

Here are some things you can do safely to make everyone's job easier when operating at large/busy airports:

Practice your controlled-airport/airspace proficiency.

Know, and use, standard ATC phraseology.
Listen carefully for your callsign. Don't make them repeat themseleves.
Have a plan in advance, know what you want, and make sure you communicate that to them clearly.

Have the airport diagram handy, and study it before the flight so you know where you'll be taxiing and won't mess up ground operations. Ideally you should be able to taxi on your own, but if you're not comfortable when you get your taxi instructions, request a progressive taxi.
Know your airplane and its capabilities. Fly your approach at the highest practical speed, but no faster. Know how fast you can go on a 3 mile final in order to be able to decelerate to normal short-final and touchdown speeds.

If you're not comfortable with your proficiency in these areas, consider getting some more practice before attempting a flight to a "major" airport. Or, bring a CFI along with you who can help you out and give you pointers.

The bottom line is under no circumstances should you compromise safety in order to please ATC or the airline pilot behind you. As long as you are proficient and do your best to accomodate ATC's requests within the safe capabilities of your airplane, you'll do just fine. (In fact, I've found controllers at major airports to often be very pleasant to work with.)


Is more cargo loaded if there is less passengers than expected?

You pose several scenarios.

  Is more cargo added if people do not show up?

No. By the time a person does not show up, the cargo is usually already delivered and loaded on the aircraft.

  If the plane is over the estimated weight - does cargo get removed? Passenger bags removed? Passengers removed?

Yes, although passengers almost always have priority. On heavy cargo flights, the cargo department will send a priority list if the load planners need to bump cargo.

  Is it within the airline's strategy to achieve 100% seat capacity utilisation?

Absolutely, although on payload restricted flights, non-revenue passengers may not always priority over cargo. This depends on the route. Many long-haul flights, if payload restricted, a scenario could happen where a staff member traveling as a non-revenue passenger will not be accepted because accepting them would exceed the max payload for the flight.


What is the recommended pressure for refueling an Airbus A380?

The A380 airport planning manual states (emphasis mine):

  Refuel pressure:
  - Maximum pressure: 50 psi (3.45 bar).

Can it be safely increased? Doubtful. Any increase may damage internal aircraft systems, and not only that, the operators will need to ask the airports to install new refueling systems.

Generally:

  For pressure refueling, a high-pressure hose is attached and fuel is pumped in at 275 kilopascals (40 psi) and a maximum of 310 kilopascals (45 psi) for most commercial aircraft. Pressure for military aircraft, especially fighters, ranges up to 415 kilopascals (60 psi).

As for the rate, from the graphic and the text:

  242 700 l (64 115 US gal) at 40 psig.

242,700 l take 36 minutes, or ~6,700 l/min.


Where do countries under international sanctions find spare parts?

The consequence of sanctions on Arpartheid South Africa was a thriving military equipment sector with some remarkable products, including nuclear weapons. Simply put, other people are clever enough to find equivalent solutions to US engineered parts and only when a super expensive fab costing billions is needed will they need to downgrade their specs. But don't think that sanctions will in the long term keep other countries from owning fancy equipment: They will learn to build it themselves.


How (or where) do I find an airfoil optimized for low reynolds numbers (100,000~150,000)?

Try the HQ series from the UIUC Airfoil Data Site. That is HQ as in Helmut Quabeck (model airfoils), not Horstmann-Quast (those would be glider airfoils).

Another possible source is the website of Martin Hepperle.

Unfortunately, there is not one, but hundreds of airfoils optimized for the model aircraft range of Reynolds numbers. To be any more specific, I would need to know more about how you plan to use that model:

Will it be a glider with a low wing loading, trying to stay aloft as long as possible?
Will it be a fast glider for ridge racing?
Will it be a powered model for aerobatics?

Each case will need different airfoils.


Malaysia Airlines Flight 370 - Why didn't Malaysian Air Force scramble jets?

There are multiple reasons for this:

The aircraft stopped communicating after the Kula Lumpur asked the aircraft to contact Ho Chi Minh ACC. The last verbal contact with the aircraft is this:

Lumpur Radar: "Malaysian three seven zero, contact Ho Chi Minh one two zero decimal nine. Good night."
Flight 370: "Good night. Malaysian three seven zero."

The Kula Lumpur Control had no way of knowing whether the aircraft had contacted as instructed (and acknowledged).

According to the Malaysian defence minister, the aircraft was deemed commercial and not hostile.

Even if the aircraft was tracked in radar by the military, that in itself is not sufficient for scrambling jets. Usually, the ATC will inform the authorities about any possible deviation; It is unlikely that the military would have real time details of aircraft routes. Note that it was not possible in this case (the aircraft transponder had gone silent before deviating from path). Also, there can be multiple reasons for loss of communications (usually equipment failure), and one does not immediately conclude that the aircraft has been hijacked.

Scrambling jets is usually the last resort and are sent to shoot the non-responsive aircraft. You don't shoot a civil aircraft with hundreds of passengers just because a microphone stopped working. The ATC must confirm that it had deviated from path and then the aircraft must be deemed a credible threat.

While the procedures for scrambling military aircraft are usually classified, it can be assumed that they are different in case of US (and Europe) and rest of the world. It takes a lot of resources to keep aircraft and pilots ready to intercept aircraft, which not all countries have (or even require most of the time).


Do wings on a plane need to be in the same plane horizontally, or can one wing root be 6" lower than the other?

The left and right wing may be at different heights.  You'd suffer from interference drag at the joint between them, or extra induced drag from the two extra "wingtips" if there is no joint, but a slow ultralight can tolerate such drag better than most airplanes.  This may be the only asymmetrical design that Rutan didn't attempt.


What are the requirements to convert a license from Iran to USA?

You cannot convert the CPL to FAA-CPL. What is possible is to obtain a FAA-PPL certificate by verification of the your current foreign license. This certificate will be valid as long as your foreign license is (plus medical conditions, and 24-months PPL flight review required for any PPL in the US).

With the PPL certificate, you will be able to obtain IR and CPL:

Pass IR and CPL written tests.
Attend training for IR and CPL practical checks.
Accumulate at least 250 flight hours. Time in the foreign country with the foreign license will count as well, but at least 3 hours are required with the FAA instructor. The instructor will vouch for the candidate is ready for the check-ride.
Pass CPL and IR practical checks.

A valid residence permit will be necessary to use the FAA-CPL.

The CFI roadmap is similar, written tests and checkrides are mandatory, there no minimum hours to be flown in the US. As a large part of the knowledge required is similar to many ICAO-member countries (teaching, meteorology, navigation, aerodynamics, etc) this shouldn't be a problem to be certified FAA CFI.

Related:

Do I need a PPL license for a CPL license?
I have a European EASA license - what do I need to do to be allowed to fly in the US?
Can a pilot with an ICAO Multi-Crew Pilot License fly an airliner into the U.S.?

References:

Required knowledge FAR 61.123 et seqq.
Required flight experience FAR 61.129.
Pilot certification in the US on Wikipedia.
Process for foreign CPL to FAA-PPL conversion (FAR 61.75).
Flight Instructors FAR 62.181


Benefit of a deswirl vane for a turboshaft helicopter engine

This is a very good question. However, there is a slight error in your question, which is causing the confusion.

Turbine power, is determined by the ratio of total pressure across the turbine (and other factors). See the formula here on NASA’s website.

$$ W_{Turbine} = \eta \cdot c_p \cdot T_{t_4} \cdot \left( 1-TPR^{\frac{\gamma-1}{\gamma}} \right) $$

Where $$ \gamma = \frac{c_p}{c_v}$$

and TPR is the total pressure ratio across the turbine:
$$TPR =\frac{P_{t_5}}{P_{t_4}}$$

In comparison, thrust is determined by the static pressure. See the “engine thrust equation” (the second formula) on this page here. The thrust is given by two terms; one due to the increase in velocity of the mass, the other is the “pressure thrust” term, which is due the the nozzle area x the difference in ambient static pressure and the nozzle exit static pressure.

