What is the correct phraseology to request a climb? If you'd like to request a climb to a higher flight level while cruising, which do you think is a more proper way to request it:

Request to climb FL350
Request climb FL350

I know they have zero difference in meaning between them, but I'm curious which one might sound more natural or professional in the EPTA test.

I would say that “Request climb FL350” is better.

I never use the word “to” in altitude requests as it can be confused with “”two” as in “request climb to seven thousand” (request climb two seven thousand)

If you get in the habit of using “to” with flight levels, you will probably use it in a baro altitude request as well.

I also leave out “climb” and just say “request FL350”. But, when ATC says “climb FL350”, I will read back “climb FL350”.


Why does this plane have vapor trails coming out of wings? See this video of Birmingham strong crosswinds landings:

At 2.57, there is a 737-800 landing (screen shot below).
One can clearly see some vapor (?) coming out of what seems to be two holes on both wings, from 3.03 to 3.10, were the plane lands.

This does not seems to be a 'classical" vapor trail, as asked in this question, as it clearly does not occur at the tip of the wing.

What is this? What explains this? Something specific to the 737-800?

Edit: While it is clear to me that this is a vapor trail, the question is more about why there is a vapor trail at this precise location of
the wing.
Usually, these appear at the wing tip, and this is clearly not the case
here. Maybe something with the flaps, as suggested ?
Thus, while the question itself is not exactly a dupe, this answer (and the associated pictures) give a clear explanation.

This are indeed the vortices a wing sheds where lift suddenly drops. That they occur at mid-span and not at the tips is due to flap deflection. They do indeed start at the outer edge of the Fowler flaps. @NilsNielsen explains well why you see a white line at the core of the vortex.

See this photo (source): This is the same thing happening. It is not specific to the 737-800, but to any aircraft with powerful flaps which end at mid-span to make space for the ailerons.


What happens to the pressure and density of air passing through shock waves? I understand that the pressure and density of air increase as the air gets closer to shock waves and the pressure and density of air that has escaped the shock waves increase as well. Then, what happens to the pressure and density of air passing through the shock waves? I guess the density of air would decrease due to the great heat produced by the shock waves (correct me if I'm wrong on this) but what about the pressure? Does it increase because of the heat?

Please rethink your understanding of shocks.

In compression shocks, pressure and density increase suddenly without any change as the air gets closer or flows away from the shock front. All change happens momentarily as the air passes through the shock front. A compression shock is caused by an obstruction to the flow.

Supersonic speed means that the obstruction (a speeding bullet, or an airplane, for example) is moving faster than information about its presence will move through the surrounding air. This information would be a pressure change (like sound waves), but the propagation speed of such sound waves is determined by the physical properties of the medium through which they travel. Only exceptionally violent pressure changes can move faster than this limit - this is why you see first a rapidly expanding ball in movies of nuclear explosions which then abruptly changes to a much more leisurely speed of expansion as the ball grows and the magnitude of the pressure change at its boundary drops. (Note the spikes at the bottom of some of the fireballs in the linked movie: They are caused by the steel beams and tension ropes of the towers on which the bombs were placed. The speed of sound in steel is much higher than in air).

Still from high speed movie of a nuclear explosion (picture source)

The opposite of compression shocks are expansion fans: They let pressure and density drop over a region and are caused by a receding contour of said obstruction. Again, ahead and past the fan region the parameters do not change, but the fan region is protracted the more you move away from the contour change causing it.


What runway has the steepest climb requirement on take-off? What runway has the steepest climb-out requirement upon take off?

This would probably be due to the need to avoid some natural obstacle, such as a mountain.

The first one that came to mind is London City Airport (EGLC) which is world famous for its steep approaches, and for which I found these requirements on its departure charts:

  OBSTACLE CLEARANCE -
  RWY 09: Maintain minimum 6.76% climb gradient to 275 (258).
  RWY 27: Maintain minimum 7.20% climb gradient to 1102 (1085).

(Where the first number is altitude in feet and the second number is AAL, above aerodrome level)


Why didn’t the Concorde have flap-canards like the Tu-144? One of only two ways of which I am aware in which the Tu-144 was “ahead” of the Concorde1 was in its use of retractable flap-canards, which increased the lift on the front of the aircraft at low speeds, thus allowing the aircraft’s elevons to be used as flaperons (flapevons?) for increased lift without pitching the nose down uncontrollably, and, thereby, decreasing the required takeoff and landing speeds;2 the Concorde, in contrast, had no high-lift devices at all as produced.3

Although the Concorde’s myriad aerodynamic advantages over the Tu-144 allowed it to take off and land at much lower speeds than the Soviet SST even without any canards, its takeoff and landing speeds (especially the former) were still very high by airliner standards, with a typical approach and landing speed of 160 kts (296 kph; 184 mph), and a rotation speed, at maximum takeoff weight, of nearly 200 kts (370 kph; 230 mph).  This made the Concorde require very long runways to take off and land (and required the readdition of afterburners in order to keep its runway-length requirements from being even longer), forced the development of a whole new type of brakes in order to be able to stop the aircraft during a landing or rejected takeoff,4 and greatly increased (due to a] centrifugal force, and b] downforce on the main-gear tyres during rotation) the stress on the tyres, and the potential (and actual) destructiveness of a tyre failure.

Why didn’t the Concorde use flap-canards to further decrease its takeoff and landing speeds?

1: The other being the use, in later Tu-144s, of a non-afterburning turbojet.

2: Despite this, the Tu-144 still had a much higher landing speed than the Concorde, thanx to all its other aerodynamic deficiencies.

3: An improved version (the Concorde B) was planned, which would have included leading-edge droops (as well as larger wings and non-afterburning engines) for improved efficiency in subsonic flight and decreased takeoff and landing speeds, but the Concorde programme was cancelled just as the production line was getting ready to build the first Concorde B.

4: Not that I’m complaining about carbon brakes!

It did not need them. Concorde could operate from most commercial airports and did not need especially long runways. Retractable canards add drag and the mechanism is a point of failure.

I fail to see how Tu-144 canards is a “superior” feature as they were added to support a less effective wing.

Very much related: Why is the Tu-144 the only commercial airplane with canard configuration?


Why is the ISOLATION VAVLE switched to OPEN during ENGINE START on Boeing 737? As the SOP says in Preflight Procedure – First Officer:
"ISOLATION VALVE switch – OPEN"
In this way, when engine starts, the ISOLATION VALVE is OPEN not AUTO.
The PACK valve is switched to OFF, under AUTO can also make the ISOLATION VALVE open.
SO why is the ISOLATION VAVLE switched to OPEN instead of AUTO?

Position OPEN is guarantee correct work supply air bleed, AUTO is not. For safety.


What to do if the captain smells like alcohol? Suppose you're the co-pilot on a flight and during pre-flight, talking to the captain, you smell alcohol.

Although you didn't see him drinking and the smell isn't strong, what does regulation stipulate you should do?

Unfortunately, at least in the US, the regulations don't stipulate that you do anything. Airline policy is a different matter, and one which I cannot speak to, as it will be different in every case.

I can provide some background and my own take on this, but it's hard to have one exact answer (what if you're wrong?).

FAA regulations rely on pilots self-regulating. If a pilot drinks within an 8 hour (or, as is often policy for airlines, 12 hour) window prior to the flight, they are required to remove themselves from that flight. If they do not take this action, somebody else must. Often, this person is the First Officer, a junior pilot who has years of flying with pilots who might come to view them as untrustworthy. Perhaps this can help explain why it's such a difficult action to take.

This is a difficult topic, and one which regularly comes up during airline flight training. That said, the courses I took that discussed this scenario essentially landed on a couple of steps (this was years ago, this is probably a bit rusty):

Confront the pilot. Ask them if they've been drinking in the last X hours. If they claim they have not been, or they push back:
Attempt to explain to them the situation they're putting their career (and you) in;
Try to get them to remove themselves from the flight and contact a union representative.

Beyond that, I don't want to make suggestions. Getting them to talk to the union they are a member of is probably a wise idea, as they can offer possible solutions or arrange treatment if the pilot has alcohol abuse problems (which is not a huge stretch, if they're showing up to work reeking of booze). AOPA Flight Training has a blog post that discusses some similar scenarios.


What and where are "flotation seat cushions"? Inspired by the question Why did the US Airways Flight 1549 passengers stay on the wings?
I read parts of the respective accident report[PDF]. They mention the flight was a
non-EOW (extended overwater) flight but was luckily equipped as such anyways and thus had life vests and
"flotation seat cushions".

Section 2.10.3.3.1 "Equipage" of the report states

  Because the accident airplane was equipped for EOW operations,
  it carried life vests for both passengers and crewmembers.
  However, given that the accident flight route was not an EOW
  operation, the airplane could very well have been equipped
  with only slides and flotation seat cushions as the primary
  means for passenger flotation.

I've never heard of such a device, I only know the life vests below a
passenger's seat. Can the seat cushion (the part where you sit on, I assume)
be detached from the seat to serve as a "swimming aid"?

Maybe it's different in the US and Europe. I sometimes fly from Germany to the UK
and the FAs never mentioned any cushions. How comes?

It became something of a meme:

  In the unlikely event of a water landing, your seat cushion can be used as a flotation device.

You remove your seat cushion and hold the straps on the back as a flotation device. It's probably more of an aircraft/airline thing than by country. It seems that the industry is favoring life vests more, as they are designed to keep a person afloat and face up even if unconscious and not adding the requirements to the cushion allows the seat to be smaller and lighter.

