Constant speed propeller blade pitch compared to fixed-pitch I just transitioned to a complex airplane (Piper Arrow II). While I get how to use the Manifold Pressure / Propeller levers, I still find myself trying to piece together how all the components would function in a given situation.

One such situation is with the prop lever full-forward. If you back off the manifold pressure with the prop full-forward, the RPM will drop because there isn't enough air / fuel for the engine to turn at a the request rate. Think coming in to land (prop full toward and start reducing manifold pressure).

My question is: Does the propeller flatten out (relatively speaking) more than in a fixed-pitch propeller aircraft in this situation or is it the same net effect as operating a fixed-pitch propeller plane?

I've heard that putting the prop full-forward and then just using the throttle is the equivalent of operating a fixed-pitch propeller plane. How accurate is this statement?

I believe an Arrow operates the same as my Cardinal.

With low manifold pressure, there is not enough oil pressure to drive the prop into anything other than flattest configuration no matter where the prop control is at.
If you were take off with prop control not all the way in, then in theory the prop would start getting more twist as engine speed came up, and it would be like taking off in 4th gear or similar, when you want to start your acceleration in 1st gear and then shift up (think of how the RPMs bog down as you cycle the prop at 1700 to ensure the prop can twist).

So you start with the prop and controls all the way in to take off (balls to the wall - RPM, prop,  mixture, carb heat - or levers if so equipped).

Once you get to altitude, you can start bringing them back, equivalant to shifting up and taking your foot off the gas (and leaning the mixture for increased). RPMs are dialed down, prop control is dialed out to increase pitch.

Then when you come from altitude and prep for landing, you play the game of reducing RPM, decreasing pitch, reducing RPM, decreasing pitch, until eventually you are in the pattern, prop is all the way to support a go-around, and RPM controls all the power, same as taking off.


Why did LaMia flight 2933 plan a flight longer than its listed fuel range? According to the wiki, the range of the airplane used in the LMI 2933 flight has a range of 1600 miles. The distance between the airports though is 1605 miles though. I presume the exact range varies on conditions, but why would a flight that is outside the listed range be planned? This seems like an amateur mistake that should have been quickly caught on pre-flight checks.

Also, the wiki states that before crashing the plane made 2 loops. If the flight was running out of fuel, why would they do this? It seems like the flight could have easily made it if they flew directly, and considering that they had declared an emergency the ATC wouldn't be able to say no.

The investigation is still on-going so I will stick to what is factually known. An airplane's range through the air should not be confused with travel over the ground, actual distance over the ground can vary significantly depending on the winds aloft. A significant tailwind will allow an airplane to travel farther than its listed maximum range, which is really just an estimate. We won't know what happened in this case until the investigation is complete.

According to the information about the flight the pilot did not declare an emergency, so was told to orbit while another airplane which had a mechanical problem landed, this explains the loops.


How can an airplane roll, yaw and pitch up and down without control surfaces? This is a Sprat 103 ultralight, it has no ailerons, and no ruddervator (on its v-tail). How then does it fly controllably?

The wing is split to two halves, each half is mounted on its own axis. By changing each half's angle of incidence (and thus angle of attack) changes the amount of lift generated by the relevant side.

See this video of a scale model.

A scheme of the mechanism


How can you navigate "Writing" onto FlightRadar Plans? Sorry if the question title here is a bit misleading, the graphic here should explain all:

I read a news story this morning about how a guy flying a Robin DR400 regularly creates inventive patterns in his flight tracks.

Source

The question is, how would the pilot be able to create this writing (and other creative patterns)?  Autopilot instructions?  Watching himself on FlightRadar?

Most Robin 400s don't have autopilots, but some do. Whether it has an autopilot or not it was almost certainly navigated using a pre-set course which was fed into a GPS. One would use flight planning software to create a course using a series of waypoints which would then be uploaded to a built-in or handheld GPS, and then either flown by hand or followed by an autopilot.

You can see that the curves are mostly a series of small straight lines, I think that these straight lines are the space between waypoints, it could be the refresh between the FlightRadar inputs causing the lines though.


Can pilots change the callsign shown on tracking websites mid-flight? Today I viewed the following flight on FlightRadar24 website. It show a flight with a callsign of 'BLEED' and with the destination missing. Is this a problem with the website or can an aircraft change its transponder data to show such a callsign?

And this is a news report item about this flight:

https://www.jpost.com/Breaking-News/Flight-enters-Israel-from-Turkey-with-call-sign-BLEED-573889

Yes, a pilot can change this in-flight, just as they would have entered the data when on the ground before the flight.

On the A320, this is done from the FMGS (Flight Management and Guidance System). To do this, the pilot presses the DATA key on the MDCU (Multipurpose Display and Control Unit) keyboard. This brings up the following display:

And then selects the A/C STATUS page, which allows them to change the code (call sign/flight number):

This can be changed in flight by the pilots at any time. This information is sent to the ADS-B and other data-link systems that show up on radars and ultimately sites like FlightRadar24.


Can an aircraft get certified for different runway lengths through the FAA based on the amount of payload it is carrying during said takeoff? When certifying a new aircraft through the FAA, will they certify the AC for just one takeoff distance based on the max payload capacity, or can you get the AC certified for multiple runway lengths based on the amount of weight it is carrying at the time of takeoff?

Generally an aircraft will be certified for a range of runway distances based on headwind/air temp/weight, a correction chart will be provided in the POH allowing you to compute the runway distance for various conditions. For example here is the chart for the PA-28-161 I trained on

The big planes have similar charts, you can find the 737-800 numbers here and if you want to go to the really heavy metal the 747 info can be found here.

The AC that covers aircraft certification can be found here and interestingly the distances are computed from standstill to the point at which the lowest part of the aircraft is 35ft above the ground.

  (1) The takeoff distance on a dry runway is the greater of the two
  distances depicted in (a) or (b) below (see page 63 of above linked doc). The distances indicated below
  are measured horizontally from the main landing gears at initial brake
  release to that same point on the airplane when the lowest part of the
  departing airplane is 35 ft. above the surface of the runway.

Interestingly the FAR does not seem to address the weight at which the takeoff distance tests are done.


What is the difference between GPS, GNSS and RNAV? I would like to know the fundamental difference between GPS, GNSS and RNAV. How are they related each other? Are all/some of them synonyms?

As stated in the othe answers,

GPS is the US Global Positioning System
GNSS is an umbrella term that encompasses GPS as well as other nations' satellite systems that achieve essentially the same capability

RNAV is the aircraft capability that allows you to navigate from point to point, defined by Latitude/Longitude and independent of any ground-based system.  There are various ways that the hardware in the aircraft maintains its position.  It may use GPS sensors, it may use GLONASS, it may uses a combination of satellite systems, it may use DME/DME updates from ground-based navaids.  But the point of RNAV is that for the most part the procedures are agnostic with regard to how the position info is obtained.

Thus, you can have RNAV routes and approaches, meaning that the airway or approach segments are defined by Lat/Lon waypoints, and as long as your system meets defined accuracy tolerances (usually 1.0 NM enroute and 0.3 NM for an approach in the US), you can fly that airway or approach.  There are more stringent tolerances incorporated into RNAV(RNP) approaches, and these require that the system can monitor its accuracy and alert the pilot if the system isn't confident that its position is accurate to within a specified performance.  This can be set to match whatever is required on the approach; 0.1 NM is common, although there are other values that can be specified.

In the US, the FAA typically distinguishes basic RNAV approaches by designating them RNAV(GPS) in the title, as opposed to RNAV(RNP).  (The RNAV(RNP) approaches require a couple of additional things beyond basic RNAV, but those are beyond the scope of this question.)  Internationally, "RNAV(GNSS)" is often used instead of "RNAV(GPS)" in the approach title, but functionally they're pretty well the same thing -- it's simply a nod internationally to the fact that if your FMC knows where it is, the approach designer doesn't care which satellite system it's getting its position data from.

In the "old days", it was possible to have RNAV operations that worked by taking radial/DME data from a single VOR and creating a pseudo-VOR essentially whereever you wanted, and the HSI or other display would act as if the VOR were in the new location.  This was very early RNAV capability, in that it allowed you to fly a straight line course by keeping the HSI centered rather than flying VOR to VOR.  These days, that capability is pretty much gone, in favor of the much greater capability of GPS.


Does the minimum power required for level flight depend on CD0? I came across this video few days back on Edx 16.101 youtube channel.

At 7.00 min of the video, the presenter derived an equation for minimum flight power which does not depend on Cd0.

$$P_\min = \frac{4}{3\pi e AR}  \sqrt{\frac{2W^3CL}{\rho S}}$$

I don't have a doubt on the derivation, but this result seems to be very contradictory for me.

For example, let's take 2 identical aircrafts, one with fuselage airbrakes deployed and one without. (Identical CL, AR, $\rho$, S, CL and e but different Cd0)
According to this expression the power requered cannot change. But,

For same CL, V is going to be the same
With airbrakes deployed, aircraft 1 drag is much higher than the aircraft 2
Power required (D*V) should be higher for aircraft 1.

May be I am missing something simple. Why is this apparent contradiction?

Thank you for the excellent question!

The whole expression is only valid for the optimum polar point where the ratio $\frac{c^2_D}{c^3_L}$ reaches its maximum. If you deflect spoilers, this optimum will shift to a higher lift coefficient, so both aircraft will not fly at the same lift coefficient or the same speed any more! Always keep in mind that in this special condition the lift coefficient can also be expressed as
$$c_L=\sqrt{3\cdot\pi\cdot AR\cdot e\cdot c_{D0}}$$
Just plug that back into the equation and the minimum power expression will make a whole lot more sense:
$$P_{min}=\frac{4}{3\cdot\pi\cdot AR\cdot e}\cdot\sqrt{\frac{2\cdot W^3\cdot\sqrt{3\cdot\pi\cdot AR\cdot e\cdot c_{D0}}}{\rho\cdot S}}$$
This is still the same equation, but now it should be obvious that opening the spoilers will require more power.