In simple form;

$$F_{N} = \dot{m} \cdot (v_e - v_i) + A_j \cdot (p_{s_{exit}} - p_{s_{ambient}})$$

(Ignoring the mass of the fuel, which is very small compared to the air mass flow, $\dot{m}$).

So, increasing the exhaust nozzle static pressure at its exit increases the thrust from the exhaust gas, but will not reduce (or change) the power provided by the turbine, because that’s a function of total pressure.

That’s not to say the amount of thrust you will get is very large, and worth the weight of nozzle guide vanes at the exit. Some turboshaft engines have them, some don’t.


What is the descent rate in emergency situations?

(wikimedia.org) Part of a Boeing 747-400's autopilot control panel.

Maximum rate climbs and descents are achieved by using a speed climb/descent mode, where the pitch (nose up/down) controls a selected speed. The button FLCH (flight level change) activates such mode (shown above). Each manufacturer has its own name for it, but it's the same functionality. On an Airbus it is activated by pulling the altitude selector knob (Airbus calls it open climb/descent).

In level change climb, the thrust levers are engaged at the maximum thrust for a climb, the autopilot then controls the plane's nose to hold the selected speed. For maximum climb rate, a low speed (ideally Vy) achieves that, i.e., all of the climb thrust minus what's needed for the low speed is used for climbing.

For descents, the reverse is true -- fastest forward speed possible and idle thrust -- combined with the speed brakes. The plane will nose-down to achieve that speed. The rate of descent will be very steep initially, then it will ease off to hold the speed. Speed brakes add drag, so to achieve the same speed the aircraft will nose down more, resulting in a faster descent rate.

As the plane descends into the thicker atmosphere, the descent rate will again start to decrease -- as the plane will be producing more lift and drag. So we can't pinpoint an exact value, but 6,000-7,000 feet per minute is not uncommon.

Once a rate of descent is achieved, whether it's 1,000 fpm or 8,000 fpm, the g-force on the passengers will be 1 g, as there will be no acceleration in the vertical.

(YouTube) A Boeing 777 flight crew demonstrating such procedure.

A lower altitude is selected
FLCH is pressed
The thrust levers are idled -- by hand is quicker than the auto flight system (this does not disconnect the auto thrust)
The speed brakes lever is deployed
A faster speed is selected -- the maximum allowable indicated airspeed increases as the plane descends into the warmer air where the local speed of sound is faster (thereby allowing a faster true airspeed, up to a limit).

The above applies for a rapid decompression, other scenarios would likely require a descent, but not that steeply.


Where is the formal ICAO flight plan text format specified?

You will want to look in PANS-ATM (ICAO Document 4444), specifically, Appendix 2. (reproducing the entire appendix in this answer is not practical; it is 10 pages long). SKYbrary is also a nice resource.

Note that the ICAO model flight plan form actually contains the text format embedded in the form. Where slashes, hyphens, prefix letters etc. are required, they are printed directly on the form. I have highlited a few in the below screenshot for clarification:

<<≡ denotes start/end of message and newline.

➝ denotes a space.


Does the FAA consider flights that generate content for profitable YouTube channels displaying airborne video to be commercial operations?

The answer here is, potentially yes, but it depends.  In the United States the Federal Aviation Administration casts a wide net out over all kinds of activity it sees a potentially commercial in nature.  Former FAA lawyer Kathy Yodice wrote an AOPA article on what the FAA considers compensation or hire activity.  Unfortunately, the answer is not always clear; the FAA sees compensation as virtually anything of value and often just “knows it when they see it”.  Yodice writes:

Certainly, compensation comes in the form of any payment of money, but it also includes those instances when no money is made on the flight or when the payment isn’t even enough to cover all of the expenses.  The simple exchange of money to reimburse all or some of the expenses like fuel, transportation, lodging, or meals is usually enough. Compensation can also take the form of accumulation of flight time. Compensation can be good will or the expectation of future business. It could be the effect of furthering one’s economic interest or the prospect of a return favor. Something of value paid or given to a third party could be considered compensation if it is conditioned on the operation of the aircraft. For now, the FAA’s policy is to draw the line at considering charitable deductions of costs as compensation:  “Since Congress has specifically provided for the tax deductibility of some costs of charitable acts, FAA will not treat charitable deductions of such costs, standing alone, as constituting ‘compensation or hire’ for purposes of the regulations.” But, that is about the only exception we’ve seen in practice.  Otherwise, if you get something for taking the flight, the FAA is likely to call it compensation; if, in fact, you get nothing, you won’t have run afoul of the regulations.

So could a private pilot run afoul for making money on YouTube for flying videos?  Possibly.  Essentially YouTube is brokering an arrangement between content creators and advertisers and videos are ‘something of value’ to advertisers.
But here’s the catch.  In the above scenario, you are not directly exchanging your ability to pilot an aircraft for something of value; you’re simply out flying an aircraft.  Recording the flight is just incidental to it.  Editing, publishing and then selling the footage for compensation is something you’re doing on your own time and not related to your flying.
Another caveat is that §61.113(b) states that a private pilot may act as PIC for compensation or hire if:

(1) The flight is only incidental to that business or employment; and
(2) The aircraft does not carry passengers or property for compensation or hire.

Now in the YouTube scenario, a professional content creator’s business is content creation, not flying and the flight was only incidental to the person’s primary business.  It’s similar to an FBO employee and private pilot asked any his supervisor to ferry an airplane from the main office to a satellite airport for use there by the business.  Here the employee, even though a private pilot, many fly for compensation or hire as the flight was only incidental to the business.
Now let’s take a scenario where, say a content creator and private pilot gets numerous requests from social media subscribers to shoot a particular location from the air or the performance of specific maneuvers or demonstrations of the aircraft.  In this case we begin to get into a gray area where the overlap of exchanging airmanship for something of value starts happening.  It becomes even more suspect if the persons making the request are authorized representatives of the firms which advertise on this pilot’s social media channel.  Potentially an overzealous FAA inspector could cite you for flying for compensation or hire.
Again it all depends.  For more information on this subject I would consult an attorney who operates specifically in aviation law.


How far can a Super Hornet fly at max supersonic speed in a clean configuration?

An estimate:

An F-18E Rhino can only obtain its maximum speed of Mach 1.8 only at 36,000 ft in ideal air conditions and only in a clean configuration i.e. no external stores.

At 36000 ft at STP, Mach 1.8 translates to approximately 550 m/s or   1069 KTAS using the equations:

v = M*SQRT(g * R * T)

Where v is the velocity of the jet in m/s, M is the Mach number, g is the ratio of specific heats, R is the Ideal Gas Const. and T is temperature in Kelvin (use OAT at -40 C, 233 K).

Now an F-18E holds 14,400 lbs of fuel internally.  The GE F414 engine burns about 36,000 lbs/hr of fuel in full afterburner, so a total fuel burn of 72,000 lb/hr would be typical for this power output.  Assuming the Rhino could start at these altitudes and at Mach 1.8 with the tanks topped off, that gives us 14400/72000 = 0.2 hr or 12 minutes of flight time.  Ignoring upper level winds this would give us a maximum range of 213.8 NM.

This might be enough to put warheads on foreheads, then run like hell back to friendly airspace and a tanker or a carrier but it's not very good for a long range cruise profile.


How is flight envelope protection implemented in Dassault Falcons?

My information on the Falcon 7x and 8x comes from Aviation Week and Flying Magazine pilot-reports.
It would appear that the Dassault FBW philosophy is very closely aligned with that of Airbus. Namely,

It employs a C* control law without speed stability;
It uses passive sidestick instead of control column;
It employs 3-axis envelope protection, complete with bank angle protection (via positive spiral stability beyond 35 deg), load factor protection, AOA protection and high speed protection;
It even has a control-by-wire backup system similar to the mechanical backup available in the A320 and A330.

