Multiple 30 minutes segments above 12,500' prohibited?

geezer said:
...my wife advised me that I had failed the hypoxia observation...
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What is "the" hypoxia observation?? This sounds like good info, for me anyway, since I haven't heard of it that I remember.
 
NoHeat said:
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.
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I can read exposure meaning the other definition too. If I'm up for 20, down for an hour, up for 20, then I'm never exposed for 30 minutes. Especially never exposed for 30 minutes duration.
 
James331 said:
It doesnt take long to bounce back once you come back down from altitude, as someone else said this isnt like radiation
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Partial pressures in different tissues are a tricky thing. I would not take a “bounce back” in a finger reading to mean that your deep tissues have regained their oxygen levels. The different types of tissues regain those levels at different rates, I would guess the finger very quickly while the brain, maybe quick, maybe not so quick. I’m no expert, but I know enough to know that your statement could be a dangerous one.

I’d like to hear more from someone like @bbchien
 
Just imagine if they decided to really refine this reg and started stating specific spo2 levels and minimum sample rates, cumulative effects and acceptable delivery systems and monitors. Some of it could be fairly well defined but the cumulative effect could get kinda complicated. Then again they could just force compliance (minimum levels) and cumulative would be irrelevant such as:

"Spo2 levels must be maintained at or above XX% on all flights above pressure altitude XXXXXft. Monitoring must be performed on all required flight crewmembers when above XXXXXft. Monitoring shall be performed every N minutes. Authorized monitoring devices are listed in [....]. The aircraft must carry enough O2 and delivery system to maintain the levels specified above for all flight crew." ... then add stuff for non flight crew / passengers but they don't need monitoring just a minimum liters per minute per person or something.

Seems to me the spirit of current regulation is that if you'll be above 12,500 for more than 30 minutes the required flight crew need to have supplemental o2 on board. If your flight has a couple of these then the clock starts over.

I find it funny that the Alaska guys popping down for a minute...there is no regulation requiring a minute. It could be a second and still reset. But going around it should be covered in whatever other regs that require the pilot to operate the plane in a safe manner...those should be vague enough to superceded the little 1 minute resets to get around this supplemental o2 FAR.

I know my body needs supplemental o2 before 12500ft so the current FAR is too relaxed for me. Probably based on super fit astronaut test pilots during the 60's or something.
 
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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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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You did use “segment” in your “reasonable interpretation” explanation in post #22. I get it. The point I’m making is the rule shouldn’t be ‘interpreted’ so as to say it doesn’t say what it does say. Now I’m all for understanding the ‘spirit and intent’ of a law and the ‘letter of the law.’ 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.
 
bbchien said:
Brain wise, 12,500 feet (48 minutes) requires about 30 minutes to recover cognitively, in young ERAU west student sin the altitude chamber flying the sim.
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Does recovery mean they brought them back to sea level and then determined it took 30 minutes to recover.
 
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.
 
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bbchien said:
Brain wise, 12,500 feet (48 minutes) requires about 30 minutes to recover cognitively, in young ERAU west student sin the altitude chamber flying the sim.
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48min? Why 48?

Did they do one at 30min?
 
Sinistar said:
Seems to me the spirit of current regulation is that if you'll be above 12,500 for more than 30 minutes the required flight crew need to have supplemental o2 on board. If your flight has a couple of these then the clock starts over.
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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).
 
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'.
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I get where you are coming from but the reg sure doesn't say that. From the regs you could fly 29 minutes at 13999ft, descend down below 12500 for an instant and do it again and again....stupid...yeah...compliant...also yes.
 
Sinistar said:
I get where you are coming from but the reg sure doesn't say that. From the regs you could fly 29 minutes at 13999ft, descend down below 12500 for an instant and do it again and again....stupid...yeah...compliant...also yes.
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Is English your first language? :)
 
PeterNSteinmetz said:
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.
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91.211 Blank slate. Write it
 
alfadog said:
Perhaps you might want to recognize that there are differing opinions on this without the disparaging side comments? Just sayin'
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I'm okay with his response. I never said its wise. But at the same time I don't see how @dtuuri could read the reg and then actually prove what I wrote would not be compliant.
 
