What does the practical CPL skill test contain? In EASA Part-FCL, FCL.310 containts on several hundred pages all the required knowledge for the theoretical skill test for a CPL. However, different from other licenses described in Part-FCL (PPL, Aerobatic, VFR Night, Mountain, ...), there is no list of what's in the practical skill test.

What's included in the CPL practical skill test? What are the tolerances for maneuvers etc?

https://www.easa.europa.eu/sites/default/files/dfu/Part-FCL.pdf

  Appendix 4 - Skill test for the issue of a CPL

  A. General
  1. An applicant for a skill test for the CPL shall have received instruction on the same class or type of aircraft to be used in the
  test.
  2. An applicant shall pass all the relevant sections of the skill test. If any item in a section is failed, that section is failed.
  Failure in more than one section will require the applicant to take
  the entire test again. An applicant failing only in one section shall
  only repeat the failed section. Failure in any section of the retest,
  including those sections that have been passed on a previous attempt,
  will require the applicant to take the entire test again. All relevant
  sections of the skill test shall be completed within 6 months. Failure
  to achieve a pass in all relevant sections of the test in two attempts
  will require further training.
  3. Further training may be required following any failed skill test. There is no limit to the number of skill tests that may be attempted.

  CONDUCT OF THE TEST
  4. Should the applicant choose to terminate a skill test for reasons considered inadequate by the Flight Examiner (FE), the applicant shall
  retake the entire skill test. If the test is terminated for reasons
  considered adequate by the FE, only those sections not completed shall
  be tested in a further flight.
  5. At the discretion of the FE, any manoeuvre or procedure of the test may be repeated once by the applicant. The FE may stop the test at any
  stage if it is considered that the applicant’s demonstration of flying
  skills requires a complete re-test.
  6. An applicant shall be required to fly the aircraft from a position where the PIC functions can be performed and to carry out the test as
  if no other crew member is present. Responsibility for the flight
  shall be allocated in accordance with national regulations.
  7. An applicant shall indicate to the FE the checks and duties carried out, including the identification of radio facilities. Checks shall be
  completed in accordance with the checklist for the aircraft on which
  the test is being taken. During pre-flight preparation for the test,
  the applicant is required to determine power settings and speeds.
  Performance data for take-off, approach and landing shall be
  calculated by the applicant in compliance with the operations manual
  or flight manual for the aircraft used.
  8. The FE shall take no part in the operation of the aircraft except where intervention is necessary in the interests of safety or to avoid
  unacceptable delay to other traffic. B. Content of the skill test for
  the issue of a CPL — Aeroplanes

  The aeroplane used for the skill test shall meet the requirements for training aeroplanes, and shall be certificated for the carriage of
  at least four persons, have a variable pitch propeller and retractable
  landing gear.
  The route to be flown shall be chosen by the FE and the destination shall be a controlled aerodrome. The applicant shall be responsible
  for the flight planning and shall ensure that all equipment and
  documentation for the execution of the flight are on board. The
  duration of the flight shall be at least 90 minutes.
  The applicant shall demonstrate the ability to: (a) operate the aeroplane within its limitations, (b) complete all manoeuvres with
  smoothness and accuracy, (c) exercise good judgement and airmanship;
  (d) apply aeronautical knowledge; and (e) maintain control of the
  aeroplane at all times in such a manner that the successful outcome of
  a procedure or manoeuvre is never seriously in doubt.

  FLIGHT TEST TOLERANCES
  4. The following limits shall apply, corrected to make allowance for turbulent conditions and the handling qualities and performance of the
  aeroplane used. Height normal flight ±100 feet with simulated engine
  failure ±150 feet Tracking on radio aids ±5° Heading normal flight
  ±10° with simulated engine failure ±15° Speed take-off and approach ±5
  knots all other flight regimes ±10 knots

  CONTENT OF THE TEST
  5. Items in section 2 (c) and (e)(iv), and the whole of sections 5 and 6 may be performed in an FNPT II or an FFS. Use of the aeroplane
  checklists, airmanship, control of the aeroplane by external visual
  reference, anti-icing/de-icing procedures and principles of threat and
  error management apply in all sections.

  SECTION 1 — PRE-FLIGHT OPERATIONS AND DEPARTURE a Pre-flight,
  including: Flight planning, Documentation, Mass and balance
  determination, Weather brief, NOTAMS b Aeroplane inspection and
  servicing c Taxiing and take-off Part-FCL – Appendices, AMC and GM V1,
  June 2016 Go back to Appendices Go back to the content 1168 | P a g e
  d Performance considerations and trim e Aerodrome and traffic pattern
  operations f Departure procedure, altimeter setting, collision
  avoidance (lookout) g ATC liaison – compliance, R/T procedures

  SECTION 2 GENERAL AIRWORK a Control of the aeroplane by external
  visual reference, including straight and level, climb, descent,
  lookout b Flight at critically low airspeeds including recognition of
  and recovery from incipient and full stalls c Turns, including turns
  in landing configuration. Steep turns 45° d Flight at critically high
  airspeeds, including recognition of and recovery from spiral dives
  eFlight by reference solely to instruments, including: (i) level
  flight, cruise configuration, control of heading, altitude and
  airspeed (ii) climbing and descending turns with 10°–30° bank (iii)
  recoveries from unusual attitudes (iv) limited panel instruments f ATC
  liaison – compliance, R/T procedures

  SECTION 3 — EN-ROUTE PROCEDURES a Control of aeroplane by external
  visual reference, including cruise configuration Range/Endurance
  considerations b Orientation, map reading c Altitude, speed, heading
  control, lookout d Altimeter setting. ATC liaison – compliance, R/T
  procedures eMonitoring of flight progress, flight log, fuel usage,
  assessment of track error and re-establishment of correct tracking f
  Observation of weather conditions, assessment of trends, diversion
  planning g Tracking, positioning (NDB or VOR), identification of
  facilities (instrument flight). Implementation of diversion plan to
  alternate aerodrome (visual flight)

  SECTION 4 — APPROACH AND LANDING PROCEDURES a Arrival procedures,
  altimeter setting, checks, lookout b ATC liaison - compliance, R/T
  procedures c Go-around action from low height d Normal landing,
  crosswind landing (if suitable conditions) e Short field landing f
  Approach and landing with idle power (single-engine only) g Landing
  without use of flaps h Post flight actions

  SECTION 5 — ABNORMAL AND EMERGENCY PROCEDURES This section may be
  combined with sections 1 through 4 a Simulated engine failure after
  take-off (at a safe altitude), fire drill b Equipment malfunctions
  including alternative landing gear extension, electrical and brake
  failure c Forced landing (simulated) d ATC liaison - compliance, R/T
  procedures e Oral questions

  SECTION 6 — SIMULATED ASYMMETRIC FLIGHT AND RELEVANT CLASS OR TYPE
  ITEMS This section may be combined with sections 1 through 5 a
  Simulated engine failure during take-off (at a safe altitude unless
  carried out in an FFS) b Asymmetric approach and go-around c
  Asymmetric approach and full stop landing d Engine shutdown and
  restart e ATC liaison – compliance, R/T procedures, Airmanship f As
  determined by the FE — any relevant items of the class or type rating
  skill test to include, if applicable: (i) aeroplane systems including
  handling of autopilot (ii) operation of pressurisation system (iii)
  use of de-icing and anti-icing system g Oral questions


What is the difference between RTOP, MTOP, and MCP? I am currently learning how to fly the SD3-60 (Shorts) Aircraft, and I am trying to gain an understanding of RTOP (reserved take off power), MTOP (max take off power), and MCP (max continuous power).  Can someone explain the difference between all three of these and which phases of flight/situations we would use these in?  Can someone also explain why we would use one over the other in certain conditions?  Thank you so much in advance!

MCP is maximum power that can be used indefinitely without shortening the life of the engine.  You might use MCP when you need all the available power during single engine cruise, to maintain an altitude for obstacle clearance, or when climbing single engine.
MTOP is normal maximum for takeoff and initial climb, with a time limit. If you exceed the time limit, you will shorten the life of the engine.
RTOP is a power reserve for special situations, like when an engine quits, where the engine goes above MTOP to save your butt.  When that happens on modern turboprops the dead engine will autofeather and the live one will automatically go into RTOP (sometimes called "power uptrim" or something similar).  If it does so it may have an impact on engine life or may require a special inspection later.


What effect would a afterburner have on the compressor if the nozzle outlet is not increased? In order to operate an afterburner, it is necessary to adapt the nozzle outlet area. As far as I understand it is necessary to open up the nozzle when the afterburner is increasing its temperature or the mass flow rate would decrease. It is also necessary to close the nozzle when the afterburner cooling down or the turbine would rev up and exceed the critical rpm.

  Now, what I want to know is what happens with the compressor if the outlet area is not adapted?

If the afterburner temperature increases and the nozzle is not adapted I guess that the compressor will reduce its normalized rpm $u/\sqrt{\gamma R T}$ because of the reduced mass flow rate and it will also come close to a compressor stall (surge).

Is it right that the compressor rpm is reduced or does it stay the same and the mass flow rate gets throttled?

Yes, when the AB is lit, the nozzle needs to be opened, because the increase in exhaust temperature causes a decrease in density (pressure remains about the same), and so the same mass flow needs a bigger nozzle area to flow through. In AB, the engine mass flow is about the same as in max dry operation. The AB basically sits behind the core, and operates more or less independently, because the change in nozzle area compensates for the change in exhaust temperature.

And you are exactly correct, if the nozzle wasn't reduced when the AB is turned off, the spools would over speed.

If the nozzle area wasn't increased, the sudden lighting of the AB would most likely stall the engine - probably the fan as the back pressure wave can easily travel back up the bypass duct. AB stalls were common on first generation low bypass military engines. If you could light the AB slowly, it should just cause the spools to slow down, and mass flow to correspondingly decrease. Modern ABs light a bit progressively, to give a "soft" light. Older designs weren't quite so refined.