The fact that it has a C* control law, which provides flight path stability and not speed stability, and that it has a passive sidestick without force feedback, the envelope protection would appear to be a must-have for certification, rather than nice-to-have. By all indications, the limitations are hard constraints that cannot be overridden by pilot inputs in Normal Law.


Can a VTOL jet such as the Harrier enter a Vortex Ring State?

The main problem with VRT is the airflow through the rotor which is disturbed because it is ingesting its own downwash.

The large area of air accelerated downwards keeps being sucked back in to the rotor because the helicopter sinks back into it. In this state the rotor provides very little thrust - it acts as a sort of divide-by-zero state, as the transition between normal flight and windmilling when the air streams upwards.

The flow field of the Harrier is different:

Thrust is produced inside the engine, which is shielded from the effects of aircraft vertical velocity: air is sucked in through the inlet next to the cockpit.
The air stream velocities are higher. Air is accelerated downward in a much smaller area at much higher velocities. There is no fuselage which partially decelerates the airstream, like in a helicopter: the downward flow field is much cleaner.

The defining problem of VRS is the lack of thrust from the rotor at downward velocities, this would not occur with the shrouded jet engine of the Harrier.


How do flight attendants know seat belts are fastened?

In addition to Jamiec's correct answer, I would add that you can tell when a seat belt is not fastened even if the buckle is covered by someone's shirt (or belly!).  You can normally see the segment of belt alongside the person's hip and it's easy to tell if that piece of strap is under tension or not.  Some people actually try to disguise the fact that their seat belt isn't fastened by covering up the buckle, hoping to avoid detection.  By looking for the strap alongside their hip, I can avoid asking to see the buckle itself.

Of course, if I can't really tell by a quick glance, I ask them to show it to me.  It's very rare that anyone actually takes offense to this.


Yes, most military aircraft, including fighter aircraft, are equipped with a "black box" called flight data recorder (FDR) / crash survivable memory unit (CSMU) / integrated monitoring and recording system (IMRS) / deployable flight incident recorder set (DFIRS).

Sources 1, ( B-1B, F-22, T-45, B-2, F-4, F-15, F-16, C-5 Galaxy, NATO AWACS, and the Space Shuttle)
2. (F-18, floating black box)


What's the difference between True vs Magnetic headings?

The "heading" refers to the direction an aircraft is pointing. For a Magnetic Heading, this is in relation to Magnetic North. For a True Heading, this is in relation to True North.

True North is directly over the earth's axis.

Magnetic North is somewhere over Canada, moving towards Russia.

To get the Magnetic Heading, you just read it off the magnetic compass.

To get the True Heading, you need to first read the magnetic compass, then either add an Easterly, or subtract a Westerly, magnetic variation; based upon the isogonic lines on your sectional (the purple dashed lines labeled 5°W, 3°E, etc).

Example 1: Magnetic Heading 177 w/ 3 degrees East Magnetic deviation = true course 180.

Example 2: Magnetic Heading 177 w/ 3 degrees West Magnetic deviation = true course 174.

Because of this, in the past, magnetic headings were used because a simple compass could be used. Finding reliable true headings was difficult until the era of things like the gyrocompass (patented in 1906 (Germany) and 1908 (USA)) and more recently, GPS.


Could wing tilting be a mechanism for VTOL and high angle of attack for jetliners?

What you describe is called a tiltwing. It has wing-mounted engines which swivel with the wing so their thrust points up for the VTOL mode. Building a tiltwing airliner will face two challenges:

Normally, the static thrust force is only one third of the weight force, so the tiltwing airliner needs to add three times as many engines - at least. Better make this four times as many so there is some excess thrust for hot and high conditions.
In order for the wing to tilt freely, it needs to be straight. A swept wing will hit the ground during tilting unless an absurdly high landing gear is installed. Now the thrust acts along one line - how do you control pitch? You will need another engine at the tail (or nose) which can be quickly throttled in order to balance the aircraft in pitch.

Needless to say that this cuts into payload and makes this design uncompetitive unless VTOL operation is a must.


The first issue with airplanes is they are stupendously, freakishly light.  Any random American freight diesel locomotive weighs more than a 747-400.  Trains rely on this mass to provide the downforce to keep them engaged to the railhead.
So your vehicle would need to do something to replace this downforce; for instance have a tubular or I-beam rail which allows the train to grab the bottom of the rail; expect switches and special work to be complicated at that point, shifting an entire track instead of just small parts of it.
So while unloading weight off the rail only makes matters worse for track design, you're also paying for that lift with induced drag. In other words you're using a great deal more fuel (or electricity) to unload weight off the rail, when the rail really doesn't mind bearing weight.
In fact from an aviation perspective, the "induced drag" on a train can be approximated to zero, thanks to Mr. Babbitt (Mr. Timken's idea is worse for drag but better for reliability).
That's why good ole fashioned railroad just keeps winning the high-speed race (or coming too close to matter). The exact TGV train that ran 357 mph could be dropped onto a NYC subway branch in Brooklyn, interchange onto LIRR, come into Penn Station and the Amtrak Corridor, through the freight rail system to Detroit and run on Woodward Avenue Q-line, then to Long Beach CA and run on the Blue Line.  The only thing I'm arm-waving is power supply, and curve and platform clearances on NYCTA.  In fact, in 1993 Amtrak dragged an X2000 and ICE high-speed trainset all over America behind diesels. No wheel modification needed.
So while your idea has merit... once you get out the sharp pencil and really start optimizing for performance, you will find it best to forget wings and load full weight on the rail, and further, to optimize for Plain Old Railroad Track so you can just use existing rails to get downtown.  Going with a wack-a-doodle guideway doesn't buy you much, and makes getting downtown a mega-project of biblical proportion  all its own. Here:

The city of Victorville was selected as the location for the westernmost terminal since extending the train line farther into the Los Angeles basin through the Cajon Pass would be prohibitively expensive.

/facepalm... Cajon Pass is not a challenging hill for HSR. If they can't even handle that, they sure aren't getting into L.A. proper where all the connecting trains are.  And L.A. is a piece of cake compared to a dense, old city like Paris or even Boston.  This: This is the folly of a wack-a-doodle guideway.  They finally retreated from that to a standard railroad design, so they could come downtown on shared rails.


What is the official FAA definition of the term enroute?

FAA follows the ICAO definition for describing the phases of flight.
FAA is a member of the CAST/ICAO Common Taxonomy Team that formed the Phase of Flight Definitions and Usage Notes in October 2002. From the CAST/ICAO Common Taxonomy Team site:

Federal Aviation Administration (FAA)- FAA has officially adopted the aircraft make model series (ACFT-MMS) and phase of flight taxonomies as an agency-wide data standard for its internal systems.

So, the enroute phase of flight is the same (just repeating from the same document):

Instrument Flight Rules (IFR): From completion of Initial Climb through cruise altitude and completion of controlled descent to the Initial Approach Fix (IAF).
Visual Flight Rules (VFR): From completion of Initial Climb through cruise and controlled descent to the VFR pattern altitude or 1,000 feet above runway elevation, whichever comes first.
This phase of flight includes the following subphases:
• Climb to Cruise: IFR: From completion of Initial Climb to arrival at initial assigned cruise altitude. VFR: From completion of Initial Climb to initial cruise altitude.
• Cruise: Any level flight segment after arrival at initial cruise altitude until the start of descent to the destination.
• Change of Cruise Level: Any climb or descent during cruise after the initial climb to cruise, but before descent to the destination.
• Descent: IFR: Descent from cruise to either Initial Approach Fix (IAF) or VFR pattern entry. VFR: Descent from cruise to the VFR pattern entry or 1,000 feet above the runway elevation, whichever comes first.
• Holding: Execution of a predetermined maneuver (usually an oval racetrack pattern) which keeps the aircraft within a specified airspace while awaiting further clearance. Descent during holding is also covered in this subphase.


