Flying with oxygen : recommended also for 20.000 plus feet?

[A64Pilot]

AFM IS regulatory.

However as I don’t have a factory installed O2 system I doubt it’s in mine.

I’m not arguing against wearing a mask, but understand the question of “what’s the FAR that requires it”?

There may not be one, without stretching one of the cover all ones.

[LANCECASPER]

8 hours ago, A64Pilot said:

AFM IS regulatory.
However as I don’t have a factory installed O2 system I doubt it’s in mine.
I’m not arguing against wearing a mask, but understand the question of “what’s the FAR that requires it”?
There may not be one, without stretching one of the cover all ones.

I do understand the question and the FAR mentioned in that sheet. How you interpret it is up to you. However since Precise Flight, who makes oxygen systems for airplanes, quotes it all through their documents, again I’ll go with that, since it works in principle.

Principles are vastly superior to specific laws, however applying principles takes common sense, which is not a strong suit of the FAA and some individuals who carry FAA certificates.  Even though the Part 23 airplane may be different, the person flying in it, breathing oxygen at specific altitudes isn’t.
 

[Schllc]

I would suspect after all the reports I have read, that if there was an accident that occurred where a mask was not being used over 18k the FAA would find the pilot at fault and a contributing factor to the event.  
And, probably, rightfully so, almost all the accidents I read about can be traced back to the chain of bad decisions. 
How does that saying go, “There are a lot of old pilots, and a lot of bold pilots, but not a lot of old and bold pilots”.  Bold of course being a euphemism for many things…Or something like that…
I think for the most part the self policing is effective, even if its Darwinian. 

[wombat]

To me this is a really interesting discussion, everyone!  Thanks for keeping the discussion civil and researching and debating this topic!   I know some other threads have turned argumentative and emotional, but this one is going pretty much exactly as I had hoped.    

While I have no intentions of using a cannula above 18,000', I do like to understand precisely what I am legally required to do, and why.

 

@LANCECASPER That page from the POH is really interesting and has some critical phrases and words. Thanks for posting it!  Also, I think it contains a mistake.    The important words are 'should' instead of 'must'.     "Should" is not a legal requirement.     And the mistake is that they say facemasks are required above 18,000ft per 23.1447.    23.1447 is Equipment standards for oxygen dispensing units and it says "If certification for operation above 18,000 feet (MSL) is requested, each oxygen dispensing unit must cover the nose and mouth of the user."

I can't find a link to the FAA's website for it, but here is a link to elaws.us: http://federal.elaws.us/cfr/title14.part23.section23.1447

 

I don't know enough part 135 or 121 regulations to be confident, but I expect that they would require the use of FAA certified equipment for supplemental oxygen.  But part 91 has no language that requires it.

 

The FAA can write regulations that require the use of certified equipment, and has demonstrated so in their transponder regulations (See 91.215 and 91.413) but they chose not to do so here.

I conclude that their intent is not to fully limit part 91 operations to only full face masks, despite a random brochure someone at the FAA put together.

Edited April 22, 2023 by wombat

[A64Pilot]

It has a note referencing FAR 23, but unless I’m mistaken we aren’t FAR 23 aircraft, but are CAM 8 aircraft.

I’m going to go out on a limb here and think if there was an applicable FAR then Mooney would have listed it and not FAR 23.

I’m not saying FAR isn’t a good idea and that it’s not a bad idea to follow FAR 23, like burn certs for example are a good idea, but not required for CAR 3 aircraft.

The question was “what’s the regulation that requires it” There may not be one.

For instance what the reg that requires us to wear a shoulder harness if equipped? There may not be one.

Part 137 aircraft, there is the requirement to wear shoulder harnesses, unless they interfere with reaching required equipment, but no requirement to wear a helmet, but that requirement exists under a letter of exemption that allowed Part 137 aircraft to not do head injury testing, but it’s not in the FAR for whatever reason, should be, but isn’t. Same letter requires 5,000 lb seat belts when normal requirement is for 3500, but that’s not in the FAR either.