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.
 
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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?
 
What would be interesting is to ask 5 CFI, 5 DPE and 5 ASI this question and see what level of agreement. I could easily ask 2 different CFI and 1 ASI and perhaps a 2nd ASI (same FSDO though).
 
WannFly said:
Anyone knows the process of submitting all these feedback and rewrite the regs?
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11-BBE7-C0-D38-C-463-D-B9-C6-1024-D77194-F6.gif
 
That's the same look our 1st class would give when our Navy Chief found something wrong in the Trident manuals and told us to submit it.
 
Based in Utah I am used to flying 11.5 to 12.5. It’s a non-factor for me. Got stuck in an updraft once up to 15-something for a few minutes. Non-factor.

But this conversation makes me want to have my CFII take us up to those altitudes for maneuvers. See if there is any major difference in perception under the hood.
 
PeterNSteinmetz said:
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?
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That would work. Says the same thing but would be less likely to be ‘interpreted.’ I like it.
 
DTOURI asked a question "What is "the" hypoxia observation?? This sounds like good info, for me anyway, since I haven't heard of it that I remember."

That was an agreed process that my wife and I created after the training on hypoxia. To understand our relationship when flying, you should know that she took and passed Commercial Ground School, with a score in the 90's. She knows and understands flying and air navigation, is a very supportive air crew member. We believe in CRM, which means, in some instances, she has veto power over my choices, but rarely uses the power.

The hypoxia test I failed related to her observation of the quality of my altitude maintenance, whether I held the CDI to 1 dot, and my response to being notified that I was outside specifications. If I promptly corrected, and did not overshoot, fine. If I laughed, and indicated that it was not really important to keep it that close all the time, I was within FAA standards, I failed the test. No debate. Failed meant an immediate descent to the pre agreed altitude. This sort of relationship is necessary for safe flight at the edges of human capability. If nothing went wrong, I probably would have been fine up there...............

The real issue is proper CRM, and reasonable rules, more than exact compliance with the letter of the FAR's. It is a well known fact that a person living at high altitude has different blood chemistry, allowing them to achieve higher levels of physical and mental effort than someone who just arrived from sea level (my normal pressure altitude). Thus, someone who lives in Denver will be safer at 14,000 feet for an hour than I after 30 minutes. It is reasonable for me to expect trouble earlier than the FAR's set as limits, and I have a process in place to capture the time when I have reached my personal limit.

I spent a week in Colorado Springs, and was well aware of my progressive acclimation to the altitude, and enjoyed our trip to the top of Pikes Peak much more at the end of the visit than I would have at arrival.

Modern flying with all the electronic aids which can hide the fact that we are failing to keep ahead of the plane can lead to skirting the real limit on the wrong side, and failing to successfully deal with an unexpected event. This is especially true if you have an autopilot.
 
alfadog said:
Perhaps you might want to recognize that there are differing opinions on this without the disparaging side comments? Just sayin'
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Sinistar said:
I'm okay with his response. I never said its wise. But at the same time I don't see how @dtuuri could read the reg and then actually prove what I wrote would not be compliant.
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"Disparaging" is in the eyes of the beholder. I assume Sinistar is a smart person, so logically the difference might be more one of translation into his first language (if English it is not) within his brain than interpreting FARs. No offense was meant, Sinistar. I am sorry if you took it that way. But for you both, here's how I parse it, FWIW, keeping in mind this rule has been around as long as I can remember, and that goes back more than 50 years, during which I've never once heard the spin on it you guys are saying:

Flight time under 91.211 is divided into two kinds, oxygen required and not required, like this:
  1. Oxygen is required for all flight time above 14,000 feet plus all flight time above 12,500 feet that exceeds 30 minutes.
  2. Oxygen is not required for all flight time 12,500 feet or below nor flight time from 12,500 feet to 14,000 feet that is less than 30 minutes.
Added together, they result in total flight time. I see no other way to parse this, even after reading your arguments.​
 
PeterNSteinmetz said:
(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;”
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A "flight" can have en route stops. Is the 30 minutes per segment or per flight?
 