How do blade cuffs help cool the engine?

Source: An Illustrated Dictionary of Aviation

The cuff is used to change the pitch of the blades (or to create an airfoil when there is none) near the spinner. The cuff increases the airflow near the engine cooling intakes. The cuff is large, and larger at the blade root because the linear speed in this area is very small compared to the tip.
Lockheed P3 Orion

Cuffed blades of a Lockheed P3 Orion. Top: Photo by palmerphoto at RedBubble. Bottom: Photo by MDLPhotoz at Flickr

North American P-51 Mustang, cuffed vs uncuffed

Awesome photo by Allan Grant/LIFE Magazine, via This Day in Aviation

Captioned:

  Joe De Bona and Jimmy Stewart with Thunderbird, their P-51C Mustang
  racer, April 1949. Placed on the ramp in front of the airplane is
  equipment that has been removed or replaced. Note the four “cuffed”
  Hamilton Standard propeller blades along the right side of the
  photograph. They have been replaced with un-cuffed and polished
  Hamilton Standard “paddle” blades.

More aviation photos by Allan Grant


Concorde thrust reversers engaged on parked aircraft, but not all engines?

Yes the left (#1) reverser is engaged in this photo. G-AXDN is the British pre-production Concorde and has some differences from the final versions. G-AXDN contained internal clam shell reversers, if the GIF at the bottom of this informational page about G-AXDN is any indicator that external engine reverser may still actuate for show and in this case was simply closed while you were there. This video shows the light up ring that they may have used in the GIF (5:02)

This Concorde also has a droop nose that still works. There is also a fairly active effort going on to restore that airframe to have some of the parts work.


On a flight with short stops, do you terminate flight following at each stop?

As @RonBeyer notes in the comments Flight Following will drop you when you land. Generally (also as Ron notes) they will ask you to call the "field in sight". It really depends on where you are and what kind of air space you are in. Where I fly in the Northeast they typically drop you when you have the field in sight but its hard to stray to far from a heavily controlled area if you are flying between DC and Boston but it may be different elsewhere.

Keep in mind that you will need to get off the frequency so you can make your CTAF announcements anyway. It may be a good idea to keep the controller as a listen only channel on COM2 if you are equipped for such in your aircraft.

Assigning you a code is not really a hassle for them so you don't need to worry. In a busy airspace ATC may want you out so they can handle IFR traffic. Remember flight following is "load dependent" so you might not always get it and you can be dropped out at any time.

When on your student XC's its always a good idea to preface one of your initial calls with "N123AB Student Pilot requesting flight following". ATC is there to help you and noting you are a student pilot may help you so they don't expect professional pilot level flying and radio chatter from you.


Can commercial airplanes be converted to drones?

Is it possible to convert a Commercial Airplane into a Drone

For what its worth, yes this would be technically possible however it comes with some risks.

When To Take Control: This brings into the simple idea that in an emergency the pilot may need to be in control of the situation as they often have the most information about exactly what is happening. If the plane had a serious issue and the ground controller did not know what was happening they may take control and only exacerbate the problem.

Connection Reliability: Keep in mind that planes are flying at very high altitudes moving quite fast. Maintaining a reliable connection in these conditions is difficult. Since a reliable connection is hard enough to maintain you again may create more issues than you solve. This also has to be a fully duplexed channel since the plane needs to transmit its telemetry and receive control inputs in what is more or less real time. At this point the data up/down rates would push the limits of what we can do today.

Connection Security: As mentioned you would need to secure the connection to prevent someone from taking it over maliciously. This in and of its self is a big problem. But lets not turn this into a digital security debate.

Cost: As nice as safety is its not free. Since there is currently no system in place on a global scale to do this it would have to be created. Someone has to pay for that and unless the FAA is going to require it you will have to get the airlines/aircraft makers on board with this voluntarily. On top of that any system that is added like this would have to be certified by the FAA.

So while it is possible there are very real barriers to a system like this include but are not limited to the ones listed above and before someone comes back with the "if it makes it safer than we should spend the time figuring it out" response I will mention that modern technology is as good as it is and there are already companies and individuals researching new tech like this but Keep in mind that with FAA regulations taking the time they do to get, planes are flying with tech that is now considered "dated" by the tech world.


Why is the time of useful consciousness only seconds at high altitudes, when I can hold my breath much longer at ground level?

When you are breathing, oxygen ($\mathrm{O}_2$) and carbon dioxide ($\mathrm{CO}_2$) are exchanged between the alveoli in your lungs and the environment. This gas exchange is based on diffusion, which means the partial pressures of each gas involved will move towards equalization:

  Henry’s law states that the amount of a specific gas that dissolves in a liquid is a function of its partial pressure. The greater the partial pressure of a gas, the more of that gas will dissolve in a liquid, as the gas moves toward equilibrium.

(source)

As long as the oxygen partial pressure is higher in the environment, your blood will gain oxygen from breathing. But if the oxygen partial pressure is lower, you lose oxygen from breathing. Therefore, holding your breath at sea level gives you more time until you run out of oxygen than breathing at 15km altitude, where total pressure is about 10 times lower than at sea level. Furthermore, as John K pointed out in the comments, holding your breath at sea level allows you to feel when you need to breathe again, because of increasing $\mathrm{CO}_2$ levels, where breathing at high altitude does not feel different because $\mathrm{CO}_2$ can still leave your system.

This principle also allows oxygen masks in aircraft to function without creating higher pressure. Since (more or less) pure oxygen is created, the oxygen partial pressure is much higher than in the surrounding air despite being at the same total pressure.


Why does ATC ask emergency aircraft about fuel on board?

It depends on the type of situation. If the aircraft is unable to land for some reason, we'll want to know the remaining fuel to get an idea of how long the aircraft can realistically stay airborne. For an aircraft coming in for an emergency landing - as you have already guessed - the reason we ask for remaining fuel is because the fire and rescue personel needs this information. We will also ask such an aircraft if they have any dangerous goods onboard, since we need to pass this info on to the fire crew as well.

During an emergency, we have a checklist to follow that reminds us which information we need to obtain, and who needs to know what is going on. For a tower position, it may look something like this:

As you can see, fuel and dangerous goods are grouped together, indicating that they are essentially the same thing - something that may cause fire, explode or otherwise cause danger during evacuation of the aircraft.


What is the requirement for fire fighting equipment on board a passenger flight?

You have this tagged  both FAA and ICAO but for the FAA thats governed under

  § 121.309 Emergency equipment.

  (c)Hand fire extinguishers for crew, passenger, cargo, and galley
  compartments. Hand fire extinguishers of an approved type must be
  provided for use in crew, passenger, cargo, and galley compartments in
  accordance with the following:

  (1) The type and quantity of extinguishing agent must be suitable for
  the kinds of fires likely to occur in the compartment where the
  extinguisher is intended to be used and, for passenger compartments,
  must be designed to minimize the hazard of toxic gas concentrations.

  (2)Cargo compartments. At least one hand fire extinguisher must be
  conveniently located for use in each class E cargo compartment that is
  accessible to crewmembers during flight.

  (3)Galley compartments. At least one hand fire extinguisher must be
  conveniently located for use in each galley located in a compartment
  other than a passenger, cargo, or crew compartment.

  (4)Flightcrew compartment. At least one hand fire extinguisher must be
  conveniently located on the flight deck for use by the flightcrew.

  (5)Passenger compartments. Hand fire extinguishers for use in
  passenger compartments must be conveniently located and, when two or
  more are required, uniformly distributed throughout each compartment.
  Hand fire extinguishers shall be provided in passenger compartments as
  follows:

  (i) For airplanes having passenger se ats accommodating more than 6
  but fewer than 31 passengers, at least one.

  (ii) For airplanes having passenger se ats accommodating more than 30
  but fewer than 61 passengers, at least two.

