Does a trent 900 engine have the ability to spin extra or more fans?

A geared turbofan can spin a different fan at a different speed than an otherwise equivalent non geared engine. But a geared turbofan does not have the ability to spin additional fans at the same rpm, or spin the same fan faster, than a non geared turbofan (if that's what you are asking?). What is required to compress air (by spinning the fan) is shaft power. The level of power provided by the turbine is not increased by adding a gearbox. Indeed, a gearbox adds friction and hence mechanical inefficiency, so the level of power that is available to the fan will actually decrease in a geared turbofan.

HP = Torque (in ft-lbs) x RPM ÷ 5252

A gearbox which reduces rpm, increases torque, but with a slight loss of power due to invetitable inefficiencies.

Your question is quiet confusingly written, but it appears to imply the Trent 900 is a geared turbofan, which it isn't. The Trent is a 3 spool engine, and is the first of the Trent family with a counter rotating HP spool.

The only large geared turbofan in current use is P&W's PW1000G family. (See comment below regard two smaller geared turbine engines). This uses a star design  gearbox to transmit 30,000 hp at a 3:1 ratio. The PW1100G, the largest engine in the family, is a 12.5:1 bypass ratio, and a max thrust of 35,000 lb. In comparison, Rolls Royce is developing their "UltraFan", and is expected to use a planetary design gearbox to transmit 70,000 hp at about a 4:1 ratio. They hope to eventually get to bypass ratio of 15:1, and an overall pressure ratio of 70:1. The thrust for the UltraFan is said to be in the range from 25,000 to 110,000 lbs, so it looks like being a signifficantly bigger engine the P&W's geared turbofan.

Power loss in the gearbox is mostly due to friction, which generates heat. In miniature gearboxes, heat is not much of a problem because the power losses and the absolute amounts of power involved are relatively small. However, it's much more of an issue in large gearboxes which usually require oil coolers to remove the heat caused by the inefficiencies.

Thus, gearbox efficiency depends on friction. This in turn depends on the quality of the gearing, the number of tooth engagements (how many times one wheel drives another) and the load torque (how much "moment" the gearbox has to deliver).

This article says that a spur gear, the type used in geared turbofans, have an mechanical transmission efficiency of about 98 to 99%. If you look at the picture above, you will notice 8 points where the gears mesh, and efficiency will be lost at ech contact point, so needs to be kept to a minimum.

For a comprehensive overview of geared turbofans, see this "flying engineer" article.


We now want to sell the aircraft - can FAA reconstruct the logbooks?

As @fooot mentions in the comments you can find most of the details on this question here. There is a brief AOPA article here.

  If costs are involved can we get the pilot to pay for it?

For this you need to consult a lawyer (I would try and get one that specializes in aviation related cases). Depending on how his contract (if he has one) with your company is arranged you may have some weight here. There is a nice document covering a lot of cases in this space that you can find here. See section VI, but you may be covered for this under your insurance,

  VI. LOST, STOLEN OR DESTROYED LOGBOOKS
  MAY BE COVERD UNDER THE AIRCRAFT'S
  INSURANCE POLICY.

  Lost or destroyed logbooks may be covered under the aircraft’s
  insurance policy. However, whether or not coverage exists will depend
  on the language of the policy and, if the logbooks are not
  specifically covered under the policy, an insurer can deny coverage
  and a court may have to decide whether coverage exists.

I would seriously take time to look for them prior to doing anything as Im sure you already have. You can take a look at this thread for some info on rebuilding logs.

It is also worth reaching out the aviation shop that you use to maintain the plane. Many shops may have work records on file that can help you rebuild your records.


Flying out from an uncontrolled field, should I contact approach or departure at the nearby control field?

Approach and departure are two facets of the same facility, the TRACON, and it doesn't matter which you call, unless you're an IFR aircraft on an active flight plan or you have a flight plan on file that you want to activate.

For flight following, more important than picking between approach and departure frequencies, is to contact the TRACON on the frequency for the airspace that overlies your position.

For example, at Hollister, the TRACON is called "Norcal," and it handles dozens of different sectors, each with its own frequency.

The frequency for approach and departure at Hollister are identical because that frequency is the arrivals frequency for San Jose International Airport (SJC). That's because Hollister is underneath the approach path for SJC, and that's whose radar screen you will pop up on.

What you should do is look up the frequency for your airport (or for a nearby airport) in the A/FD, in Airnav.com, or in your GPS database, and use that. If it has a discrete departure frequency, then you should probably use that, even though its for IFR departures, but for VFR, it doesn't really matter.


On an average, space of how many economy class seats is taken up by a suite?

The size of the seat is slightly different in each airline, but according to this table, 32"×18" is the smallest, and most common, economy seat. That is 4 ft².

According to the article you linked, the largest suite is 125 ft². That is 31¼ times more.

Remember, however, that space is not the only consideration. The main consideration for aircraft is weight and obviously first class passenger does not weigh more than economy class one.

Now consider that those 853 passengers, with baggage, will weight around 80 t. Maximum take-off weight is 575 t of which 276 t is empty weight and the tanks can take about 260 t of fuel. But that leaves you only 39 t for payload with full tanks! So on very long routes, the aircraft can't pack 853 passengers anyway. The 500 is about maximum that makes sense (for long range variant, which is most common).

So they don't mind wasting some space for luxurious first class if they can charge premium for it.


Why open up the window shades before takeoff and landing?

I'm not sure about other countries, but in the USA there is no FAA requirement mandating that the window shades be open for takeoff and landing.

Individual airlines vary in their procedures, with some requiring them to be open while others do not.  This is set by company policy, presumably set by management because they decided that there was/was not a safety benefit in doing so.

As a pilot, I would prefer the window shades to be open all of the time so that even passengers have the chance to point out something that they think might be a problem.  For example, recently a passenger on an airliner noticed a fuel leak and told a flight attendant about it before the airplane took off.

One important thing to keep in mind is that in the event of an emergency evacuation, you should always look out the window before opening an emergency exit to make sure that there isn't a fire or other hazard just outside the door.  This is why a lot of emergency exits don't even have window shades on their windows.

This answer on Skeptics.SE also points out that emergency crews responding to a crash can see through the open windows to better respond and help the people on the airplane.  It also mentions that the passengers eyes will also be more acclimated to the lighting outside the airplane if the window shades are open.  This is also why some airlines have policies requiring the cabin lighting to match the outside light (i.e. the lights will be on bright during the day and dim/out at night).

This answer on Travel.SE also goes into more detail from a person who works in the airline safety industry.


What about the DC-9's wing makes wingletting it so difficult?

I do not know, and I have looked for answers for a little bit. Interesting question. I have seen it said that the DC-9 has a high aspect ratio, which may be a factor -- resisting a wing-axial torque is easier with a longer chord, which all things being equal, would be a lower aspect ratio.  Still, a split winglet (part up, part down) or tip fence like on the A320 could mitigate that particular torque. Ground clearance comes into play then, with the low wing and very low dihedral.

So, my other suspicion is that resistance to flutter might be an issue -- podded engines (podded correctly) combat flutter. Rear-mounted engines do not. If the winglet tended to induce flutter, it might be tougher to suppress. Nobody wants to re-engineer the spar box for the scanty gain offered.


How strong would a servo motor need to be to power the control surfaces of a fixed wing ultralight aircraft?

First I'd like to say you are thinking outside the box, not a bad thing...

However for an ultralight aircraft this is impractical. The first problem you have is that most ultralight aircraft don't have electrical systems. Adding one may put you over the weight class for an ultralight. Servo's, batteries, joysticks, etc are also not very "ultralight".

The second thing you need to think about is that R/C's work because a single servo controls two surfaces in the case of ailerons, so they are synchronized. The aerodynamic forces become much, much larger as you scale up, so you will need individual (or multiple) servo's per control surface. Then you need to think about how to synchronize them, and calibrate them.

Next comes in a question of failure modes. If your elevator servo fails, what do you do? What about your electrical system? Dead battery? These FBW systems work on large aircraft because they have multiple redundancies (including traditional cable controls). You won't have the space or weight budget to do that.

It just comes down to trying to shove a complicated system into an uncomplicated aircraft.

And for a little note about "large scale" FBW systems. Usually these systems use hydraulic servo valves, which means that the aircraft includes a hydraulic system (or 3), which are electrically or cable actuated. These can provide sufficient force (along with heavy counterweights) to move the control surfaces. The servo's that you would need would not be available in electrical form since they would need to be powerful, long stroke, and fast. There are servo's that are used in some aircraft for things like flaps, but they are not fast.


What is the Mach Never Exceed number for a C-130J Hercules under ISA conditions (approximations are welcomed!)

The MMO for a C-130J is Mach 0.77 according to flugzeuginfo.net. Official values will be found in the AFM for the aircraft and may vary between production variants of the C-130.


Can horizontal stabilizer trim be worked independently (each side)?

No.  Theoretically you could have the left and right stab move independently so there is still some trim authority if one jams, but would be structurally way more complex and quite heavy, your trim authority would still be cut in half, and there isn't really a strong need to do that from a risk perspective.  There may be aircraft out there that are like that, but most moving stabs are single surfaces usually operated by a big electric jack screw.

The required redundancy is provided by redundant control channels for the trim system, dual drive motors for the screw jack that drives the stab, and a dual load path design in the acme thread and the trunnion (the "nut" part of the jack), and in the attachments that connect the trunnion to the stab and the actuator assembly to the structure.  The only single point of failure would be for the hinge of the stab itself to completely seize, and the risk of that is low enough that it doesn't need to be accounted for in the system architecture.

Two independent stab surfaces would require an attachment to the fuselage or fin that allows independent movement of each surface while cantilevered off the root structure, which would require a pretty heavy and complex center structure for not a lot of gain safety wise.


How does the engine wash improve engine performance?