The FAA often holds the manufacturers to higher standards, but doesn't back that up with the FAR’s 

Only bringing that 137 stuff up to show that it gets complicated, and unless you’re familiar and or dig pretty deep the answers are hard to find, and the FSDO guys can’t know everything either.

The FAR’s are a mess, rules that have evolved over decades and aren’t clear and often conflict with each other.

On edit, if it’s in the AFM it’s required, no FAR has to be quoted, AFM and Placards are mandatory

[wombat]

@A64Pilot regarding shoulder harnesses....

91.107(3)  says "Except as provided in this paragraph, each person on board a U.S.-registered civil aircraft (except a free balloon that incorporates a basket or gondola or an airship type certificated before November 2, 1987) must occupy an approved seat or berth with a safety belt and, if installed, shoulder harness, properly secured about him or her during movement on the surface, takeoff, and landing."

So if you can detach the shoulder harness portion without detaching the lap belt portion, you can have the shoulder harness off in flight other than takeoff and landing.

And oddly enough, for seaplanes during movement on the surface, the person pushing off or mooring at the dock are excepted.   But not just for the time period during the docking and mooring, the whole movement on the surface time.  And only if you use a dock, beaching doesn't count.    So if I was interested in malicious compliance, I could fire up one of my various amphibious seaplanes, taxi around on wheels and the floats, and as long as during that operation I moored or pushed off from a dock, I wouldn't need to have my seatbelt on at any point.   So if I'm returning from a flight, landing on the runway (gear DOWN!) and I see my least favorite FAA inspector standing in front of my hangar with binoculars and a large format picture of my in the plane without my seatbelt on, I can taxi over to the water, find a dock, get out and moore then push off the plane, get back in, taxi back to my hangar and at that point it's all legal.   Weird.

Edited April 22, 2023 by wombat

[A64Pilot]

Then you have this for FAR 137 (crop dusters)

https://www.law.cornell.edu/cfr/text/14/137.42

I called it the Air Tractor rule, because for whatever reason they don’t install inertia reels, but if you had the harnesses on, average person couldn’t reach the switches on the instrument panel. So when your 10’ off of the ground moving at 140 kts, your shoulder harnesses are off.

Wouldn't it be in the interest of safety if the aircraft were required to be designed so that shoulder belts could be worn in all phase of flight?

Thats what I meant by rules being complex and often contradicting, for instance anytime an Ag plane is flown not dispensing, it’s being operated under part 91, so which shoulder harness rules apply?

I read the above to say that in cruise flight I don’t have to wear any kind of belt, and don’t even have to occupy the seat. That’s what I mean by interpretation, it differs from one person to another.

[wombat]

@A64PilotCan you switch which rules you are flying under mid flight?    "The first part of the flight was part 137, then after my lass pass, I switched to part 91 and proceeded back to my home airport."     

If you can't switch in flight, can you switch when you do a touch-and-go?    Or do you have to come to a full stop?  Or do you have to shut down and start back up?  Or does the pilot have to get out then back in?  Do they need to get on the ground, or is just getting out of the cockpit sufficient?

 

 137.42 says "No person may operate an aircraft in operations required to be conducted under part 137" so if the operation you are doing is required to be part 137... But what exactly is 'an operation' ?  If you are actively dispensing product, sure.... But what about the turn at the end of a pass?  Or after you are empty, heading back to refill?  Can you take the shoulder harness off then?

 

[A64Pilot]

20 minutes ago, wombat said:

@A64PilotCan you switch which rules you are flying under mid flight?    "The first part of the flight was part 137, then after my lass pass, I switched to part 91 and proceeded back to my home airport."     

If you can't switch in flight, can you switch when you do a touch-and-go?    Or do you have to come to a full stop?  Or do you have to shut down and start back up?  Or does the pilot have to get out then back in?  Do they need to get on the ground, or is just getting out of the cockpit sufficient?