  (iii) For airplanes having passenger se ats accommodating more than 60
  passengers, there must be at least the following number of hand fire
  extinguishers:

  Minimum Number of Hand Fire Extinguishers Passenger seating
  accommodations:

  61 through 200:   3

  201 through 300:  4

  301 through 400:  5

  401 through 500:  6

  501 through 600:  7

  601 or more:  8

  (6) Notwithstanding
  the requirement for uniform distribution of hand fire extinguishers as
  prescribed in paragraph (c)(5) of this section, for those cases where
  a galley is located in a passenger compartment, at least one hand fire
  extinguisher must be conveniently located and easily accessible for
  use in the galley.

  (7) At least two of the required hand fire extinguisher installed in
  passenger-carrying airplanes must contain Halon 1211
  (bromochlorofluoromethane) or equivalent as the extinguishing agent.
  At least one hand fire extinguisher in the passenger compartment must
  contain Halon 1211 or equivalent.

You may also find some pertinent info here.


How to carry out a CFD simulation for determining the stability derivatives of an aeroplane?

Make a list of the derivatives you want to determine. All of them will be derivations of some force or moment with respect to some parameter or control setting. Now set up your CFD such that you get lift, side force and drag as well as pitching, rolling and yawing moment relative to the center of gravity.

Next, make those forces and moments dimensionless. Forces are divided by a reference area (projection of the wing area in most cases) and the dynamic pressure (speed squared times air density divided by 2). Moments are in addition divided by a reference length (span or semi-span for rolling and yawing moment, mean wing chord for pitching moment). The results are called coefficients. Record those coefficients for a baseline configuration (say, level flight at cruise speed).

Now make a small change in the parameter (angle of attack or sideslip, speed, air density, pitch-, roll- or yaw-rate) or control setting (elevator, rudder or aileron angle, flap setting, power setting) and record the coefficients again. Only one change at a time and leave all others at their baseline position! The desired derivative is simply the gradient of the coefficient over the gradient of the parameter, as in
$$c_{M\alpha} = \frac{c_{M1}-c_{M0}}{\alpha_1-\alpha_0}$$
with 0 denoting your baseline figures and 1 the changed ones. Use radians for all angles. The rotation rates you should make dimensionless by dividing the value by the flight speed and multiplying it with the respective reference length. And another thing: The really correct reference length for the pitching moment and -rate is the mean aerodynamic chord which is the integral of chord squared over span, divided by wing area.


Why do turbofan engines have low pressure compressors?

The low pressure compressor does not reduce pressure. It increases it, but operates at a lower pressure than the high pressure compressor.  Some engines also have an intermediate pressure (IP) stage.

https://en.wikipedia.org/wiki/Gas_turbine_engine_compressors

https://www.grc.nasa.gov/www/k-12/airplane/compress.html

Each stage increases the pressure as the air is forced back into the flame tubes.


Why would an airport have a beacon light on when there's no traffic?

The Chart Supplement says "Arpt bcn OTS indef."
("Airport Beacon is Out of Service, indefinitely")

It also says "ACTIVATE MIRL Rwy 16–34 and bcn—CTAF"
("Activate the Medium Intensity Runway Lights(MIRL) for Runway 16/34 and the Becaon, by using the CTAF")

Based on this, it is unclear if the beacon is out of service, or pilot-activated.
But it is clear that it should not be on all night.

A phone number is listed on that page for the airport manager, and I might start there.

After that, consider contacting the local Flight Standards District Office (FSDO).


When do pilots have to submit position reports?

It's not fixed. I checked ICAO Annex 10 Vol II that lists the SARPs for communication. It will be down to the FIR the flight is being conducted in. For the NATS (UK) side of the Atlantic, I found this document (may not be current).

The basic intervals are whichever comes first:

Waypoint on the flight plan
One hour had passed
ETA has changed for the next waypoint by +3 minutes
Interval based on whether north or south of 70°N.

CPDLC is used, and can be automated too (ADS-C). If the FIR does not support CPDLC, then it will be via voice. According to Boeing, FANS 1—which handles reporting via datalink—saves a lot of time and improves accuracy:

  The uncertainties of traditional voice position reporting and the delay associated with high-frequency relayed voice communications [result in 20 to 45 min to make a position report].

And depending on the ADS-C (C for Contract) agreement, the reports can be as frequent as every 5 minutes.

For the US side of things, check section 5-3-2 of the AIM and the section titled additional reports. It's similar to the above. They also note:

  For aircraft providing automatic position reporting via an Automatic Dependent Surveillance-Contract (ADS-C) logon, pilots should discontinue voice position reports.


How far are shortened replies to ATC allowed to go?

ATC is required to always use standard phraseology, and tapes are randomly reviewed to verify this--and too many violations gets them pulled off for retraining. This makes sense since talking is literally their entire job and it could be with anyone from students to veterans, including people who don't natively speak the language.

Pilots can use whatever wording they want as long as ATC can understand what they're saying, which naturally leads to shortcuts.  It saves time/effort and helps keep the frequency clear for others. In fact, if/how you abbreviate things is a sign to ATC of how experienced you are. If you read back "climb and maintain three thousand five hundred feet", they'll treat you a bit differently than if you say "up to three point five". Listen to a busy airport or approach on LiveATC and you'll pick up the patterns in just a few minutes.

"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." --Antoine de Saint-Exupery


Shouldn't the instructor in this scenario try to avoid a deadstick landing?

if that was a real event, shouldn't Captain Townsend (as the instructor) interrupt the relaxing gliding with a warning? Something along the lines of "excuse me, sir, we're losing altitude, if you want me to restart the engine we have to do it now", or even "I'm restarting the engine now". I mean, shouldn't he be checking the limit altitude for restarting the engine?

This question appears to be predicated on the idea that the instructor had no plans to land the plane with the engine turned off. Having watched the scene, I'm far less convinced that this is the case. In fact, it's not until Philip remarks that the ground is coming up that the Captain tells him they'll be landing deadstick.
In the series, this instructor featured is a renowned flying ace with huge amounts of combat flying experience including a number of forced landings and ditchings.
Bob Hoover (who you could argue with cut from a similar cloth) regularly displayed and demonstrated with the engines turned off, up to and including landing in that configuration.* On the basis that turning the engine off was deliberate and not an emergency, I don't think the scene after that point is particularly unrealistic. They appear to be making a straight in approach and land on an airfield - it's entirely plausible the Captain made a deliberate decision to land with no engine from the very start.
*Example:


How much altitude can a glider gain only from losing speed?

You can calculate a theoretical maximum (which will be well above the actual practical height gain) by considering the conversion of kinetic to potential energy. You can also make estimates based on observing a glider performing a loop.
Calculate the kinetic energy of the glider at maximum speed as mv2/2, where m is the glider mass and v is the maximum level velocity. Then do the same for the stall speed mu2/2. Take the difference. This is the kinetic energy lost in the maneuver.
Assume this is all converted to potential energy, which is given by mgh, where m is the mass, g is the gravitational constant and h is the height gained. Rearranging this (and cancelling m) gives us

h = (v2 - u2) / 2g

Again, the real number will be much less than this, because of drag during the maneuver, but it will give you a ballpark.
According to Wikipedia, a Schleicher ASK 21 has a stall of 40 mph (18 m/s) and a top speed of 170 mph (76 m/s), which seems to be one of the larger ranges among common (and non-performance?) gliders. With g=9.8m/s^2, and calculating to two digits of precision, that's a theoretical max of h=280m or 920 feet. (Thanks K A Buhr)
When a glider performs a loop maneuver, it does so by diving to achieve a high speed, pulling up to a low speed (upside down) and then diving again. This is somewhat analogous to what you are describing, although gliders don't reach their theoretical maximum speed in the maneuver, and they may in fact go under their stall speed at the top. An examination of performance gliders looping show that they can gain several hundred feet during a maneuver.


Does the MD-80 seat layout affect the balance of the aircraft?