Source


Using a standard PC gaming / smartphone headset for passengers in a small plane There is a very similar question to this, but all answers and discussion pertain to just the PC headphones, and not headsets (the headphones with microphones). Gaming headsets have a boom mic and cable with dual connectors (pink/green), both 3.5mm, one stereo (for headphones), the other mono (for the mic). Standard smartphone headsets have a mic on the cable and a single 3.5mm TRRS (tip-ring-ring-sleeve) combo connector. There are plenty cheap ones with active noise reduction, decent audio quality on both headphones and mics, and more importantly, many people already have them. There are also plenty of Bluetooth headsets (with mics).
A possible solution would be building a Bluetooth adaptor that could plug into the intercom, and then pair with the passenger’s headset to allow them to communicate with others. Bluetooth frequencies are well outside the range of any of the nav/com systems, and even so, they would give the pilot a good excuse to avoid passenger distractions during departure /approach (by turning the Bluetooth transceivers off). Resourceful home builders could easily get the necessary electronics for the Bluetooth transceiver (and adjust the impedance as needed).
If the mic (and headphone) impedances are reasonably close, wouldn’t a simple cable adapter be all that’s needed to enable connection?

This is an interesting question. But, I don’t see what this solves. There are aviation headsets as cheap as $50. That is as cheap as gaming headsets. But, they are specifically designed for aviation to include passive noise reduction. There would be no advantage to using a gaming headset in aircraft.
The primary purpose of aviation headsets for the pilot is to provide clearer communication between the pilot and ATC. But, that purpose shares equal importance with the goal of hearing protection.
Small, General Aviation aircraft are very loud. But, aircraft have speakers and microphone handsets that make communication with ATC still possible. In decades past, headsets were not even worn in enclosed cabins. And, it has only been recently that the effects of noise has been considered a factor in fatigue. Unless the headset addresses the concern of noise reduction, it is of little benefit in the aircraft.
For passengers, noise reduction can be accomplished with industrial or firearm hearing protection. Non-crew member military personnel function with only standard earplugs aboard aircraft. Communication between personnel in the aircraft even with the doors open is accomplished through shouting over the ambient noise. As far as the pilot turning off a Bluetooth device to enforce “sterile cockpit” practices, that can already be accomplished as a built in function of the aircraft audio panel.
So, although a very simple adapter could be built to enable gaming headsets, cellphone headsets, and earbuds to be used in aircraft, it does not truly solve the problem you posed so far. And, it is not truly better than purpose-built aviation headsets. However, my purpose-built aviation headset is Bluetooth enabled, and can be used with a Bluetooth enabled computer like a gaming headset.


Do commercial airliners use supercritical airfoils? I was looking how speed is distributed on this B747 airfoil:

Source.

Nearly all of the upper surface has air flowing above Mach 1. I'm wondering if this is frequent for commercial airliners to use supercritical airfoils? I'm particularly interested in the A330 case.

Supercritical aerofoils are definitely widespread in modern airliners, including the A330. In fact, the A300 which is the predecessor to the A330 was one of the first airliners to fly with a supercritical wing.

The reason for this is that maintaining slightly supersonic flow over the majority of the upper surface keeps it at high speed, hence producing low pressure and lift for longer and it also shrinks the shock from flow decelerating back to subsonic, compared to a conventional foil. As well as these direct aerodynamic benefits their thicker t/c ratio compared to efficient conventional sections makes the wing structure easier to design, making them a no-brainer for pretty much all modern airliners.


How do tailless aircraft yaw? I was doing research on control surfaces present on an aircraft and I noticed that some aircraft like the B2 Spirit does not have a vertical tail stabilizer and therefore no rudder either.

How do aircraft such as these perform turns and counteract adverse yaw in banked curves? Do they apply some sort of differential thrust system for turning?

Technically the B-2 bomber has rudders, they are "drag rudders" (or split rudder) and are located on the outer portion of the wing:

Source: Quora
The rudders open in a clamshell configuration to create a drag force on the outer part of the wing. Because these are on the outer part of the wing, they can create a significant yaw force.


Is a Mooney M20 a difficult plane to fly as a beginner? I am considering purchasing a Mooney M20 for 60k to fly for my initial certification. I'm not sure if this seems like a logical choice on the surface but let me explain my reasoning. I travel quite a bit. I live in the Dallas area and drive to Houston, Austin and San Antonio regularly. I average 60 hrs in the car a month traveling. This aircraft would be used for travel on a regular basis, 15-20hrs a month. The speed of the mooney is what is most attractive to me. I considered a 172 but the faster Mooney will save me valuable travel time. I will occasionally have 2-3 passengers with me.

My questions are:

Am I crazy?
Is a Mooney a difficult aircraft to learn in?
Should I suck it up and pay the rental fees and buy the Mooney after I get my license?

You need to be a bit more specific as "M20" refers to a lot of aircraft. An older M20C or M20D (with the fixed gear) should be quite manageable. An M20TN Acclaim is out of the question. Since you mention 60K I assume you are talking C/E variant but clocked out J's can be had for that. You can likely find an A/B but wooden wings are not for new owners or the faint of heart.

I have a Private Pilots License, an Instrument Rating, and a Complex Endorsement (which you need to fly just about any Mooney aside from the fixed gear D model) and have been pretty seriously looking at buying a Mooney as well as flying a few. Here are some thoughts:

The older Mooney's are on par with the other various trainers (PA-28/C172) size and load wise but tend to be about 10-15% faster on 10% less fuel. When it comes to flying, speed is generally what makes an aircraft "harder" to fly. The faster you go the faster things happen and the more likely you are to make a mistake or enter some airspace you shouldn't. In a Mooney, which is generally a faster plane you are of course more likely to have these issues.

You need to consider when training in a complex aircraft you are adding two additional things (gear and prop control) to an already confusing environment which can add to training time and increase your chances of messing something up.
Buying an aircraft for training can save a lot of money in the long run but what if you end up not liking it?
Although rentals are not always super well equipped in my experience they tend to be pretty well maintained as the flight schools are in the business of making money, so you dont lose training to the fact that you cant afford some AD or other maintenance issue.
Insurance premiums on a complex aircraft may be high for a new pilot. I can tell you that premiums for an M20C/E once you have your license are reasonable.
Mooney's have their own maintenance quirks but with the recent PA-28 spar issues that pretty much every GA plane has some kind of pricy issue.
You may want to define 2-3 passengers a bit better, a significant other and two kids is a lot different than 3 other "buddies". The back of most light aircraft is not exactly the most comfortable place.

I would take a serious look at this guy's thread he has a D model he has been working on for some time. The tale is a good example of what you are in for.


Is there any recorded instance of a passenger's hat or scarf being blown into an aircraft's engine? Passengers climbing the stairs into an airliner are often subject to gusts of wind; I've had to hold onto my own scarf in the past.

It doesn't seem beyond the bounds of probability that a passenger's hat or scarf could be whipped off suddenly, to be deposited into a windmilling - or even idling - jet engine.

Has this ever happened?

I would imagine that the average hat or scarf would be better for an engine than a handful of good-luck coins.

If you are boarding with an engine running, it's going to be the one on the opposite side running with the one on the boarding side shut down.  However, there's little doubt that items like that have flown off heads in high winds and drifted across to the opposite engine and been ingested, in all the millions and millions of flight hours over the decades.

In any case, something light enough to get carried off by the wind like that would just pass through the fan, or, if it was sucked into the core, get chopped to little pieces, burned and come out the back as ash particles.  A large enough item would probably cause enough flow disruption to affect the engine's idle and give a turbine temperature spike, but it's unlikely to do significant damage unless it was, say, an entire coat or something, and that would required a mighty windy day.

What's biggest Foreign Object Damage threat to engines on the ramp?  Luggage zipper tags.


Why aren't there any jets with horizontal-stabilizer-mounted engines? Looking at the spectrum of where jet aircraft put their engines, there are examples of almost every place that could conceivably used to carry a jet engine:

slung under the wings
buried inside the wings
on top of the wings
on the sides of the aft fuselage
in the aft fuselage
on/in the vertical stabilizer

Notably absent, however, are jets with engines having anything to do with the horizontal stabilizer.

Why aren't there any jets with engines mounted on/in their horizontal stabilizer?

There are two configurations I can think of.
1. The jet mounted on the horizontal stabilizer (above, below, or the tip)
Unlike the vertical stabilizer, the horizontal stabilizer is trimmable (THS). It's constantly moving, which means when it moves, so would the thrust line. A kind of thrust vectoring that you don't want. For example, trimming for slow flight during approach, the thrust line will point down and aft of the CG, which will in turn point the nose further up, this is a kind of a destabilizer. Even if the angle is not too big, the changing thrust line will always act against the intended trim. And lastly with the engine constantly on the move, the blade tip clearances will need be bigger, which will in turn reduce the engine's efficiency.
The required strength issues that result in a heavier weight are also a factor. This also impacts the loading flexibility; a tail heavy plane will reach a point where you can't put as many passengers in the back without adding a forward ballast.
2. The jet mounted at the root and doesn't move with the THS
While certainly achievable, like the L-1011's number two engine wrt the vertical stabilizer, the issue here is not why aren't the jet engines there, it's why the THS is not there.
The horizontal stabilizer of a plane like the DC-9 (and its extended family) is purposefully placed above the tail, creating a T-tail. With the tail swept back, the top of it is farther from the plane's center of gravity, giving the THS a bigger moment arm, and in turn allowing a smaller THS, and the other benefit that comes out of that is the end-plate effect of the T-tail, which also permits a shorter fin for the same control authority.
You'll also notice buried engines are of the older small-diameter type, except for large planes like the L-1011, but still that makes maintenance access a lot harder, than an exposed engine.