A performance increase after a compressor wash is expected to happen, but it does not return to the original performance as there are more degradation mechanisms at play. This answer explains that organic build-up causes a change in airfoil shape causing the recoverable performance degradation. Another source may be deposition of salts and dissolved constituents to deposit on the blades as a result of ingesting salt water from which the water evaporates in the hotter stages of the compressor. E.g. erosion is a non-recoverable degradation (for a compressor wash). This is clearly shown in the figure below.

From: Modern Gas Turbine Systems, High Efficiency, Low Emission, Fuel Flexible Power Generation, Woodhead Publishing Series in Energy

  I wonder if the engine performance would improve significantly after having a wash.

The performance increase is considered significant enough, else we would not go through all the trouble of performing the procedure. Fuel costs is one of the major direct operating costs, reducing fuel costs by washing the engine doesn't only save money, it also reduces the amount of used fuel (nice green image for the airline).

  As it is said that the water should be injected at 1 o'clock position on the LPC (aft view), why does it need to be at that specific position?

This could be done to prevent build-up of water in the lower section; now it has to travel half the engine down, by the time it reaches that location the water will be transported aft by the churning blades. The water is therefore better distributed, which is confirmed by this practical answer.


Can an airport fine an aircraft for being too noisy?

Ill answer this for the FAA (here in the US) but keep in mind this differs around the globe.

The FAA outlines some of their noise abatement information here. They created a special website that has a lot of the data here if you are interested.

There are 2 basic scenarios here in the US, towered and un-towered operations. There can be a noise abatement or related procedure in place in both cases and it is both the pilots and towers (when applicable) responsibility for knowing them and abiding by them. Some of them may be set in place by local governments (if its say a municipal airport) and you may face local legal action for violating them.

At a towered airport that has a noise abatement the tower will generally not vector you to that area or have you use a given runway provide conditions allow. For example when I fly out of KPNE there is an abatement in place, in this case they only list Rwy 15 arrival (stay above the glide slope) however there is another abatement in place on the weekends to keep you from flying over the heavily residential areas early in the morning. The tower vectors you appropriately for that one.

(source)

At un-towered airports there may be a published noise abatement that you are requested to follow. For example I fly out of KDYL which has a noise abatement in place (to keep you from flying over downtown). In this case we can see it noted in the AFD. Although its not fully explained the procedures are for RW 23 turn to 250 as soon as practically possible, for RW05 no turns under 1200 ft. and there are no touch and go's at any time.

(source)

In both cases the procedures have a similar outcome to what you have described, keep the airplanes away form the populated areas. The procedures vary heavily per airport and scenario but all generally strive for the same outcome.

The FAA advises you to first report a violation to the airport but also provides contact info for directly reporting to the FAA. You can single out a given aircraft by accurately reporting the time of the incident (and if its visible) describing the aircraft. Granted it can be difficult at an un-towered field to know who exactly was departing if no one was around to see it or on the radio to hear it. Once reported the local authorities may have the right to fine you for the violation (if that is the punishment on the books). For example in the NY/NJ area the Port Authority handles the violations and does hold the ability to issue fines.

Long beach airport lists their fines on their site

  If a plane violates the Noise Ordinance, how much are they fined?

  The initial phases of our violation process are educational: the first
  time an owner/operator violates, they will receive a complete packet
  including a copy of our Noise Ordinance, an outline of what the
  infraction was, a letter from GANC offering assistance with
  procedures, and a warning letter asking them to contact noise
  abatement staff.
  The second violation involves a notification letter
  of infraction and a request for a written noise abatement program,
  where we ask the owner/operator to communicate how they plan to
  operate without violating our ordinance in the future.
  The third violation is a fine of $100 dollars. The fourth and every subsequent fine of 300 dollars. Please note that Military aircraft
  are exempt from this policy.

And it looks like, according to the regulations, the airport manager issues the fine and the payments go to the airport. This may vary by jurisdiction on how they chose to govern things like this. Over all the answer to your question is, yes airports can fine pilots (well really owner/operators) for noise violations.

There are also noise limits on aircraft that deal with engine noise but are generally handled during the certification phase of the air frame. This helps to reduce airport noise overall.

As for global regulations the IATA has outlined some stuff here with the full text here. ICAO has a set of policies you can find some references to here.


Why doesn’t the minimum drag point meet the point at the best Cl/CD polar?

"Minimum drag" at 2deg in image 4.3 is just minimum Cd (coefficient not force). It is the most streamlined position and you will generate the least amount of drag here, for a given speed. You won't generate much lift though, if any. In fact, if you want to fly level (ie. at 1g) you will have to fly so fast that the drag will still become expensively large. Larger that if you were to fly at a more optimum angle of 5deg.
If Cl was constant over aoa, the best Cl/Cd would indeed occur at minimum Cd. ( a fixed quantity divided by the smallest ammount), alas Cl and Cd both increase with increasing aoa, reaching a best Cl/Cd ratio (in your example) at 5deg in image 4.7.
After that point, the Cd will increase a lot more than Cl, thus making the ratio worse.


Your question is not easily answered, at least in my opinion, but I'll have a go at it.

Your impression that larger airplanes are less sensitive to xwinds than smaller airplanes is correct, very much so in my experience. I lack the expertise to give you the aerodynamic basis, the equations if you will, but I'm fairly certain that saying an aircraft's sensitivity to a xwind is inversely proportional to it's mass, landing speed, and wing loading is a correct statement. As I remember, the max demonstrated xwind for a Cessna 172 is 15 kts, for a 747 either 25 or 30 kts, and I would much rather be landing a 747 in a 30 kt xwind than a 172 in a 15 kt xwind. In 747 sims we would occasionally crank the xwind up to 40 kts for an interesting but still safe landing.

Using extra speed in a small aircraft to help is not, in my opinion, a good idea. You'd certainly want to add a bit to your approach speed to handle gusting conditions (which typically accompany crosswinds), but what you need to do is transition from flying speed to non-flying speed as quickly as possible rather than extending the time of that transition. You need to get the weight off the wings and on to the wheels as quickly as possible.

There is one exception to what I just said. Back in the 1950s when I first learned to fly, they used to teach what they called 'wheel landings' for handling crosswinds in taildraggers. The problem with a taildragger is that the c.g. is behind the main gear. If you touch down in any kind of a crab, it wants to switch ends. In other words, a ground-loop. The idea of a 'wheel landing' was to get the main wheels on the runway with extra speed (after having slipped to the touchdown) so that the rudder (with the tail still off the ground) had plenty of authority to counteract weathervaning, and of course with the upwind aileron fully up. Then you were supposed to keep the airplane straight while the your speed dissipated to where the tail could no longer fly. I have no idea if they still teach that technique.

So now you're the PIC and having to decide whether to land in a xwind. Following are some of the things I can think of that might enter into your decision making:

What's your personal confidence level? If you're nervous about the situation you're probably not going to do as good a job as if you were relaxed.
What's your experience level in the airplane? Aircraft, even of the same weight class, vary in their handling qualities in a xwind, and the more you've flown them in xwinds, the better you're going to be in that model of aircraft in a xwind.
High wing or low wing? The closer to the ground you get the more the wind decreases, and that few feet of difference can make a difference. Also, I suspect, but do not know, that having most of the wing below the c.g. rather than above the c.g. helps.
What is the runway surface, and what is its condition? In other words, how slippery is it going to be. A dry paved runway is, of course, the best. However, a dry paved runway with a lot of reverted rubber in 120 F (49 C) temperatures can be interesting. Ice or wet grass is perhaps the worst. I put a Cessna 150 off the runway in wet grass back in the 1970s.
How bad do you need to land there? Some might say that doubts about being able to safely land should always override the need to land, but that's not the real world.
For a light aircraft, you may be able to turn that strong xwind into a strong headwind by using a taxiway. I've done that at a uncontrolled field.

A word of caution: Just because the xwind is within the max demonstrated xwind component does not necessarily mean you can safely land, it just means an experienced test pilot did it on a reasonable runway surface. The max demonstrated xwind is a guideline that is sometimes safe to exceed, sometimes not, and sometimes not safe to even get close to.


I'm not sure what kind of airplane that you are flying in the simulator, but the checklists for jets typically do have you turn the pitot heat on just before takeoff and leave it on until after landing, just so that this is less likely to happen.

Update: I found a French checklist for the Caravelle and it says to turn on the pitot heat before takeoff:

  Rechauffage Pitot.....MARCHE


Which airplanes are required to have a Flight Data Recorder in Europe?

ICAO Annex 6 holds the answer.
For commercial aviation (annex 6 part I):

6.3.1.1 Types
6.3.1.1.1 Types I and IA FDR shall record the parameters required to determine accurately the aeroplane flight path, speed, attitude, engine power, configuration and operation.
6.3.1.1.2 Types II and IIA FDRs shall record the parameters required to determine accurately the aeroplane flight path, speed, attitude, engine power and configuration of lift and drag devices.
6.3.1.2 Operation
6.3.1.2.1 All turbine-engined aeroplanes of a maximum certificated take-off mass of 5 700 kg or less for which a type certificate is first issued on or after 1 January 2016 shall be equipped with:
a) a Type II FDR; or
b) a Class C AIR capable of recording flight path and speed parameters displayed to the pilot(s); or
c) an ADRS capable of recording the essential parameters defined in Table A8-3 of Appendix 8.
6.3.1.2.3 All aeroplanes of a maximum certificated take-off mass of over 27 000 kg for which the individual certificate of airworthiness is first issued on or after 1 January 1989 shall be equipped with a Type I FDR.
6.3.1.2.4 All aeroplanes of a maximum certificated take-off mass of over 5 700 kg, up to and including 27 000 kg, for which the individual certificate of airworthiness is first issued on or after 1 January 1989, shall be equipped with a Type II FDR.