The "D" seat is very near the aircraft centerline, and thus the roll axis. Since roll moment is the distance from the roll axis times weight, if the distance is small, the roll moment is very small. What roll moment is created can easily be canceled by a little bit of aileron trim if needed.

The water tank on MD-80s is also placed on the LH side of the cargo. Full this is about 350 lbs, further from the centerline than the "D" seats. Also the LH side has an extra service door in the aft and the front LH door is larger than the R1 door, although the RH side also has the cargo doors.


Where is the midspan airfoil located on the 737?

The midspan airfoil is between root and tip, so somewhere along the half span of the wing. Midspan is therefore a misnomer, but sounds better than midhalfspan.


How do airplane designers determine flap deflection angles for flaps of various % wing chords?

As a rule of thumb, flap effectiveness (that is lift coefficient change per flap deflection angle or c$_{L\eta}$) is proportional to the square root of the flap's percentage. A more precise formula was derived by Hermann Glauert (search for the name and you will find that elusive answer by me)
What also changes is the hinge moment needed per degree of flap deflection; this, however, changes with the square of the flap's percentage. By trading off effectivity versus force, a designer will find the best flap percentage for each control surface.
Next, wind tunnel data is used for finding the effectiveness over deflection, because this value decreases with higher deflection angles and is hard to catch by CFD because viscous effects are strongest near the trailing edge and need lots of effort to model correctly. The desired control response and trim should be achievable with maximum deflections of below ±15° (the useable range is wider for smaller percentages) and the flight test will reveal whether the calculations were correct.


What is the ILS glide slope deviation on a 4 degree VOR check error?

The deviation detected on your VOR check is likely to be unrelated to the deviation of the glideslope. Whilst they use the same indicator instrument, the radio systems driving the instrument are typically separate.

The VOR system works on a 108.00-117.95 MHz, frequency & amplitude modulated signal. The glideslope works on a 329.15-335.0 MHz amplitude modulated signal.

Both signals have different paths to the indicator instrument, and they use different needles on the indicator.

Therefor it is unlikely that a systematic error causing a deviation in the VOR omni-bearing indicator will cause a deviation in the glide path indicator.

There may be common error sources in both indications, but that depends really on the internal design of the receiver. For example if there is a voltage bias on some part of the system it may affect both systems. But you can't say anything about the maximum degree of deviation from the actual glide slope based on the observed deviation in the VOR receiver.

The localizer receiver works on the same frequencies as the VOR, but the demodulation is different. In an analogue system with needles, they use the same needle. So for localizer there is a higher system commonality with VOR than in the glide path case, which increase the likelihood of a common source of error.


Does a conversion for wheel to floats require an STC or Form 337?

This sounds like a major mod, but I will have to see the design data to really able to come to a conclusion. If its a major mod, it has to be done via an STC.


Is it theoretically possible to create an aircraft like this?

The idea has been tried. This WWII aircraft is built around the idea very much like yours: engine in the main fuselage, pilots/passengers in the nacelle.

It must be reasons to choose this design. The design requirements were:

One engine.
Crew one or two
Best possible view into to all sides
(reconnaissance aircraft).

For the passenger aircraft as pictured it is probably just not optimal.


How much would it cost to fit and maintain every passenger life jacket with personal beacon?

The extra weight is roughly the weight saved by the introduction of iPads to replace paper. That's apparently saving close to $10K per plane, so you'd expect a similar cost for just flying all those beacons around.

That said, why do you need a full beacon for every vest? If your vests end up scattered over even 10 kilometers distance, you won't have survivors. What you need is a few beacons to locate the plane, and the medium-range active RFID tag on each vest. Such a tag only responds to queries originating nearby. This cuts down dramatically on the battery requirements, as the RFID tag is generally asleep and only woken up by the interrogation signal. Such RFID tags would cost about $20, and weigh a few grams. Battery life is similar (6 years) as that's just chemistry.


Are emergency actions an appropriate part of a captain's briefing in a light aircraft?

It sounds like you are covering the safety material you need to from a regulatory and good sense approach. Trying to convey an emergency exit briefing during an emergency is not going to work, you need to give it all at the beginning. If you get an engine fire on startup you need your passengers to be ready.

I find that people appreciate that you give a briefing as it shows a bit of "professionalism" that re-assures them, rather than scaring them it shows you know what you are doing. I do cover the same material, and I usually do it slightly tongue and cheek in the similar manner as a commercial airline. For example when I talk about emergency exits I point to the doors to the left and right, then say something like "if there is an exit behind you then things really have gone wrong". That's just my personal style, there's no hard fast rules on it. If people decide not to fly with you after your briefing maybe you are going about it wrong though.

The approach I take with small children is different than that which I take with adults. The first flight in a light airplane is a very novel experience for anyone, with kids I explain what the experience will be like a lot more than adults. An adult will understand what you mean by climb usually, but saying "the airplane will lean back a bit and we will go up" makes more sense to a little kid.


Why was the Akron’s spy basket installation so remarkably unstable?

Very interesting bit of physics going on here with the cable car swinging "up to the equator" of the airship.  Perhaps something similar to what happened with the "Galloping Gertie" Tacoma Narrows suspension bridge in 1940.

The suspension cable could be hundreds of feet long.  In a cross wind, if the mass to surface area (wind pressure) of the airship and the cable car did not match, the cable car would swing to the side and then back.  If the wind and the swing motion became harmonicly re-inforceing, each swing becomes a little higher, eventually reaching a full 180 degree sweep.

The elasticity of a cable several hundred feet long may have contributed, stretching a little at the bottom of the arc and contracting a little at the top of the swing, helping propell the object back in the other direction.

Another factor have been a very slight difference in airspeed as the car swung away from the wind, pulling the airship with it, as compared with the return swing back into the wind.  Each swing adds more energy to the system.

Without "dampers", the cable and car are wildly out of control.  The fix, amazingly, may have been to fashion adjustable "sails" for the cable car. Some wind tunnel testing may have been
helpful as well.


Does a portable ILS ground station exist?

NASA did some research on it in 1986 and published this paper. Thales was contracted to build one that the US Army has ordered and it made it to prototype phase. Eventually it was tested for a while and appears to have made it to production and the military ordered more.

It goes under the name Deployable – Instrument Landing Systems  (D-ILS). here is a short two page brochure on the unit which has some good pictures of the whole thing.

It looks like the units cost around $4.68 million each.


How come the hover efficiency for tiltrotors is better than tiltwings?

Your expectation is correct. A tiltwing has a lower drag penalty in hover. The XV-15 had a penalty of 635–680 kg, while a tiltwing would have 23 kg, for the reason you mention.

A tilt-rotor's wing stays horizontal while the nacelles tilt. In the hover, therefore, the wing is in effect a flat plate immersed in the rotor downwash. Kocurek puts the resulting vertical drag penalty on the XV-15 at 635kg-680kg. The similarly sized TW-68's wing tilts with the engines so that its aerofoil always points into the propeller wash. Kocurek estimates the vertical drag penalty at just 23kg.

The sentence on Wikipedia unfortunately lacks the context of the reference (Flight), which is down for maintenance, but the web archive version is available (PDF).

He explains the designer's dilemma: "You want low disc loading to get high hover efficiency, but you want high disc loading to match the propeller to your cruise conditions (...)"

The issue at hand is that tiltwings use propellers, while tiltrotors use, well, rotors – their big size lowers the disc loading, which improves the overall hover efficiency. For more context, a tiltwing was considered for the program that produced the V-22 Osprey. The argument in the article is that a tiltwing would offer an overall better "system" when cruise is considered, "but the long hover times required by some missions favoured a tilt-rotor."

A tiltwing with propellers; source: wikimedia.org

All quotes are from the linked Flight article.