What could be the cause of an uncommanded roll at high speed? I have a problem with a T-38. There is uncommanded roll to the left when the aircraft flies at 250 knots. But as the aircraft speed goes up around 500 knots, the uncommanded roll is now to the right. During 500 knots we could control the plane with 15-20 aileron trims.

What may be the problem?

We have replaced a lot of systems and cylinders. And we changed the travel limits of aileron, flap, rudder, and horizontal stabilizer. But no change has been observed.

I once went on-site to troubleshoot an airliner with an uncommanded roll problem.  The operator had rigged this and rigged that and were in the process of ordering new aileron power control units, pretty much out of desperation.  I asked about the trim actuator, which they had replaced with a known good unit off another aircraft, making them think that couldn't be the problem.  I centered the trim and went to look at the position of the rig pin holes in the aileron control circuit.  They were mis-aligned.

The trim actuator on this airplane was an electric linear type with an internal Linear Variable Displacement Transducer (LVDT), that supplied the position signal to the cockpit trim indicator (or EICAS in this case), that was "dithering", that is, the signal was drifting around.  When you thought the trim was centered, it was actually offset, and this error would randomly change as the actuator was moved.  On the original airplane the actuator was installed on, the dithering wasn't enough to cause a snag to be raised by the flight crew so its internal problem went undetected.

The variations in roll you saw at speed may be some other phenomenon, or it just could have been coincidental variations in the trim indication on that flight.

So, if it was me, the trim system itself would be an item to cross off the list before proceeding to more desperate measures. Do a thorough functional test of the trim system and its indication, and also look for things like backlash within the actuator itself or in the linkage.


Can audible warnings be heard from the cabin? When I fly in the front row on an all-economy A320, I can very clearly hear the autopilot disconnect sound shortly before landing.

Can passengers in the cabin also hear other warnings like EGPWS (Terrain!), TCAS (Descend, descend!) or others?

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

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


Is it possible to extend an AFSP training request? My training request expires in a week or so. Is it possible to extend it or do I have to submit a new one if I'm running out of time?

Assuming that you're in category 3 (aircraft under 12,500 lbs) then an approval is only valid for 365 days, so if you want to continue flight training after that then you need to request a new one:

  Once you have permission to train, you have 180 days to begin training
  and 365 days to complete the approved training. Both of these time
  periods start from the day you receive approval. For example, if you
  begin flight training 30 days after you have been approved, you now
  have 335 days to finish. If you do not finish, a new training request
  must be submitted.

That's from the AOPA AFSP guide; the TSA's own AFSP webpage is a bit more difficult to use.


How can an airliner make up for time lost? If a plane has been delayed at the origin how does it make up for the lost time? Does the pilot need any special permission from ATC to increase the speed so that it can cover the lost time or has the pilot the power to make such kind of decisions?

That's a common scenario, that you're pushing off the gate late and would like to make up time.  There are a number of ways that making up time can happen, although how much of that the pilot can affect doesn't often amount to a huge impact.

The flight is scheduled for whatever length of time, gate-to-gate.  This accounts for the sorts of delays that the planners foresee when they're building the schedule: it's winter, so the aircraft may need to be de-iced.  It's a busy time of day, so they plan on a slower taxi than simply driving out to the runway & taking off.  The flight is usually scheduled around a moderately worst-case headwind/(lack of) tailwind.  And so for the 1+00 (in the air) flight, you might be scheduled for 1+30 gate-to-gate.

And if some of the negative factors don't materialize, then you'll under-fly the schedule, which is nice.  Maybe the delay at the gate caused you to miss the "morning rush hour" and you did get to taxi right out, no line or delay, and take off.  There's no precipitation, so no delay for de-icing.  The tailwinds are better than average today, so instead of 1+00, your flight will only be 0+55 in the air.  All good things!

But none of that is really under the pilot's control.

The two places that the pilot can most affect things are, going faster, and getting shortcuts.  Going faster essentially means using more gas, and sometimes guys are willing to do that... the high-school tour group is in danger of missing their connecting flight & being stranded in the hub for the night, let's go fast & get them there!  Another version of going fast is flying at a more "speed efficient" altitude, usually around FL290 or FL300.  If winds are all the same, you'll generally get more speed there because your maximum indicated airspeed (Vmo) and limiting Mach number (Mmo) are very close around that altitude.  The tradeoff is, however, that you are burning more gas by doing this compared to going higher.

If you have the gas to burn, this can typically work.

Also, you can request shortcuts.  Depending on the filed route and what's going on in the airspace, this may get significant savings.  From the West Coast to DFW or IAH, you're typically routed around the north or south side of White Sands.  But, if it's Saturday night and the restricted area is cold (not in use), then you may be cleared direct right through it & save some significant time.  Of course, requesting shortcuts also saves gas (unless it takes you off a wind-optimized route -- rare but possible), so there's no real reason not to do it on every leg.

ATC may or may not cooperate with your plans.  If the restricted area is hot, then you don't get the shortcut through it.  If you're inbound to a busy terminal area (DFW, LAX, IAH, BOS, etc) then ATC probably has a sequence in mind, and they won't approve anything that changes the orderly flow of aircraft into the arrival.  In fact, they may assign you a speed in order to fit the sequence together.

Other than that sort of planning, though, they typically don't mind if you fly fast, and if they aren't too busy, ATC usually approves requests for shortcuts that don't have you driving through restricted areas (or other special use airspace).

How much time can you make up as a pilot?  If you really want to burn the gas, you might make up 5-10 minutes by going fast on a typical 1-2 hour flight, but those extra minutes are getting pretty expensive when you do that.  Shortcuts may give you another 5 minutes or so, in the best case.  (Longer flights tend to be more direct, as a % of the time, so you can't get the bigger & bigger time savings on the longer flights with shortcuts as you do with speed, compared to the short flights.)

But when a pilot tells you that he's going to make up 20 minutes off the planned flying time, most of that will probably be already baked in (tailwinds, no delays, etc) rather than things that he's doing differently than he otherwise would.  (It's still a nice line on the PA, though.)

And some days, none of the above works the way you hope, and the late flight doesn't get any earlier, or even gets later, despite your best efforts.  Speed, time, and distance can just be a bear, sometimes!


Does an rc plane tail also have airfoil or is it just flat material? I've chosen an airfoil for the wing, now i'm confused weather i should do the same for tail or just attach a flat piece of wood as tail. I'm going for conventional tail design.
This is my first ever plane so sorry for the dumb question.

A flat piece of wood with rounded edges will work fine.

The tail's job of producing downforce doesn't require the lift coefficients or angle of attack range required of the main wing, so the actual airfoil shape is not that important especially at low speeds, even more so under the low Reynolds numbers ("thick" air) that RC airplanes work at.

In fact most fabric light aircraft get by with what is effectively a flat surface wind deflector, like this Super Cub.


How is the center ILS used on the 747-400? The aircraft has 3 ILS receivers, but only ILS L and R in the CDUs. How does the ILS C is put into action?

It depends on which page you are viewing. There is the NAV RADIO page, and the ALTN NAV RADIO page.

In standard operation (i.e., nothing has failed, more on that in a bit), there are no separate L and R ILS entry lines on the NAV RADIO page (unlike for VOR and ADF).

A single entry, on either CDU, tunes all 3 receivers to that frequency. If FMC 1 and 2 failed, the alternate nav radio page (ALTN NAV RADIO) can be used. And this is where the third CDU comes in.

  If both FMCs fail, ILS receivers can be tuned on the CDU ALTN NAV RADIO page. The left ILS receiver is tuned with the left CDU, the center receiver is tuned with the center CDU, and the right receiver is tuned with the right CDU.

Source: Boeing 747-400 FCOM 11.20.6 (emphasis mine)

Here's the location of the center CDU:

(wikimedia.org)

Note: Normal operation is based on auto tuning, say unlike a 737NG where the frequency is manually selected left and right. With the approach selected, and within range, the plane auto tunes the frequency. The crew can then confirm the identifier on their displays.


What was the first aircraft fitted with both an FDR & CVR? What was the first production aircraft to be fitted with a Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) as standard by the manufacturer?

It's not easy finding out which aircraft rolled-out with the first standard CVR/FDR combination. In fact it's so hard Google thought I was a robot, maybe I am.
Here's why, first this piece:

16 July 1964
COCKPIT voice recorders that will record all flight-deck conversations between the crew and ground control will be required in large passenger aircraft under new rules issued by the Federal Aviation Agency. Designed to assist in accident investigation and prevention, approved cockpit voice recorders will be required by July 1, 1966, in jets and turboprops weighing more than 12,500 lb. Pressurized four-engine piston aircraft will have to meet the requirement by January 1, 1967.
The installation of cockpit voice recorders supplements the existing requirement for critical-data flight recorders on similar aircraft. The latter, says the FAA, have been found indispensable in helping investigators determine probable accident causes, thus aiding development of ways to prevent accidents.