Where can over age 65 airline pilots fly? Some countries have no maximum age for airline pilots while many other countries specify age 60 or 65. (Austria, Russia, Canada, Australia, etc., have no maximum age)

ICAO rules currently specify a max age of 65 which allows ICAO member states to fly into countries where the max age is only 60.

Does this rule apply to only landing and taking off, or also to in transit overflights?

For example, could a flight depart Canada, overfly American airspace, and fly to Australia with crew members older than 65?

If not, what about a flight from two bordering countries like Canada to Russia?

Pilot qualification- including age limit - is according to the law of the country where the aircraft is registered. What a pilot must abide by when flying overseas is the local operating/air traffic rules.


If "flight time is compensation", how can a PPL holder legally fly at all? I have seen a strange phrase "flight time is compensation" in a few questions and answers here, mostly related to what PPL can do for free and what is not allowed.

This looks so confusing that I ask a question. If the private pilot cannot get the compensation, and flight time is a compensation, how could such pilot legally fly? One should theoretically get CPL before having the possibility to log any flight time.

This is surely not the case, I understand. When the "flight time is compensation" and when it probably is not?

Most of the confusing questions are related to USA (so FAA).

Flight time is only considered compensation when the pilot is not paying all the costs associated with the flight.  If the costs are to be shared the following advice is recommended.

A private pilot can be compensated, up to a pro-rata share, of the cost of that specific flight.  This would include rental fees, fuel, oil and such.  It does not include items like insurance and annual inspection fees.

The overall regulation is found in §61.113(b & c).

  (b) A private pilot may, for compensation or hire, act as pilot in command of an aircraft in connection with any business or employment if:

    (1) The flight is only incidental to that business or employment; and

    (2) The aircraft does not carry passengers or property for compensation or hire.

  (c) A private pilot may not pay less than the pro rata share of the operating expenses of a flight with passengers, provided the expenses involve only fuel, oil, airport expenditures, or rental fees.

You should be able to see pretty quickly that you are allowed to transport yourself by private airplane to a business meeting.  There is good reason to fly to; depending on the distance, it could be quicker to fly a private airplane than it is to drive saving you time and money.  However, the moment the company decides that you should fly to all of your meetings it is no longer incidental to that business and operations must cease.

If you want to fly passengers, and also want them to pay their pro-rata share.  There are three things that must be considered.

There must be a bona-fide purpose for the PIC to make the flight.  The reason cannot be that the passenger has a business meeting at the destination and you want to get lunch.  You, as the pilot, must have a reason to make the trip, whether or not the passenger(s) come along.
The PIC must dictate where the flight is going to go.  Again, you cannot make a flight with passengers where you drop them off at one airport while you fly to a different airport.  Why would you land at the first airport, if you have no need to land there?
You cannot "hold out" or advertise that you are going somewhere and wait to see if other passengers are interested in going to the same location.  There are websites that have been shut down by the FAA for doing just that.

The Lamb Interpretation

The Mangiamele Interpretation

The Chero Interpretation

  December 26, 1985

  Thomas H. Chero
  Vice President - Legal
  AVEMCO Insurance Company
  Frederick Municipal Airport
  411 Aviation Way
  Frederick, MD 21701

  Dear Mr. Chero:

  Thank you for your letters to this office, dated September 9, 1985, and October 23, 1985, respectively, concerning the actions of the Pilots and Passengers Association (PPA).

  You are correct in stating that Section 61.118 of the Federal Aviation Regulations (FAR) prohibits private pilots from participating in PPA's operations. Section 61.118 provides that a private pilot cannot act as pilot in command of an aircraft that is carrying passengers for compensation or hire unless the flight falls within one of the four listed exceptions in 61.118(a) - (d).

  Section 61.118(b) allows a private pilot to share the operating expenses of a flight with his or her passengers. Additionally, the FAA has interpreted 61.118(b) so that the only allowable share-the-costs operations are those which are bona fide, that is, joint ventures for a common purpose with the expenses being defrayed by all passengers and the pilot. Nor does Section 61.118 permit pilots who want to build up time toward their commercial pilot certificates to carry expense sharing passengers to a destination at which they have no particular business. (emphasis added)

  PPA pilots apparently would not share in the expenses of the flights they would undertake. It also appears that PPA pilots could be flying to destinations at which they had no particular business. The PPA system is not a casual one of an individual pilot wishing to take some friends or acquaintances with him on a trip. The PPA system would violate the letter, as well as the spirit, of Section 61.118.

  Even if the pilot bears an equal share of the expenses with his or her passengers and indeed has his or her own need to fly to a particular destination, yet another problem arises. Since PPA's passengers would be solicited for flights by PPA from a broad segment of the general public, we conclude that each pilot carrying paying passengers from PPA would probably be engaged in common carriage. This means that each pilot would become an air carrier subject to the certification and operating rules of Part 135 of the FAR.

  We appreciate your calling our attention to this matter.

  Sincerely,

  John H. Cassady
  Assistant Chief Counsel
  Regulations and Enforcement Division


How to identify the FAP in runway during Landing? How to identify the FAP in runway during Landing ?

The final approach point is part of an instrument approach and thus can be identified using navaids as outlined in the approach procedure.


What flaps and throttle settings are used on takeoff, climb, cruise, descent, and landing? What degree of flaps and throttle setting are used on takeoff, climb, cruise, descent, and landing? This question is for private and general aviation aircraft. I have looked everywhere for FAA manuals on this but I can't find anything, if there is a manual please link it.

The exact numbers vary for each model of aircraft, so the FAA et al can't provide direct guidance; regulations just say to operate according to the manufacturer's specifications and procedures.

Still, that's not too helpful, so I'll give answers for the C172, which is one of the most common light planes. Other models will vary somewhat but likely follow the same general theme.

Short takeoff: 10° flaps, full throttle
Normal takeoff: no flaps, full throttle
Climb: no flaps, high-full throttle
Cruise: no flaps, mid-high throttle
Descent: no flaps, low-mid throttle
Landing: 30°/40° flaps, idle throttle

For the ranges, it's important to note that the pilot doesn't set the throttle to a particular position per se; he/she adjusts it as needed until the desired performance (or for cruise, economy) is achieved.


Does anyone recognise this jet engine? sorry for the terrible quality, it's what I've got. I've not been able to find anything looking like it using google image search. It looks too detailed for a random bit of clip art.
Possibly around 12-15 feet long by 2-3 feet diameter

I think it's a fairly good match for the Rolls Royce F405 Ardour. I can't quite work out which version though....
Thanks to everyone who spent time looking.
Rolls-royce.com
here's an afterburner and nozzle for a variant:
Hunini


Is failure to comply with evacuation procedures illegal? In every flight, we are instructed that we must leave our personal belongings in case of evacuation. I remember also notified that it is illegal not to follow the rules (I don't remember if this goes only for the non-smoking rule though).

So, is it "illegal" to take your stuff with you, while instructed to leave the airplane in an emergency (thus stalling the process)?

No. The intent of the statute involves "assaulting or intimidating" a crew member. Passively failing to obey a crew member has no criminal liability nor does disobeying generic safety guidance given by crew members or aircraft literature.

The actual statute reads like this (49 U.S.C. § 46504):

  An individual on an aircraft in the special aircraft jurisdiction of
  the United States who, by assaulting or intimidating a flight crew
  member or flight attendant of the aircraft, interferes with the
  performance of the duties of the member or attendant or lessens the
  ability of the member or attendant to perform those duties, or
  attempts or conspires to do such an act, shall be fined under title
  18, imprisoned for not more than 20 years, or both.

Normally, disobeying a crew member generally has the effect of getting the passenger kicked off the flight. Note that a captain can remove any person for ANY reason from a flight, nor does the captain need to give a reason. Of course, if the flight is in progress, then removal is not an option.

(Also, note that this answer is for the United States only. In authoritarian/Salic law type places like France or Germany, they have laws that generally make it criminal to disobey authorities, which is different than the United States.)


What does it mean for a door to be armed? What does "arming a door" mean?  Is the orange tape that's applied over a window related, perhaps as an indicator to people outside that the door is armed?

If a door is put into armed mode, it will trigger the evacuation slide when the door is opened.

Prior to departure (usually before engine startup), all the aircraft doors are placed into the armed (or automatic) mode by the cabin crew. Methods of arming vary from aircraft to aircraft, but ultimately the girt bar (a metal bar attached to the door end of the slide) is physically attached to brackets either in or adjacent to the door sill.[...]If a rapid evacuation is required and the doors are opened while "armed", the opening of the door pulls the slide pack out of the bustle (because the girt bar is physically attached to the aircraft floor)

This is also the reason for the famous All doors in flight announcement:

DOORS TO ARRIVAL AND CROSSCHECK “Flight attendants, doors to arrival and crosscheck.”
Meaning: Occasionally heard as “disarm your doors and crosscheck,” and announced by the lead flight attendant or purser as a plane approaches the gate. The intent is to verify disarming of the emergency escape slides attached to the doors. When armed, a slide will automatically deploy the instant its door is opened. Disarmed, it needs to be deployed manually. On departure the slides are armed to facilitate an emergency evacuation. (You might hear this as “doors to automatic.”) Upon docking, they’re disarmed to keep them from billowing into the boarding tunnel or onto the apron during servicing.

The orange or yellow tape is a visual indicator for ground workers or ramp agents that the doors are armed or not armed. The visual indicator can vary, it can also be built into the door lock mechanism, triggering a visual indicator externally if the door is locked and armed. In the following picture, the orange tape is not strapped over the window, which should indicate an unarmed door. In the video that this image is taken from, the flight attendant has just locked and possibly armed the door, the other flight attendant would place the orange tape over the door window during "cross-check".

(Image Source: YouTube "B757-200 Door Closing" - Author: Exupery747)


Do aircraft have siren to warn public in case of a crash over land? The recent crash of a Taiwan aircraft, got me thinking, do aircraft have built in siren, which can warn people on the ground of a possible crash to give them some headway.

If that is not practicable or feasible, then what solutions are feasible, or one should abandon the idea altogether and think of making planes safer in the first place?

