Multiple 30 minutes segments above 12,500' prohibited?

PeterNSteinmetz

PeterNSteinmetz

Administrator
Staff member
Does FAR 91.211 prohibit making multiple segments above 12,500 feet without supplemental oxygen in a single flight?

Got into a discussion about this today. Here is the actual language from the FAR:

"91.211 – Supplemental oxygen.
(a) General. No person may operate a civil aircraft of U.S. registry—

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;"

How exactly does "duration" get interpreted within the whole flight?
 
Landing Fees said:
Discussed it with an inspector a few years back, he stated that it was 30 minutes a day. This ruling or interpretation (can’t find a ruling) was based upon Alaska guys flying above 12,500 for 29 minutes then ducking down for 1 minute, then back up.
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I would be very curious to hear any ruling or interpretation. I don't see much justification for a per day interpretation, in medicine or the language of the reg.

My suspicion would be that it is another ambiguous regulation.
 
I think it is unclear for exactly the reason pointed out above. The definition of duration is “the time during which something continues”

So the language in the reg “for that part of the flight at those altitudes that is of more than 30 minutes duration” could reasonably be read to be “for that part of the flight at those altitudes which continues for more than 30 minutes” - in other words, only those segments of more than 30 mins require oxygen use.

This would also be a reasonable interpretation in a case where for example one is on a 4 hour flight. 30 mins in one is above 12,500 for 20 mins, then back down for 2 hours, then back up above 12,500 for 30 mins and down again.

Clearly it would not necessarily be so safe if one was only down for 1 min in between.

I think it is an example of how it is difficult to write a set of regulations to clearly cover all circumstances. Thus I am particularly interested in if there has been a ruling or interpretation.
 
[QUOTE="James331, post: 2803253, member: they have never met a extra regulation/tax/penalty/law they didnt like
[/QUOTE]

Have to agree on regulators loving to regulate.

And I certainly just fly using a common sense interpretation. My interest here is more academic.

Isn’t it interesting how even a regulation written in fairly simple words give rise here to people with interpretations on opposite sides, but both of which are utterly convinced it is very simple and they are correct. But logically both cannot be correct. And neither side can cite a ruling or interpretation to support their contention. All of that suggests it actually is not so simple.
 
luvflyin said:
I suppose you could insert the word segment in there. But it’s not there.
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But please notice that my rephrasing to use the definition of duration did not have to insert “segment”. It was “for that part of the flight at those altitudes which continues for more than 30 minutes”.

Since that is one of the few ways I can think of to incorporate the “continues” part of the definition of duration, the FAAs use of duration does strike me as less clear than it could be.
 
NoHeat said:
I'm guessing you didn't have a chance to see my post, 2 minutes before yours, when I cited an interpretation by an authority.
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True, that was like “two ships passing in the night”. Thanks for pointing that out.

Exposure of course does not necessarily mean cumulative exposure, it simply means being in contact. They say in 8-1-2 6. “After 30 minutes of exposure...”, but this is then followed by “and immediately on exposure to cabin pressure altitudes above 14,000 feet” which sort of implies they mean to consider the more than 30 minutes of exposure as an event.

There is another problem with the cumulative exposure interpretation in the AIM. After what timeframe does that cumulation expire? The AIM says nothing about it. So would it be for a flight, a day, a week?

Of course, the AIM is not regulatory in any case.
 
luvflyin said:
I have violated the ‘letter of the law’ many many times. Sometimes you have to literally do that in order to comply with it’s intent. But I don’t have to ‘rewrite’ the letter of the law to do that. I don’t think that’s a good idea. Pet peeve of mine.
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I guess I don’t understand the pet peeve really. Are you arguing that the letter of the law should not be re-written to clarify it’s intent? I am puzzled.

In this OP and thread, I have really been more concerned with the letter of the law and what someone could be violated for. I imagine most of us agree on what is safe and reasonable.

It strikes me the intent was likely to put pilots on notice that for the average pilot, if you are above 12,500 for more than 30 mins, your cognition is likely to start being impaired. Maybe the data on exact rates of recovery wasn’t available when this was written or maybe they didn’t think the up / down / up case would be frequent enough to merit trying to spell it all out.