FDR's preceded CVR's and were already standard equipment on jets and turboprops weighing more than 12,500 lb. Then came the above CVR mandate to take effect by July 1966.
But, the CVR was not a new invention, and was already fitted to many aircraft, in fact, five months before the above piece we find this:

6 February 1964
Trans Canada Airlines has taken a world lead by announcing that it will spend \$1,360,000 to equip all its 78 aircraft with maintenance recording equipment. The airline has been investigating the use of the Royston Midas system for more than a year and last October took the decision to equip its fleet. Final details of the actual installations are now being decided, preparatory to placing a firm order, some additional steps having been taken as a result of the DC-8 accident at Montreal last November. TCA are to have a 93-channel system covering engines, movable surfaces, hydraulic and electrical systems and 15min of cockpit voice, installed in a safe location in the tail of its DC-8, DC-8F, Vanguard and Viscount aircraft. The installation will cost \$20,000 for each of the larger aircraft and \$15,000 for each Viscount and will be performed at Montreal and Winnipeg.
Next airline to place a major order for Midas may well be TWA, who have been conducting a systematic and successful investigation of its application for some time. The RAF first equipped one Britannia of Transport Command and has now ordered five recorder systems and four complete playback installations, presaging much more extensive adoption. British United Airways have also been flying a Midas-equipped Britannia for some six months.

Trans Canada Airlines being the first to equip a CVR/FDR/QAR combo well before the FAA mandate.
The CVR being an Australian invention, some sources say CVR's were required in Australia before the US, but given how many aircraft manufacturers were there in the mid-60's, it's near impossible to know which one was the first.
No one was eager to market their plane as the first that tells you why you crashed.
Most articles I found from the 60's were CVR manufacturers promoting their new products, but no aircraft manufacturer mentioning them. Example below:

Source used: Flightglobal Archive


How can I find telephone numbers for FAA ATC facilities? It is often desirable to call an FAA air traffic control (ATC) facility on the telephone:

To ask a question about a "mark-the-tape" incident
To request a tour
To notify the facility of unregulated nearby operations like RC plane flying

How can one find the non-emergency telephone number for an ARTCC, TRACON, or control tower (ATCT)?

You would think the control tower phone numbers would be listed prominently and conveniently on the FAA website.
You would however be wrong1.

Your best bet would be to contact the Flight Standards District Office that covers your area - they can get you in touch with whatever other branches of the FAA you might need to talk to. You can also get tower phone numbers from Flight Service (1-800-WX-BRIEF).

AC-U-KWIK also has tower phone numbers in a conveniently searchable system (punch in the airport identifier and it will be in the results you get), and the printed edition of the AOPA airport directory used to have tower numbers as an appendix (I'm pretty sure it still does).

1 – Actually that's not strictly correct: some regions publish tower numbers prominently. Most don't, or my search skills aren't good enough to find them.


Does an aircraft landing on a carrier increase the carrier weight before it touches down? The same question goes for any runway, but I guess that for small aircraft carriers, one might actually be able to measure the exact point of weight increases (e.g. measure the submersion of the hull). For helicopters, it seems that this is the case, so I would presmue the same for fixed wing aircraft.

No. Weight is defined as the effect of gravity on a body. Until the aircraft becomes part of the body of the carrier, it has no effect on the weight of the carrier.

I think you are confusing force with weight. For example, if wind shear drives wind against the top deck, this does not make the carrier have more weight, but it does cause the carrier to move down. Likewise any gust from an aircraft may apply a force to the carrier, but does not increase its weight. You might consider that force to increase the "apparent weight" of the carrier, but it cannot be said to increase the weight of the carrier itself.

Note also that the downward wind force of a landing fighter is relatively slight. For example, a person can easily walk under rotating helicopter blades and still stand up and walk. The force is probably only around 1-2 pounds per square inch, maybe 5,000-15,000 pounds total. For an aircraft it will be even less.


Is induced drag essentially nothing more than a specific type of form drag? If I were standing outside on a windy day holding a flat rectangular object such as a food tray up in the wind, orthogonal to the direction of flow, the drag created would be classified, mostly, as form drag; a differential in pressure from the higher pressure upwind side of the tray and its lower pressure downwind side.

If an airplane's wing began at a 0 degree angle of attack and were slowly rotated to a 90 degree angle of attack, lift would increase until the critical angle of attack is exceeded, but the coefficient of drag would continue to increase up to 90 degrees.

I assume the drag created by the wing at 90 degrees is much like the form drag created by the tray in the wind.

Is induced drag nothing more than form drag with a different classification due to its usual nature of discussion in regards to lift?

No, by definition it isn't.

There is drag. Drag is caused by different physical phenomena. According to the cause, it is classified to:

Induced drag

Induced drag is side-effect of generating lift over finite wing span.

Lift is an upward force that the air exerts on the wing. By principle of action and reaction (Newton's third law of motion), the wing exerts downward force of equal magnitude on the air, and since the air is free to move, that force accelerates the air downwards.

Now there are two equivalent arguments why this causes drag:

In the frame of reference of the wing, the wing is not doing any work (because it is not moving), so it can't change kinetic energy of the air, and therefore can't change its total velocity. Since the vertical component of that velocity increases, the horizontal component has to decrease and this requires forward force from the wing. The backward reaction to that force is the induced drag.
In the frame of reference of the oncoming air, the kinetic energy does increase. Therefore the wing has to do some work on the air, which means applying force in direction of its motion. The backward reaction to that force is the induced drag.

The explanations are both equally true, just using different frame of reference.

Induced drag decreases with (square of) speed (for constant lift), because at higher speed there is more air to accelerate, so it only needs to be accelerated by less.

Induced drag is also independent of cross-section. If you cancel lift by moving elevator or aileron up, the cross-section may not change at all (the flap might still be behind the wing), but the induced drag will vanish.

By the way, it follows from this that induced drag of wing at 90 degrees is zero, because it is not producing any lift. The form drag is, of course, huge.

Form drag

Form drag is caused by imperfect pressure recovery behind the body. At the front of the object moving through fluid the fluid slows down, which comes with increase of pressure. In ideal laminar flow the fluid closes behind the object with the same slow speed and same high pressure. But as the object moves faster, the inertia causes the flow to separate and form a turbulent area behind the object where the pressure remains low. This pressure difference cause the form drag.

The form drag depends on cross-section and shape of the object. It always increases with speed.

Interference drag

When complex structure, like an aircraft, is analysed, the form drag of each component (wing, fuselage, empennage etc.) is first analysed independently. But as the components are assembled together, the pressure fields around the parts negatively affect each other and this increase in drag is then called interference drag.

Skin drag

Skin drag is caused by the friction between the surface of the object and the fluid. The skin drag depends mainly on wetted surface of the object. It increases with speed in similar way to the form drag, so for practical purposes it is usually combined with the form drag into one term, the parasitic drag.

Wave drag

As the object moving through fluid approaches the speed of sound, the flow exceeds it as it tries to avoid the object and forms a shock wave. Behind the shock wave the pressure is much higher and this increase is not balanced by any increase on the aft part of the object, therefore causing large amount of drag.

This kind of drag only appears as the flow speed approaches speed of sound, but then it quickly grows larger than the other forms.


What is the purpose of the second wifi network on board (some?) B787 aircraft? I recently flew for the first time on a Boeing 787-8 Dreamliner, registered A7-BCY. This aircraft had the universal symbol for wifi externally displayed beside the entrance door, and as wifi on an aircraft was another first for me I was keen to try it out. Which I did, without much fanfare.

The wifi used to provide internet access was named along the lines of "OneAir", which is consistent with the name of that airline's connectivity/On-board entertainment services.

What intrigued me was that there was a second wifi network available (albeit secured from public access) which was named with the aircraft's registration "A7-BCY" in the SSID of the network.

What is the purpose of this network? What data would you be able to access/see if you were to connect to it using a laptop (for example)?

(Note: I know there have been some questions here and on computer security regarding the vulnerability of modern airliners to hackers - I'm less interested in "doomsday scenarios" with this technology, and more interested on what legitimate uses there are of this network)

I think it has to do with the use of IPads by mainly the cabin crew, according to this article:

It also helps to identify customers quickly, and can be used to alert other staff of a passenger’s special meal or service requirements.

In order to have to crew communicating to each other via the IPad they need to be connected somehow, so I guess that the network you see is just linked to a locally hosted server such that all the IPads can acces the same data even if a crew member makes a change.


Writing Research: What stick sensation would you expect in an Su-15 with a total hydraulic flight system failure? The title pretty much says it all. I have a very specific research question in relation to a writing project I'm working on.
The main character is in an Su-15 performing low flying military training, and has a total hydraulic flight system failure (which I understand is extremely rare) and crashes into the side of a mountain. I envision moments before, the pilot pulling back on the stick as hard as he can, with no authority, or give in the stick, resulting in the plane smashing into the mountains ahead. However, I'm not entirely sure this would have been the case and need to be as accurate as possible for this project.
Thanks

Su-15 (as well as all Sukhoi interceptors since Su-7) had a completely irreversible control system with no manual override. This means, 100% of torque was produced by hydraulic boosters, and the force on the control stick was simulated with a special variable spring loading mechanism.
So, a theoretical total hydraulic failure would result in loss of control, while the stick would move 'normally' - just without any effect.
Su-15 had 4 hydraulic systems, with 2 of them used for flight control. The most anticipated reason for dual failure would be loss of the engines; for that, there was an electric pump in one of the systems. In case of control problems, the pilot would check and ensure that the emergency pump was on. This pump provided only a limited amount of control (and for a limited time).
Now I'll have to challenge the premise a bit. First, Su-15 was an interceptor, and low-altitude flight (even training) would be quite unusual for it (though not impossible). Its lowest altitude of intercept was 2 km, and the main emphasis was on intercepting higher altitude targets. Its radar was unable to track targets on the earth surface background. It was not meant for terrain following, so even if it was flying at a low altitude, it would be fairly clear of immediate obstacles. Which gives the pilot at least a few seconds to react.
Second, the pilot would, of course, eject. Even though in emergency situations (esp. unanticipated emergencies) people do all sorts of things, pilots, and esp. pilots of aircraft with irreversible control, know that loss of control = eject. It's pointless to 'fight' with the stick. However, as I said, in all likelihood there would be a few seconds to think. In most situations (like the engines failure) you won't have an immediate loss of control: the failure is fairly gradual. This would see the pilot trying to ascertain what was happening. Difficulties with control at low altitudes often require reducing the airspeed.1 But a catastrophic sudden loss of control is a clear signal to eject.