E.g. See page 208:

  The TF30 ... still had compressor problems going in and out of afterburner..

And here about the F100 saying:

  Some stagnation stalls were caused by "hard" afterburner lights, which were mini explosions that took place inside the afterburner when it was lit up. The pressure wave from the explosion then propagated forward through the duct to the fan, causing the fan to stall and sometimes even causing the forward compressor stage to stall as well. These types of stagnation stalls usually occurred at high altitudes and at high Mach numbers.

Also read Goodbye F100 Stagnation Stalls, see:

  To reduce the influence of pressure waves traveling back up the fan duct, the compressor inlet lip has been moved to bring it closer to the rear of the fan.


Does flutter disappear above the flutter speed? Okay, lets assume we have an airplane with some sort of superstrong wing, but otherwise conventional configuration. We accelerate it gradually. Eventually, it will reach flutter speed, at which the wingtips will flap up and down with ever increasing amplitude in a standing wave. But we don't stop there - we keep accelerating. 1.5x flutter speed. 2x flutter speed. 5x flutter speed. 10. What happens to the flutter? Does it disappear, then reappear again with more peaks and troughs of the "standing wave", at every multiple of the initial flutter speed? Or does it continue to get worse and worse?

Flutter happens when elastic and aerodynamic frequencies converge. Normally, the elastic one is (almost) fixed and the aerodynamic one increases with flight speed. When speed increases further and the frequencies move apart again, flutter will die down. However, with further increasing speed more elastic modes will be encountered with ever smaller gaps between them.
There are indeed cases of airplanes which have a flutter mode below minimum speed but are safe to operate within their certified speed limits. The linked article doesn't mention this, but if you fly that thing slowly enough, the tail surfaces will wildly swing caused by a torsional elastic mode of the rear fuselage being in frequency neighborhood with oscillating separations on the tail surfaces. Pretty scary but harmless at that low speed.


What are the differences between "Off/On Time", "Total AC Time", and "Offset"? Can somebody please help explain to me the difference between all of these. I understand that "Off/On time" is probably the Hobbs time which is determined by the time my battery master switch is turned on - but I do not understand the total AC time and the Offset. I am assuming that one of these is the time that my plane is in the air. Picture attached for reference, and I fly a Cessna 172R.

There are different definitions for times in the U.S. FARs.
For example FAR §1.1 has a definition for flight time

Flight time means:

(1) Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing; or
(2) For a glider without self-launch capability, pilot time that commences when the glider is towed for the purpose of flight and ends when the glider comes to rest after landing.

This would typically be your OUT and IN time.
The Hobbs meter (depending on how it is wired) indicates the hours the engine is running or the hours the airplane is flying.
FAR §1.1

Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing.

FAR §91.409(b)

Except as provided in paragraph (c) of this section, no person may operate an aircraft carrying any person (other than a crewmember) for hire, and no person may give flight instruction for hire in an aircraft which that person provides, unless within the preceding 100 hours of time in service the aircraft has received an annual or 100-hour inspection and been approved for return to service in accordance with part 43 of this chapter...

So the OFF-ON times are used for maintenance intervals.
I am personally unaware of total aircraft time or offset.
Most FMS installations have the ability to capture this data automatically.  It is called the OOOI value or OUT-OFF-ON-IN times.  Use the OFF-ON for maintenance and the OUT-IN for pilot logbooks.


How do we derive Lift Coefficient of an airplane's wing? In many references I read that lift coefficient ($C_l$) is a product of wind tunnel test. But many times I read the formula to calculate the coefficient of lift. From the lift equation, $$L=\frac{1}{2} \rho v^2 S C_l$$ $C_l$ is rearranged to derived the $C_l$ equation as below: $$C_l=\frac{2 L}{\rho v^2 S}$$

In my opinion, even it correct mathematically, but is not correct in the engineering process as it is not a product of a mathematic. The Coefficient of lift ($C_l$) is required to calculate the lift that will be produced by an airplane's wing with the given speed and the wings' area.

Am I correct with my opinion? Or, is any formula to calculate the coefficient of lift so the lift force can be calculated without any wind tunnel test?

The lift coefficient accounts for complex aerodynamic effects that are impossible to calculate by hand in any practical way. I'm not sure what you mean by "In my opinion, even it correct mathematically, but is not correct in the engineering as the it is not product of mathematic." My best guess is that you're pointing out that even though you can rearrange the lift equation to calculate $C_L$, it's not derived from first principles, which is correct. It's a convenient way to represent more complex interactions that are difficult to calculate.

Essentially, we know lift varies linearly with dynamic pressure ($\frac{1}{2} \rho V^2$) and it varies linearly with surface area. So the lift equation may be written, in its most reduced form,
$$L = C_L q S.$$
Notice the similarity to the drag equation:
$$D = C_D q S$$
And the pitching moment equation:
$$M = C_M q S c$$

Each of these quantities varies linearly with dynamic pressure and surface area, so it's useful to express them as products of these quantities. Changing either of these variables will probably affect the aerodynamic coefficient as well, but for modeling purposes that don't require extreme precision, in most cases, the aerodynamic coefficient won't change nearly as much as dynamic pressure can.

As a result, knowing $C_L$ and $C_D$ for a variety of flight conditions, you can model your body of interest with fairly good accuracy without having to go through the complexity of computational fluid dynamics, which is the numerical way to predict aerodynamic forces.

To answer your question about a formula to calculate the coefficient of lift, there are methods that will allow you to get a rough estimate (e.g. lifting line theory), but to get results comparable to wind tunnel testing, you have to use computational fluid dynamics, which will require a computer to achieve meaningful results.


Why should AKE LD3s not be used in the A380? I noticed some LD3 ULDs (Unit load device, container type LD3) - like AKE (LD3 without forklift holes/half ALF) - mention DO NOT USE A380. What is the difference between normal LD3 and A380 LD3?

Emirates uses multiple kinds of ULDs.

The AKE with "DO NOT USE WITH A380" are made out of aluminum metal. The tare weight is 80 kg. Contrasted with the AKE (light weight) 66 kg tare weight and the AKL (ultra light weight) 56 kg tare weight, the difference may seem small, but multiplied over the large number of AKEs can reduce the payload and therefore fuel burn considerably.

Emirates Skycargo website.


Why is the position of the pilots' head (eyes) so important? From this question:
What are these Lights on Center Holm between Windows on the A320?
I learn that the pilots' eye position is important. Enough to justify an extra piece of equipment.
But why? Can't a pilot tell if they see enough, above/below/on each side, by just looking?

The correct seating position is important to ensure

A consistent viewpoint, which results in the final approach and flare always looking the same to the pilot. This is important when hand-flying the aircraft to ensure consistent landings.

Having a consistent viewpoint gives several operational advantages such as easing the handling of the aircraft by providing pilots with a consistent visual reference, repeatable at every flight. This is especially useful during final approach to be familiarized with the final approach path angle and also for the flare phase.

Best forward visibility, which maximizes the area in front of the aircraft you can see (Visual Segment):

Having the seat further backwards or lower would reduce the Visual Segment.

Good View of the Instruments, which allows seeing the PFD and ND without having to move your head down. This is how it looks with the correct seating position:

And this is how it looks if you are seated too high or too far forwards:

All sources: Airbus - Are You Properly Seated?

You also asked

Can't a pilot tell if they see enough, above/below/on each side, by just looking?

Yes, not all aircraft have the three balls for finding the optimum seat position. You can do it by looking over the glareshield and ensuring good visibility of the PFD/ND. On Boeing aircraft, this is how it is supposed to be done since they don't have a dedicated eye reference indicator:

Pilot Seat Adjustment
Adjust the seat position with the appropriate controls to obtain the optimum eye
reference position. Use the handhold above the forward window to assist. The
following sight references are used:

Sight along the upper surface of the glareshield with a small amount of
the airplane nose structure visible (A)
Sight over the control column (in the neutral position) until the bottom
edge of the outboard display unit is visible (B).

(Boeing 737 NG FCOMv2 - 1.40.44 Airplane General - System Description)


Why does the NTSB release transcripts of Cockpit Voice Recordings, but not the actual recordings? From what I have read it is illegal for the National Transportation Safety Board to release Cockpit Voice Recordings, while they are allowed to release its transcripts.

From AirDisaster:

  It is illegal for the National Transportation Safety Board, who regulates these recordings, to release them to the public.

From NTSB:

  The transcript, containing all pertinent portions of the recording, can be released to the public at the time of the Safety Board's public hearing.

Why? What's the issue with releasing Cockpit Voice Recordings?

From NTSB site, regarding FOIA requests:

  "Cockpit Voice Recorder (CVR) tapes. Title 49 U.S.C. § 1114(c)
  prohibits the release of any CVR tape. However, the NTSB may release a
  CVR transcript (edited or unedited), in accordance with 49 U.S.C. §
  1114(c)(1)."

Transcripts may be disclosed, but not 'tapes'. Which makes sense, as transcripts may be edited to remove parts that are not meaningful for the investigation, but can be  unnecessary intrusions into private life.

In addition, when the NTSB is participating to foreign investigations:

  Records or information relating to the NTSB's participation in foreign
  aircraft accident investigations. 49 U.S.C. § 1114(f) prohibits the
  release of this information before the country conducting the
  investigation releases its report or 2 years following the accident,
  whichever occurs first

See 49 U.S. Code § 1114 - Disclosure, availability, and use of information


What exactly does the MB-326's 'relight' button do? The following picture shows the engine throttle of an Aermacchi MB-326, which is powered by the Rolls-Royce Viper turbojet:

(source - all photos © Drive&Fly Model Club)

I wonder what exactly the RELIGHT push-button is for. It's clearly not the 'reheat' control (another word for afterburner, which is not fitted on the Viper, apart from some amateur variants...)

