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FAR Part 91, Appendix G, Section 2 says:

(c) Altitude-keeping equipment: All aircraft. To approve an aircraft group or a nongroup aircraft, the Administrator must find that the aircraft meets the following requirements:

...

(2) The aircraft must be equipped with at least one automatic altitude control system that controls the aircraft altitude

Note that it does not say that it must be engaged, or even operative. Simply "equipped", and also that this is to approve an aircraft for RVSM. From what I can find, there is no operational requirement for the autopilot to actually be working or engaged.

Assuming that my MEL allows me to defer the autopilot and still fly, can I fly in RVSM airspace? Some people however say that if you are in RVSM airspace that the autopilot must be working and engaged. Right or wrong?

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    $\begingroup$ That's pretty bald-faced rules lawyering. By that logic, anyone could throw an cardboard box with the word "autopilot" sharpied on and have "the autopilot" "equipped" and do the exact same amount of good. Equipment has to be operable, or it's as good as not there. (Worse, actually, because it adds to the plane's mass.) $\endgroup$ – rsegal Dec 19 '13 at 5:23
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    $\begingroup$ @rsegal: The regulations are written by lawyers using very specific wording for a reason. There are minimum requirements for the autopilot which must be met (as pointed out in Quantas's answer below), however what happens when the autopilot breaks? It is still technically "equipped" with the autopilot that meets the requirements. Part of our job as pilots is to operate the airplane as efficiently as possible while still remaining safe and legal. Intimate knowledge of the regulations is essential in order to accomplish that. $\endgroup$ – Lnafziger Dec 19 '13 at 12:46
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About whether or not you can fly with an inoperative autopilot, take a look at §91.180:

§91.180 Operations within airspace designated as Reduced Vertical Separation Minimum airspace.

(a) Except as provided in paragraph (b) of this section, no person may operate a civil aircraft in airspace designated as Reduced Vertical Separation Minimum (RVSM) airspace unless:

  1. The operator and the operator's aircraft comply with the minimum standards of appendix G of this part; and
  2. The operator is authorized by the Administrator or the country of registry to conduct such operations.

(b) The Administrator may authorize a deviation from the requirements of this section.

You also can't say that your aircraft is allowed to operate in RVSM airspace:

Section 4. RVSM Operations

(a) Each person requesting a clearance to operate within RVSM airspace shall correctly annotate the flight plan filed with air traffic control with the status of the operator and aircraft with regard to RVSM approval. Each operator shall verify RVSM applicability for the flight planned route through the appropriate flight planning information sources.

(b) No person may show, on the flight plan filed with air traffic control, an operator or aircraft as approved for RVSM operations, or operate on a route or in an area where RVSM approval is required, unless:

  1. The operator is authorized by the Administrator to perform such operations; and

  2. The aircraft has been approved and complies with the requirements of Section 2 of this appendix.

If it's not operational, the aircraft no longer qualities for RVSM, and therefore must be provided with 2000 feet vertical separation (each way) between other aircraft. Alternatively, ATC can refuse entry into RVSM airspace.

Regarding having the autopilot engaged, Appendix 4 of AC 91-85, Section "5. In-flight Procedures" states:

e. An automatic altitude-control system should be operative and engaged during level cruise, except when circumstances such as the need to retrim the aircraft or turbulence require disengagement. In any event, adherence to cruise altitude should be done by reference to one of the two primary altimeters;

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    $\begingroup$ @lnafziger: in its current state, it's unable to do so... But yes, it would have been more obvious if it did explicitly say "all must be operational" or words to that effect. $\endgroup$ – Qantas 94 Heavy Dec 19 '13 at 12:58
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    $\begingroup$ Okay, so it looks like 91.180 and FAR 91 Appendix G, 4(b)(2) contain the requirement for a working autopilot. If you add the second reference (and relevant quote) I'll mark this as the correct answer. Thanks for all of your help! $\endgroup$ – Lnafziger Dec 23 '13 at 2:55
  • $\begingroup$ @lnafziger: since you've edited your question, I've changed my answer accordingly. $\endgroup$ – Qantas 94 Heavy Dec 24 '13 at 1:12
  • $\begingroup$ @lnafziger: is that better? ;) $\endgroup$ – Qantas 94 Heavy Dec 24 '13 at 1:25
  • $\begingroup$ @rbp Nice edit, although this is not a mandatory requirement (shall -vs- must and it is an Advisory Circular which is not regulatory). Good reference though, thanks! $\endgroup$ – Lnafziger Dec 9 '14 at 1:14
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For RVSM, the autopilot (and altimeter) has to be operable, certified for maintaining a tight altitude tolerance, and maintained in an approved RVSM maintenance schedule.

FAA Part 91, appendix G, Section 2.

In the event the autopilot fails at RVSM altitudes, the pilot shall contact ATC and state "Unable RVSM Due Equipment". ATC will provide non-RVSM separation and/or clear the aircraft out of RVSM airspace.

AIM 4-6-8.

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  • $\begingroup$ Haha, thanks, but that is the link that I posted and says nothing about it being operable. :) $\endgroup$ – Lnafziger Dec 19 '13 at 18:50
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    $\begingroup$ It says, "The aircraft must be equipped with at least one automatic altitude control system that controls the aircraft altitude—", which implies operational. It could not control the aircraft altitude if it was inop. In addition, the plane's required equipment list almost certainly would not allow flight at RVSM altitudes without autopilot. $\endgroup$ – xpda Dec 19 '13 at 19:00
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    $\begingroup$ Well, your quote is a subitem of "To approve an aircraft group or a nongroup aircraft, the Administrator must find that the aircraft meets the following requirements:". Note the "to approve" portion, not "to operate" or "to fly" or anything like that. Also, the autopilot IS listed in the Master MEL (MMEL) and may be inop (I believe for up to three days, but I'm not positive on that). $\endgroup$ – Lnafziger Dec 19 '13 at 19:09
  • $\begingroup$ Also, I appreciate your answer and you looking into this. I'm just trying to find out for sure and get the "right" answer! $\endgroup$ – Lnafziger Dec 19 '13 at 19:11
  • $\begingroup$ I added AIM info to the answer. $\endgroup$ – xpda Dec 19 '13 at 23:38
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I can't trace this back to the CFR's, but I'll tell you that our OpSpecs and MEL's require that the autopilot DOES have to be engaged (and thus, operative) when in level flight in RVSM airspace.

The aircraft is APPROVED to go into RVSM airspace based on the equipment that it has, with an assumption that it all works. That approval process happens outside of anything that the actual line pilots ever see. We have our operating manuals, which are driven by Part 121 and our carrier's OpSpecs, and they're pretty clear on the point. Our MEL likewise says that RVSM operations aren't allowed if both autopilots are deferred, and I strongly suspect that everybody else's manuals say exactly the same thing.

Of course, the exception to all this is that ATC could clear you into the airspace anyway and provide 2000' of separation from everybody else, and at 0300L that might actually work. And I've heard a few military jets that aren't RVSM approved (old altimeter systems, I think) get that treatment as well. So the general answer to the question is "no," although the precise answer is "yes, if..."

But generally, no, you need the autopilot engaged while in level flight in RVSM airspace.

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  • $\begingroup$ Yeah, they let some /A military guys go RVSM sometimes, but you can't file for it and you obviously have to request it. Usually its aging training aircraft (in my experience) that aren't RVSM certified. $\endgroup$ – Rhino Driver Mar 24 '15 at 20:44

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