1 By the way, early Su-15 had pitch control problems at transonic speeds at low altitude due to insufficient booster torque. It felt like no response (or poor response) at higher G manoeuvres. This things could be resolved by reducing speed.


Why are most turbofans tractors, but most propfans pushers? Turbofans and propfans are, in concept, quite similar: both have a turbojet core, plus one or more additional turbine stages that drive a fan(s) which blows air around the core (this is known as bypass air, because it bypasses the core rather than going through it).  The single defining difference is that, with a turbofan, the fan(s) is enclosed in a large cowling (hence the alternative name "ducted fan", as the bypass air passes through an enclosed bypass duct), while, with a propfan, the fan(s) is left un-cowled (hence the alternative name "unducted fan").

However, in practice, there is one additional, rather odd, difference between most turbofans and most propfans.  Most turbofans operate in the tractor configuration, with the fan(s) placed out in front of the compressors and pulling the engine (and the airplane attached to said engine) through the air, while most propfans operate in the pusher configuration, with the fan(s) aft of the turbines and (surprise, surprise) pushing the engine (and, hopefully, aircraft) through the air.  There are exceptions on both sides; the General Electric CJ805-23 turbofan, powering the Convair 990, operated in pusher configuration, while the Progress D-27 propfan, which powers the Antonov An-70, operates in tractor configuration; however, both are exceptions, and the tractor-turbofans\pusher-propfans rule holds true for the vast majority of engines in both categories.

Why is this?

"Most propfans" is a bit of a strong way to put it. The An-70 is the only production propfan aircraft, making the Progress D-27 the only mass-produced operational propfan. So its configuration is the norm.

As for the reasons for experimental propfans using the pusher configuration, it's generally more efficient in aircraft to begin with, as the airflow is accelerated after passing the obstruction (fuselage). In a propfan, it also avoids the need for a long LP shaft.

As for why turbofans near-universally use tractor, the main reason is that the compression provided by the fan takes part in compressing air for the core. I'm less than 100% sure that it's actually worth the extra components and drag for placing the fan forward, but the alternatives are either having a long suction duct or having a separate ring cowling for the fan, none of which are ideal.

The tractor configuration of turbofans also helps a bit with core cooling. That wouldn't apply to a propfan, which needs a cowling for the core either way.


How to calculations deviation on a magnetic compass and effect of it? I am told to do self study and mainly for the part of the formula reading and i did some research and don't understand a single thing that i read online http://opac.vimaru.edu.vn/edata/EBook/Magnetic%20Compass%20Deviation%20And%20Correction.pdf. I also not very sure what is the effect of deviation have on the compass. Can someone pls help.Thank in advance.

P.S. I did it with zero knowledge of aviation as i just take this course.

We think of the earth as having a grid of lines covering it, which re use for defining a grid-position for a place, and for using as the basis for angles for defining our direction to travel from one place to another. These grid lines are latitude and Longitude, but they are a purely-human imaginary idea, they do not physically exist.

The Earth does have a naturally-occurring magnetic field, which at the moment is coincidentally vaguely aligned with the lines of Longitude. And this magnetic field has the huge advantage that its direction can be sensed using some very special lumps of rock, ie with a compass.

Problem 1 - the magnetic field is not actually aligned with the lines of Longitude, so there's an error. This mis-alignment is called Variation (sometimes called Declination in American books) and it's a simple geometric difference between the compass pointing at one place versus pointing at another place; so the value of Variation changes depending on where in the world you are. And this is complicated by the magnetic field moving over time!

Problem 2 - you insist on mounting your compass inside a ship/vehicle/airplane which is made of meta or has large lumps of metal in it, which will push or pull the Earth's magnetic field as it passes through the ship/vehicle/airplane. This causes a directional error in your compass which is called Deviation - and this varies depending on which direction your vehicle is pointing, ie depending on where the lumps of metal are around your compass.

The acronym for working with all this is T-V-M-D-C ("True Virgins Make Dull Company"). So starting with a bearing that you measure from a chart in degrees True, you add Variation to get degrees Magnetic. Then you take into account your particular vehicle by adding in Deviation to get degrees Compass. If you fly degrees Compass, you will be flying degrees True, but you've taken into account where you are, when you are, what vehicle you're in a dn what direction it's pointing.

Simples!


Does the FAA have a best practice for highlighting memory items on a checklist? voretaq7 mentioned the following two months ago in an answer:

  The process of designing a good checklist is an interesting Human Factors problem - there's a lot of literature on it but it's way out of scope for this site. The usual solution to badly designed checklists is that pilots get frustrated and write our own.

Funny he mentioned that, because I'm frustrated with a badly designed checklist and I'm writing my own.

Are there FAA-specific best practices for creating checklists in general and highlighting memory items in this specific case?

By this I'm referring to underlining, red-boxing, font changes, color changes, and so on.

The short answer is to use color in some way.

I couldn't find anything very detailed on this: there's plenty of general checklist information out there from the FAA, NASA, universities and so on, but nothing that goes into specific details on how to use colors, fonts or the other things that you mentioned.

There is an FAA report called The Use and Design of Flightcrew Checklists and Manuals that was part of the response to the Northwest 255 crash. Unfortunately it's from 1991 so some content is already dated, and it's aimed at part 121 and 135 operators with multiple crew members, but it's an interesting report anyway.

Their main recommendation on memory items was simply to reduce them as much as possible because memory is very unreliable compared to checklists, but again that's in the context of multi-member crews. As for design, layout, formatting etc., they did make some specific recommendations (see section 4.1 and Appendix A) and the most applicable one to your question seems to be the use of color-coding. They strongly recommended the use of color as a general method, e.g. headings in yellow for "abnormal" items and in red for "emergency" items.

Interestingly, the report says that at that time (1991) airlines resisted using color because of the costs of printing, but today it seems to be the generally accepted way to highlight critical checklists and items. However, each checklist provider has their own approach to coloring headers, text, blocks or even entire pages.

I don't think there's any such thing as a standard 'style guide' for checklists, so if you're making your own then you can obviously do whatever you want that works for you. But the 1991 report noted that most checklist problems were caused by missing or inaccurate items, so make sure you get the content right before you break out your paintbrushes :-)


Helicopters with landing skids, no wheels; How are they taken in and out of a hangar? I'm sure many helicopters also need/use Hangars frequently. How do you take them to a hangar and take them out of it without wheels?

Specially when they have to be taken indoors for some maintenance work on them. Are there any special forklifts/carts used for ground handling of helicopters that do not use wheels and need to be moved without actually flying?

Basically, you put wheels on the skid and tow them.

In some cases, towing wheels are attached to the skids (which usually have sleeves in them for mounting), and a tow bar is attached to the front (one or two sets of wheels may be attached to the skids), which is then towed by a vehicle.

Image from incrediblediary.com

There are also specialised tow carts available for helicopters, which basically grip the skids (usually in a couple of places on either side) and lift them up, after which the helicopter can be moved by the operator by controlling the cart.

Image from hasmak.com


How strictly are language rules adhered to between Pilot and ATC? My understanding is that there are general sentence structure rules that must be adhered to when there is contact between Pilot and ATC are well defined, like this.
Are these rules strictly followed in the real world, and is all other conversation fully avoided?

If not, does it happen often enough to be considered while designing an automated ATC response system?

(Based of videos of pilots sharing lighter moments with the ATC on YouTube)

Standard Phraseology is what should be used, but especially in those countries where the local language is an allowed IFR language, you will get deviation from that in daily use, either due to dialect, accent or simply colloquial terms influencing the phraseology used between pilots and ATC.

In countries like the USA, where English is the local language anyway, you will sometimes hear non-standard phraseology being used. In countries like Germany, where English is not the local language and IFR is only allowed in English, you will have pilots and ATC adhering to standard phraseology more closely, especially to avoid misunderstanding due to local accent.

Anecdotal comment: I fly in Germany and usually use English also for VFR. Germans have a very phonetically hard sounding pronunciation in English, making the language sound clipped and sharp, which carries over to phraseology being used. Many native English speakers have commented though that this makes it really easy to understand, because every word is spoken very distinguishedly. Although I speak English fluently without accent in normal day use, I tend to slip into a German accented English in aviation... because it's easier to understand.


Where did the terms QNE, QNH, and QFE come from? In the aviation community (at least outside North America), the terms QNE, QNH, and QFE are used to describe standard pressure, local altimeter, and field elevation, respectively.