I would guess it controls the engine ignition for use in case of flame-out, but then I noticed this other photo, showing what appears to be the starter/ignition controls (located in front of the throttle):

so my question is: what exactly does the relight button do, as opposed to the starter/ignition controls?

The Aermacchi MB-339 was developed from the -326 and it is also powered by one Rolls-Royce Viper Mk. 632 turbojet. From its aircraft manual, the relight button is for the in-flight re-ignition:

  Premuto - Attiva il sistema di riaccensione in volo.
  Pressed - Activates the re-ignition system in flight.

The start button in your picture is for activating the starter, and the guarded ignition next to it is likely a ground/start-only ignition mode.

Typically, an in-flight ignition mode is of a lower energy rating compared to the start mode, this helps prolong the life of the igniters. It's used when flying in rain or icing conditions, and for maneuvers that could momentarily choke the engine (e.g., an extreme spin or side-slip with side-mounted intakes).


Is there any formula that directly relate density to altitude for a wide range of altitude? I am working on a code to simulate a vehicle trajectory based on forces act on it in different altitudes, I need a formula that gives density in an altitude range between 0 and 40 km to obtain lift and drag in different altitudes. Is there a formula that gives it to me even with a reasonable error?

There are the right way and the easy way.

Rigorous way would be to use the ICAO Standard Atmosphere (Doc 7488-CD in 1993) a link for document
Then your code looks for temperature gradient (Table D) and uses eq.12 or 13 for pressure calculation. It depends on the temperature gradient. Then you can easily compute the density eq.14.

Easy way would be calculate density for few altitudes and fit the result with some proper function.

Cheers Robert


Is there any FAA Regulation who may wash a private aircraft such as Cessna Skyhawk or Citation? Should it be mandatory to hire a mechanic? or someone else with any kind of FAA license? or could anyone wash one?

There is no regulation on who can wash a plane. You'll probably find that quite a few planes (at least of those used for instruction) are in fact washed by student pilots.


Why do pilots wait for a positive rate to put the gear up, When V1 means “commit to takeoff”? To explain further, V1 means they cannot stop in time if anything happens. Therefore they must commit to taking off. So why wait for a positive rate? Shouldn’t it be retracted as soon as they see a difference in altitude? From my understanding, is that the landing gear deployed during a crash landing can rupture the fuel tanks??

V1 is the speed at which you are committed to take-off, it doesn't mean you are off the ground. You can't retract the gear at V1 because you are still rolling on it heading down the runway.

Vr is the speed at which you rotate the nose up to get into the air. Again you are still rolling down the runway with your nose in the air, you can't retract your wheels if you are using them.

V2 is the speed at which you are able to climb with one engine inoperative. It doesn't mean you are in the air yet, you can't retract the gear.

And just because the main gear come off the ground doesn't mean a gust won't push you back down, so usually you leave it down until you are reasonably assured that you won't touch again. It's a lot gentler on the aircraft if you touch the wheels than if you rub the skin off the aircraft. Positive rate is pretty much the only indication of this since there is a little bit of a lag in the VSI, by the time it shows positive rate you are far enough off the ground that you really don't need to worry about touching again.

  Shouldn’t it be retracted as soon as they see a difference in altitude?

The best indication is not the altimeter, it is the VSI. It reacts faster than the altimeter.

For GA aircraft, a lot of pilots won't retract the gear until "there isn't any runway left". This means that taking off on an 8,000 foot runway, they would be airborne by the 1500 foot mark and leave the gear down in case the engine fails they can just put it back down again.

What you really don't want to happen is for the gear to be retracted prematurely. When you are rolling down the runway you get "light on your feet" and the gear retraction mechanism can pull the gear up before the aircraft is ready to fly. The squat switches may be unloaded so they won't stop the system. Best thing to do is to wait for the positive rate, verify visually and then retract. Personally I leave it down until I'm 500' below pattern or no more runway left.


What's the plug used on airliners for ground power? What's the plug pair called?
What's the ISO/whatever standard involved?
What do they look like close-up?
Is it pretty standard today worldwide?
Is the plug identical for the hugest airliners as for say commuters?
Is the power specs identical for the hugest airliners as for say commuters?
Is the plugpair used on any non-aviation (say, industrial) cases?
Do some craft have more than one type of plughole (ie, to allow for different airport standards?)
And military aircraft?
Do any small personal craft (I mean 2-4 seater craft) use the same plugpair, or in some cases do they just use a domestic-like plug (rather as a motorhome may have), or generally do small craft never have this?

 (found a pic but not a close up of the plug/hole!)

Is there a switch (for example, perhaps near the pylon in the first photo?), or a switch near the plug, or does it just hot connect?

What's the plug pair called?

I don't think there's an "official" name for it, but it's usually referred to as the "ground power connection" or something similar. Also, there's usually only one connection; only the biggest commercial aircraft need two connections simply because one connection can't supply enough power.

  What's the ISO/whatever standard involved?

ISO 6858

  What do they look like close-up?

I wasn't able to find a copyright-free picture, but here's a PDF catalog from an aircraft parts supplier that has some pictures. (Note that this catalog also has a bunch of rarer plugs in addition to the common ones.)

  Is it pretty standard today worldwide?

The international nature of aviation kind of militates towards better standardization than most other fields. It's not perfect, but you're a lot more likely to find a compatible plug for your plane in a foreign country than you are for, say, your electric razor.

  Is the plug identical for the hugest airliners as for say commuters?
  Is the power specs identical for the hugest airliners as for say commuters?

The plug is based on what kind of power the airplane needs, rather than the size. So, all airplanes that take 120V 400Hz power will (usually, see above about standardization) have the same plug.

  Is the plugpair used on any non-aviation (say, industrial) cases?

No, not that I know of.

  Do some craft have more than one type of plughole (ie, to allow for different airport standards?)

It's a pretty big world, so I'm sure that some airplane, somewhere, has multiple plugs.

  And military aircraft?

That I don't know. Someone else will have to answer that one.

  Do any small personal craft (I mean 2-4 seater craft) use the same plugpair, or in some cases do they just use a domestic-like plug (rather as a motorhome may have), or generally do small craft never have this?

Generally, most small aircraft use 28V DC power, the connector for which can be found in the catalog I linked to.

  Is there a switch (for example, perhaps near the pylon in the first photo?), or a switch near the plug, or does it just hot connect?

Generally, the switch is in the cockpit rather than next to the plug, and it's the pilot's job to make sure there's no hot connect/disconnect.


Why do narrowbodies have longer life than widebodies? Is it fair to say that narrowbody aircraft have a longer life than widebody aircraft? This is the conclusion drawn from a report written by Dick Forsburg from Avolon (.pdf), where he says that the average life of a narrowbody is 26.6 years, while the average life of a widebody is 24.6.

Is it generally accepted that narrowbodies have a longer life than widebodies? If so, what are the reasons for narrowbodies having a longer life that widebodies?

The author does a very good job explaining the jet market. The key take-away is that it's all about economics. In many ways, narrowbodies may "wear out" faster as they typically fly shorter routes and accumulate more cycles in a shorter period of time. Pressurization cycles are a big factor in structural fatigue.

But that's not the primary reason for retirements. Airplanes get retired when operating them is no longer profitable. Profit is generically income minus  costs. Income for aircraft is maximized by flying as much as possible (high utilization) with the highest load factors possible. Costs are primarily driven by capital depreciation, fuel, crew, and maintenance.

The shorter lifespan he identified for widebodies is driven by a few key factors:

Widebodies are a smaller percentage of the total fleet, so that even
a few "early" retirements will cause a larger shift in the average.
Widebodies are suited primarily for long-haul, high density routes.
So a shift in travel patterns can quickly leave a route
unprofitable. Covering that reduced demand will often mean shifting
to a smaller aircraft to keep the load factors up. Narrowbodies have
more inherent flexibility.
And what I would say is one of the most significant factors is the
shift of widebodies from 4 engines to 2 engines over the last 20-25
years. It's not a fast process as widebody construction is not very
high rate, but the cost benefit of 2 engine widebodies (B777, A330,
A350) means a lot of 4 engine aircraft (B747, A340) have been
retired in the last 10-15 years.


In an emergency, can an airliner land at Pyongyang or another North Korean airport? If a flight was, say, en route to Seoul, but could only make it to the closest available airstrip and that was Pyongyang, would that be allowed? What would they be met with on the ground?

I can see at least three questions here and only one of them is fully aviation-related. First, can an airliner legally divert to Pyongyang in an emergency, under the laws of its own country? For US airlines, the answer is yes. 14 CFR 91 SFAR 79 bans flights over North Korea, but does allow an exception in an emergency:

  2. Flight Prohibition. Except as provided in paragraphs 3 and 4 of this SFAR, no person described in paragraph 1 may conduct flight
  operations through the Pyongyang FIR west of 132 degrees east
  longitude.

  [...]

  4. Emergency situations. In an emergency that requires immediate decision and action for the safety of the flight, the pilot in command
  on an aircraft may deviate from this SFAR to the extent required by
  that emergency.

Second, will North Korea allow the airliner to land? This is a political question, not an aviation one. Either they say yes or they say no. If they say no to an airliner in distress, how will they enforce that? Are they willing to shoot it down rather than let it land? Would that decision depend on the country of the airliner? Can they even make that decision within minutes, or is it already made and they simply initiate a defined procedure? The pilot is probably just going to try to land anyway; assuming the alternative is a crash, he would have little to lose.

Finally, what will the 'reception committee' on the ground look like? No idea, this is a political/military question.

