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In the US, is there a highest legal altitude allowed for certain planes and does it depend on the plane? I heard from a sort-of-reliable source that the maximum is 45,000 feet but I haven't been able to confirm this. I ask since a plane I travelled in very recently was travelling at an altitude of over 55,000 feet and, when it did, turbulence was terrible (some told me I was lucky to be alive).

Note: I have tried Googling this and have found no answers.

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    $\begingroup$ Each plane has it's own maximum altitude at which it's safe and able to fly. Some are very very high - the U2 can go up to 75,000 feet $\endgroup$ – raptortech97 Dec 28 '14 at 23:14
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    $\begingroup$ Just curious, which plane were you in? $\endgroup$ – Jon Onstott Dec 29 '14 at 4:48
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    $\begingroup$ @Jon Emirates EK237. $\endgroup$ – Ahaan S. Rungta Dec 29 '14 at 13:58
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    $\begingroup$ It's almost certain that you were not flying at 55,000 ft. That's 12,000 ft. higher than the aircraft that is used to operate that flight (a Boeing 777) is certified for. It seems unlikely that it would even climb that high if they tried to get it up there. $\endgroup$ – reirab Dec 29 '14 at 14:45
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    $\begingroup$ @reirab while the pressure and absolute altitude can vary, it doesn't vary by 10-12,000 ft even if we assume the plane was at its service ceiling $\endgroup$ – Jon Story Dec 30 '14 at 5:05
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There's no legal limit of how high you're allowed to fly by law: there's no law that says

It is illegal to fly above X,000ft

In some juristictions there are more specific laws, eg

It is illegal to operate an unpressurised aircraft above 25,000ft

However, each aircraft has a service ceiling when it is certified, and it would be generally illegal to operate the aircraft above this altitude (because it's unsafe).

I'm fairly confident that you weren't at 55,000ft. No currently-operating commercial airliner I know of has a service ceiling higher than 45,000ft (the newer -800 version of the 747) and they almost never operate above 41,000ft. A few private jets can go a little higher, up to around 50,000ft, but I know of no non-military/experimental aircraft which is currently capable of going much above 50,000ft, even if you were daft enough to try.

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    $\begingroup$ There are actually a number of private jets certified to 51,000 feet.... $\endgroup$ – Lnafziger Dec 29 '14 at 0:28
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    $\begingroup$ "Around 50,000ft" - near enough for the purposes of this answer, and either way none I know of hit close to 55,000ft $\endgroup$ – Jon Story Dec 29 '14 at 0:29
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    $\begingroup$ If the service ceiling is in the LIMITATIONS section, then it's a hard limit like Vne. If it's in the performance section, then it's information. And not a limitation. 91.13 applies. See this accident report en.m.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701 $\endgroup$ – rbp Dec 29 '14 at 0:51
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    $\begingroup$ The Concorde actually had a service ceiling of 60,000 ft, but, as far as I know, you're right that no current airliners are anywhere near that. EK237 is operated by a B777, which has a service ceiling of 43,100 ft. $\endgroup$ – reirab Dec 29 '14 at 14:42
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    $\begingroup$ @AngelKoh No, if an aircraft is certified to 51,000 ft. (as several that I have flown are, such as the Bombardier Learjet 31A), then it has been demonstrated that it can actually fly there and it is legal to fly there. In some conditions, it may be possible to exceed that altitude, but it is not legal because it was not certified to do so. $\endgroup$ – Lnafziger Dec 29 '14 at 20:58
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Jon Story's answer is correct, but I will add that the cabin displays often have incorrect information on them. I have seen wrong times, wrong locations, impossible flight paths, impossible air speeds, etc. The mere fact they call it an "entertainment system" tells you something.

I suspect the altitude may be coming from a cheap, dedicated GPS unit. A lot of GPSs have inaccurate altitudes. Some have a "barometric" sensor-derived altitude which is often wildly incorrect.

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The max allowed altitude has little to do with jet ability climb over 50k feet. The regulation that determines it is simple: it must be 4 minutes or less it takes the jet to get to 14k feet safely in the event of sudden decompression. Private jets are usually capable of doing that such as the Cessna Citation X rated at 51k feet.

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  • $\begingroup$ This is one factor that determines the max permitted altitude but certainly not the only one. E.g. another is maintaining sufficient margin to coffin corner. $\endgroup$ – pericynthion Mar 24 '18 at 16:09
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In your question you asked if "certain planes" have altitude restrictions and the answer is yes. Very small or light aircraft have altitude restrictions, for example: light-sport aircraft are limited to 10,000ft MSL. As for the rest, I can guarantee you were not at 55,000ft, airliners nowadays have service ceilings (the plane physically can't climb higher, not a law) at 45,000ft max. The Concorde could cruise as high as 60,000 but it stopped flying in the early 2000s, some business jets can go up to around 50,000ft.

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  • $\begingroup$ Welcome to aviation.SE! Do you have a source for the 10,000' limit on LSAs? As far as I know, recreational and sport pilots are limited to that altitude, not the aircraft themselves. $\endgroup$ – Pondlife May 19 '18 at 15:12

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