For general aviation (annex 6 part II):

3.6.3.3 Flight data recorders - aeroplanes for which the individual certificate of airworthiness is first issued on or after January 1989
3.6.3.3.1 All aeroplanes of a maximum certificated take-off mass of over 27 000 kg shall be equipped with a Type I flight data recorder.
3.6.3.4 Flight data recorders - aeroplanes for which the individual certificate of airworthiness is first issued after i January 2005
All aeroplanes of a maximum certificated take-off mass of over 5 700 kg shall be equipped with a Type IA flight data recorder.

As rules and regulations tend to change from time to time, you should always check the latest edition of ICAO Annex 6 for current requirements.


What is this object that followed me up the street?

This is a quadcopter, so called because it uses four rotors to generate lift. They are now made cheaply in China and can be purchased in most technology-related online shops. They are remotely controlled, so it is safe to assume that the owner was close, but not in plain view. It might have been the police, but it could as well be a hobbyist, taking his new toy out for a spin.

Since most units are equipped with a cheap webcam and a wireless link, I would guess he/she was sitting in front of a computer or using his/her smartphone for controlling the device and watching the camera stream.


In parallel runway ops, is it better to dedicate a single runway to landings, or is it best to have a mix?

That would no doubt depend on a lot of factors. Geometry for example. If the parallels are far enough apart there's no chance of a missed approach on one interfering with traffic on the other, you're a lot more flexible than when they're close together.
Maybe you have noise abatement procedures that make the use of one of the runways for either landing or departures illegal at specific times (e.g. Schiphol can't use certain approaches during the morning rush because overflight of parts of the city are not allowed at those times).
Type of traffic is another. If you're getting a lot of inbound heavies at an hour where you have a lot of outgoing smaller aircraft, it soon becomes a good idea to have one runway set aside during that period for landings, one for arrivals (the wake turbulence of the heavies would mean longer waiting times on the runway for the lighter aircraft).
So overall, there's no definite answer. It all depends on traffic, local conditions, etc. etc.


How do fighter jets communicate with an intercepted plane that's lost comms?

This is covered in the FAA's AIM, Chapter 5, Section 6. The UK has similar procedures.

First, the standard guard frequency is 121.5 or 243.0 MHz. If you aren't listening to this frequency and get intercepted, you should start listening.

Methods like LED signs or possibly as whiteboard as you suggested can also be used. Otherwise, they maneuver their aircraft to send standard signals. See the guides above for details on the signals sent by interceptors and how they should be acknowledged. Basically:

You have been intercepted, follow me

Interceptor: Rocks wings (and flashes lights irregularly at night)
Intercepted: Same

You may proceed

Interceptor: Breakaway, climbing turn away from aircraft
Intercepted: Rocking wings

Land here

Interceptor: Circling airport, lowering landing gear, overflying runway (landing lights on at night)
Intercepted: Lower gear, land

The intercepted aircraft can also send signals. The interceptor will respond with one of the signals above.

Designated airport is inadequate

Intercepted: Raise gear, flash landing lights

Cannot comply

Intercepted: Switching on and off all lights, but distinct from flashing lights

In distress

Intercepted: Irregular flashing of all lights

In the case of the Washington, DC Special Flight Rules Area (DC SFRA), there is a Visual Warning System (VWS) of red and green lights that will let the pilot know that they shouldn't be there. The pilot is supposed to turn directly away from the center of the SFRA. If they are in contact with ATC they must advise that they have been illuminated by the system, otherwise they should contact ATC on a guard frequency and identify themselves.

Of course, an interceptor can't force an intercepted aircraft follow instructions. It goes on to explain what will happen if you don't follow those rules, which probably apply in any situation where the risk is too high:

  Further noncompliance with interceptor aircraft or ATC may result in the use of force.


Can excessive G-force break or dislocate bones during pilot maneuvers?

Yes.

Even if the pilot remains conscious.

For example see http://medind.nic.in/iab/t00/i2/iabt00i2p1o.pdf which describes compression fractures suffered by pilots.


Could the Busemann's biplane concept be used in a turbofan engine?

No.

The Busemann biplane is a clever concept to have all shocks cancel each other, but unfortunately, the same canceling happens to all the lift. Therefore, a Busemann fan would not create any thrust.

The key of the idea is that shocks occur only between the two wings, the outer surfaces being aligned with the external flow so no shocks are created there. This means the concept would only be workable if every other gap functions as a Busemann biplane, the rest having straight and parallel walls.

In addition, the concept only works at one specific supersonic speed which depends on the geometry of the gap between the wings. On a fan you get a continuous increase in Mach number when moving from the spoke to the fairing. At Mach = 1 the chord of the wing would have to be zero for the concept to work over the whole span.


Do hospitals have radio communications with air ambulances?

Kind of...
Hospital heliports are "uncontrolled airports" normally, and don't require a clearance from ATC (unless the hospital itself is within positive control airspace because it's near a regular airport). However, the helipads are private "prior permission required" airports, which means the hospital, as the owner of the pad, needs to give permission to land (same way that a helicopter couldn't just land in your back yard unless you gave permission).
The helicopter will be equipped with an FM 2-way comms radio (examples of frequencies here), that is used to talk with a given hospital's flight coordinator or EMS dispatch to coordinate arrivals and departures for logistics purposes, similar to the radio a police helicopter would use to coordinate with dispatch/911.
So if you were just buzzing around in your own helicopter and thought it would be cool to land at the hospital's helipad because you had the urge for a wonderful hospital cafeteria lunch, you'll get a tongue lashing from somebody. To do it legally, you'd have to have the
required FM radio and get permission.
There will be a normal aircraft comm radio frequency assigned for VFR advisories when coming and going, like here (where you have a VFR advisory frequency on 119.4 mHz).  The pilot will just broadcast intentions on that frequency when arriving and departing, for the benefit of any other helicopters in the area, similar to arriving and departing from any other uncontrolled airport.


How often is the exterior of airliners cleaned?

According to Lufthansa Technik, with the new cleaning agents, once every 6 months.

  Until just a few years ago, wide-bodied aircraft had to be washed four times a year with foam and up to 13,000 liters of water. Today, thanks to newer cleaning agents, a resource-friendly dry wash every six months is enough.

It takes between 8 and 24 hours to wash or dry wash an airliner.


When applying a FEA loadcase, you should always keep in mind the complete picture of which forces are applied on any surface, and in what situation you consider the wing "undeformed".
If you start out with a solid wing in the vacuum of outer space, and descend into the atmosphere, then indeed the wing will compress under a hydrostatic pressure. But this is an unlikely scenario.
A much more likely scenario is that you want to compare the deformation from standing still to flying. The initial situation is already in the atmosphere, and you would typically say this is the undeformed situation. When you want to calculate the deformation when flying, you would only apply the pressure difference. This is the most common way of doing FEA analysis.
If you're interested, the following explains what happens if you do apply atmospheric pressure. Under the assumption of linearity, we're allowed to split the loadcase into differential pressure and atmospheric pressure. So the question is really what happens if you apply atmospheric pressure. The answer is: very little. Remember that atmospheric pressure also acts on any surface on the inside of the wing. The net result is that the entire wing is under hydrostatic pressure. This adds a measly 0.1MPa to the stress of the wing. Furthermore, most failure criteria for structural materials explicitly remove the hydrostatic stress. For example, in the Von Mises stress, hydrostatic pressure doesn't show up at all. So in effect, very little happens and only pressure differentials are applied in FEA.


Why is the nosewheel of the MiG-29 placed in front of the engine intakes?

The MiG-29 series of aircraft are designed to operate from poor quality airfields, and for this reason, they feature separate air intakes for use while moving on the ground.

See this article, including pictures of the aircraft:
https://www.airforce-technology.com/projects/mig29/

Notice the additional louvre-shaped intakes on top of the aircraft's leading edge extensions.

Quote from the article:

  The MiG-29 is the world’s first aircraft fitted with dual-mode air
  intakes. During flight, the open air intakes feed air to the engines.

  While moving on the ground, the air intakes are closed and air is fed
  through the louvres on the upper surface of the wing root to prevent
  ingestion of foreign objects from the runway. This is particularly
  important when operating from poorly prepared airfields.

In general, aircraft designers will have to consider factors such as the aircraft's weight distribution and center of gravity when choosing a position for the landing gear.
If you compare with other fighter aircraft of similar layout and configuration, such as the F-15 or the F-18, you will notice that most aircraft have the landing gear approximately in line or in front of the air intakes, mostly because either changing the landing gear position or the length of the air intakes only to move the landing gear behind the air intakes would likely create other problems, such as undesirable taxi characteristics, unstable takeoff/landing roll or undesirable aerodynamics in flight.
The configuration where the landing gear is approximately in line or in front of the air intakes, on the other hand, has been used successfully on many existing types, so it can be assumed that there are no major problems that would be solved by moving the landing gear further back.

As it can be seen on the MiG-29, there are also other ways to avoid specifically dirt or foreign objects ending up in the air intakes during takeoff and landing.


Is there an official FAA source for time zone of an airport?

Each airports timezone is listed in the Airport/Facility Directory. I think the FAA is starting to call these "Chart Supplements" now though. You can search for specific airports here but it looks like the results are in .pdf format. The value you want is circled in red here:

EDIT: As far as digital sources, explicit time zone information seems missing from the NASR airport (APT) data here. The next best thing is Latitude/Longitude it seems.


Why is it not recommended to hold the nose up on the A320 after touchdown?

In flight mode the stick commands a load-factor. Which means it will be impossible to flare the aircraft, because as you pull on the stick, you'll be commanding a positive g-load.

Because of this the Airbus has a flare mode which activates at 50' RA. At 50' the pitch angle is stored (memorized). At 30' the aircraft commands a 2° nose down (it takes 8 seconds). The pilot would gently counter this by pulling back, resulting in a nice flare and no increase in the auto-thrust.

If the pilot did not float for way too long (they should not), the plane will touchdown before the 8 seconds pass, further eliminating the need to push forward on the stick to keep the nose gear planted.

The logic reverts to ground mode when two conditions are met: on ground for 5 seconds and pitch angle <2.5°.

