Multiple 30 minutes segments above 12,500' prohibited?

PeterNSteinmetz

PeterNSteinmetz

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PeterNSteinmetz
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?
 
duration - the time during which something continues

I do not see disjointed segments as constituting "continuance". IANAL, esp. IANAFAAL.
 
@bbchien This is a question for the good Doctor Chien. I believe he has considerable expertise in this issue.

If you want to do your own research, get a pulse oximeter and take it up to 12,000 without using oxygen. Measure and record your O2 saturation. Call this reading "A". Then climb to 13,999 ft using supplemental O2 for 30 minutes (includes the time to descend to 12,500 within the 30 minute window. Once back at or below 12k, measure and record your O2 saturation. Then fly level watching your O2 sat and see how long it takes to climb back to reading "A".

Remember everyone has a different tolerance for hypoxic conditions so 1) what works for you may not work for all, and 2) YMMV from flight to flight.

The rules are written to keep most everyone alive and healthy. You may be a healthy young pilot or you may be too old to cut corners like this.

-Skip
 
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. Way to lazy to search for it but came up because we have big pointy clouds in CO and it would be simple to just go to 13 and dip down every so often.
 
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. Way to lazy to search for it but came up because we have big pointy clouds in CO and it would be simple to just go to 13 and dip down every so often.
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Sounds like BS to me....... Where's the letter stating "a day" ?
 
PeterNSteinmetz said:
Does FAR 91.211 prohibit making multiple segments above 12,500 feet without supplemental oxygen in a single flight?
...
How exactly does "duration" get interpreted within the whole flight?
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I don't see the problem with interpreting this. A flight exists between takeoff and landing, so for the cumulative time above 12,500 feet that exceeds 30 minutes the crew must be on supplemental O2.
 
MooneyDriver78, congrats for hitting the nail firmly on the head! Why is it so many people choose to ignore the plain truth that being legal doesn't mean you are safe or smart. And, if something bad happens you are just as injured, or worse, dead? Go look at the number of people who have mangled airplanes and bodies by taking off in 0/0 conditions, or not escaped hypoxia or any of a long list of adverse events.

Be legal, safe, AND smart...
 
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.
 
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. Way to lazy to search for it but came up because we have big pointy clouds in CO and it would be simple to just go to 13 and dip down every so often.
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Unless I see it’s a FAR or opspec or something mandatory, that and 25 cents won’t get you on the buss in a logical real world, ofcourse it’s administrative law so the goal posts are subject to random leaps and bounds.
I’d just follow the FARs as they are written and try not to attract attention, as Hoover and many others have shown, if you anger the FAA logic and facts don’t matter.
 
alfadog said:
I missed the word "cumulative" in the reg?
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Seems pretty clear that oxygen is required for that part of a FLIGHT at the affected altitudes that exceeds 30 minutes. There is no apparent provision in the reg for "resetting" the 30 minute clock during a single flight.

I suppose you could land and take off again to "start the clock again" for another flight, but that doesn't really affect physiology. Common sense should prevail for safe operation.
 
Wonder how the NTSB would write the report after you pogoed your way in 29 min increments to the scene of the crash...above says it...common sense should apply...
 
"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;"

My interpretation is it is the total time on a flight.
 
Skip Miller said:
@bbchien This is a question for the good Doctor Chien. I believe he has considerable expertise in this issue.

If you want to do your own research, get a pulse oximeter and take it up to 12,000 without using oxygen. Measure and record your O2 saturation. Call this reading "A". Then climb to 13,999 ft using supplemental O2 for 30 minutes (includes the time to descend to 12,500 within the 30 minute window. Once back at or below 12k, measure and record your O2 saturation. Then fly level watching your O2 sat and see how long it takes to climb back to reading "A".

Remember everyone has a different tolerance for hypoxic conditions so 1) what works for you may not work for all, and 2) YMMV from flight to flight.

The rules are written to keep most everyone alive and healthy. You may be a healthy young pilot or you may be too old to cut corners like this.

-Skip
Click to expand...

That. And read the O2 testing flight that myself and brad did
 
Just stating my opinion here. But I don't see it as something like a radiation exposure where you have a set number of RADS exposure per day for instance. Correct me if I'm wrong but it's not a cumulative issue. Yes, there is recovery time but I see it as don't stay above 12,500 for over 30 minutes. Boom. Obviously, the aeromedical folks can chime in with informed opinions
 
Unfortunately this is one FAR that needs improving by adding a minimum threshold for O2 saturation or something medically appropriate. Look at FAR 91.17. Most of us know the part reading no flying within 8 hours of drinking alcohol. How many of us are aware of the later verbiage adding a BAC of 0.004% or more is forbidden?

User common sense!