But practically speaking, this situation should never arise anyway (ignoring movie plot stuff like hacked navigation systems). If your country isn't friendly or at least neutral to North Korea, your airlines simply won't plan flights where the only emergency landing possible is in Pyongyang, and for US carriers specifically it would be illegal anyway.


How much oxygen is put in say a 180-seater A319 or A320 aircraft? I read the answer in How much oxygen do commercial airliners carry? but it doesn't go into any details about two things:

How much oxygen is carried? I do imagine it would be quite a bit.

How much weight does it have? I am imagining that it probably would be liquid oxygen as that it would be much easier to carry, more compressible, fill everything better than in the gaseous state. I have been reading about liquid oxygen in different contexts hence thought it would be good to ask.

An A320 carries oxygen generators for passengers and cabin crew, pressurized oxygen for flight crew (including observers) and some portable oxygen bottles [1].
I can't find the exact volume of the pressurized container, but it is pressurized to around 1800 psi (124 bar) when full; [2] (page 148) gives minimum pressure for flight and how long for it should suffice.
Average amount of air inhaled by an adult human is usually given around 2 000 l/h, which contains around 400 l of oxygen (at standard pressure). The passenger masks are required to last quarter an hour, so they need to provide oxygen that would have 100 l at standard pressure (but at 0.15–0.2 bar only) per passenger. Plus there are some (around quarter) extra masks for people who are walking in the aisle at the moment decompression occurs.
Only flight crew masks must be able to provide pure oxygen at sea level pressure to be able to keep smoke or fumes out in case those enter the cockpit. These are always supplied from a pressurized bottle, because it must be possible to turn them on and off as they may be used in other cases too (fumes, pilot feeling unwell, preemptively if the pilot is alone for some time etc.) and the chemical generator will release all their oxygen once triggered.


Where can I find the planned and flown paths for certain flight routes? Are there official definitions of air traffic corridor pathing? Specifically European & Mediterranean routes.

I'm working on an application that needs this input data to perform an analysis. I and others in my company have been unable to find anything, and I really don't want to have to derive something approximating it myself if I don't have to.

Edit: Since what I'm asking for doesn't seem to be very clear I'll try a different way.

When an commercial jet starts a flight from one airport to another. I assume it had a generally predetermined path (or options of paths). These are not straight shortest path between two points on an ellipsoid so the data at OpenFlights.org isn't helpful, as it is not accurate enough. Obviously though no one can fully predict exactly where an aircraft will be in the future because that changes in respect to many different unknown variables, but I need something more like this, which was done tracking one commercial jet from one airport to another which includes no amount of variation, and it takes a long time to do this live.

Ideally I could get the general routes that these individual flights tend to follow, but to get an approximation of the actual routes between airports would be a whole lot better than I am know.

In a perfect world there would be lat/lon/alt/ pairings of the paths with some sort of standard deviation on those points. I doubt that exists but anything that could get me closer to that would be excellent.

Paying for something is not necessarily a problem, as long as I can prove it to my boss that it is what we need.

Yes, depending.....
On FlightAware.com you can see the routing of a flight after it's flown, and the same flight the next day will probably file for the same route.

On FltPlan.com you can find typical routes that a plane is likely to be cleared on and have actually been cleared on over time. Pretty accurate, but you probably need flying skills to interpret it, or get training on understanding routing, airport ICAO codes, nav fixes, departures arrival and enroute routing.


Is it safe to wear earplugs in flight? Speaking in terms of health for the ears and eardrums, would earplugs that form an airtight seal be dangerous to wear in flight due to cabin pressure changes? What about in the event of a rapid depressurization? And does it make a difference in which phase of flight they're first put on (before take off vs when in cruising altitude)?

I wear earplugs all the time flying in both pressurized and unpressurized environments, and have done it for many years.  Air pressure changes have no noticeable effect when wearing foam earplugs as the interface between the foam and ear canal is not totally air tight.   The silicone flanged ones made for airline flying have a tiny bleed hole in them (flanged ones are way too uncomfortable for me though).

If anything, on an explosive decompression, the earplugs would help by delaying the escape of pressure on the outside of the eardrum while the pressure equalizes on the inside through the eustachian tubes, which can take a second or two if you have to work your jaw to open them.

Put them in whenever you want and take them out whenever you want.


Why does the J58 engine of the SR-71 have a diffuser after the inlet spike? I heard that the diffuser allows the compressed air after the inlet spike to "spread out". What does this mean? If this means expansion, wouldn't it be beneficial to have it compressed before entering the compression chamber, so why would it spread out?

Generally, a compressor cannot work efficiently at supersonic speed due to the shockwaves, the role of the inlet cone and diffuser is to slow the air below Mach 1. There is a similar need for a ramjet, so that the combustion can occur within the engine and produce thrust.

The cone position and diffuser geometry are adjusted according to the airspeed. The overall shape of the diffuser is diverging.

From Bernoulli's principle, the diffuser decreases velocity and increases pressure according to:

$\frac 1 \rho \; dp = - \mathrm V\;d \mathrm V$ where $\rho$ is air density.

Look at this video: Converging Diverging Nozzles for more details about how pressure and velocity are affected in a nozzle / a diffuser. Here is a summary:

The J58 is turbojet within a ramjet. The forward section of the engine has a complex role. It adapts to a large range of speed (0 to Mach 3.2) and altitude (0 to 85,000 ft), and modifies the airflow to work either as turbojet, or as a ramjet, depending on the airspeed.

Simplified adjustment of the airflow (source).

Actual mechanism used at different airspeed ranges in the J58:

(Source)


Calculate g's per radian I'm currently attempting to assign handling qualities to the A-4D, and I would like to know how to find the term:

$ n / \alpha = \overline{q} \times C_{L\alpha} / (W / S) $

where $C_{L\alpha}$ is the lift-curve slope. I think I could solve for the lift-curve slope by using the value $1/T_{\theta2}$ or $1/T_{P2}$, the phugoid frequency, somehow, but I cannot find that equation.

I'm not given a chart of the change in lift-curve slope per Mach number.

The solution that I needed is the following image:


Why do the F-22 and F-35 look similar to each other and different from previous designs? Is there a reason the F-22 and F-35 look very similar other than style, they look very different to F-16s so is there a conscious effort to make them look cool?

ymb1 is right - stealth and not styling determine the looks of both the F-22 and the F-35. But there is more to it.

Watch Lockheed test pilot Tom Morgenfeld talk about them in this video:

The juicy bits are at 37:15' and at 43:35' into the video. Concerning the F-22 he says: Northrop built the F-23 exactly to what the Air Force asked for, while Lockheed built what the Air Force secretly wanted. And that was another F-15, with similar manoeuvrability.

Concerning the F-35 he says Lockheed's goal was to build an aircraft which is at least as good as an F-18 around the ship. This means manoeuvrability to land on a carrier even from off-nominal conditions; very forgiving to fly. By using the F-22 baseline, this manoeuvrability could be ensured.

Now look at all three of them:

McDonnell-Douglas F-15 Eagle (picture source)

Lockheed-Martin F-22 Raptor (picture source)

Lockheed-Martin F-35 Lightning II (picture source)

They look similar, don't they? Differences like a forward swept trailing edge and canted verticals are due to stealth, as is edge alignment.


What makes airplanes pitch up during landing? So what exactly pitches the plane upward with the rear end down? Do flaps help lower the nose when deployed 80%-100% down with such low speeds?

The change in pitch during the landing is called the flare and it is controlled by the pilot (or autopilot for an autoland) using the elevators (i.e. pulling on the yoke). From the Boeing 737 NG FCTM (6.10 Landing):

  When the threshold passes under the airplane nose and out of sight, shift the visual
  sighting point to the far end of the runway. Shifting the visual sighting point assists
  in controlling the pitch attitude during the flare. Maintaining a constant airspeed
  and descent rate assists in determining the flare point. Initiate the flare when the
  main gear is approximately 20 feet above the runway by increasing pitch attitude
  approximately 2° - 3°. This slows the rate of descent.

  After the flare is initiated, smoothly retard the thrust levers to idle, and make small
  pitch attitude adjustments to maintain the desired descent rate to the runway.
  Ideally, main gear touchdown should occur simultaneously with thrust levers
  reaching idle. A smooth thrust reduction to idle also assists in controlling the
  natural nose-down pitch change associated with thrust reduction. Hold sufficient
  back pressure on the control column to keep the pitch attitude constant. A
  touchdown attitude as depicted in the figure below is normal with an airspeed of
  approximately VREF plus any gust correction.

The flaps are set much earlier during the approach phase. They are not changed any more during the landing phase.


A couple of questions about Aeroflot flight 593 I recently heard about Aeroflot flight 593 and I know the cause is pilot error or whatever you would like to call that, but I have a couple of question about the aircraft.

First of all, I have never heard of part of the autopilot disconnecting. I have never heard of just the ailerons of the autopilot disconnecting, was this just a feature of the aircraft? Can any new Airbus or any modern day aircraft's autopilot partly disconnect to a system?
Lastly I know the autopilot pitched up and increased thrust to gain altitude but why did it stall, why didn't the autopilot stop pitching the nose up and increasing thrust once it got to high and dangerous?

The autopilot will disengage if the controls are manually manipulated while the autopilot is on.  The main issue with this particular airplane was that there was no audible autopilot enunciation that indicated that the autopilot turned off which is what the pilots were used to hearing on Russian made jets.  Rather there was only an indication light that would go on if autopilot disengaged and could go unnoticed.  The autopilot disengagement was not noticed right away and the aircraft entered into a spiral spin.  The pilots tried to recover from the spin but they pulled up too much (over corrected) and the plane entered a stall.

Autopilots can disengaged automatically for a number of reasons.  For example Air France 447 autopilot disengaged due to conflicting information from the airspeed indicators.  Incorrect actions by the pilots after the autopilot disengagement caused that accident.  In modern day aircraft the autopilot disengagement is heard as an audible signal so the pilot knows to take over.  If Aeroflot 593 had this feature the accident could have been avoided (besides not having your kids fly the airplane).