But what is the origin of the "Q" code names?

QNE, QNH, and QFE are Q Codes - the Q Codes are designed for telegraph (or radiotelegraph) use where information is transmitted in morse code and brevity is essential (e.g. "QNH KJFK 2992 INS" is much shorter to tap out in morse code than "JFK Altimeter 29.92 inches of mercury")

They are still used in verbal communication (radiotelephone), though much less frequently.
ICAO defines a list of standard Q codes for use in aviation (this site has a list).

Regarding the choice of Q as the prefix for these codes, this is to avoid confusion with station callsigns. The ITU currently will not assign prefixes beginning with Q to any country.
(There may be further historical reasons behind the choice of "Q", but I'm not aware of any.)


Why does operating the rudders in the engine slipstream offer improved rudder authority at low speed? The above question is usually presented as an advantage for H-tail configurations. How does it help?

A propeller accelerates the air flowing through it in order to create thrust. This acceleration is highest at low speed.

The acceleration will increase the dynamic pressure at the tail if it is in the slipstream. A higher dynamic pressure will cause a proportionally higher aerodynamic force. A H-tail will, therefore, only be in the slipstream if two engines are mounted ahead of it, like in two- or four-engined designs with wing-mounted propellers. Also, by placing the area of the vertical low, a H-tail offers better dynamic flying characteristics.


Under what circumstances does the F-16 and possibly similar fighters deploy leading edge slats? What does the F-16 (perhaps other fighters as well) use to decide when to deploy leading edge flaps? I would assume angle of attack, airspeed, stick deflection, or some combination of the three, are the main factors.

Technically, F-16 and "similar fighters" have leading edge flaps (LEF) (or droop flaps), rather than slats. The difference is that they don't form a gap between themselves and the main surface when deflected. This makes them usable at high speeds, whereas slats are typically used for low-speed takeoff/landing.
For fighters, the most important use for them is to extend the range of usable angles of attack (AoA), which is important for manoeuvring as well as for takeoff/landing.
For F-16, @Mr R posted some details. I have some info for Soviet fighters of the same generation.
MiG-29
LEFs have two positions, up and down (20°). They are deployed:

When landing gear is down (including takeoff and landing).
Automatically in flight when AoA > 9° and M < 0.8 (Mach number).
On manual override by the pilot.

Su-27
LEF on Su-27 don't have fixed positions and constantly track AoA in flight. Maximum deflection 30°.
They are automatically deployed to 3/4 of travel when landing gear is down for takeoff or landing.
The pilot has a manual override (down-auto-up selector).
For both aircraft, if LEF fail, the allowed AoA is limited to 10°, which is roughly half the normal (depending on speed).


Which way (if at all) do the ailerons need to be deflected in a full-rudder sideslip in a Cessna 152 or 172? Do you typically have to maintain an aileron deflection in a constant-heading full-rudder sideslip in a Cessna 152 or 172? If so, in which direction?  And why -- what is the source of the roll torque that needs to be countered>

Note that aileron deflection is not the same thing as bank angle.

Yes. If you apply full rudder with no aileron, you initially just get a flat skid, but then differential lift starts to have an effect and the inside wing drops because that wing has slowed down, the fuselage is obstructing some of the flow on that side, and if there is wing dihedral, it creates a geometric angle of attack differential. One or more of these factors generate the rolling torque.  It's called "roll/yaw couple".

Some airplanes roll with rudder-only input stronger than others.  On swept wing airplanes the effect is intensely magnified due to the wing sweep and they roll really hard once the yaw angle exceeds 10 or 20 degrees.  Pilots doing jet type ratings discover this right away on their first V1 cut (engine failure) on take off when they don't correct the yaw from asymmetric thrust fast enough and it's taking full aileron just to keep from flipping over.  Side slips are generally not done in swept wing airplanes except in some extreme circumstance.

So the amount of opposite aileron to maintain a constant heading side slip is a function of how strong the airplane's roll/yaw couple is.  A 172 or 152's roll/yaw couple is moderate and you will need some opposite aileron just to keep the wings level.  Plus, to prevent a skidding turn, the amount of aileron has to be more than the minimum required to keep the wings level because some opposite bank is also required to keep the heading constant or else the skid itself starts to pull the nose around. So you end up with quite a lot of aileron in, maybe one third to one half of the available travel, with the wing banked perhaps 10 to 20 degrees, to keep from turning.

There is a lot of variation from airplane type to airplane type and on some the roll/yaw couple is quite weak and it takes only light aileron inputs to hold heading in a skid.  On any airplane you are flying for the first time, this is something you experiment with to find out how strong the roll/yaw couple is and how much counter aileron is required in a side slip.


Why does the Yak-28 cockpit have two attitude indicators? Why are there two attitude indicators in the cockpit of the Yak-28? Below is a picture from this YouTube video.

It's possible that the soviet attitude indicators are subject to tumble when operated inverted. the easy way to overcome this is to provide two instruments, one of which does not tumble when flying mostly right-side up and the other does the same for flying upside-down.

Soviet-era acrobatic planes had dual G-meters installed for this same reason. One was installed upside-down and registered negative G's while the other was installed right side-up and registered positive G's.


How is this rotor setup flying? I've been researching about helicopter flight without a tail rotor and the closest I've found is intermeshing rotors or this: https://www.quora.com/Why-dont-helicopters-have-rotor-blades-at-the-bottom

Looking at this new method:

Seen in this frame, the rotors are single winged and I'm guessing they rotate at opposite phases. What is this called and where can I find more information about it?

You are right, the two rotors move in opposite direction. This is called a co-axial rotor and is used by the Russian helicopter design bureau Kamov. A co-axial rotor can also be found on many model helicopters for indoor flying. They are a subspecies of helicopters with contra-rotating rotors.

Helicopters with contra-rotating rotors do not need a tail rotor and are much easier to fly than Sikorsky-type helicopters, because they suffer much less from instability. This group also comprises intermeshing rotors like those used on Flettner or Kaman K-Max helicopters.

Kamov Ka-32 with co-axial rotors operated by HeliSwiss (picture source)

Kaman K-Max with intermeshing rotors modified as an unmanned vehicle (picture source)

For more info, just follow the links.


Could airliners fetch data like AoA and speed from an INS? If I understood what an inertial navigation system (INS) is, it should be able to calculate speed and orientation of the aircraft.
If this is possible, why do airliners solely rely on sensors to measure speed and angle of attack (AoA)?

An INS gives your speed & orientation in space, but without reference to what the airmass that you're flying in is doing.
The Pitot tube and AOA sensors give speed and pitch orientation in relation to the local airmass, only.
An indicated airspeed of 60 knots, measured by the Pitot tube, may correspond to a stationary aircraft pointed into 60 knots of wind, or an aircraft moving 30 knots over the ground into a 30 knot headwind, or 60 knots of groundspeed in still air, or some other case.  The wings fly (and stall) relative to the air, not the ground, so measurements of air data are vital.


Why fewer operations on weekends? Why are there fewer air carrier operations on weekends? Looking at PHX data, we have the following annual trend that clearly shows a weekly drop of about 8% on weekends:

and when I average the data a strong weekly pattern is evident:

Is this simply telling us that most traffic is business related? Or is it, in part, that major cargo haulers don't work as much on weekends? As the charts show, we're talking about a 1200 vs 1000 daily operations difference.

Your data TELLS us that the airlines schedule fewer flights on the weekends, from which we can INFER that there is less demand for travel on those days.  (The numbers of cargo flights at PHX are dwarfed by the numbers of passenger flights there. The data at a major cargo hub like MEM or SDF might be different in that regard.)

To what extent that is driven by business travelers or leisure travel patterns, is beyond your data, and might even get into some fairly complex data and calculations that USAir and Southwest and others use to build their schedules.


What is the definition of taxiing? According to Wikipedia the definition of taxiing is:

  the movement of the aircraft on the ground under its own power [however]
  push-back is not considered taxiing

In contrast, Eurocontrol seems to define it as:

  any movement on the ground including push-back

Any other reliable sources to look up for the correct definition?

Definitions always depend on their context, that is why documents often included a list of definitions. It allows authors to define terms in the context of the document. A definition context is not always a document, it could for example be a field of expertise as well.

The Commercial Aviation Safety Team / International Civil Aviation Organization (CAST/ICAO) Common Taxonomy Team (CICTT) taxi is defined as:

  The aircraft is moving on the aerodrome surface under its own power
  prior to takeoff or  after landing

More detail can be found in the phase of flight definition document.
This is definition can be applied in many situations.

The Eurocontrol definition you link to comes from the Air Traffic Flow & Capacity  Management (ATFCM) and Airport Collaborative Decision Making (A-CDM) domains where statistics about gate-to-runway time play an important role for planning purposes.

In that context it is not really interesting to distinguish the time that was spend in pushback from the time spend actually taxiing to the runway. The taxi-out time is hence defined as the time between off-blocks and take-off.


Does DA/DH refers to ceiling? If airport is reporting FEW001 or SCT001 and RVR is above 600m, does it means that there will be no LVO because ceiling is defined as more than 4/8 and DA/DH will be more than 100ft because DA/DH is defined in the name of ceiling.
Or what if some of the SCT001 clouds will get over missed approach point, which is exatly at DA/DH, when pilots have to make decision. So they might not see the RWY at DH200ft, because of SCT001.