If the 5 seconds pass and the nose is still +2.5°, the logic will remain in the flare mode and the THS will not reset to 0°. The pitch will revert to the one set at 50'. As the plane continues to slow down this may result in a nasty nose landing gear slam or a tail strike depending on the stored pitch angle and any gusts (kind of like this funny TV ad).

I do recommend you check your company's Flight Crew Operating Manual (FCOM) and to not use the internet for flight. If your instructor does not like too many 'why' questions during class, you can try and ask them after class. When you get your answers, try to validate them from the FCOM.

Some companies that fly extreme approaches have custom logic set by Airbus. So the installed logic may differ.


Is the F-16 capable of taking off during a nerve gas attack?

Source: Pilots Don MOPP Protective Gear - 25th Fighter Squadron, YouTube

If the base is equipped, then yes. The ground/flight personnel don the specialized suits for chemical/biological warfare.

And according to thedrive.com, a suit is also available for the F-35, though it took a decade to design. The delay was due to the F-35's complicated "enhanced man-machine interface".


What are the minimum requirements to pass the FAA medical exam?

There are no height or weight requirements as far as I know and you dont need perfect vision. I wear glasses and have a "corrective lens" note on my medical. I think that at minimum your vision needs to be correctable to 20/20. See this link for some information as well as the information for doctors here. You can also get special dispensation for certain medical conditions.

On a small side note, if you are asking this in relation to a Private Pilot License, they may be doing away with the current third class medical regulations which will ease the regulations greatly.


Can you verify that this aircraft is not a variant of the T-34 Mentor?

Looks like a CJ-6. Popular as an affordable "warbird" type of aircraft, without the rarity.

Various other images of the CJ-6 that seem to match up to what you posted.


Was John F. Kennedy Jr.’s accident airplane equipped with an autopilot?

According to the NTSB, the accident airplane did have a functioning autopilot and GPS.

The airplane was equipped with a Bendix/King 150 Series Automatic Flight Control System (AFCS), which was approved for use in Piper PA-32R-301 model airplanes by the FAA on November 1, 1982. The AFCS provided two-axis control for pitch and roll. It also had an electric pitch trim system, which provided autotrim during autopilot operation and manual electric trim for the pilot during manual operation.
The AFCS installed on the accident airplane had an altitude hold mode that, when selected, allowed the airplane to maintain the altitude that it had when the altitude hold was selected. The AFCS did not have the option of allowing the pilot to preselect an altitude so that the autopilot could fly to and maintain the preselected altitude as it climbed or descended from another altitude. The AFCS had a vertical trim rocker switch installed so that the pilot could change the airplane's pitch up or down without disconnecting the autopilot. The rocker switch allowed the pilot to make small corrections in the selected altitude while in the altitude hold mode or allowed the pitch attitude to be adjusted at a rate of about 0.9 degree per second when not in altitude hold mode.

According to the same report, at least two different CFIs judged the accident pilot at least adequate in the operation of the airplane’s autopilot.

A second CFI flew with [Kennedy] between May 1998 and July 1999. This CFI accumulated 39 hours of flight time with the pilot, including 21 hours of night flight and 0.9 hour flown in instrument meteorological conditions (IMC). The pilot used this CFI for instruction on cross-country flights and as a safety pilot. On July 1, 1999, the CFI flew with the pilot in the accident airplane to MVY. The flight was conducted at night, and IMC prevailed at the airport. The CFI stated that, during the flight, the pilot used and seemed competent with the autopilot.

Also:

A third CFI flew with the pilot between May 1998 and July 1999. This CFI accumulated 57 hours of flight time with the pilot, including 17 hours of night flight and 8 hours flown in IMC. The pilot also used this instructor for instruction on cross-country flights and as a safety pilot. This CFI had conducted a “complex airplane” evaluation on the pilot and signed him off in the accident airplane in May 1999. According to the CFI, on one or two occasions, the airplane’s autopilot turned to a heading other than the one selected, which required the autopilot to be disengaged and then reengaged. He stated that it seemed as if the autopilot had independently changed from one navigation mode to another. He also stated that he did not feel that the problem was significant because it only happened once or twice.

53N’s GPS was capable of driving the autopilot.

The accident airplane was equipped with a GPS receiver, Bendix/King model KLN-90B. The GPS was capable of presenting moving map displays; bearings and distances to programmable destinations, such as airports and waypoints; airport information; ground speed; and other information. The GPS was also capable of interfacing with the AFCS and the pictorial navigation indicator.

The accident occurred in July 1999. The KLN-90B’s navigation database was not current.

The navigation database indicated that it was effective on October 8, 1998, and that it expired on November 4, 1998.

As to operability

On July 29 and 30, 1999, the avionics were examined at the AlliedSignal/King Radios Facility, Olathe, Kansas, under the supervision of a Safety Board investigator. On October 13 and 14, 1999, a follow-up examination of the navigation and communications transceivers and all three autopilot servos was also performed at the AlliedSignal/King Radios Facility under the supervision of a Safety Board investigator. [P]arties to the investigation were present during both examinations.
The accident airplane’s AFCS was examined. Examination and functional testing of the AFCS pitch, pitch trim, and roll servos did not reveal any evidence of a preimpact malfunction or jam.


Why would all passengers be asked not to eat peanuts when there is one allergic person on board?

The problem with a severe peanut allergy is that you don't have to eat a peanut to be affected.  With a severe enough allergy, inhaling peanut "dust" can trigger a life-threatening emergency.  In a confined space, any number of events could cause an issue: people dumping peanuts into their hands, dusting their hands off, accidentally sneezing while chewing the peanuts, etc.


What is "alternate takeoff" in this PT6A performance table?

Alternate Take-off is a reduced power option feature, similar to flex thrust on turbofans.  The aircraft manufacturer will provide performance data applicable to the reduced power setting that can be used when circumstances permit.  It's all about reducing wear and tear by not running the engine as hard if it's not essential.
The Max Continuous power setting is intended for emergencies (mostly single engine climb, or both engine climb in some marginal situations, or maintaining altitude single engine where you are one engine and high terrain makes it imperative to not descend) and as such is rarely used, so there is a higher limit to allow even a tired engine to make Max Continuous HP in a critical situation.
The reduced AT ITT limit reflects the objective of limiting wear and tear with a power setting used regularly, whereas the MC limit reflect the balls-to-the-wall limit the engine can take for extended periods when the power is desperately needed.


Can I save money on becoming a helicopter pilot in the US if I do flight hours in Mexico?

As far as I can tell from the FARs as long as your training is performed by an FAA-certificated flight instructor and complies with the appropriate requirements of part 61 of the FARs you could theoretically do parts of your (primary/private) training anywhere you want, get all your endorsements, then come back to the USA to take your checkride and get a regular US (FAA) pilot's license for the appropriate category/class of aircraft.

From a practical standpoint I think this may be more work than the money you save.
If you do your pre-solo training in Mexico any instructor you come to in the US is going to want to fly with you a bit before they endorse you to solo.
If you try to do the whole thing in Mexico you would have to comply with Mexico's flight training requirements (Medical, student pilot certification, solo endorsements, etc. - about which I know basically nothing) as well the US FAA's requirements (like holding a US student pilot certificate with appropriate endorsements prior to taking your checkride).

Note that the procedure is a little different if you want to get a Mexican pilot's certificate and then convert it to a US/FAA certificate (that's all detailed in FAR 61.75 if you're interested. It doesn't sound like that's what you want to do, but at least as far as the regulations go that seems to be a more well-traveled path and something your local FSDO could probably advise you on - at the very least it would involve paperwork, possibly also a checkride).

I'd like to say a couple of words on Primacy since we're talking about training: Where you learn and the procedures you learn first will form the foundation of your aviation knowledge.
What that ultimately means for you depends on how different the regulations are where you do your training versus where you will do most of your flying. The FAA has been moving to standardize our procedures to be more in line with ICAO standards for a number of years now, but there are still differences and you may have to re-learn some of the regulatory bits of aviation if you did the bulk of your training elsewhere.

It makes sense to me to learn to fly where you intend to fly -- ideally in the same region (a sleepy corner of the midwest versus lower New York's airspace can be a culture shock!) but if cost is a factor find the best bang for your training buck in the airspace system you'll be spending most of your time in.


Why can't turbojets or turbofans be overtemped or overtorqued the way turboprops can?

You certainly can. The equivalent to overtorquing is called overboosting and is defined as an exceedance of the primary thrust setting parameter, N1 or EPR.

Modern FADEC engines contain software protection, but it is certainly possible in mechanically controlled engines. Thus, older aircraft, such as the DC-9 have mechanical or electronic controls which set N1/EPR bugs depending on flight condition and outside temperature.

EGT exceedances are also possible. Many, if not most, modern FADEC turbofans do not have EGT protection in normal operation so pilots do need to keep an eye on the EGT gauges during high power situations, especially when ambient temperatures are high and the engines are worn.


In this context, it would mean the aircraft is loaded in such a way that the Center of Gravity is too far forward or aft.  That's actually not the way we usually use the word "trim" in aviation but it's what it means in this case.


Could airliners use a steam or electric powered catapult for take-off?