To answer your questions about he various levels of autopilots there is really only one autopilot that works in conjunction with other automated systems to fly the plane below is a description of the various systems:

Autopilot:  Automatically flies the plane according to instruments.  This system is responsible for manipulating the control column.

Auto-Thrust:  Automatically adjust thrust to maintain a constant airspeed.

Yaw-Dampening: Automatically adjust rudders for coordinated turns.  Yaw-Dampening can work when autopilot is on or when the airplane is manually flown.

Just because the autopilot disengages does not necessarily mean the other systems disengage.


What is the source for the flight data shown on in-flight entertainment systems? This question which claims that an altitude of 55,000 ft. was observed on a passenger's in-flight entertainment system on an Emirates B777 made me wonder: What are the normal sources of information for the flight data displayed on passenger IFE systems?

Of particular interest are the common sources for the following information:

Altitude (Is this a pressure altitude? Indicated altitude? A GPS-measured altitude? A radio-altimeter-measured absolute altitude?)
Speed (This seems to typically be true ground speed, which I'd assume comes from GPS, but any further insight would be appreciated)
Latitude/Longitude position (Is this from GPS? INS? radionav? some combination?)
Wind speed

I work on these panels which get the data (both IFE and cockpit display panels for a big OEM and there are very few in the world :)). This is all Air data systems which are providing all the data. We get this data from various sensors placed inside the cockpit or on aircraft exterior including wings and tail. Their are different kind of data transmission buses like ARINC which transmit that data then the required data is fed to IFE system through a protocol but most crucial data like data coming from Weather Radar etc is kept for Pilot usage and is displayed on the cockpit display panels.

For your question Altitude, elevation. azimuth there are some radars in the aircraft which gives that data and some of these radars measure and send this data using CAN protocol with very high speed varying from 40ms to 100ms.


If I need to do a course reversal before initiating an approach, do I need to notify ATC that I'm doing it? If I need to do a course reversal before initiating an approach, do I need to notify ATC that I'm going to do the course reversal, or is it implied that I'm going to do it?

For example:

If I'm approaching the VIR VOR with a course of 230, I would need to do a course reversal to get established on the outbound course. Should I notify ATC that I'm going to do the course reversal?

It is implied.

When you are cleared for the approach you are cleared for the procedure turn, or base turn as indicated on the plate.  Since your current heading puts you outside the entry sector, you do a racetrack to get aligned with the entry to the base turn.

It is always good to know when you have to call and when you don't because there could be heavy traffic, high workload, or who knows what. But if we're talking a competency ride or something like that, you should know whether you need to make the call or not.  All that said, one can of course report the course reversal if there is doubt.

In this instance, there is no requirement to report the turn.


Is flow turning different from the Magnus Effect? If so, how? The production of lift is much more complex than a simple
  differential pressure between upper and lower airfoil surfaces. In
  fact, many lifting airfoils do not have an upper surface longer than
  the bottom, as in the case of symmetrical airfoils. These are seen in high-speed
  aircraft having symmetrical wings, or on symmetrical rotor
  blades for many helicopters whose upper and lower surfaces
  4-8
  are identical. In both examples, the only difference is the
  relationship of the airfoil with the oncoming airstream
  (angle). A paper airplane,
  which is simply a flat plate, has a bottom and top exactly the same
  shape and length. Yet, these airfoils do produce lift, and “flow
  turning” is partly (or fully) responsible for creating lift. As an airfoil moves through air, the airfoil is inclined against the airflow, producing a different flow caused by the airfoil’s relationship to the oncoming air (my emphasis).
  PHAK pp.97-98

In what way is the "flow turning" being explained above different from the Magnus Effect (Bernoulli's Principle)? Are there any fundamental difference between the two? Aren't they the same in that they both use a speed difference in airflow between the upper and lower surface of an airfoil to produce lift?

When air comes into contact with a barn door or whatever at an angle, it will want to follow the top surface down (due to viscosity). Air will try to stick to the surface as much as it could, it usually fails above angle-of-attack of 15° or so.

When the flow sticks, the part exactly at the surface will have zero velocity. Above that part (layer) it will be a bit faster, and so on. Think of the layers within 2-3 cm of the top surface (that's the boundary layer).

Since the top most layer is the fastest, and the bottom is the slowest, the air will turn down (like a tank with different speeds for the different tracks).

The phenomena can be thought of as a force pointing down and causing the air stream to bend. With the airfoil's reaction being an opposite upwards force.

This downward motion pulls air from above and directs it down, causing the downwash. Bringing air from ahead and below is the upwash.

This rushing of air above the surface decreases the pressure, below the opposite happens but at a smaller magnitude. The end result is pressure differential and the air below pushes up toward the lowest pressure.

Flow turning:

Above is considered flow turning, the turning may become more apparent when you look at what happens to the air by a passing airfoil. It is usually depicted like this:

(Sources and more: allstar.fiu.edu, this video, and this video.)

Above is a different frame of reference of looking at how the lift is created. It has nothing to do with the Magnus effect. See PK's answer, both are lift, both can be described in many ways.

The Magnus effect:

The Magnus effect is of usually a spinning cylinder or ball, where the top/bottom surfaces change the speed of the flow in opposite ways. For example, in a back spin, the top surface moves in the same direction as the air stream, further accelerating the air near the top surface and further pulling more upwash, etc.

(Source)


Proportionally, what is more affected by a hot and high takeoff - a electrically driven propeller or a turbofan? My assumption would be the electrically driven propeller would be less affected compared to turbofans at high altitudes and take off as although the air would be less dense at these ambient conditions, the electric motor itself should be unaffected. In a turbofan my assumption would be that both combustion efficiency in the core and propulsion efficiency by the fan would be negatively affected.

Is this assumption correct?

Is this assumption correct?

Generally, yes. However, specific combinations of powerplant and propeller might make that difference moot.


Do pilots have procedures and safeguards against unintended altitude captures? Most advanced autopilots with a guidance panel allow you to select an altitude and fly to it.  It will often switch over to an altitude hold mode if the airplane is close enough to the selected altitude and the flight conditions like current vertical speed are right.  My question is about how vigilant the pilot has to be to prevent this altitude capture from happening at the wrong moment.

The Garmin G1000 manual describes the behavior like this:

  As the aircraft nears the Selected Altitude, the flight
  director automatically transitions to Selected Altitude
  Capture Mode with Altitude Hold Mode armed (Figure
  6-7). This automatic transition is indicated by the green
  ‘ALTS’ annunciation flashing...

  At 50 ft from the Selected Altitude, the flight director
  automatically transitions from Selected Altitude Capture
  to Altitude Hold Mode and holds the Selected Altitude
  (shown as the Altitude Reference).

However, this preselected altitude stays on as the flight proceeds, including during most mode changes.  There are some mode changes where this old altitude could cause problems if it initiates an altitude capture, like a transition to a go-around mode or an approach mode.  (For an example, see "A Sea Level State Of Mind" in this newsletter). The autopilot would try to reach the old altitude once conditions are right (which may require turbulence or other conditions to make the AP think it's trying to fly to the preslected altitude).  The plane would be doing what the pilot previously had told it to do, not what he was directing the plane to do at the moment.

From a human factors perspective, having the autopilot follow the old altitude target in a problematic scenario would make the system easier to understand, but would require more mental work from the pilot to maintain mode awareness.  Under certain conditions this altitude capture could potentially create a safety issue if the autopilot doesn't otherwise mitigate the sudden motion in an unintended direction.

Having seen a case where the pilot asked "why is that happening"  then realized he had mis-managed his altitude selector, I'm wondering about how smart the autopilot is and what the procedures are for managing the altitude selector.  Does the pilot usually expect the autopilot or flight director to ignore or clear the preselected altitude when necessary, or does he have to carefully manage the altitude selected to avoid an unintended maneuver?

EDIT: I'm asking if there are any safety features for altitude capture (like not allowing altitude capture while in glideslope mode) or checklist/procedures related to altitude capture.  If you think there aren't any of those and that the pilot takes full responsibility for any unintended altitude captures, please answer why you think so.

On the Boeing 737 NG:

ALT ACQ is always armed when flight directors and/or autopilot is engaged in a climb/descent mode (V/S, VNAV, LVL CHG, TO/GA, CWS P), it is however, as you suggest, inhibited in G/S and G/P (glide slope, glide path) modes.

On a typical ILS, I would typically set the missed approach altitude (which would be captured during missed approach in TO/GA mode) on glide slope capture. You could also set the missed approach altitude when ALT HLD is engaged, and you know that you will not need to change altitude again until when intercepting the glide slope. (When changing the selected altitude with ALT HLD engaged, the "held" altitude is maintained, until a new vertical mode is engaged, regardless of selected altitude).

HOWEVER, performing a Non-ILS approach in V/S or VNAV, the set altitude WOULD be captured on descent. To avoid this, the approach MDA is usually set on the altitude selector, and kept there until sufficiently (typically 300 ft) below the missed approach altitude. When passing through this altitude, the missed approach altitude would be set (logic is implemented to make sure the altitude is not captured during the "winding up" of the selected altitude).

Lastly, performing a Non-ILS using IAN (Basically Boeing's solution for performing Non-ILS with ILS display and control laws, using FMC data), the final descent would be performed in G/P mode, which behaves roughly like G/S mode, eliminating the use for initially selecting the MDA.


How would a fighter be changed from having static stability to having relaxed stability? A good portion of aircraft, especially those designed before the 1970's, possessed static stability. However, modern fighters (and some airliners) have been build with relaxed static stability.
This question was aroused by the book Designed for the Kill by Mike Spick. On page 119, it states (in reference to the Shenyang J-8 II Finback B):

In 1991 improvements were stated to be in hand to improve subsonic manoeuvrability, and one of the obvious moves would be to introduce variable camber by using leading edge slats. There can be no doubt that FBW and relaxed stability would also benefit it considerably, while weight reduction could be achieved by the use of composites.