If I am understanding your question correctly:
An LVO is Low Visibility Operations which is defined by the FAA in AIM 2-3-4 and 4-3-19 as well as Advisory Circular 120-57a & ICAO OPS Low Visibility Operations (LVO)

Low visibility operations are those that occur when the runway visible range (RVR) is below 1200 feet (360m).

So, your RVR above 600m would not indicate the need for LVO.
A Ceiling is defined by the FAA

Ceiling means the height above the earth’s surface of the lowest layer of clouds or obscuring phenomena that is reported as “broken,” “overcast,” or “obscuration,” and not classified as “thin” or “partial.”

And, Broken (BKN) cloud layer is defined in AIM 7-1-31

9. Sky Condition.
The sky condition as reported in METAR represents a significant change from the way sky condition is currently reported. In METAR, sky condition is reported in the format:
Amount/Height/(Type) or Indefinite Ceiling/Height
(a) Amount. The amount of sky cover is reported in eighths of sky cover, using the contractions:
SKC clear (no clouds)
FEW >0 to 2/8
SCT scattered (3/8s to 4/8s of clouds)
BKN broken (5/8s to 7/8s of clouds)
OVC overcast (8/8s clouds)
CB Cumulonimbus when present
TCU Towering cumulus when present
Note 1: “SKC” will be reported at manual stations. “CLR” will be used at automated stations when no clouds below 12,000 feet are reported.
Note 2: A ceiling layer is not designated in the METAR code. For aviation purposes, the ceiling is the lowest broken or overcast layer, or vertical visibility into an obscuration. Also there is no provision for reporting thin layers in the METAR code. When clouds are thin, that layer must be reported as if it were opaque.

So, the cloud layers you described as FEW001 or SCT001 would not be considered a ceiling. And, they would not be considered IMC.
More insight on what can be done at the MAP can be gathered from this question:
Missed Approach below DA/DH


Do pilots switch their cell phones into airplane mode? I think that my question is pretty self-explanatory. I‘m interested in both general-aviation and commercial jet pilots.

Almost always.

If they don't, you often end up with this annoying sound on the radio:


Why don't jetliners maneuver to avoid a bird strike if spotted in time? With 75%* of the bird strikes hitting the wings and engines, why isn't there any training to avoid such strikes by banking if a flock was spotted with enough time to react?
It seems what Boeing recommends* is to ride it out then assess the damage.

Avoid or minimize maneuvering at low altitude to avoid birds.
(...)
Fly the airplane and maintain flight path control.

In the Flying Wild Alaska TV show one time the pilot of a light plane supposedly (exact clearance not shown) banked to avoid the birds. (YouTube)
Is there a correct banking maneuver? Suppose the flock is heading for the right wing, here's what I think of the two alternatives:

Dip the right wing to move the upwash away from the flock's path, or
Raise the right wing because birds are better divers than climbers.

In US Airways 1549 both engines suffered, and I don't know if dipping one wing or the other could have saved one engine. According to the CVR transcript, from announcing "birds" to the strike there was a full second. With a typical human reaction time of 0.3 seconds to announce birds, there would have still been a complete second to roll the plane one way or the other. Enough to roll 15° in an Airbus (max normal law FBW roll rate is 15°/s).
Why is riding it out better than a bank? (Worst outcome is the same for doing nothing and doing something.)
I'm neither claiming a solution, nor discussing flight 1549 in particular, rather inquiring about the flaws in my understanding of bird strikes and the related avoidance maneuvers.

* https://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/

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

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

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


Is there a surface of a commercial jet exposed to air flow at speed near Mach 1? With commercial aircraft flying slightly above Mach 0.8, is there any surface exposed to speed of air significantly larger, e.g. near Mach 1? ignoring:

The engine components,
The boundary layer as clarified by Trebia Project.

Edit: Reading useful information provided in comments and answers, I realize the key notion is "critical Mach number", and the question boils down to:

  Are commercial jets flying at critical Mach number speed or higher?

since the critical Mach number speed is -- by definition -- the one at which some airfoil portion experiments a supersonic airflow. See also:

How does exceeding the critical Mach number of an aircraft affect its operation?

Of course! If you check the wikipedia page the Critical Mach Number of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it.
The Drag Divergence Mach Number is usually bigger than the Critical Mach Number, it means that at that speed there are big surfaces exposes to speed of air larger than 1.

It can happen because the figure of an airplane is shaped in order to avoid shock waves with flow and to postpone the maximum as possible the Drag divergence Mach number (in order to have a greater cruise speed).

Where?
On the upper part of the wings, where the flow is accelerated in order to produce lift.

Clarification about engines (thanks to the help of one of the comments):

The flow from a jet engine has a speed about double of the cruise speed of the airplane. Anyway the outflow from an airliner jet engine is much hotter than the surrounding air, so the speed of sound in this gas stream is much higher; its Mach number is still subsonic.


What engine power setting is used during cruise? I am trying to work out what engine power setting is used during the cruise phase of commercial flights but I can't find anything about it in the usual spots. Anyone have any idea what percent of engine power is used? Like 50% engine power maybe?

At first, I was tempted to close the question as a duplicate, but then I could not find one that would address the point directly. But there are many questions and answers on this site which allow one to cobble together the answer:

Why are many jet aircraft designed to cruise around FL350-370?
Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years?
Why do jet engines get better fuel efficiency at high altitudes?
How much fuel does it take to start/land an aircraft, compared to normal flight?
What is the one-engine-inoperative maximum range flight configuration?

To save you to read through all linked answers, here is the gist of it: Jet engines are run at close to their maximum power during cruise, but their thrust is much less at altitude due to lower air density. Airliners want to fly as high as possible to fly faster for the same drag and to gain efficiency, and their designs are balanced to achieve reasonable take-off distances and good cruise performance at close to maximum thrust.


Where can I find more about a cargo pickup technique that doesn't require landing the plane? A number of years ago, I read about a technique for cargo pickup and recovery at remote sites using a low-and-slow-flying plane.  The plane would enter a slow orbit around a point on the ground and lower a bag to the ground on a long (hundreds of feet?  A thousand feet?) line.  Once the bag was down, the plane would maintain its turn around a point so that the line stayed slack and the bag stayed in position.  Cargo (perhaps mail?) could be retrieved from or placed in the bag, then once the transfer was complete, the plane exits the circle and lifts the bag.  I'm a lot less clear on that part.

However, I don't have any idea where I read about this, and haven't been able to find any more descriptions of this.  Can anyone tell me if this technique is real, what it's called, where/when it's been used?

See the notes on this page under the "Delivery" section. Looks like its formally called " long-line loiter". There is a brief note on it here and a US Patent here and this manual from the 70's that seems to show how to do it and some related research on it.

Here is a nice image of the maneuver


How do partial- and full flaps compare for gusty approaches? From an aerodynamic aspect, how do partial flaps and full flaps compare for gusty approaches?

I’m not sure when it comes to large aircraft, but when you select partial flaps or opt for a no-flap approach and landing, it results in a higher speed on approach and landing.

If you then break down the wind components in vectors, the cross-wind component becomes relatively smaller, so it is as if you have less cross-wind and don’t need to have such a large cross-track angle upon landing (less crab) or less cross-control when touching down. Even though the effect is small, it is noticeable.

You can compare it with a small single-engine piston trying to stay on course with 30° of crosswind at 100 kts needing perhaps 15-25° of cross-track angle while a fighter flying at 450 kts only needs 3-5° or so under the same conditions.


Why do the A320's centre tank pumps stop working 5 minutes after the low level has been reached? I'm new here and I'm in training course for Airbus A320. In the training material, it's said that the centre tank pumps are controlled to stop automatically 5 mins after the low level fuel has been reached. Why do they need to wait for a certain amount of time rather than stop right away?

To elaborate on Ron's commment, the pumps are timed because the when the level of the center tank is depleted to the minimum level that can be sensed by a low level sensor, there is usually still residual fuel sloshing around that the pump is able to draw.  For both electric pumps and ejectors, you don't want them sucking air for extended periods, so you want to be able to fully deplete the tank without having the pumps run too long un-ported.

Airbus would have done testing to establish the average time to suck the tank completely dry, added a margin of some sort, then added the timer to the low level shutoff signal with the appropriate delay to achieve that end.


What do pilots actually see through the windows? As I have never flown inside a cockpit, but only played with simulators I find that the dashboard takes most of the field of view(or am I wrong?).

So what actually can pilots see given good weather conditions, especially during critical parts of a flight, like take-offs and landings ?

I'm generally interested in big airliners.

P.S. I am not asking if they could takeoff/land without visual contact.

This really depends on the type of aircraft and the seating position of the pilot. In smaller aircraft, you will have a good view of the area around you, depending on the canopy. In larger aircraft, the instrument panel and cockpit design can restrict your outside view a bit more.

Below you will find two pictures taken from the cockpit of a Super Dimona HK36, used for VFR general aviation flights. Both are approximately at eye level.

(Source: Own Work - SentryRaven)

(Source: Own Work - SentryRaven)


Why does fuel vaporization in a carburetor cause a temperature decrease rather than a rise? So I know the most "prominent" conditions of carburetor icing is anywhere from 20 to 70 °F with visible moisture. There is also a tendency to have icing in the carburetor in the venturi throat due to a drop in temperature due to fuel vaporization.

The problem I'm having is if fuel is vaporized, wouldn't that be increasing the temperature? I don't understand how the temperature would drop.

Good question! There's two parts to the answer.