I understand where you are at with this, I'm going to start off with a bit of math to show how it's not workable. Commercial airliners move quickly, even in a controlled glide one is going close to 3 miles (4-5 km) per minute. To give people on the ground enough useful warning to perhaps find some sort of cover you would need to give at least 20 seconds. This siren would have to be able to penetrate the walls of buildings and houses and cut through the background noise of a built up area at least a mile ahead. This is a very powerful siren and you'll have the following challenges:

At close range you would deafen anyone nearby, injuring the people you are trying to warn
The mechanism to generate this siren would likely be large, heavy, and challenging to design into an aircraft frame
You would need a great deal of mechanical or electrical power to generate that amount of noise. If you have no engine power you won't be able to sound the siren, and if your engines are working you won't need to as the engines make very good sirens already

There are very, very few cases where a siren such as this would save very few lives compared to justify the costs.


Are NACA airfoils used in modern aircraft design? I know that NACA is famous for its ducts:

Gratuitous Ferrari F-40 from Wikipedia. Mmmm... pretty...

It is also well known for its airfoils, and many planes in the early years of aviation used NACA designed airfoils for their wings (for example the Piper Cherokee referenced here).

Piper PA-28 also courtesy of Wikipedia

Do current aircraft manufacturers still use stock NACA airfoil designs, start with a NACA standard design then modify it to meet needs, or are the airfoils completely bespoke?

I'm asking about the major airliner manufacturers like Boeing & Airbus, regional jet builders like Embraer, as well as private/GA companies like Cessna, Gulfstream, and, of course Piper. Information on the (few, dozens, hundreds?) of other aircraft manufacturers (and kit designers) that don't pop to the top of my head is also welcome and appreciated.

Thinking about this further, I realize it could quickly devolve into a very broad this aircraft uses a NACA standard wing, that one doesn't list. That's not really my intent. A simple yes, this aircraft/wing from 5-10 years ago uses a NACA standard would answer the question completely, as would a the last one I'm aware of is from 35+ years ago.

Also, the use of "modern" is rather vague as the Boeing 757 certainly feels "modern" (having been launched in 1982) but has been out of production since 2004, while the 747 started production in 1969 and is still being built. If someone wants to jump in to help define "modern", I'd take no offense.

Just three data points: The tail surfaces of the Pilatus PC-12 still use the venerable NACA 0012, even though a better alternative (from the Wortmann FX 71 L series) was proposed. It did not help that the Wortmann airfoil is used on many small airplanes, has more lift and less drag and an abundance of data exists on it: The (mainly British) engineers at Pilatus were too conservative to use anything newer than an airfoil from the 1920s.

Pilatus PC-12 (picture source).

The wing of the Dornier Seastar, designed by a group of old Dornier engineers in the early 1980s, used the same airfoils as the venerable Do-17 of the 1930s, namely the NACA 23012. Later flight tests showed the need to add a leading edge droop on the outer wing, a modification that cost several knots in top speed and would have been entirely avoidable with better airfoils and/or the use of washout.

Dornier Seastar. Picture by Rschider (own work).

The excellent Polish aerobatic glider Swift S-1 uses indeed a NACA 6-digit airfoil, the $64_1412$. As Jerzy Makula explained to me, it gives excellent snap roll and spin control, and when flying the prototype, I could control the exit direction from a spin within ±15° with very little practice. Jerzy simply took what had worked before.

Swift S-1. Picture by TSRL (own work).

Generally, small companies or experimental airplane builders still rely sometimes on the NACA series, but in general better alternatives exist. Big companies use custom-made airfoils, helped by computer codes which model not only the two-dimensional flow around the isolated airfoil, but can optimize the specific wing section by including the influence of engine nacelles, pylons and the fuselage. Well-designed wing roots do not use one single airfoil, but a three-dimensional shape which minimizes interference drag.

This is true even for glider companies. While Wolf Lemke used his own creations for the early LS series of gliders on the basis of their good looks (and with good success), todays gliders are designed in the computer, helped by university departments which relish the chance to let students work on real-world designs.


When departing from a class C or D airfield, what is the proper VFR procedure? Specifically, when is it legal to turn to your on-course heading?

I find that sometimes the tower will give me an instruction to "turn on course" but sometimes they don't. Are you supposed to stay on the runway heading when you do not get the instruction to turn on course, or do you just go ahead and turn after reaching some altitude?

Either C or D controllers will likely accept your requested heading, which can be given as a rough compass point, on initial contact. This contact will be after picking up the terminal info on ATIS, when you contact ground.  Your preferred direction will be passed up the chain.  A class D may tell you something like "cleared for takeoff, Northbound departure approved", in which case I would feel free to turn as soon as I deemed it safe.  In a class C scenario, the same thing could happen, but they might vector you around other traffic.  In all cases "resume own navigation" will be permission to take your heading.

If you are still on runway heading and feel you have not been given a clearance sending you where you want to go, you may contact tower or departure control, depending on whom you are with, and say something like "Tower, Diamond two-eight bravo, request heading zero six zero"  They may respond with an "approved as requested" or "heading zero six zero approved" or they may give you instructions to "fly present heading, I'll call your turn" indicating they are not ready for you to take your heading yet.

The short answer is, you can take your heading when you have been cleared to do so.  Understanding when you have been cleared is a matter of becoming familiar with standard phraseology.

Controllers I have worked with, especially at C and D airspaces have been accommodating.  Their job is to send pilots where they want to go while keeping aircraft out of each other’s way.  They have rolled along with me when I have changed my mind about landing,  I can say "I changed my mind, I'd rather depart the pattern to the south" but to be brief I'll say "Cancel landing intention, request south departure."  As airspace gets bigger and controllers are busier (which can vary by location and even time of day) brevity becomes increasingly important.  To get practice, you can find out when an particular airspace is less busy.  Controllers have been known to be chatty when traffic volume is low, and you may even be able to ask questions about preferred phraseology.


What are the common private pilot practices for helicopter off-airport landing in US? These questions address the legal aspects of off-airport landing and basically conclude that the relevant laws and regulations are very fragmented.

Aside from the legal aspects, what are common practices and habits in terms of off-airport landing in US for private pilots? Are there clearly identified "off-airport-landing-friendly" states or regions where this is commonly practised?

As a comparison, in Switzerland, off-airport landings are nearly systematically practised by private helicopter pilots. In France, you need an easy-to-obtain authorisation and then make a few calls for each occurence/location, but it is an otherwise rather common practice. In Germany, off-airport landing is a big no go for private pilots. How do things fare in US?

There are minimum altitudes for cruise flight but altitude may be reduced below these minimums as needed for approach to landing. I don't know of any FAA regulation that requires landing at a designated airport(or heliport)

Title 14(aerospace) of the federal code of regulations part 91.119 (part 91 is general flight rules for all aircraft) simple says that;
"Except when necessary for takeoff and landing, no person may operate an aircraft below the following altitudes:"

A: Anywhere. At an altitude as to create an "undue hazard" to people and property on the ground in the event the engine fails. (Will you hit a building or dense crowd, or will you have time to aim for an open spot?)

B: Over any congested area of a city or open air assembly of people, below an altitude of 1000feet above the highest obstacle within 2000 foot horizontal radius from the aircraft.

C: over other than congested areas, no less than 500 feet above the surface, except for over water or sparsely populated areas. In those areas the aircraft may not be operated within 500 feet in any direction from buildings or boats. So no actual minimum altitude limit if you are over a field 500feet to the side of a barn.

D:Helicopters, powered parachutes, and weight-shift controlled aircraft(hang gliders and ultralights), if conducted without hazard to person or property o the surface may be operated at less than the minimums prescribed in B and C, provided the operator of a helicopter complies with any special routes or altitudes specifically prescribed by the FAA.(Generally special provisions are only found in high air traffic areas near major airports or over high security areas.)

These are paraphrased slightly for clarification and because I type how I likes to type, but the actual wording of the law is very close.

There may also be some local laws about noise limits if operations are frequent but this is not limited to aircraft.


How did the nose landing gear of JetBlue Flight 292 get stuck sideways? The nose landing gear of the Airbus A320-200 was jammed, but the tires were perpendicular to the fuselage. How did that happen?

According to the complete NTSB report, following is a summary of what had caused the nose landing gear (NLG) to rotate 90° on Flight 292.

  During flight, Brake Steering Control Unit (BSCU) performs1
  cyclic tests which slightly rotates NLG from the 0° position. Due to
  this fatigue, two of the four anti-rotation lugs on the NLG upper
  support assembly fractured and separated. This allowed NLG to deviate
  from the 0° position. Another contributing factor was BSCU system
  logic, which prevented NLG from centering. Also contributing was the
  lack of a procedure to attempt to reset the BSCU system under these
  conditions.

This website has some nice pictures of nose landing gear before and after the landing.

A summary of the investigation can be found here.

1: BSCU has other functions too.


What are the best tips for circuit practice with strong crosswind? I am a student pilot with around 30 hours of flying right now. I am yet to solo and I am currently in the final stages of closed circuit practice.

Overall, my pattern work is good. However, maintaining the perfect "rectangular" circuit gets tricky for me when facing strong quarterly crosswinds (10 knots gusting 16).

I guess its the visualizing the wind that really gets me confused. I set the heading bug to sort reference where the wind is coming from which helps a lot.

But just wondering if I could get more tips on this. Anyone else had the same issue during their student days?

I fly a Cessna 172S.

Try visualizing the pattern.

In your mind's eye, overlay the airspace around the airport with the track that you want your flight to take, visualizing all sections of the traffic pattern from your point of view as you fly.  Now check to see if there are visual references on the ground eg buildings, roads, parks, golf courses, etc. which align with this pattern you are visualizing and use them as additional aid for pattern legs and turn points.  If the airplane drifts off this track, adjust your crab angle and/or your rate of turn in order to track correctly.

As mentioned above, ground reference maneuvers such as rectangular patterns, turns about a point, S-turns etc are very useful and may be good basic practice for training yourself to visualize the pattern in space.


Wing loading in conceptual design Is it possible to have a minimum wing loading at climb segment of our design aircraft (air superiority)?
Which segment would have minimum wing loading i.e. climb, take off, cruise, instantaneous turn, sustained turn, etc?