How would a fighter such as the J-8 physically be changed to change the centre of gravity in relation to the centre of lift? Would the wings be resized/moved? Would the tailplane be made smaller? Would internal items be shuffled around to put heavier ones at the back? Or could some sort of clever aerodynamic device be added to modify the airflow somewhere?

The first and most important step is to move the center of gravity back relative to the neutral point of the configuration. This is done either by shifting masses on the airframe back or by shifting the wings forward. This needs to be complemented by the addition of a multiple redundant and fast flight control computer.
Now the tail will add lift instead of downforce, so the wing area required for manoeuvring and take-off/landing can be reduced. Or performance improves - compare the minimum speed of the Mirage III to that of the Mirage 2000.
To see how much the wing area could be reduced, here is a comparison drawing of the regular SEPECAT Jaguar with one designed for the same requirements, but with relaxed stability (copied from this answer). The forward shift and reduced area of the wing should be obvious.

Comparison of conventional Jaguar (top half) and CCV version (bottom half) by Ray Whitford.
What is done to a specific airframe depends on the objectives for the move to relaxed stability: This could be much better supersonic range or better short field performance. For the first you will shrink the wing, for the second you better keep wing size but move it forward and heavy items back. The change from the one engine of the MiG-21 to two more powerful engines certainly helped to shift the center of gravity of the J-8 back.
Usually all of the methods you mention are used in combination (except for the clever aerodynamic device, unless you mean a sophisticated FCS):

The wings are resized/moved
The tailplane would be made smaller
Internal items will be shuffled around or exchanged to shift the center of gravity further back.


Rotor Tip Speed vs Forward Airspeed - IAS or TAS? I created this graph to illustrate how the tip speed of the advancing and retreating blades vary with forward airspeed but am confused as to what would be the most correct way to label the x-axis:

IAS
TAS
it doesn't matter
it depends on the application

NB: Graph is based on the following data:

  The y-axis is a derivative of the x-axis: $$y= 672 ± \frac{6076x}{3600}$$

  eg: At $x = 100KTS$, $$y=672±169 FPS$$
  From POH: rotor RPM @ 100% = 510RPM = 672FPS @ 151 inch rotor diameter

For this graph, only TAS can be correct.

More precisely, you should have the same kind of speed on both axes. Otherwise, you would need to qualify the altitude.

Your tip speed (the vertical axis) is (presumably) the simple geometric speed, which depends only on RPM. Or in other words, TAS (with no wind). It will have simple and universal linear relationship with forward TAS. But with IAS, it will be valid only at a certain altitude.

This could be both IAS, but I don't think helicopters just increase their rotor RPM with altitude the way airplanes increase TAS. This could be true for very slow rotors, but the real ones seem to be Mach-limited, so IAS is just not very useful. But correct me if I'm wrong.


Will it be more efficient if airplanes flap like birds? Many airplanes have parts that are designed to mimic some features of animals. I have also read that birds are incredibly more efficient than most of the airplanes we see today. I wonder, will the future passenger airplanes resemble a big flapping bird? Considering that in the future we might have a lighter and more durable materials for wings.

In short, the answer is No. For many centuries, many proto-aeronautical engineers believed that the secret to manned flight would be found in complex flying machines that mimicked the flapping techniques of birds. These ornithopter designs were doomed from the start.

Aside from the obvious issues involving strong, rigid, durable, and light materials, there are tremendously complex psycho-muscular factors involved in biological flight mechanics that are impossible to duplicate with machinery. A bird has the benefit of nerve endings all over its body which provide immediate and intimate feedback of every minute shift and change. Additionally, the bird has fine motor control over its flight surfaces to a much greater degree than any aircraft can realistically replicate, and all at the speed of thought.
The good news is, efficiency can be relative. While the deft flight of a bird can be graceful, beautiful, and evolutionarily effective for its avian lifestyle, it will certainly never accomplish a trans-Pacific trip at 500 knots. Mankind has learned a lot from watching our feathered neighbors, but ultimately, our journey among the clouds lies along a different path from theirs.
That said, some small drone applications show promising possibilities for mimicking insect wings, so mother nature may still have a few more tricks to teach us.


How does FlightAware correlate flights to Part 91 flight plan data? I'm looking at some flights in FlightAware. With the scheduled air carrier flights, their call-sign can be crossreferenced with a flight schedule database to determine the origin and destination. How are they populating the origin and destination fields on small Part 91 IFR flights being conducted by a Cessna 172?

Do they have some sort of access to the Aeronautical Message Handling System (AMHS) or Aeronautical Fixed Telecommunications Network (AFTN). If not, how else could they be receiving this data?

In reference to the possible duplicate question, it's unclear to me if the term "flight data" in the context of that thread is in reference to the near real-time (NRT) flight track flight data, or a more robust data set which includes the details of a flight's route,  as filed and/or cleared.

Normally that type of flight plan routing data is transmitted over the AFTN/AMHS. It would be very very interesting if the FAA is integrating AMHS flight plan FAA data into the ADS-B/SSR flight track data.

Whilst I doubt know for sure, I’m relatively certain the flight plan routing data is integrated with track data by air traffic management (ATM) system and available to ATC personnel. What I need a better understanding of is how and at what point that integration occurs.

Is it an automated process occurring upstream or is it entered manually by the ATC personnel? If it's automated then is it AFTN/AMHS data or another source? If FlightAware is receiving this data, is it included as a single feed our do they have a separate feed? If the flight is scheduled, assuming the majority of origin/destination information results from callsign/ flight schedule cross-referencing, if either sources routing information conflicts with the other, which has primacy?

I concur that I understand the 5 minute FAA track feed delay was eliminated, but I don’t have a source to confirm.

The data that FlightAware first receives for most commercial flights
  is sometimes delivered a year in advance via schedules published by
  the airlines. That data then usually remains unchanged until a few
  hours before the flight. Pilots or air traffic control operators
  controlling airspace on the route of flight will push out new data
  with a flight plan that provides specific details about the planned
  routing, altitude, and speed of the plane. But that’s where the static
  data end and the real-time data begin.

  “When the door is shut and the parking brake is released by the
  pilots, the aircraft or airline will send us an ‘out’ message that
  indicates it’s pushed back from the gate, and we know that departure
  is imminent,” says FlightAware’s Baker. “As soon as the weight is
  lifted off the landing gear, we often get an ‘off’ message from the
  airlines or the aircraft itself that indicates the plane is airborne
  or a departure notice from air traffic control.”

  Once en route, FlightAware continues to get position updates from the
  plane via radar installations at air traffic control centers and via
  ADS-B, along with continued updates on the plane’s route from air
  traffic control. All of this information is then fused together by
  FlightAware’s software, which uses it to determine the plane’s
  estimated time of arrival, and then displays the aggregate data for
  the flight on its website and in its apps.

  “We detect the landing either by seeing the plane slow down below
  flying speed, by getting an ‘on’ message from the airplane, or by
  receiving an arrival notice from air traffic control. From there, we
  may have surface coverage to track the taxiing on the ground, and
  eventually receive the ‘in’ message from the airline indicating it’s
  safely parked at the gate,” says Baker.

  Now multiply all the above steps by the thousands, or one for each
  plane in the sky across the world at any given time, and you’ll begin
  to appreciate the amount of data that fight tracking websites’ servers
  and algorithms are crunching each and every second.

  https://www.fastcompany.com/3044490/how-flight-tracking-apps-work


How to read the Appleman chart to predict contrail formation? I stumbled upon the Appleman-chart, that makes it possible to predict the formation of contrails.

How do I use this chart?

First of all, the Appleman-chart itself:

Source

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

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

Source

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

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

Source

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

Now we can look this up on the chart.

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

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

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

Here's the data for the humidity:

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

Source

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

Picture from flightradar24.com

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

Now the look out of the window:

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


How does the angle of attack vary in turns? I read somewhere that when the aircraft banks to turn, its angle of attack increases.Since angle of attack is the angle between the relative wind and chord line, how does turning increase it? Is it because the relative wind is now from different direction or is it because the wing that goes higher meets the air at a higher angle?

Just to avoid some confusion that I feel in your question:

It doesn't!

That is, it doesn't happen by itself. The pilot or autopilot must actively pitch up (and possibly do other adjustments, e.g. increase thrust). Without active control, the angle of attack will stay about the same (initially), and the airplane will start descending if it enters a turn, because the lift becomes insufficient for level flight (see pictures in other answers).


If airliners profit by moving luggage from checked to carry-on, why do some LCC gate-check luggage? According to this answer, the less luggage is transported as checked luggage, the more "room" (in terms of weight) there is to bring along cargo, and thus more profit.

At the same time, some LCCs have the practice of gate-checking a bunch of bagage, essentially moving stuff from carry-on to checked luggage. It seems to me that that too is motivated by profit. But I'm not sure how.

These two practices seem to be contradictory, since they move luggage in other directions. While I can see the profit in the former, I don't directly see it in the latter. So what is the LCC's motivation to gate-check luggage?

A number of LCCs don't carry cargo at all or have a more limited cargo business, especially in Europe and the US. This is particularly the case if they're flying smaller narrowbody aircraft on shorter routes, where freight has to be bulk loaded. Ryanair and easyJet aren't in the freight business, though Southwest and AirAsia are.

