A friend surprised me the other day by saying that single engined aircraft are not allowed to fly in class A airspace.

I understand that the aircraft is under IFR in class A, with ATC clearance, (flight plan) and must meet PBN specifications, however I can’t find any documentation in my textbooks, EASA or ICAO stating that single engined aircraft are not allowed to fly in class A.

If anyone could resolve this issue it would be much appreciated.

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    $\begingroup$ This isn't true. $\endgroup$ – Ron Beyer Feb 13 '20 at 12:59
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    $\begingroup$ Do you mean that SE can fly in class A or SE can’t fly in class A. $\endgroup$ – ob318 Feb 13 '20 at 13:00
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    $\begingroup$ I mean they can fly, there is no requirement for multiple engines in Class A airspace (or any engines at all). For example the Cessna P210N has a service ceiling of 27,000 feet and owners regularly cruise in Class A airspace. $\endgroup$ – Ron Beyer Feb 13 '20 at 13:53
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    $\begingroup$ In fact, zero-engine aircraft can and do legally fly in Class A airspace, as long as they have the appropriate waiver or IFR clearance $\endgroup$ – quiet flyer Feb 13 '20 at 14:00
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    $\begingroup$ Are you asking about EASA regulations? $\endgroup$ – Pondlife Feb 13 '20 at 18:40

Single-Engine aircraft can fly in Class A airspace. Pressurization or oxygen masks are required above 18,000 feet (no cannulas).

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    $\begingroup$ That requirement is not listed in Part 91 or in Part 121 but is noted in the FAA document linked in the post by Ron Beyer. Do you know which regulation is the source of the requirement? $\endgroup$ – JScarry Feb 13 '20 at 15:20
  • $\begingroup$ I thought it was a bit odd to reference the 18000ft thing, then I realised that class A starts at higher altitudes in the states. Not like the U.K. where some class A airspace starts at altitude 2,500ft! $\endgroup$ – ob318 Feb 13 '20 at 22:12
  • $\begingroup$ @JScarry, it is 23.1447(c). $\endgroup$ – Dave-CFII Feb 14 '20 at 3:20
  • $\begingroup$ @Dave-CFII Part 23 starts at §23.1457, so there is no §23.1447. There are a bunch of rules in Part 25 regarding oxygen, but those apply to transport category planes and don’t mention masks specifically, but it may be implied by the pressure requirements. $\endgroup$ – JScarry Feb 14 '20 at 21:55
  • $\begingroup$ I guess you got me. It used to be in 23.1447, but I guess they've up and changed the entire part. $\endgroup$ – Dave-CFII Feb 14 '20 at 22:51

Here is what the FAA says about operations in Class A airspace:

  • Must conduct operations under instrument flight rules (unless otherwise authorized)
  • Must obtain ATC clearance before entering the airspace
  • Unless authorized by ATC, you must have:
    • Transponder with altitude reporting
    • ADS-B (as of January 1, 2020)
  • Oxygen required if not pressurized
    • Crew at all times above 14,000 feet
    • Passengers at all times above 15,000 feet
    • Cannulas can be used at altitudes less than 18,000 feet
    • Oral/nasal rebreathers can be used up to 25,000 feet

There is no mention about aircraft equipment (other than being on an IFR flight plan, which means you need to have an aircraft with IFR instruments). Single engine aircraft like the Cessna P210, the Pilatus PC-12, the Piper M350... the list goes on, all designed to operate at high altitudes with a single engine. The Cirrus SF-50 cruises at 28,000 feet on a single turbojet engine.

It may be that your friend was thinking about ETOPS operations required of commercial aircraft, those require at least 2 engines for certain routes over water or remote areas.

  • $\begingroup$ How about EASA or UK CAA $\endgroup$ – ob318 Feb 13 '20 at 14:29
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    $\begingroup$ @Ollie As far as I know, EASA and CAA are the same requirements, the only difference is in the UK, some airport terminal control areas are also class A, like around Heathrow. Also around the Channel Island Zone, Class-A starts at 8000 feet. $\endgroup$ – Ron Beyer Feb 13 '20 at 14:35
  • $\begingroup$ By my reading, you've actually reworded 91.135 to mean something different than what it says. The first sentence: "Except as provided in paragraph (d) of this section" and the first sentence of paragraph (d) "An operator may deviate from any provision of this section under the provisions of an ATC authorization issued by the ATC facility having jurisdiction of the airspace concerned." means that your first bullet (must conduct under IFR) is not always correct. An example would be a glider operation using a wave window that allows entry into Class A. $\endgroup$ – bclarkreston Feb 13 '20 at 18:25
  • $\begingroup$ @bclarkreston I added clarification, ATC can clear you into Class A without IFR, but typically you need to be on an IFR flight plan. There are exceptions that ATC can handle (this is the case with pretty much all controlled airspace). $\endgroup$ – Ron Beyer Feb 13 '20 at 18:55
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    $\begingroup$ @Ollie I said "airport terminal control areas, like around Heathrow"... It shouldn't be construed that I meant "only around Heathrow". Central England is pretty busy airspace wise, you have London, London City, Gatwick, Birmingham, Norwich, (and a little further north) Doncaster, Manchester, etc. Not saying those are all Class-A, but yes, it is very busy throughout the central area. $\endgroup$ – Ron Beyer Feb 13 '20 at 22:28

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