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alfadog said:
I can read exposure meaning the other definition too. If I'm up for 20, down for an hour, up for 20, then I'm never exposed for 30 minutes. Especially never exposed for 30 minutes duration.
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Yep. The reg is written vaguely enough to allow anyone to complete a flight with short exposures to altitudes above 12,500 for any amount of total duration.

If I have a flight that is six hours in duration and during that flight I am above 12,500 ten times for five minutes each, I am well within the allowable exposure in the regulation. If 30 minutes is an absolute, it would say so.

Army regulations concerning use of oxygen specifically allow this also...
 
Navy and USAF friends said they had to go on oxygen anytime at or above 10,000 feet but they were all attack and fighter folk.
 
Arguing about this is pointless. The only way to get a definitive answer is to write in for an official interpretation.
 
PeterNSteinmetz said:
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;”
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The use of the negative "is not using supplemental oxygen" adds an unnecessary logic layer. A clearer statement would be...

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) for more than 30 minutes total between take off and landing unless the required flight crew is using supplemental oxygen.

I can see both sides of this debate; my initial interpretation of the reg was that the 30 minutes was a continuous block of time, and not, say, three 10 minute blocks here and there that added up to 30 minutes over a long flight at various altitudes. Spending 10 minutes above 12,500 then 50 at 6500, repeat three times, may not be a very practial or routine flight plan, but it wouldn't lead to hypoxia, either, over a three hour flight. The intent, however, is clear. In any situation that MAY lead to hypoxia, use supplemental oxygen. Perhaps THAT would be the best wording,
 
WannFly said:
Anyone knows the process of submitting all these feedback and rewrite the regs?
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Yes, it's described in 14 CFR part 11. That said, the FAA doesn't have rulemaking teams sitting around looking for regulations to add or revise. It is VERY VERY VERY hard to change the regulations. The administrative procedure act ensures it is not easy. Not to mention various executive orders, the Trump 2 for 1, etc. Rulemaking is based on limited resources and is done by priority. Rulemaking for clarity is seldom justified on its own, but is often included in other wider-spread rule making efforts.
 
Typically when there is a question about the intent of a regulation, you track down when that regulation was added or amended and look at the rationale for rulemaking. Modern day rulemaking includes a significant amount of explanation, intent, response to comments, etc. In this case, 91.211 has remained unchanged from when it was first codified in part 91 back in 1963, meaning it probably dates back even further. Back then they didn't keep very good records of why they enacted certain regulations, and comments weren't publicly adjudicated.

Based on my personal experience with inspectors and enforcement attorneys, I wouldn't expect them to ever take enforcement action for a violation of 91.211(a)(1) because someone did multiple intervals above 12,500 that resulted in a cumulative exposure of more than 30 minutes. Here's why:

1) What did it come to their attention? Was it a result of an accident? A complaint? If so, I suspect there are many other regulations that are much more concrete that were violated. An inspector is going to look at the situation as a whole. This might come as a shock to some, but when someone breaks one rule, they're typically not afraid to break another. Someone may call the FAA to complain about a reckless pilot who's flying too low, but ultimately the FAA pursues certificate action because the pilot hadn't bothered to get a medical, flight review, or annual on the airplane in the last decade.
2) Without any interpretation or rationale defending a more liberal interpretation of 30 minutes, enforcement attorneys aren't going to try to risk enforcement action that is questionable. It takes too much time, and there are too many other things to deal with. Though the general impression of FAA attorneys (on the internet) is that they're out to get people, they're typically the ones pumping the brakes on pursuing any certificate action that is in any way on shaky legal ground.
3) Compliance philosophy- a vague interpretation of a regulation is much better handled through counseling and discussion, than certificate action. If there is a disagreement between the pilot and the inspector regarding the intent of the regulation, the inspector can pursue a legal interpretation. That happens frequently. But again, there'd be no reason to believe the pilot intentionally violated the regulation, so there would be no need to pursue enforcement action.
 
dtuuri said:
But for you both, here's how I parse it, FWIW, keeping in mind this rule has been around as long as I can remember, and that goes back more than 50 years, during which I've never once heard the spin on it you guys are saying...
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I do not find it odd that more than just a few of us interpret this in a way other than you do. That is because it is not specific enough.