From lowest to highest wing loading:

Climb: if a fixed wing plane and the nose is pointing up, some of the vertical force must be generated by the thrust.
Cruise: the lift must only compensate for the weight.
Inducing a turn: the rolling velocity has very little effect on wing loading.
Take-off: a slight positive g-loading during the nose-up motion.
Sustained turn: up to the maximum design load factor. 2.5g for passenger aeroplanes, up to 9g for fighter jets, with a proportionately greater wing loading that that in cruise.


What are the different types of take-off minima at the bottom of a Jeppesen airport diagram? Anyone that could explain the bottom plate, what’s the difference between all those minima?

The used acronyms are defined in the Jeppesen charts legend:

CL Centerline Lights
RCLM Runway Center Line Markings
RL Runway (edge) Lights
RVR Runway Visual Range

The first column tells us that a takeoff is authorized with RVR in touchdown zone (TDZ), midfield (MID) and rollout (RO) of at least 150m, if the RL and CL are operational (except during snow, where 400m is required, and for runway 18, where 250m is required).
The second column tells us that takeoff is authorized, if the RVR is at least 200m with RL and CL operational. In this case not all RVR values need to be available (e.g. one of them could be inop).
The third column tells us that takeoff is authorized, if the RVR is at least 300m and RL and RCLM are available (CL is not required, except at night).
The fourth column tells us that takeoff is authorized, if the visibility is at least 400m and either RL or RCLM (day) / RL or CL (night) are available.
The fifth column allows taking off with adequate visual reference during the day with at least 500m visibility. The "adequate vis ref" is defined in the charts legend as:

ADEQUATE VIS REF (Adequate Visual Reference) — Runway markings or runway lighting that provides the pilot with adequate visual reference to continuously identify the take-off surface and maintain directional control throughout the take-off run.


Where to do the Run-up and Safety on the Return Flight? At my home airport, we do the run-up on the ramp, but I guess each airport has its own preference.

What is the "standard" run-up location? If I recall from my training early on, you can do it at the runway if you angle yourself against the departure end. If this is correct, how do I know that I've angled myself in a way not to blow any debris into an aircraft behind me. And if I do the run-up at the end of the runway, don't I risk obstructing an aircraft that wants to takeoff behind me but has to wait for me to do the runup?

The simplest thing is to ask someone local where runups are usually done: the FBO, Ground Control or another pilot. If you can't find out then you can do them anywhere you like as long as it's safe.

Some airports have specific runup areas but they aren't always obvious. For example, KPDK has runup areas at both ends of taxiway A, they're shown on the airport diagram as 'bulges' in the taxiway but they aren't labelled. You might notice them when you land and taxi but you might not. I've circled one of the runup areas in red here:

If there are no runup areas, the 'default' location is the one you remember from training: on the taxiway just before reaching the runway, angled into the wind. If the taxiway is wide enough, you can move to the edge so that other aircraft can pass you if they're ready before you. That's very common and it's what many pilots will expect you to do, even if you have to block the taxiway for a couple of minutes. This is where you have to use some judgement: if you know that you need to take your time on runups - perhaps it's an unfamiliar aircraft, or you've just had maintenance done and you're double-checking everything - then you might look for another spot where you won't be in the way.

Blocking other aircraft from reaching the runway is always a possibility, but at airports with a lot of GA traffic - and especially a lot of flight training - it's common and just something to be expected. That doesn't mean you should take forever doing your checks and of course some other pilots will always get annoyed at even minor delays, but if the only safe place to do runups is the taxiway then just do them there and the others will wait.

Another option is to do runups on the ramp or before entering the movement area so that you don't block other aircraft anywhere. That's especially important at airports with scheduled commercial flights because they usually have very precise departure times and getting stuck behind another aircraft for even a few minutes could be an issue. If you're in that environment, then you should definitely check with Ground Control what they want you to do. But be careful about doing runups on the ramp because of people and vehicles moving around. Also be wary about doing runups a long way from the runway: during a long taxi you might change something (e.g. the mixture or fuel controls) and then forget to reset it for takeoff.

The one place you should never do runups is on the runway itself. Sitting there for several minutes blocking the runway for landing traffic and unable to see final approach behind you isn't a good position to put yourself in.

Finally, avoiding blowing debris into other aircraft should be simple: just look around you, and don't position the aircraft so that your prop blast is going somewhere it shouldn't.


How miraculous was the miracle on the Hudson? The "miracle on the Hudson" was extremely unusual - dual engine failures and successful off-field landings in commercial A320-size aircraft are very rare. The event has been dramatized and the crew (and captain "Sully" in particular) have been widely praised as heroes.

The crew certainly did an excellent job ensuring that all those aboard lived to tell the tale. But was it really exceptional? Aren't all commercial pilots trained to handle emergencies? I don't want to belittle the fantastic job the crew did, but I wonder whether they did something no other crew could do or whether this is something most crew would be able to handle if called upon.

Here is a more precise question:

If a random commercial airline crew were placed in the same situation as the crew of US Airways Flight 1549 on 15 January 2009, how likely is it that they would achieve an outcome with no fatalities?

I understand that to a certain extent this is a matter of opinion, but I hope people can provide some objective comments about what situations crews are trained for and whether there are other comparable examples with similar or differing outcomes.

This would be an extremely difficult question to answer without being opinionated, but I'll give a try. As part of the investigation, the NTSB, along with other agencies carried out a number of tests on simulator, where pilots were tasked with either landing or ditching the aircraft.
There were three different scenarios contemplated:

Normal landings on runway 4 at LGA, starting from an altitude of 1,000 or 1,500 feet on approach;

Attempted landings at LGA or TEB after the bird strike, starting both from zero groundspeed on takeoff from runway 4 at LGA and from a preprogrammed point shortly before the bird strike and loss of engine thrust, and;

Ditching on the Hudson River starting from 1,500 feet above the river at an airspeed of 200 kts.

In the first case, all the landings were successful, which is not surprising. However, in the second case, landing was successful in (slightly) more than half the cases, but only where the response from the pilot was immediate (i.e. there was no delay between loss of thrust and decision to return to airport).

Regarding the second flight scenario, 20 runs were performed in the engineering simulator... Five of the 20 runs were discarded because of poor data or simulator malfunctions. ... In eight of the 15 runs (53 percent), the pilot successfully landed after making an immediate turn to an airport after the loss of engine thrust.

In the one case where a (35 sec) delay was included, the landing was not successful.

One run was made to return to an airport (runway 13 at LGA) after a 35-second delay, and the landing was not successful.

It has to be noted that in all these cases, the pilots were already briefed about the manoeuvre they were about to perform.
The third series of tests were conducted to see whether the pilots were able to achieve the target flight path angle of -0.5$^{\circ}$. Only one Airbus test pilot was able to come near that value. From the report:

Regarding the third flight scenario, a total of 14 runs were performed in the engineering simulator in which pilots attempted to touch down on the water within a target flightpath angle of -0.5°, consistent with the structural ditching certification criteria. Two of the 14 runs were discarded because of poor data.
In 11 of the 12 runs, the touchdown flightpath angle ranged between -1.5° and -3.6° (the touchdown flightpath angle achieved on the accident flight was -3.4°). In 1 of these 12 runs, a -0.2° touchdown flightpath angle was achieved by an Airbus test pilot ...

From these simulations, it appears that the flight crew took the correct decision to ditch in the river. Also, we have to take into account that taking decisions in real world under extreme stress is quite different from taking them in a simulator. The report notes that,

The one simulator flight that took into account real-world considerations (a return to LGA runway 13 was attempted after a 35-second delay) was not successful. Therefore, the NTSB concludes that the captain’s decision to ditch on the Hudson River rather than attempting to land at an airport provided the highest probability that the accident would be survivable.

Another thing to note is that there was no simulator training to the pilots, either as part of the airline or manufacturer program. In fact, the dual engine failure scenarios were presented only at high altitudes.

Ditching scenarios were not included in either the US Airways or Airbus simulator training curriculum.

A similar incident happened in case of the Scandinavian Airlines Flight 751, where the pilots successfully landed the aircraft without any fatalities.
One also has to consider the other issues in ditching in water (like the associated visual illusions). From these, we can form the opinion that a sizeable minority of airline crews would have ditched the aircraft successfully on the river after bird strike so as to enable rescue. As for zero fatalities, it would be near impossible to say that with any certainty, as there are too many factors in play here.


Why would the engine quit when turning on the R magneto after an overhaul? I just finished overhauling a Lycoming O-360; it's currently on a stand, i.e. it's not in the aircraft. I replaced the capacitors and point gaps on both the L and R mags. I adjusted the E-gap and engine timing at 25 degrees as per the engine plate.

I have two toggle switches connecting the P-leads to ground: one for the R mag and one for the L mag. I turned on the L mag only to start and when I started the engine for the first time it fired up right away. But when I then turn on the R mag the engine just stops.

I can start the engine on the L mag only any time. As soon as I turn on the R mag, the engine dies. It’s as if when I turn the R mag on the L one goes off. I did everything I could to troubleshoot but I did not find where the is. What could be the issue?

There's 3 potential problems. Magnetos are very simple in how they operate, and the system basically runs on 3 things that can be easily tested.

Spark plugs, engines can die because of 1 bad spark plug, I've had engines become extremely rough and die within 5-10 seconds when checking R/L because of 1 plug with a piece of lead shorting the electrode.
Magneto itself. I highly suggest against opening up and replacing anything in high-time magnetos in the field for multiple reasons. In case of Slicks, the magneto components are designed to wear at an even rate i.e replacing point contacts or a capacitor is not a wise decision for maintenance or for cost-effectiveness over time. An overhauled 4300 series magneto is ~600 dollars, the labor and parts for internal parts reaches that quickly for a substandard magneto as the finished product. I can't speak as much on Bendix but magnetos are a mix of old, complicated, and mechanical that means high wear and high chance for improper reassembly. In this case I assume your O-360 is running 437X Slicks.
Wiring in the ignition switch. You cannot improperly wire a magneto(as far as the operation of the magneto is concerned on a 360, any absence of wires won't stop the operation), and personally this is the least likely of the 3 especially if you didn't touch the ignition. Improper wiring of the backend or improper switch installation could cause this, but again I would highly advise checking the 2 before.