Let's see what the savings are:

A mid-sized airliner carries maybe 20% of its mass in fuel. This fuel has an energy density of 43 MJ per kg. Of that chemical energy at most 40% is converted into useable work. Heck, let's make this 25% so we are really conservative. Thus, the energy for the whole trip is $$E_{\text{trip}} = 0.2 \cdot 0.25 \cdot 43,000,000 \, \frac{\mathrm{J}}{\mathrm{kg}} \cdot \text{mass} = 2,150,000 \, \frac{\mathrm{J}}{\mathrm{kg}} \cdot \text{mass}$$

Now assume that this airliner saves the energy to accelerate from 0 to 150 knots by using a catapult. This energy is $$E_{\text{accel}} = \frac{v_{\text{takeoff}}^2 - v_0^2}{2} \cdot \text{mass} = 2,977.35 \,  \frac{\mathrm{m}^2}{\mathrm{s}^2} \cdot \text{mass}$$

Since I picked metric units, conversion is easy: $1 \, \mathrm{J} = 1 \, \mathrm{Ws} = 1 \, \frac{\mathrm{kg} \cdot \mathrm{m}^2}{\mathrm{s}^2}$. I use $\text{mass}$ for the take-off mass so you don't think it is the unit meter. Now let's put that into proportion:
$$\frac{E_{\text{accel}}}{E_{\text{trip}}} = 0.001385$$

Using the catapult saves 0.1385% of the energy needed to fly a typical airliner trip, assuming the same efficiencies during acceleration as during the flight. If we take into account that jet engines are most efficient during cruise, let's double the fuel need for acceleration and make it 0.277%. Granted, it is more for short-range flights, but still insignificant to what is needed to move the aircraft 10 km up into the sky and then for a couple of hundred miles through the air at Mach 0.8. In terms of fuel mass, these 0.277% are taken from 20% of the take-off mass. So the fuel needed to accelerate to v$_0$ is 0,000554 times take-off mass.

To make a catapult launch feasible, you need to add some strength to the nose gear and the forward fuselage. The typical landing gear fraction of the take-off mass is about 3%, and the nose gear is 10% - 15% of that, so $m_{\text{nosegear}} = 0.00375 \cdot \text{mass}$. Relative to the nose gear mass, the fuel saving from using a catapult launch is $\frac{0.000554}{0.00375} = 0.0148$ or 15% of the nose gear mass. Thus, the reinforcements need to add less than 15% to the mass of the nose gear.

If we assume an acceleration of ½ g = 4.903 m/s², the take-off run to accelerate to 150 kts is 607 m. I expect that even this moderate acceleration (which requires a pulling force of half of the lift at take-off) would translate into much higher mass increases than those 15% of the nose gear mass.


Why doesn't ADS-B use satcoms like ADS-C?

It's already here, but it's private

Your proposed geostationary orbits are very high, and since aircraft are the transmitters, that means high power antennas are required from the aircraft.

However, low Earth orbits (LEO) are more forgiving. By using 72 ADS-B receiver-equipped satellites in LEO (icao.int), Aireon will provide 100% global coverage by Q3 2018 (aireon.com).

This requires no change to the existing ADS-B technology as long the antenna is top-mounted and capable of 125 watts (most airliners already support 200 W). But it is not a free service to ATC units. Interested ANSPs can use Aireon's data to supplement their own surveillance for a fee. NAV CANADA will use their services for the North Atlantic region by Q4 2018, for example.

The power demand and the provider being a private entity, explains the why not. If surveillance is meant to be publicly owned by each government to be in control of the data source, then each country will need its own constellation of satellites – sort of like the countries and regions that are launching their own GNSS constellations.

Slide 16 (shown below) is from the linked icao.int presentation. The presentation also explains how ADS-C is different:

  ADS-C is an Alternative, But Has Limitations

  ADS-C tracking is not comparable to ADS-B surveillance
  Slower ADS-C update rates results in higher separation (mins vs. sec)
  Barrier to entry: ADS-C requires costly installation and subscriptions
  Multiple providers require individualized equipage on aircraft
  Several commercial aircraft types can’t be retrofitted
  Almost no coverage over polar regions for certain providers
  No service is provided to unequipped aircraft


Must quadcopters have the same propeller sizes?

The main point of a quadcopter is that it can be controlled by engine power using much simpler fixed-pitch rotors¹. Assuming this construction, you need to be able to separately adjust power of

forward and rear set of propellers for pitch control,
left and right set of propellers for roll control and
clockwise and counterclockwise-rotating set of propeller for yaw control.

If you had two bigger and two smaller rotors, then one of the combinations would have the two bigger ones in one of the sets and the two smaller ones in the other. That would make it really, really hard to balance all the parameters to maintain appropriate controlability.

I think it might not be completely impossible, but it certainly makes no sense.

¹ Of course once you add cyclic and collective control, you can fly with one rotor only (well, two, or one with anti-torque rotor or jet) as most full-scale helicopters do, but then you've lost the simplicity of fixed propellers.


What is the possibility of technology like Google's balloon reducing overall connectivity and internet costs?

I doubt it, let's take a look at Project Loon from X (previously Google X):

The balloon is to be flown at an altitude of 20km (about 65,000 feet). The balloons cover 5000 square kilometers (about 1930 sq miles). So the balloon and its service (red triangle) kind of looks like this:

The full length of (a) is 60,000 meters (60km). Assuming the ground area is circular, the area of service at the ground (b) is about 94.9km in diameter. So you need to figure out what the service area is at 40,000 feet (about 12.2km). I won't go over the math here (that is for a different section of SE), but you get:

Beam Angle at the balloon: 134.2°
Length of (d): 37km
Service area at 12.2km: 1075 sq km

So the problem here is that the balloons would have to be spaced much closer since the (d) of the balloons would have to overlap to give continuous service. At the speed of an airliner (550mph, or about 885kmh) the airliner would speed through the 37km wide circle (assuming it takes a straight line through the center) in about 2.5 minutes. This is either hindered or helped by the balloon speeding through the stratosphere (Project Loon's record is currently 162kmh). So you would pass through anywhere from 3.1 minutes (with the balloon) to 2.1 minutes (against the balloon) worst case.

So looking at it from purely an "is it possible to provide internet service by balloon to airliners" perspective, I would say no, not economically anyway. You would need roughly 3 times the number of balloons to cover the same area at altitude as you would be on the ground. The balloons are designed for ground service, so if airplanes did use them, they would have to switch back and forth from satellites and balloons every 2-3 minutes.


Is the A320 family allowed to take off with the flaps retracted?

For the A320 family it is not allowed. Above shows the takeoff configurations. Anything else and the takeoff warning will be triggered. I also checked the abnormal and special operations, nothing says a 0/0 takeoff is possible.

Each plane is certified for certain configurations. What applies to the A300 or 767 does not apply to all planes.

I took it one step further and checked the MEL (ignoring the fact that if the flaps are inoperative, the crew will be in for a treat when it comes to landing). At least one slats/flaps computer is required, and for the flaps/slats to be tested before the flight. The same MEL allows a takeoff if the landing gear can't be retracted.

(Click to enlarge.)

Is it impossible? Of course not. A 737-300 once crash landed on grass, was fixed, and took-off from that same grass field. Nothing is impossible. But for the day-to-day operations, the answer is no.


Are there any current projects/plans for a VTOL passenger airliner?

US patent 9,475,585 describes a Tilt-Rotor Vertical-Lift Aircraft. This patent was awarded to Boeing on October 25, 2016. The subject aircraft may be anything from a personal aircraft to a regional commercial aircraft for at least 100 passengers.

The two tilt rotors (36) are powered by a number of turbine engines (40) which are fix mounted under the wings. The novelties claimed by this patent are about the transmission of power from the power plants (engines) to the rotors.

Figure 1 - in vertical mode:

Figure 2 - in horizontal mode:

Images source: United States Patent and Trademark Office, www.uspto.gov

Of course, the filing of a patent is an evidence that a company is spending at least some limited resources to the subject. However, this does not mean that Boeing is actually developing such an aircraft.


Are those devices allowed on a flight which create their own WiFi signals?

No, the rules are about any transmitter or receiver, regardless of whether it comes under the specific category of phone/tablet/laptop etc

If anything your device is worse as it transmits at a higher power and range than a receiver.


A vehicle moving within a fluid may control its velocity by reaction, by accelerating a mass of that fluid in a convenient direction, and at a convenient rate. Using a wing is an excellent way to achieve that; birds and airplanes are able to fly by using wings that accelerate air down- and rearwards, and a propeller is nothing but a set of slender wings attached to a rotating hub.

In order to achieve a given thrust, that propeller must have a convenient size, and has to rotate at a high enough speed, so that it accelerates a mass of air and the change of momentum of that mass of accelerated air is transformed into a force that we call thrust. The magnitude of that change of momentum is proportional to the mass of air moved and to its change of velocity.

The rotor of a helicopter is just a large propeller that accelerates air downwards (and also rearwards, and sideways too, by means of a control called 'the cyclic')


Why do aerobatic planes have symmetrical wings?

One goal for most aerobatic planes is neutral pitch stability, which eliminates any pitch response related to air speed, which allows for clean straight lines during dives or climbs without requiring elevator adjustment for speed.

Cambered airfoils produce a pitch down torque which increases with speed, and this would interfere with the goal of neutral pitch stability. This would be another reason for using symmetrical airfoils on aerobatic aircraft.


What values can/should be used for the isentropic efficiency of a compressor and turbine?

An answer is in the table of the linked question: What is the efficiency of the turbine of a modern jet engine?. Column 4 is for modern engines, column 1 is for old engines, about 1960’s technology. So, take your pick. In order to get a simulation running, an exactly correct figure isn’t necessary, something in the ball-park is fine.

The third comment above gives another similar source. Either would be fine.