You make it seem as if this has been crystal clear for the entire existence of the regulation and completely clear to all but a few of the hundreds of thousands of pilots who have had to learn this stuff. You seem to imply that no one has questioned your interpretation and therefore you are right. You throw in your experience of 50 years as if there is any other doubt then you are just right because you've been doing this longer than most. I could care less about your language comment it was just another way of you trying to shame and/or disqualify my reading of the regulation.

You can parse it any way you like but it is just your interpretation, not mine. I believe your parsed interpretation is far more clear...and safe! But just because some wording is vague (in this case the assumption of "cumulative") does not mean it must default to an interpretation that is more safe. Yes, defaulting to the safer case makes sense but it doesn't mean your parsing and the actual written reg result in equivalency.

If I had my say, I'd skip the whole interpretation process and provide a modern regulation. If the new regulation called out minimum spo2 levels then there would be no need for any cumulative requirements. It would also allow high elevation acclimated pilots more leeway. It would also skip another weak spot in the regulatio... how much o2 is needed and how often they should use it. Requiring a spo2 level doesn't require how they achieve it so that wording can be avoided all together.
 
Sinistar said:
I do not find it odd that more than just a few of us interpret this in a way other than you do. That is because it is not specific enough.

You make it seem as if this has been crystal clear for the entire existence of the regulation and completely clear to all but a few of the hundreds of thousands of pilots who have had to learn this stuff. You seem to imply that no one has questioned your interpretation and therefore you are right. You throw in your experience of 50 years as if there is any other doubt then you are just right because you've been doing this longer than most. I could care less about your language comment it was just another way of you trying to shame and/or disqualify my reading of the regulation.

You can parse it any way you like but it is just your interpretation, not mine. I believe your parsed interpretation is far more clear...and safe! But just because some wording is vague (in this case the assumption of "cumulative") does not mean it must default to an interpretation that is more safe. Yes, defaulting to the safer case makes sense but it doesn't mean your parsing and the actual written reg result in equivalency.

If I had my say, I'd skip the whole interpretation process and provide a modern regulation. If the new regulation called out minimum spo2 levels then there would be no need for any cumulative requirements. It would also allow high elevation acclimated pilots more leeway. It would also skip another weak spot in the regulatio... how much o2 is needed and how often they should use it. Requiring a spo2 level doesn't require how they achieve it so that wording can be avoided all together.
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Then they have to say how often you measure. And provide TSO specifications for your now mandatory “certified” $300 o2 monitor that has to be calibrated bi annually.

I see nothing wrong with the current reg. I’ll be on the conservative side of it anyway.
 
This thread is a great example of why we can't have nice things. When people are trusted to apply common sense, they find a way not to. Which forces regulators to be overly proscriptive, which makes people feel over regulated, which makes more people try to find more ways to get around the rule, which forces regulators to be even more overly proscriptive, rinse, repeat, yadda, yadda, yadda.
 
Salty said:
Then they have to say how often you measure. And provide TSO specifications for your now mandatory “certified” $300 o2 monitor that has to be calibrated bi annually.
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Shame we can’t make the “do gooders” who would mandate that cost upon us pay for these things out of their, and only their, pockets.
 
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
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There’s nothing medical about the oxygen regs. They wrote them based off of the altitude and time it would take the DC3s to get over the Rocky Mountains back when they were used as airliners
 
I live at 6500 feet. Whenever I go to sea level, I forget to breath.....
 
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