I know this is long past a point of help but I think it helps to explain for anyone else interested


Why is KLAX and KSEA depicted class D in IFR low enroute chart? I was looking at ifr low enroute chart and just figured out that KSEA and KLAX are depicted as class D.
Aren't they Class B airports? why do they have D mark?

Your question is interesting but the answer is not fully obvious without a bit of research.  In looking at the KSEA IFR Enroute chart (L01 IFR enroute chart -third image below) it does indeed show that a portion of the the Seattle International Airport is within Class D airspace.
The second image below shows an excerpt from FAA Order 7400.11E describing the Class D airspace as it relates to KSEA.
The third image is from the L01 IFR Enroute Chart for Seattle.
The fourth image below shows part of the legend for an IFR Enroute Low Altitude chart.
So, although some general information relating to the OP's question may be addressed by looking at the link shown above by @randomhead as it applies to LAX, the OP is asking a reasonable question which is fundamentally different (from the question addressed in the link mentioned above) and probably should be left open.
Further, it is a fairly unusual circumstance to have Class D areas attached to the primary airport upon which the Class B airspace is predicated, so a discussion relating to identifying the affected areas that are Class D versus Class B may be very informative.
Likely, the Seattle Class D airspace (dimensions shown above), is to handle go-arounds, (that turn and enter a downwind to return to the airport as opposed to returning to the TRACON to be vectored out for another full [longer] approach), helicopter traffic, traffic watch aircraft, etc. (being on or staying on the Control Tower's frequency, for example) .
If you do the research for KLAX, it's the same principle (but different dimensions for the Class D).


How the fuel in the wings is managed in case of an engine failure? Consider an aircraft has fuel tanks only in wings (No central tank).

Will the fuel for the respective engines will be consumed from the respective wings?

In case of a single engine failure, if the fuel is keep on consumed by the active engine, whereas not consumed in the inactive/damaged engine, will this affect the aerodynamic property of aircraft?

That’s a pretty broad topic and depends on the aircraft in question and the fuel systems which it uses.

Large airplanes like jetliners have complex fuel management systems which feed fuel from the main tanks into feeder tanks which the engines can “drink” from.  The process is automated in modern aircraft - around the same time that the Flight Engineer went the way of the dinosaur - so little, if any, input from the crew is required in the process.

On smaller twins, say, for example, a Cessna 310, fuel is provided to the engines via a dedicated main fuel tank and optional aux tanks for each engine.  In the event of an engine failure, the pilot can select the ability to cross feed the good engine on the fuel system for the bad engine in order to prevent a fuel imbalance.


How dangerous is airborne debris? I live next to HTDA Julius Nyerere International Airport and I do occasionally see Airborne debris, mostly plastic bags flying around at 1000 or more feet.

How dangerous can this be?

The FAA's advisory circular on Airport Foreign Object Debris (FOD) Managament mentions plastic bags and other trash as a type of FOD and says these are the dangers:

  FOD Hazards.   FOD can severely injure airport or  air carrier personnel or damage  equipment.  Types of potential damage include: cutting aircraft tires; being  ingested into engines;  or becoming
  lodged in mechanisms affecting flight  operations.  Personnel injuries
  or even death  can occur when jet blast propels FOD through the
  airport environment at high velocities.

Since you're asking specifically about airborne items, that would mean the most likely dangers from that list are engine ingestion or "becoming lodged in mechanisms affecting flight operations".

The main issue with a plastic bag seems to be that it damages the engine, rather than stopping it entirely. This paper recommends an inspection if any "soft material" (including plastic bags) are ingested:

  Remains on impellers and/or LP diffuser exit ducts confirm a bird or soft material has passed through the Engine and possibly
  contaminated the secondary air system, fuel nozzle and HP turbine vane
  cooling air passages.
  If contamination occurs, hot section components deteriorate rapidly, increasing the cost of refurbishment. Therefore, operators are
  recommended to carry out a hot section inspection (HSI) as soon as
  possible after a bird strike or ingestion of soft material is
  confirmed

As for affecting flight instruments, the main danger is probably that the bag covers the pitot tube, resulting in false airspeed readings. That can be catastrophic if the pilots don't realize what's going on, but many larger aircraft have multiple pitot tubes so it would probably need a lot of plastic bags (or a lot of bad luck) to cause an accident. And a bag stuck on the windscreen could block a pilot's view but if there are two pilots then that shouldn't be critical.

Of course, all of the above applies to airliners. If you fly a light piston single through airborne debris the results could be worse because of the lack of technical (and perhaps crew) redundancy.


Why are winches not used for towing commercial planes up? In this video a glider is pulled up by a winch on the ground, like this:

(Source)

I would say you could apply the same principles with bigger planes, possibly even using sustainable energy sources.

The plane would not use its engines at all to get to cruising attitude (unlike a suggested catapult in a previous post), so this part of the flight would be "for free".
Using a back of the envelope type of calculation with 5% efficiency it takes 17000 litres of kerosine to lift a 747 to 10km (which agrees with this paper).

However, this would however cost at least (calculated below) 25km of towing line(s). If we use a UHMWPE fiber a 400g/m and 1.2 cm radius cable would be able to support 2x the 400kN thrust maximum output of a typical airliner.

Sure there are a lot of hurdles to overcome, but since some airports in cities cannot expand because of noise problems this seems like one solution.

Logistically this seems like a large extra challenge for the crew on the ground, but would this be possible?

If you ever get the chance, do try a winch start in a glider. It is, to say the least, an interesting experience. I do not believe it would be accepted by the general public.

So, that is one more reason, it would scare the paying passengers.


Should I add balloons in my Ultralight wing to help it float if I land in the water? I like to fly over rivers and lakes in my ultralight. One of the things that scares me the most is if my engine died, I might drown down in the depths of the water as I egressed out of my ultralight.

My Hy-Tek Hurricane has an aluminum front and rear spar, with a few spreader tubes, and then it has simple aluminum tube ribs which slide into pockets in the Dacron wing covering. This leaves nothing but empty hollow space inside 99% of my wing.

Has anyone ever thought of adding some lightweight durable air-filled balloons inside their ultralight wing to add buoyancy in case of a water landing which would almost certainly flip my tricycle gear ultralight? As it is, the wing has plenty of gaps in it which would allow water to rush inside and sink my plane. I don't know how long that would take, but I would rather not find out!

My aircraft weighs just slightly less than 254lbs. So I would need approximately 254/8 = 31.75 gallons of air to maintain a neutral buoyancy, and I would probably want to add another 30% or so to that to turn my ultralight wing into basically a flotation raft if I ended up in the water.

So does anyone have any good ideas on what to stuff inside my wing so my little "ultralight" doesn't turn into an "UltraAnvil" and sink to the bottom with me drowning next to it? If I crashed in the water, I figure I probably have a 50/50 chance of extricating myself from the wreckage without drowning right away, considering the impact will probably knock the wind out of me. It would be difficult, but I think I could do it. If I was at a full stall when I touched down I think I would survive, but would certainly flip upside down, then it would be a mad scramble while upside down underwater to get the safety belt off and yank my helmet and it's wires off and kick free.

But if I CAN get out, the next problem is that I am fully clothed with shoes, maybe a ski jacket, gloves, jeans, thermals, and everything else. I have had an unlucky experience of being fully dressed while flailing in the river before when I dashed out to rescue an R/C plane once, and it was very dangerous, and I nearly did drown (I will never do that again!).

It sure would have been nice to have a partially sunk ultralight next to me to hang onto! So I was thinking balloons, because that would be easiest. I could just inflate maybe 100 balloons or so and then stuff each of them up in the zippered inspection seams, 50 in each wing. The weight would only be maybe 8 ounces or so of all the balloons, and I can't imagine that they would hurt anything inside the wing. Is this a good idea?

Not practical to put balloons in the wings.  They would expand at altitude, messing up the wing profile.  How would you control that?

The best option, possible if the fabric is reasonably impermeable, is to seal all possible ingress points in the wing, leaving a small vent hole at a point least likely to be submersed, like the wing root trailing edge.  This will at least delay the sinking.   You could use ripstop repair tape used for fixing tents.

That'll slow down the sinking process, giving you lots of time to get out.  Then wear one of those compact inflatable vests that boaters use that drape around your neck that you inflate when needed, for swimming to shore.

Even better, with all the weight you would add with various other solutions, might as well get a set of Puddle Jumper amphibious floats.  Might as well make it possible to land on water anyway.  Problem solved.


How to supply a flying club with MOGAS? I've noticed that there are very few airports that serve MOGAS. If I wanted to start a flying club with a MOGAS powered airplane, but there wasn't an FBO nearby that served MOGAS how would I go about it?

Is it worth it to an FBO to offer MOGAS?
Should I have the FC members supply their own gas with a couple of personal fuel stations like the one pictured below? (anyone have any experience with this method?)

Update: Tried to reword questions to make it less business & more "how-to".

The FC I used to belong to had it's own fuel trailer (custom-built with dual double-walled, insulated cryogenic 100-gallon tanks, a manually-operated fuel pump, a totalizer, a delivery hose and nozzle, and appropriate grounding cables.  Excluding the cost of the basic flat-bed trailer itself (one of the FC members loaned it to the club) we had less than $1500 invested in the outfit - including inspection and trailer licensing fees.

Considering we would be carrying 200 gallons of MOGAS on public highways we had to be VERY careful as to WHEN we were ON the highways (basically very late at night, and we drove on lightly-used roads/streets) - and we had to have insurance commensurate with the commodity we were carrying.  We used this trailer for several years - without any incident(s) - but, in the end, we all felt un-easy about doing so and eventually we abandoned the idea and reverted to using hand-carried gas cans.

The FC disbanded years ago and I don't know what ever happened to the fuel rig - I believe it went back to the FC member who built it in the first place (his materials costs and his labor bought him a club membership, whereas the rest of us had to ante up actual cash to help buy the airplane the FC bought.)

Ahhh, the good ol' days....