The exact number of air marshals is not public information, and they certainly don't disclose what flights they fly on or other operational details. However, the number has been reported to be on the order of ~3,000-4,000 and reports indicate the number has decreased somewhat since then. All of them are, of course, not on duty 24/7/365. There are around 87,000 flights a day in the US alone, but only around 28,000 are commercial passenger flights, where air marshals are presumably most likely (hopefully there's not a need for air marshals on military flights, for instance).
So for some back of the envelope math, let's conservatively say there are 3,500 air marshals who all work five days a week, they all work alone (in reality, they appear to work at least in pairs), and they somehow manage to average protecting four flights a day. Even with these conservative assumptions, that would only be 5000 flights/day covered by air marshals. From this, it should be clear that there cannot possibly be an air marshal on every commercial flight in the US.
The President of the Air Marshal Association/CWA (their union), not entirely a disinterested party, agrees:

"There are around 30,000 commercial flights per day over the U.S.," says Casaretti. "If you were to attempt to place a team of just two FAMs on each flight, it would require an agency of over 75,000 FAMs (accounting for training and days off). FAMs cover a very small percentage of commercial flights."
Which flight air marshals get on is determined by a computer program that assesses the probability of threat based on the aircraft, departure and destination cities, as well as the amount of fuel on board. This is the threat matrix that comes out of the missions operation center.
The TSA will not release statistics on the number of air marshals. TSA's Pascarella acknowledges only "many thousands." But Biles estimates that there are approximately 3,300 FAMs and of those, 34% are filling ground assignments in training, operations and management.
"We call them 'chair marshals,' riding out their career in management," says Biles. That leaves 66% of the workforce to perform in-flight security duties.
"If one accounts for vacations, sick leave, medical leave and days off, some air marshals working in operations have told me that this accounts for less than one half percent of all U.S.-flagged aircraft being covered by federal air marshals," he says.


Does the movement of the magnetic poles affect aviation?

I don't think magnetic shifting affects the pilots directly, but it does force airports to re-number their runways because of the fact that runways derive their numbers from their magnetic headings.

Other than that, I don't know of any direct effect this would have on the landing itself, as approaches rely on the ILS's radio signals or direct visual contact with the runway.


What is the chime that can be heard roughly 30 seconds after takeoff?

It's signalled from the cockpit (the cabin chime) to let the cabin crew know it's OK to move around.  If you watch, this happens before the seat belt sign goes off which at the earliest, is at 10,000 feet.


Can the parking brake be set on an 737-800 if the aircraft has no power?

This function is provided by the parking brake valve which is an electrically-operated hydraulic valve that, when the parking brake is commanded to be set, closes and traps hydraulic pressure in the brake lines. You set the parking brake by pushing both brake pedals all the way down, and then pulling up on a separate lever that locks the pedals in the applied position and at the same time commands the parking brake valve to close and trap the hydraulic fluid. You can then take your feet off the brake pedals.

If there's no electrical power, that valve can't close. If there's electrical power, but no hydraulic power from the pumps, that valve can close, and the hydraulic pressure to hold the brakes is then supplied by the accumulator. But that's not as reliable as having the hydraulic pumps operating, and you're not assured that the pressure supplied by the accumulator is sufficient to prevent airplane movement.

Moreover, closing the parking brake valve doesn't ensure a perfectly sealed system. Over time, internal leakage will mean that, if hydraulic power isn't constantly supplied, the trapped brake pressure will gradually leak to the point that the brakes can't hold the airplane, even though the parking brake lever and the brake pedals in the flight deck are still locked.


How could I calculate the correct distance from the runway to be able to fly a continuous downwind to final turn?

Turning at 3 deg/sec, a 180-degree turn will take 60 seconds. If the entire turn is performed at 63 knots, the aircraft will travel 1.05 nautical on a half circle (assuming zero wind). The radius of the circle will be the circumference, 2.10 divided by 2*pi = 0.3342 nm. Therefore, x = 2*0.3342 = 0.6684 nm.
If starting at 90 knots and slowing down to 63 knots, the trajectory will not be a a semi-circle but rather a section of a spiral. The starting radius will be 0.4775 and the final radius 0.3342. In this case, x will be approximately 0.8117 nautical miles. To get an exact value for x, an integration must be performed.


Is there a commonly recognized placeholder airline name?

I think Oceanic Airlines is well known fictive airline. It is used widely in Lost and also Alias, Castle, JAG, Category 6: Day of Destruction and in Executive Decision (the material from this movie was reused in a lot of low budget movies).


Why are propellers de-iced before the engines are started, and does ice on the fuselage affect the flight characteristics of the plane?

The props are done before starting because you need to make sure the blades and spinners are fully cleaned off while they are stationary. Otherwise, they'd vibrate like hell when starting and shed bits of ice all over. Also, if you just sprayed the props while running the engines would ingest a lot of glycol, which, if it doesn't make the engine flame out, can gum things up and cause cabin smells as cooked fluid makes its way into the air conditioning system through the compressor bleed system (a lot of turn-backs from "cabin smoke" reports on departure are from the stink from cooked glycol getting into the cabin via the bleeds).

Even done stationary, some fluid will make its way into the engine and it's typical to run the engines at a moderate power setting after the treatment for a couple minutes to try to purge whatever glycol residue is in the compressor before opening the bleeds.

Fuselages are deiced depending on the airplane and the conditions.  On some jets, especially those with tail mounted engines, the upper fuselage is treated as if it was a flying surface and must be clear of ice and frost, even small amounts (it varies with the regulatory jurisdiction).  Otherwise it will depend on whether there is any significant accumulation, mostly for weight considerations.

If there is an obvious layer of snow/ice on the fuselage, it will be removed... mostly; don't expect a perfect job and they won't normally shoot down as far as the windows. If it's just morning frost, the fuselage may be left alone although the wings and tail must still be done (ANY frost on leading edges can be fatal).  The Capt is in communication with the deicing personnel working the boom and will give instructions on what is to be covered, and what to avoid (like APU air inlet in the tail, or heat exchanger inlets, etc.), whether to use Type I only or Type I and II/III/IV (Type one is for melting/removal and II/III/IV is for follow-on residual protection for a limited time).

A deice with follow on residual anti-ice protection costs the airline a couple thousand bucks per flight so avoiding unnecessary fluid application is important in the long run.


I believe it's the French Couzinet 71 'Arc-en-Ciel'
https://www.hydroretro.net/etudegh/arc-en-ciel_atlantique_vol1.pdf


Why is the GP7200-powered A380 fleet not grounded?

The one that decided to ground the fleet was Qantas. Qantas was having a new airplane model and potentially made a trade-off between having a not known design flaw and keep flying and the risk. At that time the A380 entered in service three years before and around 20 aircraft were in service with a mix of engines.

Today, there are 200 A/C in service for 10 years. The possibility of having a design flaw or an unknown problem is really low.

It was not a airworthiness directive as the directive was created 2 months after in January 2011. Qantas starting to get back in service the airplanes on 27th November (incident was on 4th Novemeber)


Will wind tunnel modelling ever be completely replaced by computer models?

The thing about computer models is that they are just that; models. They can only approximate the actual behavior we see in the real world.

Computer models are good for trying many different ideas and making predictions. It can be faster to create a new computational test than to make a physical model for a wind tunnel. But very detailed fluid dynamics calculations require large amounts of computing power, and this takes time and money as well.

Wind tunnels can give much more detailed and accurate information, and are useful for validating the results given by the computers. The results don't always match, which means that the computer models must be revised. This is where wind tunnels are still very useful. They can test an entire airplane in actual flow, where computing that detail across the whole aircraft would require long computations.

Although a wind tunnel is also only a model of real conditions, it provides an actual body in actual flow conditions, which means the results can correlate much more closely to the real conditions being tested. Computational analysis is limited by assumptions, the chosen modeling method, and computational power.

Until computing power reaches the point where it can run models that will truly match a wind tunnel's accuracy and detail, there will still be a need to use wind tunnels to provide data.


Why is a (jet) engine in flight shutdown so critical?

Having an engine shutdown during the flight is an engine failure. An engine failure is one of the procedures where every pilot is trained to deal with because it is easy to simulate. Engine failure is an emergency, meaning that the pilots must land the aircraft as soon as possible.

  Can't a jet engine be just restarted?

Maybe, maybe not. It depends on the diagnostics in the cockpit. You certainly do not want to restart a damaged engine. All jet engines are capable of being shut down and restarted in flight, provided that nothing is broken and proper procedures are followed.

Now, of course, if everything was working then the engine would not have shut down in the first place. It is an event which pilots are prepared for, but it should not have occurred. When it does, that means something is wrong. The decision of whether to attempt a restart is evaluated by the flight crew based on engine data, distance to nearest airport, weather, and possibly a discussion with ground support. In short, it is a risk management exercise.

  Why are in flight shutdowns so critical?

With one engine shut down, your chances of making it to the destination are virtually none. Aircraft performance is calculated assuming that all engines are working. With one engine shut down, the amount of thrust is reduced and the aircraft must descend to a lower altitude. At lower altitude, fuel consumption is higher, therefore you will not have enough fuel to reach your destination and you need to land somewhere closer.

Furthermore, you are now running on your last good engine. If that engine fails as well, the airplane will become a glider. ETOPS is designed so that an aircraft may limp to the nearest airport in no more than X minutes, and the presumption of ETOPS is that the engine failure rate is low enough. In other words, the aircraft failed to meet its certification standards.


Where can I get a picture of a specific aircraft by registration?

Have you checked what data is used at flightradar24.com (http://www.jetphotos.net)? Probably only commercial airliners, though.


What are the advantages of a Pelikan tail compared to a V-tail?

The X-32 was Boeing's entry for the JSF contest, which was supposed to serve USAF, USMC and USN. JSF called for an affordable VTOL capable aircraft operated by all three services. Boeing decided to go for a tailless single piece delta with a direct lift system, similar to the Harrier.

Image from militaryfactory.com

The adoption of direct lift system and other considerations meant that X-32 had weight issues (They actually had to strip off some parts for VTOL). However, midway through the program, USN changed its requirements, requiring improved performance and payload capabilities. This caused serious problems for Boeing as its present design was expected to fall short of the requirements.

In order to overcome this, Boeing decided to change the wing and tail design of X-32. For tail design, two designs were proposed- a conventional four poster tail (like Lockheed's X-35) and a Pelikan tail (it was conceived by Ralph Pelikan, who worked for McDonnell Douglas and now for Boeing after their merger). The main points put forward in favor of Pelikan tail were,

It caused less drag compared to conventional tail
Offer pitch control at high AoA.
It had better stealth characteristics (two tails would be better than four).
The design would look different from the Lockheed concept.