To answer your questions:

A crop duster does not have to file a (normal) flight plan. They do have to file a special "operations" plan if they are going to be spraying chemicals. Notice of the intended operation must be given to the public by some effective means, such as daily newspapers, radio, television, or door-to-door notice. A plan for [the spraying] operation must be submitted to, and approved by appropriate personnel of the FAA Flight Standards District Office having jurisdiction over the area where the operation is to be conducted. The plan must include consideration of obstructions to flight; the emergency landing capabilities of the aircraft to be used; and any necessary coordination with air traffic control.

All aircraft must maintain a height of at least 500 feet above ground or objects on the ground, like a house. (Minimum Safe Altitude) A crop duster can go below this height only to operate to apply chemicals and for no other reason. The exact text of the exception reads as follows: "No person may operate an aircraft over a congested area below the altitudes prescribed in part 91 of this chapter except during the actual dispensing operation, including the approaches and departures necessary for that operation."

You cannot prevent someone from flying over your house.

If someone is flying over your house at less than 500 feet, you can file a complaint with the FAA by calling (703) 230-7664. Please observe the following:

• Identification - Can you identify the aircraft? Did you record the registration number which appears on the fuselage or tail? (On U.S. registered aircraft, that number will be preceded with a capital "N".)

• Time and Place - Exactly when did the incident(s) occur? Where did this happen? What direction was the aircraft flying?

• Altitude - How high (low) was the aircraft flying? On what do you base your estimate? Was the aircraft level with or below the elevation of a prominent object such as a tower or building? Did you obtain photographs? Are there any witnesses who could confirm your estimate - do you have their names, addresses, telephone numbers?

• Supporting Evidence

• Witnesses, Police

• Photographs


This is a METAR with the addition of U.S. Observations, and according to the details of the abbreviations used there is no such value as DSPTD.

I suspect you are right, that it should have been DSIPTG - which does indeed mean "dissipating". The full decode of the Remarks section of your example METAR is as follows

A02 - automated station with precipitation descriminator.
PK WND 35037/0325 - Peak wind 350 degrees at 37 knots between 03 and 25mins
RAB04 - Rain began at 04mins (You can infer the hour from the main report)
PLB25 - Ice pellets began at 25mins (Again, inferring the hour from the report)
TS DSPTD - Thunderstorms which dissipated
P0000 - Trace amount of  hourly precipitation

I should add that I'm by no means an expert at decoding this part of a METAR, I made judicious use of this page.


What is the dimensionally smallest 2-seat helicopter?

My vote would be for the RotorWay Scorpion II.  Tiny little things would fit in a living room!


Can Ballistic Parachute Recovery Systems be safely deployed in a storm?

Manufacturers are going to have different opinions of this scenario, but this answer follows the opinion of Cirrus Aircraft in their flight manuals and CCIP syllabi for the SR2X airplanes.

First off, your best bet is to obtain a proper weather briefing prior to departure and obtain in-flight weather updates enroute so you can stay out of a thunderstorm in the first place.  The CAPS has very specific guidelines for operations as well as a maximum demonstrated safe deployment speed, depending of the model of aircraft.  The flight manuals for the SR2X aircraft all state that:

"However because the CAPS is expected to result in structural damage to the airframe and, depending upon adverse external factors such as high deployment speeds, low altitude, rough terrain and high winds, the CAPS deployment may result in severe injury or death to the occupants and its use should not be taken lightly".

Barring that and you actually enter a thunderstorm which is so severe that it either causes departure from controlled flight or structural failure, there is a clause in the CAPS literature stating that if an accident is imminent, even if the acitivation of the CAPS is outside the demonstrated safe deployment range, it should be utilized and activated nonetheless.  The reason has to do with minimizing the amount of energy on impact and even a partially deployed or damaged CAPS is going to slow the aircraft considerably, increasing your chances of survival.

Bottom line is that you did something stupid vis a vis a serious lack of judgment where a safe recovery is no longer possible.  Whatever happens in the next few minutes is probably going to hurt really bad; the only thing we can do is make every effort to minimize how badly we are hurt and minimize the chances that we are going to be killed.  Even an unsafe CAPS deployment in this situation is better than riding down to impact without.


What is this device protruding from the rear of this 787?

As you have already imagined, it's the APU fuel line shroud drain, as visible here:

(Source)

Detail:

The fin gives an aerodynamic profile to the drain. The reason this drain exists seems to be:

  Natural fuel leaks from the auxiliary power unit (APU) fueling line
  were supposed to drain harmlessly out the bottom of the structure as
  designed, though rather than do that, the fuel was pooling into the
  APU exhaust cone.

(Source)


Does ATC use mode S addresses to identify planes?

The Mode S address is not used for identification of aircraft in the higher levels of the ATC system such as the Flight Data Processing System.

Mostly the assigned 12 bit code (also known as Mode A code or squawk code) is used to correlate a radar track to a flight plan. The major exception is that in Europe, when the Mode A code is set to 1000 (octal notation), the Mode-S downlinked Aircraft Identity (ACID) is used for flight plan correlation. This is to free up Mode A codes. Usually planned flights are assigned discrete Mode A codes but using ACID / Flight ID correlation, multiple aircraft on a flight plan in the same area can use Mode A code 1000.

The downlinked ACID must be equal to the Flight ID used to file the flight plan.

The Mode S 24 bit address is only used in low level systems; in the Mode S radar, in multilateration systems, in ADS-B receivers and to some extend in tracking systems.


Why did this plane fly in a zigzag pattern?

Alrighty then, that took some detective work.
Here's another flight around the same time, SkyWest 4458, which arrived 2 minutes later. Notice it's one deviation, compared to two deviations in your example.

Weather seemed fine, but KSEA has TBFM (Time Based Flow Management) since Aug 2013. If the ATC asks a plane to delay its arrival time, the way it's done is to deviate from the route, then get back on it again—that's if slowing down alone won't meet the time target.
Pilots then use the RTA (Required Time of Arrival) function of the FMC. Initially the function was rarely used, but now with NextGen in the U.S., SESAR in Europe, and similar systems elsewhere, it is frequently used.
It can be arranged way ahead of the airport, i.e., it can be ordered by the approach controller, yet the center controller of another ARTCC delivers the message.
It looks exactly like that. Deviate, if not enough, deviate the other way.
Behind the Scenes
The system is called ERAM (En-Route Automation Modernization).
ERAM detects future conflicts, and based on that, traffic is asked to speed up, slow down, or deviate to slow down further. It reduces/eliminates hold time.
Europe—the first to use it in 2012—refers to it as initial 4D trajectory management. Planes arrive at waypoints at agreed times.
For whatever reason—most probably sudden traffic influx—they were asked to slow down.

The difference between this, and the regular vectoring/doglegging in the terminal area, is the way it is predicted, coordinated, and then relayed to airplanes far from the airport.
Below you can see as the jet turned, it slowed down as well. The initial upward spike is just the tailwind when the plane turned.

Source: flightradar24.com


What exactly is the afterbody of an aircraft?

Each vessel, whether land, sea, or air, should (might) have a defined afterbody. The afterbody is defined as:

  The afterpart of a vehicle; The part of a vessel abaft midships; A companion body that trails a satellite or spacecraft; A section or piece of a launch vehicle, rocket, or spacecraft that enters the atmosphere unprotected behind the nose cone or other body that is protected for entry

and Merriam-Webster Online defines it as:

  :  the after part of a body: such as
  a :  the part of a ship abaft midships
  b :  the bottom portion of a seaplane hull or float aft of the main step

To show you, visually, an easy to see set of examples, consider the following pictures of floatplanes (seaplanes):

In the first and second images, the afterbody is that part of the aircraft behind the step, which is the little 'notch' or, well, 'step' just behind the main wheels. In the third picture, the afterbody is everything after the step, which is the more steeply angled section under the wings. The step is generally just aft of the center of gravity of the plane.

Generally speaking, if one were to discuss the afterbody of a large airliners, such as the Airbus A380, the afterbody would be the fuselage from the wings back, but not including the tail (where the rudder and elevators are.) I could not find any Airbus references to 'afterbody' however. I did find some references to the afterbody of a Boeing 787, being that part of the plane behind the pressurized cabin, which is the very back of the plane, including the tail.