Do modern airliners have a flaps warning indication? Years ago I was on a flight from San Francisco to Los Angeles, a 737 if I remember rightly, and was sitting just behind the wings and could not help noticing the flaps were partly extended for the whole flight.

I thought they looked odd out the window but did not bother mentioning it to the cabin crew since I was not sure what I was seeing. However, on landing in LA, the pilot retracted the flaps after using them for landing, and they were then correctly seated.

I assume the pilot felt something was off, since after landing I could see ground crew wandering around and inspecting the aircraft with puzzled looks on their faces.

I understand that the flap controls are a bit out of the pilots normal sight lines and this got me wondering whether there is instrumentation in the cockpit that alerts the pilot to the fact that the flaps are not fully closed once in normal cruise attitude. Perhaps even an indicator similar to the landing gear lights.

It could have been as you witnessed.

In 2005, a modification package dubbed Quiet Wing was offered for the 737-200 and the 737 Classic (-3/4/500) that would droop the flaps by 4° for all phases of flight.

  [It] decreases drag for cruise, and increases the aerodynamic efficiency of the wing by between 2% and 3%.

The NTSB in 1981 also found that many 727 pilots were doing the same thing in cruise—but manually and unapproved. They would pull a CB to keep the slats on the leading edge of the wing retracted, while the flaps extended to the their first stop.

  Investigators believed that 727 pilots (in general, and this flight specifically) were setting the trailing edge flaps to two degrees during high altitude cruise, while at the same time pulling the circuit breaker for the slats so that they would not activate. This configuration was rumored to result in increased lift with no increase in drag, thus allowing more speed, higher elevation, or decreased fuel consumption. Flaps and Slats were intended to only be deployed at low speeds during take-off or landing.

To answer the title question, yes. Flap position indicators exist, and combined with the electronic speed tape, the maximum speed indicated will be slower.

If the flaps were to be extended at above design speed, an overspeed warning will be triggered as well.


Why does the CF-100 autopilot have a toggle switch labeled 'ATTACK'? I took this photograph of the autopilot controls inside the cockpit of a CF-100. There are a bunch of switches for the autopilot. Why does one have a label of "ATTACK" and what did turning it on/off do?

The [Avro Canada CF-100] Mk 4 had collision-course fire control, the new interception method in which the radar and autopilot interlinked to steer the aircraft automatically to launch the rockets in a salvo to pass through a "box" of sky at the same time as the hostile aircraft. It freed interceptors from the need to attack from behind, and in a side on interception gave a much better reflective target for the radar.
— all-aero.com

By coupling the radar to the autopilot, the autopilot would steer the aircraft for a firing solution toward where the [unguided] rockets would meet the target (the CF-100 was armed with Mighty Mouse).

Come to think of it, it's the airborne version of a Torpedo Data Computer.

The [F4D Skyray]'s search radar would be used to locate an incoming bomber after initial vectors. The fire-control system would then direct the pilot on a collision course until it determined that the moment had come to fire a salvo of unguided 2.75-inch folding fin rockets. The pilot would then be free to break away. The collision course and rockets were necessary because there was not enough time to position the fighter for a classic attack with guns.
— U.S. Naval Air Superiority: Development of Shipborne Jet Fighters - 1943-1962 p.143

A similar system was also used on the Douglas F4D Skyray, but it seems it was guidance only, i.e., no steering.
The Skyray text above hints as to why the CF-100 would also have a BREAKAWAY toggle switch.


Can two airports have a different ICAO code but share the same IATA code? I am searching some airports databases and I find some airports with the same IATA code with different ICAO codes. Is it mistake in the database? Is it OK?

For example:

Beaufort MCAS - Merritt Field (ICAO KNBC IATA BFT)
Beaufort County Airport       (ICAO KARW IATA BFT)

Edit: Another example;

Paamiut Airport    (ICAO BGPT IATA JFR )
Paamiut Heliport   (ICAO BGFH IATA JFR )

Another example with 40 km between them:

Desierto de Atacama (IATA: CPO – ICAO: SCAT)
Chamonate           (IATA: CPO – ICAO: SCHA)

You're right that two airports can share the same 3-letter code, but they're not necessarily IATA codes (they could actually be FAA identifiers, or just locally assigned codes).

In implementing Otto the Autopilot in our chat room, for commands like !!weather JFK, I needed to find a way to reliably convert IATA codes to ICAO codes. I ended up using the same source as you linked to, and imported the columns we needed into MySQL. A quick query shows 65 (i.e. >=130) duplicates:

AHT AJL API APS ARS AUS BJW CGY CLG CPO CSZ DDU DZN GIG HKG HYD IOR ISG IZA JFR JRS KFE KMM
KWB KYF LIM LUZ MCJ MCU MJF MNI MPD MPT MRE MUC NST NWT OBI OHE PCO PDG PHG PIV PPJ PRI PRM
PSV RCH REQ RZS SEA SFK STI SYC SZR TFY THO TNO TPJ UCN ULG VME VQS WRW YDT

The problem is, that IATA wants you to pay several thousand dollars for access to their list. So OurAirports attempts to collect all the known IATA codes, but it is user-editable, like Wikipedia. So there are inaccuracies in their database; and as I mentioned, there is some overlap between IATA/FAA/local.

The actual IATA codes are unique (although sometimes reused).


What flying boat has the highest maximum takeoff/landing sea state? I assume that flying boats have limits on the sea states they’re certificated to take off and/or land in (for instance, hitting a ten-meter wave head-on in a five-meter wooden plane is probably somewhat hard on the plane’s structure, not to mention its contents), the aircraft’s precise maximum sea state rating presumably depending primarily on its size and structural strength.

Which flying boat can legally take off and/or land in the roughest seas?  Are there any flying boats certificated to operate in full hurricane conditions?

The Grumman Albatross was capable of open sea operations and could operate in as high as ten foot seas, possibly higher with JATO rockets installed.

  The Albatross was capable of open-ocean landings (optimally in seas no
  higher than 10 feet) due to its deep-V hull cross-section and long
  keel length, although higher seas could be downright punishing on the
  aircraft and crew. HU-16s could utilize jet assisted takeoff (JATO)
  bottles to shorten takeoff runs in rougher seas.

This Albatross pilot offers some more specifics on the certifications and says

  Its certified for class 6 seas, which can be swells up to 10 ft. or waves up to 6 ft.

Although he says he would not really want to do it as his operation has no need but has landed in 4ft seas.

According to this source a Boeing 314 Clipper was successfully landed in 30 ft. seas but thats by no means regular operations.

  The weather was far from ideal, with a big storm blowing, and 30 foot
  seas running.  But the big Boeing was successfully landed without
  damage.  The seas were so high, it was almost impossible to transfer
  the occupants to the Cutter.

I don't think anything is certified for takeoff in hurricane conditions, seaplane or not.


Are there items bigger than an aircraft section transported by air today? This question about engine transportation made me wonder what is the size of the biggest item ever transported. Then I remembered that it should have been a space shuttle (either Buran or the American Space Shuttle), but those items are no longer transported. Nowadays whole aircraft sections are transported, thanks to A300-600ST and B747LCF.

Are there cargo items bigger than a high by-pass ratio jet engine or an aircraft section that are transported by air today (in 2015)? How are those item handled?

According to Wikipedia, the An-225 is the world's largest cargo aircraft and it's transported both the heaviest and longest items of cargo ever carried by air:

  On 11 August 2009, the heaviest single cargo item ever sent via air
  freight was loaded onto the Antonov 225. At 16.23 metres (53.2 ft)
  long and 4.27 metres (14.0 ft) wide, its consignment, a generator for
  a gas power plant in Armenia along with its loading frame, weighed in
  at a record 189 tonnes (417,000 lb)

  [...]

  On 11 June 2010, the An-225 carried the world's longest piece of air
  cargo, when it flew two new 42-meter test wind turbine blades from
  Tianjin, China

It's also carried the Buran spacecraft (the 'Soviet space shuttle'), which was actually what the aircraft was originally built for.

The An-225 is still in operation and the operator gives some examples of large cargo that can be carried:

  The aircraft has the spacious cargo compartment with length of 43.32
  m, width of 6.4 m and height of 4.4 m, that allows carrying a variety
  of cargoes inside. For instance,

  sixteen standard aeronautical containers of UAC−10 type;
  50 cars;
  single piece of cargoes up to 200 t (turbines, generators, dump trucks − Belaz, Kamatsu, Euclid, etc.).


How long can an ELT run before the battery is dead? I recently learned that ELTs are required to run a maximum of 60 minutes before the power supply battery has to be recharged or replaced.  This really doesn't seem like a great amount of time for this device to operate in order to facilitate locating by search and rescue crews.  I would have said a more reasonable figure would be around 24 hours.  Is it really true that ELTs are only effective for such a short period of time?

The reference you quote is correct as it defines the "useful life" of the battery.  that is: if you use it for more than 1 hour (that would include the cumulative test time) it must be recharged or replaced before being returned to service.  But that isn't what you are asking about.  You are asking for the duration of operation.

The requirement for Duration of Operation is 24 hrs.

RTCA DO-204A, MOPS for 406 MHz ELTs, states

  1.5 Operational Goals

  b. Operability

  (1) The technical requirements of the 406 MHz beacon radiated signal
  are based on the COSPAS-SARSAT system.

  (a) The 24-hour operating life requirement (§2.2.1) is based upon the
  maximum COSPAS-SARSAT system waiting time, the number of satellite
  overpasses required to optimize the beacon location solution and
  battery capacity limitation at low temperatures.

and

  2.2.1 Duration of Operation

  Refer to COSPAS-SARSAT document C/S T.001.

and from C/S T.001

  4.5.1 Duration of Continuous Operation

  The minimum duration of continuous operation shall be at least 24
  hours* at any temperature throughout the specified operating
  temperature range.

  The minimum duration of continuous operation for an ELT(DT) to meet
  the ICAO GADSS requirement at any temperature throughout the specified
  operating temperature range shall be 20† hours.


What would happen if the elevators were set to opposite angles? For example left elevator angle = +30 deg, right elevator angle = -30 deg. Would these settings be able to induce a rolling moment on the aircraft? What would happen with the pitch?