LCCs have strong motivations to reduce turnaround times and ensure maximum utilization of their aircraft. Freight can slow down operations (somebody has to get it to the gate on time, it has to be loaded/unloaded) and so can carry-on bags (everyone has to carry them, find a space for them, lift them, and once the bins are full, it takes time to collect the excess bags, tag them, and get them downstairs and into the hold). Getting passengers to gate-check bags early can help speed the boarding process. It's the gate agent's job to get the aircraft off on time, so they're motivated to gate-check bags before there's a problem fitting them in the overhead bins.

In addition, passengers find carry-on baggage convenient. You don't have to wait for it, don't have to worry about it getting lost, and you can access it during the flight. LCCs make extensive use of ancillary revenue, with a la carte airfares that involve extra charges for anything passengers might consider convenient, from a preferred seat to a beverage. As such, some airlines charge for carry-on bags (or disallow them on their cheapest fares), extracting more revenue from those who value this convenience and speeding the boarding process by reducing the number of carry-on bags.


Where to find historical locations of North Atlantic Tracks? I'm looking for historical, daily locations of the North Atlantic Track (NAT, published daily as NOTAM) system for the past 10/20 years.  I've already contacted what feels like dozens of organizations (FAA, Gander, Shanwick, ...) but no-one seems to actually archive the NAT locations.

I'd be extremely grateful for any pointers towards possibilities to acquire these data, be it free or paying.

This guy has a 365 day history online.

You could contact him for older values.

You can also get some history using Archive.org.


What integration of aircraft propulsion would be more efficient at sea level high speed flight? A turbofan, unducted fan or a turbojet? For educational purposes I am designing a small single seat twin engine aircraft that will be as efficient as possible at sea level and at a variety of speeds 150-500+ mph. The goal is to be able to travel long distances at high speed while offering great acceleration and loiter characteristics.

All of the information I've found is regarding cruising altitudes where at speeds of 400mph or less the turboprop is more efficient then a turbofan.

The chart below shows the results at altitude.

My top two choices are a variable pitch unducted fan or a high bypass turbofan. Both would be mounted in the wing with unducted unit having the blades aft of the wing. Both could possibly include afterburner for accelerating to top speed.

None of these charts take into account the drag of the different sized engines and their respective arrangements. The TSFC is usually quoted at design intention or static thrust and not sea level at high airspeeds so it's hard to compare known engines.

The turbofan aircraft could likely be designed quite a bit differently as you could use thrust vectoring and a variable nozzle reducing the number of necessary control surfaces and therefore drag which is extremely important in the thicker atmosphere.

Penguin ancestors took to the sea for food, not to set speed records.  There is absolutely no reason to design an aircraft to cruise at sea level.  Plus you take away a very important lifesaver in the event of engine failure, the glide.  Far better to fly in thinner air, where true airspeed can be pushed all the way to your Mach limit while the indicated airspeed is far lower.

Simply apply your graphs to higher altitudes for greatest efficiency, and, unless you plan to go over 400 knots, the turboprop should be your choice, unless you find a good mechanic for your turbo-compound radial.

The weather is also a bit smoother up there too.


How much can a plane benefit from another planes wake? Could a smaller plane fly in a V formation behind a much larger plane to reduce fuel consumption significantly more than a plane its own size? At what point does flying in a larger planes wake become to turbulent or increased fuel efficiency stops?

Related: How do planes benefit from flying in formation?

No, airplane wakes do not work like this. The streamlined body has very little wake, it is not like a cube shaped truck. The main wake on an airplane is found at the wingtips in the form of a strong vortex like horizontal tornado, aided somewhat by the down wash of the mid wingspan.

The tip vortex from a large plane will make a small plane spin like a windmill. A german bombardier challanger(mid size business jet) flew under an A380 at cruise altitude a few years ago and was turned over so hard the plane had to be sold for scrap, broke a one passanger's ribs, recorded near 4G force, lost 8000 ft of altitude before recovering control.


Do any aircraft use throttle steering during normal flight? If the engine(s) on one side of a multiengine airplane are set to a higher throttle setting than those on the other side, the airplane (all else being equal) will yaw towards the lower-throttle side; this is best known as a technique for controlling airplanes that have suffered a partial or complete failure of their primary flight control system(s).

Are there any airplanes that make use of throttle steering during normal operation?

Yes, The Northrop Grumman B-2 Spirit Stealth Bomber.

  The leading edge of the wing has an internal structure that helps it
  absorb radar energy. The outermost wing segment features a "rudderon"
  or "deceleron", a vertically-split airbrake / rudder that
  simultaneously opens up and down. To act as an airbrake, both the
  decelerons are opened, while to act as a rudder only one is. This
  clever gimmick goes back to the original Northrop flying wings. There
  is an elevon inboard of the deceleron on the outermost segment of each
  wing, and then two elevons further inboard, on the next segment.
  Finally, there is a single control surface for pitch control on the
  "beavertail" at the center end of the aircraft, giving a total of nine
  control surfaces.

  The decelerons have to be opened about five degrees before they are
  effective, and in normal cruising flight they are left slightly open.
  However, this undermines stealth, so when the bomber is in hostile
  airspace, it uses differential engine thrust for yaw control.


Are flights being shown as "hijacked" on airport departure screens in case they are? In the movie The Net a flight appears as "hijacked" on a departure/arrival screen. Would these screens really show an airliner as hijacked when they are, and did this ever happen?

Anything can be shown on a digital screen, but there is no way any airport would do that. What would be the purpose?


What is a localiser back-course approach and how does it work? What does back-course approach mean ? How much signal strength should the back lobe of ILS should have in order to trace it and commence landing. How common is this type of landing for a pilot. What all instruments are required for this type of landing?

A localizer back course is simply flying on the back side of the localizer to the runway.  How a localizer works is it sends out two signal lobes:  one at 90Hz and the other at 150Hz.  The localizer needle in the airplane compares the relative strength it receives from both lobes and then shows a deflection.

See this figure from the Instrument Flying Handbook (2015) published by the FAA.

Notice the top left of the picture shows the same lobes on the same side of the runway.  Now imagine flying the front-course, the blue lobe is on the right.  If you are flying the back-course, the blue lobe would be on the left.

The localizer needle doesn't know if you are on the front-course or the back-course and will show the same deflection for both situations.  The problem comes in for the back-course is that the needle deflection is deflected the wrong way.

To answer your questions.

What does back-course mean?  It simply means you are flying on the opposite of the localizer signal.  If there is a back-course published, the signal strength will be strong enough to fly the approach as required.
How common is a back-course approach?  There are currently 69 back-course approaches in the United States.  There are approximately 1,893 ILS approaches.  This is around 3.5% of back-course approaches as compared to ILS approaches.
The same flight and navigation instruments required to fly a front-course ILS is required to fly a back-course ILS.

From a technique standpoint.  Whenever I fly a back-course approach, irrespective of whether I am using an HSI or VOR receiver, I will always set in the front course.  For pilots that use an HSI this will provide for "positive sensing" meaning the needle will deflect correctly.  For pilots using a VOR, the needle will shade bottom numbers that correspond to heading that need to be flown to get back onto the back-course approach.

If this was a back-course approach, notice that the needle is deflected to the right.  Conventional wisdom says you need to turn away from the needle to re-intercept.  I say to select a heading under the needle to fly.  That heading will be approximately 120°.  Take a look at the heading indicator and determine that you most likely need to turn left to re-intercept the back-course.  Try it and you will see it works.  Conversely, I also teach the same concept for an ILS except the heading to fly is on top of the VOR indicator instead of on the bottom.


How does engine exhaust temperature affect contrail formation and why? There was a german study about the "Influence of propulsion efficiency on contrail formation". In this study, an Airbus A340 and a Boeing 707 flew right next to each other.

  The two contrail forming aircraft were

  (i) a Boeing B707 equipped with four jet engines of type JT3D-3B with bypass-ratio of 1.4 and

  (ii) an Airbus A340-300 with four jet engines of type CFM56-5C4 with bypass-ratio of 6.8.

The A340, with the high bypass-ratio, formed contrails behind it, whilst the Boeing with the low bypass-ratio did not form any contrails behind.

Source

This has to do with the different exhaust gas temperatures of engines with different bypass-ratios.

How exactly is the formation of the contrails affected by the EGT (and therefore bypass-ratio), so whats the difference between low EGT and high EGT in terms of contrail formation? What is the physics behind it? Just why does the Airbus form a contrail, whilst the Boeing doesn't?

Note, 'How does contrail formation differ from turbofan to turbojet?' does not answer the question regarding the EGT.

There are some building-blocks to the answer:

Part 1: Assumption/Simplification
Let's assume for a moment that the only difference between the two planes is the exhaust gas temperature (EGT). A less efficient engine will utilise less of the available (chemical) energy of the fuel. This means a less efficient engine will have a hotter and faster exhaust jet (wasting caloric and kinetic energy).

Part 2:
The water-content of the exhaust gas contains water from two sources: first the water (very low fraction) from the ambient air humidity and second from the combustion of the fuel (carbon-hydrates).

Part 3: Assumption
When humid air (from an engine exhaust) mixes with the atmosphere it is a reasonable assumption that the state of the atmosphere will not change measurably given enough time for the exhaust to mix out.

Part 4:
The mass of water vapour which can be contained in a given mass of air depends on pressure and temperature of the air. This dependency is often visualized in either the Mollier-Diagram or Psychometric-Chart. The following simplification of a Mollier-Diagram shows two areas or states humid air can have. For a given temperature and low water content the water is in its gaseous phase. If the water content is increased (over the saturation point) than part of the water will be condensed (fog, small water droplets).

Part 5: Answer-Part I
When hot humid air exits the engine it will cool down an partially/continuously mix with the atmosphere. This means temperature and water content/ratio (per a given volume) will decrease. The following sketch illustrates this for two starting points. At the end of this process the jet reaches the state of the atmosphere (see part 3). In the case of a lower EGT the cooling of the exhaust can cause the humid air to cross the saturation-line which will result in a contrail.