However, the problem was that nobody has flown with this design so far. After some discussion, Boeing decided to go with the Pelikan tail. However, after a few days, the decision was reversed as the design was found to be heavier by a considerable amount as the larger control surfaces required beefier hydraulics and Boeing decided to go with a conventional tail, which turned out to be around 1500 lb lighter compared to the original design.

However, the prototype was not actually modified due to lack of time. The modified aircraft would've looked like this:

Image from aerospaceweb.org

Saab is testing a (sub-scale) concept with Pelikan tail called the FS2020, which has Pelikan tail.

Image from gripen4canada.blogspot.in


What advantage might interplane-strut mounting offer to ailerons, on the Curtiss Model F?

Disclaimer: I can only speculate, having no direct involvement with the development of the Curtiss Model F.
Stick forces were not really an issue with the small and slow early aeroplanes. As both size and speed went up, they would become a design consideration first because the pilot strength is lowest for lateral motion of the stick or control horn. With more aerodynamic experience, elaborated ways of reducing stick forces were employed.
My explanation, therefore, is that this is an early attempt at reducing stick forces. Hinged at the trailing edge, the complete chord length of the aileron would be behind the hinge line and no offsetting moment could be produced. Also, being part of the wing, ailerons hinged at the trailing edge will float up once lift is created. This requires both ailerons to be interlinked with stiff control cables which again raises stick forces, now from friction. Also, this preload from lift limits the effectiveness of a downward deflection of a wing-mounted aileron.
The free-flying aileron, on the other hand, has the advantage of starting with a clean sheet, if you will:

No preload exists, so it will be equally effective in up- and downward deflection.
It is not encumbered by the boundary layer of a wing flying before it, so its neutral axis will be easy to find and be constant over angle of attack, unlike that of a wing-mounted aileron. This was certainly not formulated this way at the time of the design of the Model F, but experience would bring the designers to exactly the same conclusion. The same considerations brought Junkers (more precisely: Otto Mader) to the offset flaps and ailerons in their designs from the late 1920s to early '30s.
With the aileron position between wings, the hinge line can be freely chosen at any chord position. The picture below (source) shows that a small part of the aileron was ahead of the strut, suggesting that the hinge line was not at its leading edge, but set back a bit. This enables the forward part to act as a balance, thus reducing stick forces.

I would expect that the Curtiss Aerorplane Company tried out different hinge line positions, which is easily done with the inter-wing arrangement, and settled on the one shown above, because it reduces stick forces considerably but still produces a clear centering force, which is important for agreeable handling qualities.
I do not think that the inter-wing position would reduce wing flex: Lift forces from the aileron are introduced into the wing by the rear strut, so both torsion and bending are very similar to a wing with ailerons on its trailing edge. To reduce torsion, the aileron would have to be mounted on the forward struts. Then they would even warp the wing in a way supporting the intended rolling moment. I speculate, however, that Curtiss and his engineers maybe considered that option but were afraid of the resulting aerodynamic interference between wings and ailerons.
That the inter-wing position lost against the balanced, wing-mounted aileron is certainly due to the much lower drag of the latter. Note that the inter-wing aileron needs its own rigging. With the increased experience of balancing ailerons, the wing-mounted version lost its main disadvantage and became the overall better solution.


Do U.S. aircraft carriers still include a Marine Corps squadron?

According to Wikipedia's page on Carrier Air Wings, there are nine active carrier air wings currently active (for eleven aircraft carriers).  Of those nine, CVW-9 includes Marine Corps squadron VMFA-314 operating the F-35C Lightning II, and CVW-17 includes VMFA-323, which operates the F/A-18C Hornet.
So out of nine carrier air wings, two include Marine Corps squadrons.  Not all carrier air wings include Marine Corps squadrons.  I believe other Marine Corps squadrons train on aircraft carriers, but are not permanently associated with air wings like VMFA-312 and VMFA-323 are.


In the IMA architecture, processing modules are hosted in a cabinet and are interconnected via a high speed bus. B777 uses "SAFEBUS" which is ARINC 659 on the backplane and ARINC 629 externally (same protocol, different physical layer). Airbus uses ARINC 664 internally and externally for the bus. Legacy bus interfaces go through an I/O module or other bus conversion interface.

The Airbus IMA contains 7 CPIOM (Core Processing & I/O Modules) that support both processing capability and I/O interfaces on a single module. It also includes one I/O Module (IOM) connected to the ARINC 664 bus for additional I/O.

The B777 AIMS cabinet contains Core Processing Modules (CPM) and separate I/O Modules (IOM).

The same functions exist in both, it's just that the Airbus CPIOM is a single module where B777 has two modules for the equivalent functionality.

And in a similar vein, the B787 IMA contains "GPMs" or General Processing Modules. It also contains two ARINC 664 network switches (network I/O for the cabinet). There are no direct legacy connections to the GPMs. Legacy (ARINC 429, CAN, discrete, analog) buses are connected to the external ARINC 664 network using Remote Data Concentrators (RDC).


Is Rutan's method of foam core construction obsolete?

I was a regular at Oshkosh during Rutan's heyday in the 70s, and had a chum that was building a Dragonfly, which used the same construction method.  Rutan's mold-less process is only suitable to one-off projects, like prototype parts, or amateur built airplanes.  It's a sub-optimal process from an engineering perspective because it is very time consuming to produce an ascetically decent component, and tends to be somewhat heavier than molded sandwich parts.
Rutan advertised extreme speed at creating a structure compared to metal or wood/fabric.  It was much faster to create a wing or fuselage... but then all the time saving was eaten up in finishing.  The method leaves a rough and somewhat uneven outer surface (due to the hot wire cutting process, where the wire bends under stress as it's cutting, producing a dished result when cutting a curved profile) that requires hours, and hours, and hours of filling and sanding (using looooong sanding blocks) with a lightweight filler made from epoxy and micro-spheres (hollow glass beads) to get anything close to the finish you get with a mold.
The hot wired foam cores, done by hand, always have surface continuity imperfections that need lots of filler, plus the outer surface of the epoxy tends to be rough.  You have to sand very carefully to avoid going down into the glass cloth.  The original layup method didn't use vacuum bagging and produced a heavy part with excess epoxy resin.  Later on builders started to vacuum bag the layups and use peel-ply fabric (polyester fabric similar to aircraft covering fabric, which epoxy won't stick to) with an absorbent material to soak up excess epoxy and provide a better outer surface (which ended up with about the smoothness of the peel-ply fabric, the outer surface being an impression of the peel-ply weave.
My chum sold the Dragonfly project before finishing it.  He just didn't have the time to do all the finishing work.
If you are going to build your own airplane from glass and foam, that method is pretty much the only option.  Beside Rutan's designs, the EZ's and Quickies, and the Viking Dragonfly, I can't think of any other designs off hand.  There was another scratch built homebuilt that used sheets of polyurethane foam bent to the skin curvature on a form, then layups done on the skin, that produced something closer to a modern fibreglass sandwich system without using molds, but I can't recall the name.
Here's is a complete guide to the Rutan moldless method.


Do I need special permission to land at a Landing Rights Airport?

According to the FAR's

  (2) Private aircraft. The pilots of private aircraft are required to
  secure permission to land from CBP following transmission of the
  advance notice of arrival via an electronic data interchange system
  approved by CBP, pursuant to § 122.22. Prior to departure as defined
  in § 122.22(a), from a foreign port or place, the pilot of a private
  aircraft must receive a message from CBP that landing rights have been
  granted for that aircraft at a particular airport.

This only matters if you are inbound from an out of country origin. An LRA airport is

  Landing rights airport. A landing rights airport is any airport, other than an international airport or user fee airport, at which flights from a foreign area are given permission by Customs to land.


Why does a phone's flight mode also disable FM radio?

All broadcast-band radio receivers contain local oscillators which are used in their intermediate frequency (IF) circuits to downconvert the (higher) frequencies they receive. These IF circuits are prohibited by law from radiating more than very small amounts of radio frequency power while operating, but to prevent any possible chance of having the airplane's navigation receivers pick up interference from portable radios, they have to be shut off during flight.
This is a minor problem today, but old-school shipboard radio receivers during WWII were supposedly capable of radiating enough power off their IF stages that submarines could tune in on them and use them as homing beacons to track convoys and then sink them.


Why do the emergency oxygen masks for some 787 premium class seats have an extra 'streamer' to pull them down?

So in premium there's an extra step

For what I see in the picture you posted, not really.

There is always the step "grab the mask and pull firmly" to bring it from the compartment to your mouth (and break the supporting cable, that is now unneeded, in the process).

What I understand from the third picture (first row) inside the image you posted is that they made this step "easier" for the premium class, they attached a string/made the usual one longer, so that you don't have to reach up to the mask pulling yourself up, but you can make the mask come down the full distance by pulling the extra string that will come down near to you. Similar to what is shown in this other card found by mins.

  I can't see how this is not an extra step though. Economy = grab the mask, Premium = pull the string, grab the mask.

I see where you are coming from, but in the economy version you still have to pull.
I agree that having to grab two objects in a sequence rather than only one seems to be counter-intuitive for an emergency situation, but without seeing the mechanism in action we cannot say much more than this.
The leaflets seem to indicate that the "premium" solution is made to be more comfortable to reach, nothing else.


Is it possible to take checkride past AFSP training request expiration?

As far as I can tell (and from my own experience), you don't need any TSA approval for a checkride.

Looking at the regulations, 49 CFR 1552.1 defines flight training as "instruction received from a flight school" (including from individual instructors). A checkride isn't instruction, as you said, although I can't find a regulation that explicitly says that (probably because there's no real need for one).

And looking at the FAA's requirements for checkrides:

The FAA's instructions to examiners for an instrument checkride don't mention security or say that they have to check anything related to the TSA or AFSP as part of the preliminaries (see section 5-434, Establishing Eligibility and 5-446, Procedures)
There's no mention of the TSA either in 61-65F - Certification: Pilots and Flight and Ground Instructors (apart from some notes on verifying identity)

There's also nothing in the IACRA process about the TSA or security either, which makes sense because that should match the checkride eligibility instructions.