This would be an elevon application (ailerons + elevator).  Found on flying wings and deltas.  Theoretically possible on a standard tail.

With elevons, one up and one down will roll the aircraft with out pitching it.  Interesting that this can be done from the front, back, or center of the aircraft.

Someone may wish to correct me, I believe Burt Rutan put both elevator and aileron function in the canard of one of his planes to simplify the control linkages.

So, as a designer, yes this is possible.


What is the difference between a MEL, MMEL, KOEL and Equipment List? When we are determining what equipment must be operational for an aircraft to be considered airworthy we are presented with different kinds of equipment that could be installed on the airplane.

What is the difference between these different types of equipment lists?

Minimum Equipment List (MEL)
Master Minimum Equipment List (MMEL)
Kinds of Operation Equipment List (KOEL)
Equipment list

I would like to have answers for all the different aviation authorities.  US, EASA, Canadian, etc.

Definition of Master Minimum Equipment List from ICAO Master Minimum Equipment List/ Minimum Equipment List Policy and Procedures Manual:

“Master Minimum Equipment List” means a document approved by the Director General that establishes the aircraft equipment allowed to be inoperative  under conditions specified therein for a specific type of aircraft.
A Master Minimum Equipment List (MMEL) is an approved document created specifically to regulate the dispatch of an aircraft type with inoperative equipment. It establishes the aircraft equipment allowed to be inoperative under certain conditions for a specific type of aircraft and still provide an acceptable level of safety. The MMEL contains the conditions, limitations and procedures required for operating the aircraft with these items inoperative. The MMEL forms the basis for development and review of an individual operator's  Minimum equipment List (MEL).

Definition of Minimum Equipment List from the same document:

“Minimum Equipment List” means a document approved by the Director  General that authorizes an operator to dispatch an aircraft with aircraft  equipment inoperative under the conditions specified therein.

and

The MEL is a joint operations and maintenance document prepared for or by  an operator to:
a) identify  the minimum equipment and conditions for an aircraft to maintain the Certificate of Airworthiness in force and to meet the operating rules for the type of operation;
b) define operational procedures necessary to maintain the required level of safety and to deal with inoperative equipment; and
c) define maintenance procedures necessary to maintain the required level of safety and procedures necessary to secure any inoperative equipment.

Regulatory authorities use similar definitions. For example, Transport Canada uses nearly the same definition, replacing 'Director General' with 'minister'. So the ICAO definition can be used as the base.
Kinds of Operation Equipment List (KOEL) are lists one finds in some aircraft POH that indicates what equipment (generally optional) si required for flight under certain conditions. From FAA Advisory Circular Minimum Equipment Requirements for General Aviation Operations under FAR PART 91 AC NO: 91-67:

Kinds of Operations List (KOL). The KOL specifies the kinds of operations (e.g., visual flight rules (VFR), instrument flight rules (IFR), day, or night) in which the aircraft can be operated. The KOL also indicates the installed equipment that may affect any operating limitation. Although the certification rules require this information, there is no standard format; consequently, the manufacturer may furnish it in various ways.


Does the civil industry use the CAN FD bus? Does anyone know if commercial aircraft are using the CAN FD communication bus?

It's hard to prove a negative, but I would say the answer is no for the following reasons:

In all my years in the avionics industry, I've never heard of anyone
even discussing the possibility (though I realize CAN FD is fairly
recent).
There are numerous manufacturers that use ARINC 825 which is an
adaptation of the basic CAN.
The AEEC has no
active committee working to update ARINC 825 to include support for
CAN FD which would be the normal process before it would be used in
avionics.

Avionics suppliers just can't decide to use a new databus.  Their equipment has to talk to equipment from other manufacturers and if you don't have a defined protocol and agreement between suppliers it just won't work.


Is it possible to detect a pitot static failure (blockage) of air data probe during flight and alert the pilot? Loss of static and pitot tubes affect the display of airspeed, altitude, vertical speed information. Loss of this information can  be catastrophic for flight. How are the pilots communicated about the failure of these ports (ex: when they get blocked). Or is there a system in place already that detects the blockage and unblocks it. Even if such system exists, what is done to ensure that pilot does not trust the airdata information displayed during the time when the ports are blocked?

The crew checks the pitots and static ports before the flight to ensure they are in good condition and not blocked by objects or insects. Pitot tube (pitot-static) can be obstructed in-flight. Static ports are less affected.

Detecting a blocked pitot or static port: This is not done, but is possible (e.g. send some air from the back of the tube in a pitot, and see if it can exit the tube at a normal rate (which is dependent on several parameters).

Unblock a blocked pitot: In some cases yes:

Melt ice or snow by heating the tube in flight, but the tube may be frozen for a minute from time to time. Some pitots are not heated and must be deiced naturally, which will be longer (while cruising in -50°C air, friction prevents aircraft skin to be cold. Concorde skin was about 100°C, meaning air friction just increased its temperature by 150°C).
Drain water using drain holes in the pitot.

Redundancy for pitots: Yes, two or three exist on most airliners.

Alert for blocked pitot: Not a direct alert, since a blocked pitot is not detected, but air data processors compare the different pressure values received from the different pitots, and in case of significant difference alert the crew and disconnect the automated units relying on pitot pressure (like the autopilot).

A message is displayed to emphasize that airspeed is unreliable

Dangerous? Yes because if the unreliability of airspeed is not taken into account by the pilot, then stress and inappropriate actions can occur because the aircraft is apparently not reacting to attitude changes.

AF447 disaster is sadly a perfect demonstration of the stress that can be generated.

If the crew detects correctly the situation, then there is nothing special to do, they just need to continue (manual control) at the same altitude and with the same aircraft attitude until the speed becomes reliable again.


Can a helicopter carry a large airplane? I saw on YouTube a helicopter carrying an airplane.

Is this possible, I mean is the maximum load compatible with the mass of this aircraft?

If you look more closely, this "airplane" is only the husk of a Tupolev Tu-134, a rather small airliner, and the helicopter is a Mil-26, the heaviest helicopter ever to go into production. Not only are the empennage and the outer wings missing, but also the engines, which helps to reduce the load considerably.

Mil-26 lifting a Tu-134 carcass, seen from below (source)

The empty weight of a flightworthy Tu-134 is 28 tons, but the engines alone weigh 2.3 tons each. Now remove the outer wing, empennage and cabin interior, and the remaining weight is within the 20 ton load limit of the Mil-26.


What is transition altitude? Now I know the definition of transition altitude - it's the altitude where pilots change their barometric altimeter datum from regional pressure setting to 1013.2hPa. In USA the TA is 18,000ft. But I just don't understand the whole concept. Why can't they just set the datum as 1013.2hPa at ground before takeoff. Why does it have to be 18,000ft. Also isn't the atmospheric pressure at 18,000ft much lower than 1013.2hPa, so isn't it wrong to put this as the datum?

The atmospheric pressure is dropping quite signigicantly with altitude - and this is the very point of the concept of the altimeter - messure the pressure and show this as an altitude.

The basic concept of a flight level is that all high flying planes share a common reference - and do not neet to consider local weather, which can change quite dramatically during a flight. The main topic here is traffic seperation - so all should use the same reference and thus can quite compare their altitudes.

But flying low there is a nice problem called "ground" - planes should mostly avoid it. On charts the minimum altitude is noted, as well as special places like airports. Here a more precise view on the altitude is needed - so pilots need to set their QNH. Before takeoff, before landing - or when flying low for a longer time quite frequently.

But where to change from one reference to another? That much depends on the location - in the US it is mostly 18000, but in other regions this can differ substantially.


Why don't El Al 747's stay at the gates at JFK? I was recently travelling through JFK in New York City and saw the El Al 747, presumably arrived as ELY1 and departing as ELY4, sitting on the apron near terminal 4. What I saw was similar to as shown in the video capture below. The fellow plane-nerd I was travelling with claimed that it was parked there because the onboard missile defense systems of a El Al 747 include a pyrotechnic MAWS, which is considered dangerous to ground personnel. He claimed that this, in turn, is why the plane sits on the apron rather than at the gate or in a hangar (where it would be closer to maintenance personnel).

(YouTube)

Which, if any, of these facts are true?

The MAWS on the 747 is the pyrotechnic type (such as flight guard) rather than the newer
laser.
The MAWS on the 747 is considered dangerous by whichever
governing body is salient.
The MAWS is the reason the plane is sitting where it is.

OR is this just a convenient spot to keep a massive object for the 5 hours it's not needed?

I would split these questions into three separate posts but they seem too closely related for that.

Flare (pyrotechnic) type
According to Wikipedia and ynetnews.com, the flare system burns at low temperatures and doesn't pose a danger. Nonetheless Europe in 2006 objected to it and Switzerland threatened to ground El Al if such system was found on board.

"If we catch Israeli planes fitted with this system in our airports, they will be grounded," a spokesman for the Swiss aviation authority told Der Spiegel.

A plane that is deemed unsafe, would be unsafe anywhere at the airport.
El Al defense system
According to ABC News (2014), El Al carries the laser-type.

[The] new system, housed in a pod under the fuselage, employs an infrared missile-tracking camera, an "infrared (IR), ultra-violet (UV), or radar missile-approach warning (MAWS) sensor to detect a missile launch in the very early stages of an attack" and a laser system meant to jam the incoming missile’s "seeker" and "cause it [the missile] to be diverted away from the aircraft."

El Al seen at the gate at JFK and how planes move around

In this JFK time-lapse video, you can watch an Etihad plane being moved from the gate to a remote stand. At the gates is a parked El Al 747 as well. Later a Swiss airplane is towed from a remote stand to where the Etihad was.

(Source) El Al 747 at the gate. A passenger took this photo after deplaning at JFK in 2011.
Long wait
Sitting from 5:10 am to 12:55 pm is most likely the reason for it being moved away from the gate. According to the Port Authority, if the Air Terminal Manager ordered an airplane to be moved and it didn't move within 10 minutes, the airplane is charged extra for each 15-minute delay thereafter.

Related:

How does the Guardian counter-MANPADS system work?
How common are missile defense systems on civil airplanes?


