Why are airplanes not permitted to operate to/from airports at over 9,200 ft if Engine Bleed Air Supply System #2 is inoperative?

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    $\begingroup$ That is not a limitation for all airplanes. What particular aircraft IS that a limitation for? Without this context, the question as posted makes no sense & will be closed as "Too Broad" or "Unclear What You're Asking." $\endgroup$ – Ralph J Jun 30 '18 at 1:02
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    $\begingroup$ The question is very unfortunately worded. There is a huge difference between limit to operating altitude, as most seem to have understood it, and limit to landing at or departing from airports at high altitude as the body of the question actually asks. $\endgroup$ – Jan Hudec Jul 1 '18 at 11:50

Without more details on the specific aircraft you are talking about, it isn't possible to give a very specific answer.

In general, if a commercial aircraft is unable to pressurize the cabin fully (usually to <8,000 ft, thanks @jwzumwalt, for both safety and comfort reasons), the operating ceiling is reduced to compensate. The human body doesn't play nicely with high altitudes, so to make sure that passengers and crew don't asphyxiate, the cabin must be pressurized to a safe level.

If one of the engine bleed air systems is inoperative, which among many other things provides for cabin pressurization, the remaining compressed air capacity is diverted to more mission-critical systems on the aircraft. This leaves the cabin pressurization system starved of the compressed air it needs, resulting in it not being able to fully pressurize the cabin to a safe and comfortable level.

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    $\begingroup$ FYI - In the US, cabin pressure must be at or below 8000ft for flights over 30min or oxygen must be made available to passengers. (14 CFR PART 121 SUPPLEMENTAL OXYGEN REQUIREMENTS.) $\endgroup$ – jwzumwalt Jun 30 '18 at 9:16
  • $\begingroup$ @jwzumwalt Thanks, I didn't know that. Learn something new every day! $\endgroup$ – ifconfig Jun 30 '18 at 14:09
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    $\begingroup$ The question is not asking about operating ceiling, but about operating to/from airports higher than 9,200 ft. Such airports are notable by their pattern altitude being higher than the standard limit for unpressurised flight at 10,000 ft (but note that nepal has at least two such airports serviced by unpressurised planes). $\endgroup$ – Jan Hudec Jul 1 '18 at 11:55

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