Part 6: Answer-PartII
A lower by-pass-ratio-engine is likely to have a higher velocity difference between the ambience/atmosphere and the jet from the engine. This will increase the mixing of the exhaust gases which suppresses the condensation as well.

The model used in the paper (Schumann 2000) also includes basic thermodynamic considerations for the jet-engine which do increase the predictive accuracy of the model. But the thermodynamic effect should be captured by the parts 1-6 given here.


What are the data elements shown on the GE235 flight data recorder (FDR) plot? The Aviation Herald already has an image of the Flight Data Recorder information from the crash of TransAsia GE235:

(click to enlarge)

I have determined that the green lines are for engine 1 and the blue lines are for engine 2, but beyond that, I'm a bit lost. Can someone translate the abbreviations and describe what information each graph is indicating for non-pilots.

From top to bottom:

  main gear : whether there is weight-on-wheel not [scale on the left, in blue: "air/gnd"] (thanks to DeltaLima for pointing this out)
  VHF1 : probably if there was communication of that radio channel (speculation on my side) [no scale]
  Master warning : if the MW signal for engine flame out was active or not [scale on the right, in green : "fault/-"]
  CLA : Conditioner Lever Angle [scale on the right, in green : "fuel SO/no FSO"]
  Beta : usually is used to indicate aircraft sideslip, in this case is referring to the propeller blades, 90 degrees signal feathering. [scale on the left, in green : "90//10"]
  Bleed valve : whether it was open or closed (as labeled on the right) [scale on the right, in green : "open/closed"]
  PLA : power lever angle, aka throttle lever position [scale on the left, in green : "80//30"]
  ITT : inter turbine temperature [scale on the right, in green : "700//100"]
  NP : propeller RPMs as % of max RPMs [scale on the left, in green : "100//0"]
  Fuel flow [scale on the right, in green: "2000//0"]
  Objective TQ: objective torque (*) [scale on the right, in green : "100//80"]
  TQ : torque [scale on the right, in green : "200//0"]
  NL : low pressure shaft RPMs [scale on the left, in green : "100//0"]
  NH : high pressure shaft RPMs [scale on the right, in green : "100//0"]
  Oil pressure [scale on the right, in green : "100//0"]
  Barometric corrected altitude [scale on the left, in cyan: "2000//0"]

*: from page 2 of that link:


Can pilots wear glasses/corrective lenses inside the cockpit? I was wondering If I could wear corrective lenses/glasses inside the cockpit If I have a certified class 2 medical certificate?

Yes.  All current classes of FAA-issued medical certificates allow for the use of corrective lenses in the cockpit.  See Title 14 §67 Medical Standards and Certification.


I want to be a French fighter pilot. Any advice? Hello everyone!

I want to be a French fighter pilot and I would like some advice from retired fighter pilots about how you should do things if you were at the same age as you were when you entered the army but having all the knowledge you have now.

Thanks for reading. If you see anything that can be improve (even the question), let me know! It's the same for questions or/and remarks, let me know!

The third point in your original list is a clear red flag:

  I'm a huge fan of airplane (but I'm not the type of guy loving learning every thing by heart)

I don't mean to put you off with what follows, but honestly, you've got to love learning everything by heart in the military in general, let alone the airforce.

Becoming a professional pilot is demanding, becoming a military pilot even more so. Both require high intellect, the ability to learn and memorize things easily and preferrably, especially in military aviation, a burning desire to do so.

On top of that, to make it as a military aviator, not only do you have to be enthusiastic about aviation in general, but you have to have just the right mindset: utmost dedication for the military way of life, deep patriotism, and absolute altruism. Any succesful military person is first and foremost a soldier, only in addition to that can one be something more.

The guys and gals at military aviation operate on a whole different level from an average pilot. You simply are not going to make it if you are not all in. About aviation and more importantly about military.


Why are Low Cost Carriers ordering several hundred aircraft? Indigo is a low cost carrier, which already has 99 A-320s in its fleet has  ordered 431 more. This airline currently covers 35 routes, while the full service carrier Emirates has 221 planes, and covers a fancy 164 routes. In its home country as well, the biggest player Air India has 102 planes and covers 95 routes. So, what are these LCCs planning to do with so many aircraft? Renting could be an idea, but you just do not go for renting as much as 4 times of your crew size.

Similarly,

AirAsia has ordered 304 A320s,
EasyJet has ordered 100 A320s,
RyanAir has ordered 100 B-737.
Norwegian has ordered 100 A320s, 100 B737,

Volume Orders Discounts

These result in significant discounts to the airline. While discounts are commonplace in the industry, Ryanair ordered 737-800 for an estimated 40-50 million dollars as compared to the list price of around 90 million dollars. With an order of that size Boeing could not risk losing it to another manufacturer, and will be satisfied with less profit per aircraft. Source

Fleet strategy:

Some airlines sell their old aircraft after only a few years while their value is still high but the maintenance costs start to increase. Increased maintenance is bad when you try to squeeze out as many flights as possible and you have small profit margins on every flight. You can find some of Ryanair's old aircraft by the company code (AS) with other operators by searching 737-8AS.

Another suggestion is that the customers perception of Low-Cost airlines is generally negatively biased and having new aircraft counters this effectively.

Old Aircraft

Some operators (such as charter operators) will not have the same sensitivity to a slightly higher fuel consumption on their aircraft. They may not use their aircraft the same number of hours, so having an increasingly expensive jet sitting on the ground is not cost-efficient. The aircraft ordered by IndiGo are all new fuel efficient A320NEO.

Some of these ideas are emphasized in your link.

  Of its 530 orders from IndiGo, Airbus has so far delivered 99 aircraft. The airline currently has a fleet of 83 planes and has phased out 16 planes that were over six year old or among the first in its fleet.

A bit of Ryanair strategy is outlined in this document.


Will driving experience benefit flight training? I think my question/situation is a little bit of rare so I start this question and want to hear from you experience pilots.

I'm a 30+ migrant from China working as a software engineer for 10 years. Now I use my weekends taking flight training for Private Pilot Licence in Sydney. Currently I don't see any big problem with my training and probably in next couple of weeks I will have my first Solo. What concerns me is my past experience. I can say I'm rather a good programmer and writing code for computer(iPhone) is really different from driving or flying. My flight instructor tend to say (and I agree) I always fly with the exact numbers rather than make necessary adjustment according to situation outside. So I guess with the past 10 years indoor in-front-of-keyboard office life/experience. The more you get your life/experience aligned with computer/coding, the harder you could get out of it.

What's worse is I don't have any driving experience until two months ago I started to practice for my Australian driver's licence. Now I have my licence issued for one month and I still only drove four or five times with rented car. Though I love public transportation and I'm not that declined to own a car, now I start to thinking about the benefit of driving experience for my flight training. At least driving skills are accumulated with "hours" (which is the same as flying) and it will get me out of computer world.

Do you have any suggestion or advice on this? Thanks for reading and replying. Cheers~

P.S. if possible, my target is CPL one day.

I don't think driver training is beneficial to flight training, the physical acts of driving and flying are too dissimilar. Driving is a handy skill to have for sure, it's usually much easier to get to the airfield for one thing, it's not going to translate to flying though.

As for flying the numbers you are falling back on what you are good at: attention to technical detail. Attention to technical detail is a very good thing in flying - having a plan and rehearsing for emergencies can save you neck. What your instructor may be telling you is that you need to focus your attention to other details. You may be spending too much time looking at your instruments and not enough looking outside. I did this at first because I had spent a lot of time playing flight simulators and I'm also in IT and spend a lot of time looking at displays in front of my face. The cure is simple: force yourself to get in the good habits of looking outside the aircraft and developing situational awareness. You can only get that through flying practice.

It sounds like you are concerned that you don't have a sort of instinctual "feel" for flying. Everyone has a different set of aptitudes, some people are better at certain aspects of flying than others. If there's an area you are weak in then focus your training and practice on developing it into a strength.


What are the chances that you are on plane that has an incident? ICAO Annex 13 defines an "incident" as

  An occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation.

Is there good record keeping about incidents globally? Not like Aviation Global Incident Map which only really only lists accidents and some airport issues.

For completeness, the same document defines an "accident" to be

  An occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, in which (a) a person is fatally or seriously injured [...], (b) the aircraft sustains damage or structural failure [...] or (c) the aircraft is missing or is completely inaccessible.

Only incidents that an airliner pilot is aware mid-flight and can do something about -this a start to follow-up.  question. Exact likelihood is not important- is it 10% or 20%. For passengers, the likelihood is not important since pilots handle mainly well.

I don't know if there is a global compilation. But for Australian operations data exists to allow us to establish a likelihood of being in an incident. Accidents are so rare that it's difficult to get a reliable indicator, however if we are just measuring reported incidents I believe we could get somewhere.

The Australian Transport Safety Bureau (ATSB) has published an "Aviation Occurrence Statistics" report covering 2004-2013.

Let's focus on high-capacity RPT operations, because lets face it, that is probably what most people are interested in.

According to the report, in 2013, there were 597,000 departures of Australian-registered high capacity RPT or charter flights (unfortunately the report doesn't seem to split it into RPT only, possibly because we have a lot of high-capacity charter flights to the mines). In the same year there were 3292 reported incidents to the ATSB and 2 accidents. Therefore I would conclude that if in 2013 you boarded an Australian-registered high-capacity RPT or charter flight, your chances of being in a reported incident were around 0.5%, and chances of being are an accident is 0.06%. The incident percentage is approximately the same for the couple of years prior, so I am confident that this remains around about the mark today - though I would not consider the accident rate to be reliable because there were so few.

The incidents cited in this data vary from loss of separation to a pilot being sick to birdstrikes.

Have a read of the report but before you take it as gospel, keep in mind, as they say, "there are lies, damn lies, and statistics!"