Is there an issue with an acceleration followed by a deceleration when flying a SID? Sometimes I see SIDs with a long straight climb segment (say 10 nm), followed by a wide turn with an IAS constraint (e.g. MAX 210 KIAS).

Is there any issue in accelerating to 250 KIAS and then decelerating shortly before the turn? Is that ever done?

EDIT
Fictitious example:

EDIT #2
Here's the actual chart (I hope no copyright infringement):

There is another limitation apart from the 250/10,000 one, according to ICAO Annex 11 Chapter 5 Appendix 4:

  Speed limitations applicable to both IFR and VFR aircraft:
  — 250 knots below 10 000 ft ASL; and
  — 200 knots below 3 000 ft AGL within 10 NM of a controlled airport.

So within 10 NM and below 3,000 ft AGL of the controlled airport, you are not supposed to exceed 200 knots.

Note: In the Rome example before the 210 knots PRA turn, the leg is 4+10+6 (20) NM, but all of it is still within (or very close to) 10 NM of the airport. Also note the 'at 3,000 ft' point, which is still below 3,000 feet AGL, so it's hard to justify trying to accelerate after that only to slow down again in 6 NM while climbing to 'at or above 6,000 ft'.

I checked the Italian AIP for any differences from the above ICAO limitation. AIP GEN 1.7 refers to Commission Implementing Regulation (EU) No 923/2012, in which no differences from Chapter 5 are listed, which is to say the quotation above applies in Italy.

What if it's more than 10 NM from the airport?

In this case the procedure design group (PDG) that designs the procedures will typically make any speed restriction clear.


Is the ATC of the lower and upper areas of the Netherlands combined or segregated? I am simulating the capacity of the Netherlands airspace by using the sector capacity. But I am wondering for different height, the capacity works for both or a single level.

Therefore, I want to know if the controller control lower and the controller control upper area are from same system or not. The question can be paraphrase as, would there be a controller control both flights for two areas simultaneously?

And if possible, are there any documents explain it?

The map below comes from AIS-Netherlands.

Note that the Netherlands is a bit of a special case.

Below FL245, Air Traffic Control is provided by Luchtverkeersleiding Nederland (LNVL, the Dutch Air Traffic Control) and Dutch Mil (Dutch military ATC). Until one year ago, the Dutch military  operated from their dedicated air traffic control centre in Nieuw Milligen. Since January 2018, they are colocated with LVNL at Amsterdam Airport Schiphol and largely use the same systems as LVNL.

On the lower area map (below FL195), all sectors marked as Amsterdam Radar are controlled by LVNL. The  sectors marked as Dutch Mil  are controlled by the military, and despite some of the sectors are still named NW Milligen, they are controlled from the same room as Amsterdam Radar at Schiphol. As you can see on the upper area map, all sectors are marked Amsterdam Radar.

Their systems are partly combined, but military sectors and civil sectors are never combined. So if a lower sector is controlled by Dutch Mil, the upper sector will be controlled by a different controller.

When both the lower and the upper sector are controlled by LVNL, they can be combined during hours of low traffic. In that case there may be a single controlled controlling flights in the lower airspace and in the upper airspace. Combination is possibly also with adjacent sectors.

But wait, that's not all. Note that the map mentions that the Upper Area is between FL195 and FL245. The upper airspace mentioned so far in this answer, has a ceiling of merely 24500 feet.

Above FL245, ATC is provided by EUROCONTROL's Maastricht Upper Area Control (MUAC). They are located in Maastricht, far away from Amsterdam. They use the same radars, but their control system is totally different. Sectors of Amsterdam and Maastricht can thus not be combined.

Within MUAC's airspace, there is horizontal and vertical sector splitting. Especially the Delta sector is a busy one, with lots of transit traffic to/from UK/Atlantic and with climbing/descending traffic from/to London, Frankfurt, Cologne/Bonn, Brussels, Amsterdam and many more airports.


What's the difference between a two-blade prop and three-blade? I read that a three blade can improve climb performance and decrease noise.  How does that work?

At the absolute simplest, compared to a two-bladed propeller, a slightly smaller three-bladed propeller can produce more thrust at a given RPM, improving climb performance. Because of the smaller diameter, the propeller tips actually travel slower than the equivalent two-bladed design, reducing noise inside and outside the airplane.

Hartzell Propeller has a great set of technical answers about propellers. Their explanation of why more blades produces less noise is pretty good:

  A 2-blade propeller produces two pressure pulses per revolution, where a 3-blade propeller will produce three smaller pulses per revolution (for the same amount of total thrust) which is inherently smoother and therefore quieter. The 3-blade propeller will generally have a smaller diameter than the 2-blade propeller that it replaces, which also reduces the tip speed and noise.


Can I fly internationally as a commercial pilot, without an ATP certificate? Are commercial pilots allowed to fly internationally? Are Commercial Pilots required to take an Airline Transport Pilot (ATP) program/training to fly internationally? And is a commercial pilot the same as an airline pilot?

A US rated pilot (private, commercial or ATP) can operate an N- registered airplane anywhere on earth (subject to the persons ability or inability to enter certain countries airspace).

At the regional airlines it was common that the first officer only possessed a commercial certificate (the full ATP is earned during the pilots first upgrade training to become a captain).  These first officers will have no restriction on international travel based on their certificate and can operate international flights. These days FOs will have restricted ATPs rather than commercial certificates, but this is unrelated to the ability to operate internationally.

Outside of airlines you'll find positions where the only a commercial certificate is necessary and these pilots can operate internationally.

If the airplane in question requires a type rating then if the copilot does not have a full type rating, they will need an "SIC type" to operate internationally. This stems from an ICAO requirement that both pilots be type rated. The SIC type can be added to a private or commercial certificate, not just an ATP so this won't be a restriction based on certificate level.


How does a constant pressure chart affect your preflight planning? Would you choose a route or altitude based on the information in a constant pressure chart? How does a constant pressure chart help a pilot plan his or her flight?

As others wrote, I don't think in and of itself the constant pressure chart will help with a go or no-go decision by itself.  However, I do believe it would help to get the big picture of what's happening with the weather; fronts, etc.  Knowing the big weather picture is more important depending on what kind of flying you do.  The constant pressure chart can help with that.  Regarding choosing a flight level or altitude to fly in I would use winds aloft, airspace charts like a sectional, anticipation of ATC given altitudes in the area you plan to fly in, etc.  Like many others have said: with regards to weather the more you know the better off your preflight planning will be and the constant pressure chart adds to your knowledge of the weather.


What are the requirements for a 'complex' airplane? Requirements for 'complex' airplane seem to vary between regulators and between pilots, so let's have this settled once and for all.

What is the definition of a 'complex' airplane as defined by FAA and EASA?

For the FAA, a "complex aeroplane" must have:

A retractable gear (not necessary for a seaplane);
In-flight adjustable flaps; and
A controllable pitch propeller.

The FAA's definition is given in 14 CFR 61.1:

  Complex airplane means an airplane that has a retractable landing
  gear, flaps, and a controllable pitch propeller, including airplanes
  equipped with an engine control system consisting of a digital
  computer and associated accessories for controlling the engine and
  propeller, such as a full authority digital engine control; or, in the
  case of a seaplane, flaps and a controllable pitch propeller,
  including seaplanes equipped with an engine control system consisting
  of a digital computer and associated accessories for controlling the
  engine and propeller, such as a full authority digital engine control.

However, the EASA has a different definition of a "complex motor-powered aircraft" that is an airplane, which is considerably more "complex":

  an aeroplane:

  with a maximum certificated take-off mass exceeding 5 700 kg, or
  certificated for a maximum passenger seating configuration of more than nineteen, or
  certificated for operation with a minimum crew of at least two pilots, or
  equipped with (a) turbojet engine(s) or more than one turboprop engine

Note that 5700kg is about 12567 pounds.


Is this statistic about the fatal accident rate correct? This link says that:

  fatal accidents occurred once every 200,000 flights in the 50s and 60s. Now, fatal accidents only occur once every two million flights

While many sources, including this one, agree that the average number of commercial flights per day is around 100,000.

If that is the case, then we should see a fatal accident every 20 days or so (2 million flights), but in 2017, there were no fatal incidents on commercial flight at all.

What is the explanation for this? Is it just that the first link is plain wrong?

The passage you're asking about is a paraphrase of something Boeing spokeswoman Julie O'Donnell said. If you follow the citation in the article, you can see exactly what she said, and when she said it.

  "During the 1950s and 1960s, fatal accidents occurred about once every 200,000 flights," says Julie O’Donnell, a spokeswoman for Boeing. "Today, the worldwide safety record is more than 10 times better, with fatal accidents occurring less than once in every two million flights." [Emphasis added.]

O'Donnell is being quoted in 2014. According to the latest IATA safety fact sheet (published January 1, 2018), IATA measured a fatal accident rate of about one per 2.36 million flights in 2012, and one per 2.58 million flights in 2013. If I were rounding that down for a reporter in 2014, "less than once in every two million flights" is exactly what I'd say.

IATA counted 15 and 14 fatal accidents in 2012 and 2013, respectively. That's an average of one fatal accident every 25 days or so—just like you estimated. As @fooot pointed out in their answer, we've seen fewer fatal accidents in more recent years: an average of one every 30 days, 90 days, 40 days, and 60 days or so in 2014, 2015, 2016, and 2017, respectively.

Statistical postscript

I agree with your gut feeling that, if fatal aircraft accidents were happening at an average rate of one every 20 days, I'd be very surprised to see no fatal accidents at all last year. If fatal accidents were Poisson distributed in time, with a rate of one per 20 days, your chances of seeing no accidents in a year would be less than one in 80 million!

On the other hand, a year with no fatal large commercial passenger jet accidents is totally plausible, given the accident rate of one per 16 million flights that @fooot quotes. In 2017, that comes out to an average accident rate of less than one every 140 days—maybe a lot less, if large commercial passenger jet flights make up only a small fraction of all flights. If fatal accidents were Poisson distributed, with a rate of 1 per 140 days, your chances of seeing no fatal accidents in a year would be better than one in 14.