My own experience is also that it isn't relevant to the checkride. I've done two instrument checkrides after getting the TSA's approval for training and neither DE asked me for any information about the TSA or AFSP, they were only interested in my logbook (and medical etc.). I suppose there could have been some extra check behind the scenes or in IACRA that I wasn't aware of (and my TSA approvals were still valid) but I doubt that was the case.

Finally, I realize that all this still doesn't give a positive confirmation that it's allowed, so if you want to have that I suggest you call the AFSP hotline and/or your local FSDO to get a definite statement.


Does the AP disengage if the plane is upset and how would the flight controls react if not being held?

For non FVW airplanes:

Yes it will disengage if certain pitch and roll attitudes are exceeded.  When it disengages, the controls are "let go" if the A/P was applying an input at the time, and the control column will move to whatever its natural trimmed state is at that time if the elevator is manually operated with trim tabs.

If the airplane has irreversible hydraulic controls and an artificial feel system and a trimmable stabilizer, the column will just spring back to neutral and the airplane will seek its existing trimmed speed.  If the trim speed is the same as the current speed, pretty much nothing happens, if the trim speed is much different that trim speed, the nose will pitch up or down to try to accelerate or decelerate to the trim speed set by the current state of the pitch trim system.

It's as if your copilot was flying, minding his own business, and you shot him dead.  The column will just go to wherever it wants to go when no-one is holding it.  The airplane has natural static "stick-free" stability so it will seek its natural trimmed state and if the A/P input was different from that, it'll just start going where it trim state wants it.  As if you pulled on the column and then let go.

On an airplane with control cables, the autopilot is a little computer running a bidirectional electric winch (the A/P servo) back in the tail who's winch cables are tied into the elevator cable run.  It drives the cable circuit from back there instead of from the column.  The autopilot also usually works the pitch trim that same way a human pilot would, to relieve the need for the servo to hold control pressures beyond a small threshold same way a human would.

So if the airplane was more or less in trim when the A/P kicks off, not much happens.  If the airplane was in some crazy attitude because of some outside event, the A/P kicking off is like you were flying and got flipped over and you took your hands off the controls to cover your face in fright (that's what I would do lol). The controls will just return to where they are trimmed to go to in that state.  On most airliners with powered controls and a moveable stab, the column always springs back to the same neutral position regardless of trim state.

If the a/c is FBW, the A/P is integrated into the computers that actually run things and it gets a lot more complex, although the end results are not that much different.


Why most military transport aircrafts use turboprop engines?

It depends on the main purpose of the mission.
For example, for long haul flights, carring many pallets, they will use probably the turbo jets, because they have more endurance, and normally they will land on longer runways.


Is this one of the engines from the 9/11 aircraft?

They are definitely not jet engines. They look more like electric motors or generators or blower units or something.


Why is the combustion temperature in a turbojet engine kept low?

Because the fuel-air mixture in a turbine is much leaner than what it would be for a stoichiometric combustion. It needs to stay lean to restrict the maximum gas temperature inside the engine - higher temperatures lead to exponentially shorter lives of the turbine components.


Why do helicopters not roll over when flying forwards?

Juan de la Cierva's first autogiro did roll over, twice, and he then applied the principle of blade flapping, a stroke of genius. Flapping is created by allowing the blade to move up and down. Depending on rotor head design this is done in different ways:

By a flapping hinge at the hub, allowing vertical rotation.
By a teetering hinge on two-blade designs, where both blades together are hinged so they can teeter-totter, one flapping up while the other flaps down.

The lift stays equal at both sides because of blade flapping. If the blades can freely travel up- and downwards, the forward going blade indeed experiences more lift, but as an effect of this starts to travel upwards and reduces its angle of attack. The rearward going blade experiences the reverse, less lift makes the blade descend and increases angle of attack. The lift distribution with and without flapping is depicted in this figure from Prouty, Helicopter Performance, Stability and Control:

The local angle of attack distribution of an example helicopter travelling at 115 kts looks like this:

The rearward going blade has a local AoA of 9°, not very far from stall. Increasing airspeed will at one point result in retreating blade stall, with associated loss of lift and increase of drag, and then the helicopter will start to roll over.

Notice that the reverse flow region is not really a big problem in lift creation:

It is close to the disk centre, where lift creation is minimal anyhow.
The loss of lift is reduced because of the increased AoA
Not only lift reverses, drag is negative as well: in this region the airstream actually helps to propel the blade, reducing the required profile power a bit.


At which speed is a plane traveling at hypersonic?

Hypersonic flight is generally any speeds between Mach 5 to Mach 10.  Although we set a speed delineation for the boundary between supersonic and hypersonic flows, the real boundary is where simple compressible flow aerodynamics using Mach and Reynolds numbers are no longer adequate to models the flow and multiple relationships between fluid mechanics, thermodynamics and heat transfer come into play.


Yes, here is a river landing.

and another, even tighter. This might technically be a beaver dam pond in a river.

and another, prettier. I'd back this one up and watch the approach.


Where can I download flight data containing pitch, roll and yaw angles?

FlightRadar 24 has an API that you can get data from. This is only from aircraft with ADS-B transponders, so it excludes some smaller and older planes. This would indirectly:

Give you points with which you could calculate the turns.
Give you pitch as the rate of climb.

This might give you a bigger but less exact dataset. Unfortunately, you might be disappointed in that normal commercial aircraft make relatively few manoeuvres at cruise.

Depending on the sort of simulations you might find that making a simulated flight in FlightGear (Open Source Simulator) might yield better results. If memory serves me right there is some equivalent to a flight data recorder so you can pull the data when you are finished.


Is the hydraulic fluid artificially colored?

A common hydraulic fluid used in aircraft is called Skydrol. The fluid is artificially colored, but this does not depend on which circuit it is in. The FAQ on the manufacturer's site addresses the color.

  Skydrol fluids are given a purple dye to make it easy to distinguish them from other fluids. But the dye does not usually last as long as the fluid does. The color may change from purple to gray or yellow or green, yet the fluid can still meet all used fluid specifications. Color is not a reliable indicator of fluid quality, and we recommend that the system be sampled for chemical analysis to determine if it is suitable for use. A dark amber color, however, is a cause for concern, and can indicate a severely stressed fluid. Call Solutia's Technical Service for assistance if you are unsure about a fluid's color. Our technical bulletin has a color chart to use as a guide.

Initially the color helps to distinguish from other fluids, and having multiple colors would make it more complicated. It notes that the color also does not remain constant, so even if it were colored initially, it would probably end up changing anyway. It also mentions that a dark amber color can be an indicator of issues.

I can't find any good pictures, but the lines are probably not color coded. Any colored hydraulic system components are generally purple (like the fluid). The lines themselves can be labeled, but the standard for hydraulic lines is blue and yellow. The end fittings are colored to identify the tube material type.

The maintenance manuals will show the layout and label the different lines. Also, on this ASRS page, one report is from a mechanic that confused the green and yellow system fittings, which probably wouldn't have happened if they were color coded.


How are aviation regulations treated on a global stage?

I'm going to answer this from an aviation safety regulation viewpoint only. There are many broader considerations, such as criminal juristictions, employment, and environmental laws, which will have differing answers. I'll also add that my experience is with the Australian situation, but I don't think it varies too much around the world - happy to be corrected.

So with all that considered, the answer is... sort of both! The short answer is that they must follow the direct operating procedures of the country they are flying in, but some "back office" regulations do not apply.

Firstly to ICAO. This organisation isn't really concerned about individual airlines. Their primary purpose is to set international standards for the individual regulators to implement. But these Standards and Recommended Practices (SARPs) are not enforceable - individual states can simply lodge a 'difference' and continue to do their own thing. Another important job of ICAOs is to basically regulate the regulator, giving them a rating on how safe they are. The FAA and EASA also conduct their own audits for the same purpose.

Each airline needs to be certified in its home country with an Air Operators Certificate (or Part 121 Certification, or the many other variants around the world). Part of this process involves approving pretty much every single procedure the aircraft would ever do in normal operations - including the procedures at international ports. That means that for an Australian airline wanting to fly to LAX, the Australian regulator CASA has to inspect the port and approve it for use, checking that what the airline has proposed complies with the local airport procedures.

So, once the operations at LAX have been approved by CASA, the airline then approaches the FAA for a Foreign AOC/Part 121 approval etc (I'm not certain of the US naming convention). This certification process for a foreign certificate is almost always no way near as thorough as the full version. A lot of it depends on the home countries regulator and their status with ICAO or the FAA/EASA. If the FAA knows that the oversighting country is up to scratch, issuing the foreign certificate might just be a tick and flick exercise.

This 'foreign' status of this approval is key to your question, because many regulations are written like "the Part 121 operator must..." and NOT necessarily "the Foreign Part 121 operator must..."

Take a breath now and try to follow this. In the majority of occasions, the foreign approval says that the airline must operate in accordance with what has been approved by CASA. But, the procedures which CASA has approved are already tailored to LAX-specific operations! So you can see that the Australian airline has to obey the conditions of its FAA approval, which is to follow the operations set by CASA, which is to follow the US procedures!

But what if CASA and the FAA have differing regulations? We do have different requirements for things like fatigue management. Pilots who get a medical clearance here might not get one from the FAA. These 'risks' are pretty much just accepted by the regulators as being extremely unlikely to bring down a plane in their territory given the handful of flights a week they will be making. In extreme circumstances the FAA could place some sort of condition on the approval to further mitigate the risk of differing regulations.


Do pilots adjust the throttle setting during a Red Bull air race?

The only reference I could find is here (watch the video too):

  Pilots keep throttle on full for racing.

It is a race. Only the fastest one wins.