The first part is the ideal gas law.
The formula of the ideal gas law is $PV = nRT$, where

P = Pressure
V = Volume
n = amount of substance
R = the ideal gas constant, which can be ignored for our purposes
T = Temperature

Since we're ignoring $R$, we're left with $PV = nT$.
Now, say that you send some air through the throat of a venturi. Pressure decreases greatly (that's the point), volume stays close enough that we can leave it alone, the amount of molecules remain unchanged, so to keep the equation in balance, the temperature drops.

The second part is the latent heat of vaporization
In order for a liquid to change state and become a gas, a certain amount of heat is required. Consider a firefighter spraying water on a fire. The liquid water is heated by the fire and evaporates into steam. The energy of the fire is decreased by the amount of energy that went into the steam and which is now floating away into the atmosphere.
Now, replace the fire with your carburetor, and replace the water with fuel. The heat energy in your carburetor is transferred to the fuel in order to cause it to vaporize. The fuel gets hotter (but who cares, it's about to get burned in the cylinders anyway) and the carburetor gets cooler.


What does this symbol mean? Does anybody know what the icon inside the circle mean ?

Found at aviationweather.gov

It seems to be the symbol "M" for "missing cloud information". Note that CWIJ has a circle for cloud coverage that is slightly bigger than the standard circle size used for most other airports.
Southeast of CWIJ, there is CWIC which has the symbol M as well, but there the edge of the circle coincides with the lower part of the symbol shown in the CWIJ circle.

Another example can be found with CXDK (normal size circle) and CXLL (big circle size)

There is another station towards the east (CYBK) that has a bigger circle as well, and it has a 6/8 cloud coverage symbol that does not fully fill the circle. For comparison, PAUM has a standard circle size with the same 6/8 cloud coverage symbol filling all the way to the circle's edge.

This leads me to believe that the software behind aviationweather.gov has a symbol library which includes cloud coverage symbols designed for a certain standard circle size. Some airport are represent by a circle which is bigger than the standard, and this leads to the strange representation of the symbol 'M' seen at CWIJ.


Is there an aerofoil that gives reasonably good lift for both air flow directions: forward and backward? Could an aerofoil be designed to give reasonably good lift for both flow directions?
I was motivated by this related question on Aviation SE: Can a plane fly backward if its propeller is in reverse?
It seems that in practice most wings are indeed optimized for one direction of travel. And that makes sense in the context of the use case they are designed for.
But hypothetically, had a designer to design a wing profile for an aircraft that wanted to be able to fly both ways could it be done? The means of flow reversal could be varied e.g. reversible pitch propellers etc.
Any examples of such profiles?
Why Would You Want To Do This?
I don't have a good answer here. Maybe just curiosity.
More speculation: It could give a fighter or acrobatic aircraft some special manouveres? The ability to reverse without stalling at the end of a steep climb etc.?
Modified Question:
What about an aerofoil that's primarily optimized for forward flow but still has sufficient lift to not perform abyssmally in reverse? i.e. Not strictly symmetric performance. With good lift to drag ratios in forward flight but somewhat draggy in reverse.  Say, a use case where 99% of the flight time is in forward motion but for the other 1% you don't want absolute crap lift in reverse motion.
Perhaps this flexibility can bring out more creativity in the designs?

There is no airfoil with good lift in both flow directions, but one with some lift is conceivable. However, the lift-to-drag ratio will be nothing to write home about.

One reasonable candidate would be created if we use the forward half of the venerable NACA 66(2)-415 and copy it again for the last half. Like that:

As you might recognize from the plot, this was done with XFOIL. However, the iteration does not converge. But when real air hits this thing, it will create lift, much like a cambered plate will do. Its inviscid zero angle lift coefficient is already 0.5, however, viscous effects will reduce this lift coefficient.

In a good airfoil, the pointed trailing edge defines the point for flow separation, while the rounded nose leaves it to the flow to find a suitable stagnation point. Here we have a rounded contour on both ends, so the separation point widens to a separation area, and this will creep up on the top side once the flow develops some suction at the top. Hence, lift will be poor and drag will be high.

With a little trick, XFOIL can be convinced that this is a regular airfoil with a really blunt trailing edge. Then this is the result at a Reynolds number of 5 million and Mach 0.3:

However, now the separation at the trailing edge is prescribed and will not as easily move up, so the results might be too positive. It seems that L/D exceeds 70 (which surprises me! The original 66(2)-415 has a lower L/D at the same flow conditions, which is a strong hint that we are misusing XFOIL here). Compare that to a good glider airfoil L/D of over 200 at this Reynolds and Mach number.

Applicability

I cannot think of a good reason to do this. The consequences of flying backwards include:

What was stable previously will become unstable - in all directions! Remember that the neutral point is at the quarter chord, measured in flow direction. If the flow direction is reversed, the distance between neutral point and center of gravity will suddenly be more than half the wing chord - in the wrong direction! The same goes for the vertical, which is now destabilizing.
This includes all control surfaces: They will run into their stops and stay at maximum deflection. A manual control system will become unusable, and even a hydraulic, computer-controlled one will experience extreme loads which overpower conventional actuators. When combined with Gurney flaps or directed blowing on both sides, the control issues should become manageable.
If done with reversing a variable-pitch propeller, most of the propeller will not work anymore, because the blade twist runs now opposite to how it should. You could, however, create enough thrust if you use a VJ-101 style propulsion where the engine gondolas swivel through 180°.

VJ-101 (picture source)

EDIT: @Marius mentioned in a comment below the S-72 X-Wing, an attempt to make a helicopter go faster by stopping the rotor above a certain forward speed. The X-Wing actually used an elliptical airfoil and forced the Kutta condition by directed blowing. This enabled it also to use a rigid wing and to adjust blade lift for cyclic and collective control by blowing. This is indeed the only sensible application of an airfoil that works in both directions.

ANOTHER EDIT: I just found this on Airfoiltools.com: The Sikorsky DBLN-526 double ended rotorcraft airfoil. It was most likely used on the S-72, and its 26% would only work with directed blowing, anyway.


How do airports charge airlines for using their gates? I'm wondering how the airports charge an airline for using a gate or a parking spot (if they use buses). Does the airline have to pay per time or per "event" or do the larger airlines have fixed gates for which they pay a yearly rent?

Could you elaborate on what systems there are and when they are used? How much are the costs?

Gates are usually not charged to airlines separately. Gate fee is usually part of the landing fee package. Landing fees are an important part of the airport revenue, with passenger fees.

Airport pricing is subject to recommendations from ICAO, IATA, and other organizations, as regard scope of costs to be taken into consideration, and non-discrimination of airlines. Pricing is determined by the organization managing the airport and/or State or local administration.

Single till vs dual till: Distinguishes between aeronautical and non-aeronautical (commercial) charges. Airport schedule pricing may use single or dual till. See: Single till - IATA.

ICAO Policies on Charges for Airports and Air Navigation Service. ICAO guidelines tries to maintain some principles for airport business across all countries:

Landing charges: Should be based on the aircraft weight formula. The maximum certificated take-off weight as indicated in the certificate of airworthiness (or other prescribed document) should be used, while considering local restrictions that may affect aircraft maximum take-off weight. Allowance should be made for the use of a fixed charge per aircraft or a combination of a fixed charge with a weight-related element, in certain circumstances, such as at congested airports and during peak periods.
Parking and hangar charges: For the determination of charges associated with use of parking, hangar and long-term storage of aircraft, maximum permissible take-off weight and/or aircraft dimensions (area occupied) and length of stay should be used so far as possible as the basis.Any period of free parking time for aircraft immediately following landing should be determined locally by considering aircraft scheduling, space availability and other pertinent factors.
Other charges:

-- Passenger service charges
-- Security charges
-- Noise-related charges
-- Emissions-related aircraft charges

Albeit a bit old, The Airport Business by Rigas Doganis has a chapter on Aeronautical charges and pricing policies which discusses this topic in depth. Extracts:

Landing fees: Charged per aircraft, usually based on MTOW (maximum takeoff weight). On most airports covers ATC, runways, taxiways, parking at stand or apron for a certain time (e.g. 2 hours), use of gates / fingers / terminal for disembarking (use for departure may be paying), take-off.
Surcharges or rebates in addition of landing fees: For noise, peak-hour operations,
Parking and hangar: Beyond the free-parking period covered by the landing fees. Usually based on weight.
Passenger charges: per departing passenger, sometime per arriving passenger too.

It is easy to find pricing for airports online.

Adelaïde airport (2015)

Rates are different for domestic and international flights.
Charges per passenger for landing and passenger facility.
For domestic flights, additional landing charges per ton of MTOW.
Charges for diversion.
Parking charges beyond 2 hours, paid per arrangement with airport.

New York LaGuardia (2015)

Charge for aircraft landing, per thousand pounds of MGLW (maximum gross landing weight).
Additional charge for day landing or takeoff (not for schedule airlines).
Charge for using public passenger ramp and apron area (in some cases, when congestion).
Charge for parking and storage, per 8-hour slot, based on MGTOW (maximum gross takeoff weight). Agreement possible for operators of aircrafts.
No charge for air terminal use.
Charge for each passenger departing.

Los Angeles Intl (2013)

Landing fee, based on MGLW, different between permitted and non-permitted air carriers.
No charge for remote gates bussing service.
Charge for using ramp, apron and remote area, (in some cases, when congestion).
Charge for parking, per 1000 lbs of MGLW, per day, after 3 hours.