Of course with any regulation there will always be those that are going to try to cut it at the edge.
 
dtuuri said:
No way. The crew needs to be USING the O2 during all flight time more than 30 minutes above 12,500. No "resetting" nuthin'. You guys don't need a doctor to explain this, you need a lawyer (or a CFI).
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If you read the comments in this thread, you’ll see that there are multiple people on both sides of this, and both sides believe the truth of their side is obvious. That usually suggests the issue is not so terribly clear.

If you read a careful parsing of the definitions and regulations above, I think it is clear that the meaning of the regulation is not unambiguous. It was an unfortunate use of the words part and duration. There was clearer language which could have been used, but it was not.

But is this really any surprise? There are tons of FAA regulations that are not so clear and specific interpretations or rulings are required. Perhaps the circumstances have never arisen requiring such.
 
luvflyin said:
91.211 Blank slate. Write it
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Fair enough. If the FAA wanted to say that the cumulative total time above 12,500 in one flight can not exceed 30 minutes, they could have said something like

“91.211 Supplemental oxygen.
(a)General. No person may operate a civil aircraft of U.S. registry -

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL), when the required minimum flight crew is not using supplemental oxygen, for more than 30 minutes in any one flight;”

I will leave the rest alone for now as it does not pertain to the original question.

Isn’t that a clearer way to say that the cumulative time cannot exceed 30 minutes?
 
Brad Z said:
Pretty much. Face it, unless you're a sherpa, you have no business flying around at 13,000 with O2 on board.
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There is a lot of individual variability on this. My son tends to fall asleep above 10,000. I tend to fly just fine at 12,500 and do fine up to 14,000 for 30 mins.
 
asicer said:
Is your son doing the flying? It's strange, but when I'm a passenger aboard a pressurized airliner, I fall asleep right after takeoff. When I'm PIC of an unpressurized GA plane, I'm wide awake the entire flight. My SpO2 stays in the 90s even above 12.5k
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He says he feels too sleepy to fly. I think being PIC is fairy energizing, but that doesn’t seem to help him. I have not checked this since he moved to a higher altitude.
 
dtuuri said:
If it isn't a translation issue my only other guess is they are looking at it from "their" perspective of a linear route where a "part of the flight" is measured in miles
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My belief that one could interpret this non-cumulatively is based on the use of the term “part” and the definition of the term “duration”. It suggests that there are different parts of the flight which have a duration.

Potentially poor choice of words, but one that has apparently been in use since prior to 1963.
 
dtuuri said:
Then it would have said "...those parts of the flight..."
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That would have been clearer, for sure. As would the suggested language for specifying it is cumulative.

What the regulation does say is “that part”, suggesting there is only one.

Definition of “part” - part n. A portion, division, piece, or segment of a whole. “

Definition of “portion” - portion
n. A section or quantity within a larger thing; a part of a whole

So the majority of the definitions here imply that part is a singular piece or chunk, as does the use of the phrase “those parts”. One could make the argument that the “portion” definition of part and its sub definition as “quantity” imply a cumulative interpretation, but those are the minority of the listed meanings.

The regulation then says “duration”, which is defined as the time something continues, not the sum of a number of things.

I suspect the writers did not contemplate a flight with multiple segments above 12,500’ altitude. Perhaps they thought of one hop over the Rockies.

I’m not saying it is clear one way or the other, just that it is not clearly one way or the other, as some have contended. Language can be imprecise and there are many regulations which suffer from ambiguity. No reason to insist there is absolute certainty about them all. That is why there are interpretations and rulings. And in this case, there apparently aren’t any of those.
 
Interesting article. It says about the age 60 rule “Implemented, in part, at the urging of the American Airlines president”. Was this because AA could pay the younger pilots less?
 
dtuuri said:
Your answer here:

"Smith was instrumental in lobbying for the FAA to implement a mandatory retirement age of 60 for commercial airline pilots in large part because he was eager to remove older, expensive pilots from his cockpits and replace them with young men who would work for lower salaries
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So get the government to do the dirty work for you. Classic regulatory capture.
 
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