Be legal, safe, and smart...
 
jonvcaples said:
How many of us are aware of the later verbiage adding a BAC of 0.004% or more is forbidden?
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That’s perfectly legal. Hell, if I look at a bottle of liquor my BAC will be .004%. Now, .04% BAC? That’s a whole nuther problem.....
 
PeterNSteinmetz said:
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?
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It’s written in English. It doesn’t need interpretation. Unless you’re hoping for a way to find a way to say it means something other than what it says, then interpret away.
 
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.
 
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PeterNSteinmetz said:
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.
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I suppose you could insert the word segment in there. But it’s not there.
 
PeterNSteinmetz said:
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.
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^ This is why we cant have nice things

NO, its written in simple English, small words even, quit reading things into it to further limit yourself that arnt there.
Do you honestly need laws to keep you from doing something silly? Have you no common sense? Do you NEED government to make your life paint by numbers?
....because this is how you get the government to make ALL OUR LIVES paint by numbers, and the government would love to do it, they have never met a extra regulation/tax/penalty/law they didnt like

Just read it the way it was written and be a adult with a above room temp IQ (which if you managed to solo you should be) and youll be just fine.
 
Unit74 said:
Sounds like BS to me....... Where's the letter stating "a day" ?
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Seems like you don’t read so good if you can’t read my post, then what good would a document from the FAA mean to you? I told you I discussed it with an inspector and didn’t find a document.
 
Landing Fees said:
Seems like you don’t read so good if you can’t read my post, then what good would a document from the FAA mean to you? I told you I discussed it with an inspector and didn’t find a document.
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In which case, meh
 
I would be very careful about going that high even for 30 minutes without oxygen, Regs be damned. I’ve done it a few times for 15-20 minutes and my o2 was still fine, but a lot of factors can determine when it isn’t fine, and if it happens, it puts you in a very bad place to get out again safely.
 
Landing Fees said:
Seems like you don’t read so good if you can’t read my post, then what good would a document from the FAA mean to you? I told you I discussed it with an inspector and didn’t find a document.
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There was no value in your post then.... So why post it? Who gives a rats heiny what a guy says. if it aint' in writin', it doen't mean nuthin.... period.
 
The authors of the AIM interpreted the phrasing as "30 minutes of exposure."

"The CFRs require that at the minimum, flight crew be provided with and use supplemental oxygen after 30 minutes of exposure to cabin pressure altitudes between 12,500 and 14,000 feet and immediately on exposure to cabin pressure altitudes above 14,000 feet."​

To me, "exposure" means a cumulative measure.
 
[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.
 
Also it doesnt take much time, like minutes, to "recharge" your SpO2 once you drop back down to altitude and thicker air
 
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.
 
PeterNSteinmetz said:
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.
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It doesnt take long to bounce back once you come back down from altitude, as someone else said this isnt like radiation
 
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.
 
Unit74 said:
There was no value in your post then.... So why post it? Who gives a rats heiny what a guy says. if it aint' in writin', it doen't mean nuthin.... period.
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Good to know that your more valuable post makes it all better. If it ain’t in writing...now that is a good one.
 
I always interpreted that FAR as a cumulative number. Both my wife and I attended a Hypoxia seminar, with an excellent video. We understand what is happening up there.

There are only two things to entice us above 12,000. tall rocks and a strong tailwind that increases as we climb.

Flying a C172 with a 215 HP Franklin and constant speed prop give higher altitude to you rather quickly.

Departing central Missouri one morning, we found the wind at 270 degrees, and at 11,000 feet, 60 knots. That gave us a ground speed of 200 knots in the Skyhawk. After 2 hours up on the edge of trouble (and checking our condition regularly) we descended to Dayton for fuel stop, and food break. A short time later, departed, and in 15 minutes, were back at 11,000 feet. We were still below the magic numbers in the FAR, but well aware that time is a big factor. At a little less than 2 hours, my wife advised me that I had failed the hypoxia observation, and although I felt fine we immediately started a cruise descent to 5,000 feet, and stayed there for the remaining miles. Ground speed had decreased to 150. but speed is not everything, arriving is.

Landing for nearly an hour did not reset the deterioration of my oxygen system, even though I was at the time in my early 30's, and very healthy. It is fascinating to see how all the small things that go slightly wrong become funny, and keeping the needle centered on the CDI is only casually responded to. Altitude variations are amusing too. I was in much worse shape at 1 and a half hour the second leg that at 2+ hours on the first, as on the first, my wife detected no deterioration of my mental state.

As I aged, I stopped even considering altitudes above 10,000 for long legs, particularly IFR, and as a result, have had no additional explorations of the effects of depleted oxygen. Being in the engineering field of endeavor, I expect both the airplane and pilot to have predictable response to increasing altitude, and plan accordingly
 
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