Not a very good solid definition where everyone agrees, sorry.


What would happen if a Cessna flew into a power line?

There are a lot of variables so its hard to make a flat out call. Here is at least one example of it happening that was caught on film. In that instance it seems to have ripped through the cords (which also appears to have started a fire). However here is an example of a similar situation where the plane simply got tangled into the cables and hung there. This one from my home field (ill go do some more digging) but it looks like the cable ripped it apart.

I would say you have a few mitigating factors,

Is the engine running? the prop is sure to do some slicing on impact if your engine is running and your prop is turning.
The cable type. As Ron mentions in the comments the type of cable will have an effect on this. The higher voltage cables tend to be solid twisted cable securely affixed to the larger towers. While the stuff out side your house is of a much smaller gauge and possibly is a phone line or other coax line etc.
Speed and size. There are lots of aircrafts that are all capable of very different types of flights. A Mooney Mite on departure is going to impact a power line in a far different manner than a King Air on departure. Its simply a matter of inertia.
Insulation Joints. Power lines are generally connected to towers via some kind of insulated connector. Often times the connectors used can break away under enough force allowing the line to drop to the ground. This of course depends on the type of connection joint and direction of force applied.


Do tower-controlled helipads have a standard naming convention?

Normally helipads are allocated names depending on what taxiways they are adjacent to. For example, Helipad Alpha would be off or near taxiway Alpha. Helipad Charlie would be off of Taxiway Charlie. Results may differ depending on the airport/heliport layout, but this is how the normal naming system works.


Do GA IFR flights out of airports w/ SIDs typically use them? What about STARs?

I cannot speak for all of General Aviation (GA), but throughout the IFR portion of my flying career I have generally used SIDs wherever available.

NOTE: This choice of using SIDs was not always mine, as ATC will often include a SID in a clearance unless requested otherwise. A pilot has two opportunities to avoid SID's if so desired: firstly, when filing the IFR flight plan the statement "NO SIDS" can be included as a request; secondly, when receiving the IFR clearance, the SID can be declined.

I typically like using most SIDs, and I understand that ATC also likes giving them as part of a clearance. Many SIDs are essentially just radar vectors in normal usage with further instructions in case of lost comms.

My experience with SIDs has included numerous aircraft with typical climbout speeds ranging from 90–280 KIAS. As far as I have been able to tell, my aircraft's speed has never been a problem that ATC couldn't handle.

I have less experience with STARs. In flight training I used them occasionally, and ATC seemed to handle my slow speed without issue. At my current operation—which you may or may not consider to be GA—ATC rarely gives of STARs, but usually just gives us clearances direct or vectors. I personally like filing STARs since it helps me know what to expect.

A note on General Aviation (GA): multiple uses exist for the term, "general aviation" (see my query below your question). All of the definitions I am aware of would include the flights in smaller single and multi-engine aircraft that I have flown during flight training. Some of the definitions I am aware of would include some of the turboprop flying I have done (non-charter §135), some would not. But I think that all of the definitions I am familiar with would include private business aviation under §91—which includes some of the fastest civilian jets out there.


Do Diesel engines have a mixture option?

For fuel, any fuel, to burn, it must be mixed with suitable amount of air. Neither too little nor too much would burn. Spark-ignition engines pre-mix the fuel with air, so they must do so in the right ratio, hence the need for mixture control (which might be automated, but it must be there).

However, compression-ignition (Diesel) engines are different. They inject fuel directly into the cylinders and as the fuel spreads from the injecting nozzle, it mixes with air and ignites at the moment it is sufficiently mixed. The cylinders always take full charge of air, otherwise the compression would not heat the air enough to ignite the fuel.

At low power, the flame is only small around the nozzle and at the large power it expands to fill the cylinder, but either way there is a point where the mixture is just right and the fuel ignites. Therefore compression-ignition engines don't need mixture control. The power lever simply controls the fuel flow into the engine and there is no throttle on the air intake (so calling power lever ‘throttle’ is inaccurate for Diesels (and turbines)).


How did this air force plane likely get into the eye of Hurricane Florence?

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

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

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

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

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

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

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

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

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

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


On a axial flow turbo fan or turbo jet engine what comes first the rotor or the stator?

There are two aspects to consider here:

The aerodynamic principle:

The simple aerodynamic principle requires a compressor stage to have first a rotor followed by a stator.
The constructive aspects:

Constructive aspects to be considered are:

a) Pre-rotation of air before the rotor: in order to reduce the relative speed of the airflow on the rotor blades (to avoid the shock waves of supersonic airflow) a set of stators can be placed in front of the rotor; this will rotate the air towards the direction of rotation, reducing by this the relative speed of the airflow on the rotor blades; even in such cases a stator stage is required after the rotor.

b) Bearing location: some designs put the bearing behind the rotor, other designs put the bearing in front of the rotor; in such case the bearing before the rotor needs to be supported by a system of vanes.

Consequently, many smaller diameter (or high speed military design) engines will take advantage of a) and b) above and have a stator in front of the first stage compressor.

To answer the same questions on turbines, there the aerodynamic principle requires to have first a set of stators and then a rotor.


How do I know if an arrival procedure (STAR) clearance includes altitudes?

In the U.S., the phrase "Descend via the (arrival)" means that you are cleared to the altitudes as published.  Without that phrase, simply cleared for the ___ arrival, then your clearance is the fixes, but ATC will assign your altitude explicitly. In this case, the published altitudes may later be assigned, so descent planning should still be based on making the next fix at its altitude. You just don't go below your assigned altitude until cleared lower.

FAA Explanations:
Starting on page 8 for "descend via" clearances: http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/pbn/media/rnav1_rnp1_rnav2/climb_descend_via_faq.pdf

More succinctly: https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2014/InFO14003.pdf


How can a foreign pilot get renter's insurance in the USA?

Most flight schools in the US have an easy policy for renting out their planes:

You go there, you do a checkout flight on an airplane with one of their instructors, and you can go ahead and fly as much as you want.

The planes are then insured by the flight school, and you pay for the insurance by paying an hourly fee to the flight school. The checkout flight is necessary for the insurance, and is most of the time valid for 90 days. After that, another checkout flight might be required.

You, though, might not be included in that insurance. If something happens to you, the flight school's insurance will probably not cover the costs you might have.

I don't want to advertise on here, but for if you are interested I can show you a nice flight school in Florida.


Can a pilot still land if the tower gives confusing Information?

At or near touchdown on the runway? Ignore it. The last thing any pilot should do in the critical period near runway touchdown is try to determine what a confusing or unclear radio transmission actually meant.

On the other hand, if "at the time of landing" includes two minutes prior to touchdown, up on downwind, or 4  nm out on extended final approach, different story.

What the cutoff is between these two extremes is what we pay pilots for. It's called situation awareness and exercise of good judgment.


Is there a website similar to FlightRadar24, but showing general aviation?

Yes, and no.
FlightAware (and I believe FlightRadar24) will show General Aviation aircraft (I panned around a bit and found N802AF, a Pilatus, buzzing around over Bethlehem, Pennsylvania just now).

The catch is most of these systems are fed with ATC data, and generally only pick up flights that are either on an instrument flight plan, or which have picked up flight following & been entered into the ATC system by the controller who set up the strip.

Most light GA aircraft are flying around VFR (transponder code 1200), and don't show up on these flight tracking sites. Similarly if you're assigned a "local" transponder code rather than a system-wide one  you typically won't show up on the tracking sites either (this is often the case when you're flying VFR and go through Approach/Departure for Class C or Class B transitions/arrivals).

As more of the fleet is equipped with ADS-B this coverage may improve, as anyone can set up an ADS-B receiver and skim the traffic data. That data is currently only broadcast when a "participating aircraft" (ADS-B Out equipped) is in the area though...