 

 137.42 says "No person may operate an aircraft in operations required to be conducted under part 137" so if the operation you are doing is required to be part 137... But what exactly is 'an operation' ?  If you are actively dispensing product, sure.... But what about the turn at the end of a pass?  Or after you are empty, heading back to refill?  Can you take the shoulder harness off then?

 

I’ve not really dug into it at that level, for me conducting production test flights and Certification test flights, even though they were in a Restricted Category aircraft meant for 137 ops, I was flying under part 91. Part 137 for example is relieved from the 500’ rule of course, but if I’m flying under 91. I can’t buzz someone’s house.  

But in Summer I’d fly over the house, the kids would come out and I’d dump water on them, was that illegal? Probably, but as no one made a complaint I don’t think it ruffled any feathers.

On edit to answer your question, it’s my opinion that the ferry part of an Agricultural flight is conducted under part 91, but once you get to the field, you operate under part 137, and the flight back your part 91 again. Now that’s my opinion, but just because I’m in a crop duster I believe I’m not allowed to fly very low level over people’s houses on the way to and from the field for example, but if the Farmers house is in the middle of his field, then yes we will.

 

[N201MKTurbo]

24 minutes ago, A64Pilot said:

I’ve not really dug into it at that level, for me conducting production test flights and Certification test flights, even though they were in a Restricted Category aircraft meant for 137 ops, I was flying under part 91. Part 137 for example is relieved from the 500’ rule of course, but if I’m flying under 91. I can’t buzz someone’s house.  

But in Summer I’d fly over the house, the kids would come out and I’d dump water on them, was that illegal? Probably, but as no one made a complaint I don’t think it ruffled any feathers.

On edit to answer your question, it’s my opinion that the ferry part of an Agricultural flight is conducted under part 91, but once you get to the field, you operate under part 137, and the flight back your part 91 again. Now that’s my opinion, but just because I’m in a crop duster I believe I’m not allowed to fly very low level over people’s houses on the way to and from the field for example, but if the Farmers house is in the middle of his field, then yes we will.

 

What? no spray heads?

[jaylw314]

13 hours ago, Schllc said:

The precise flight conserver has altitude settings. 
Presumably this increases that flow rate right?
I have never used the mountain air or any other ones, but they appear to have fixed rate disbursement. 

Oh, no, AFAIK most of the prebuilt kits nowadays have demand regulators that work in a completely different way.  The Oxymizer NC/masks with reservoirs are popular because they can just use regular regulators

[A64Pilot]

13 minutes ago, N201MKTurbo said:

What? no spray heads?

They were there, if you look just behind the wings you can see the spray bars, just that’s a mist. Opening the gate box dumped 500 gls in about 4 sec.

I tried over the years a bunch of silly things, like if I sprayed water in well below freezing conditions at altitude, would it create snow?

I thought it would, but it didn’t. Even the Emergency dump at any significant altitude, no water ever reached the ground, I’m talking say 2000 ft or so, it evaporated I guess.

Coming over the house at I’d guess 75 ft the water was like hard rain for a second, didn’t even soak them, the trees were at least 50.

[MikeOH]

My read of 23.1447 indicates that even BELOW 18,000 you have to have a "oxygen dispensing unit covering both face and mouth AVAILABLE" even when using a nasal cannula. See: 23.1447(b)(2).  Also, I note that 23.1445 seems to require a backup source for the crew; my Precise Flight system doesn't have that!

So, I don't think Part 91 requires anything legally (or, we'd be in violation below 18,000).  We are back to the AFM supplement making it a legal requirement.

[exM20K]

From the FAA brochure:

"Nasal cannulas. These are continuous-flow devices and offer the advantage of personal comfort. They are restricted by federal aviation regulations to 18,000 feet service altitude because of the risk of reducing blood oxygen saturation levels if one breathes through the mouth or talks too much."

So keep your mouth shut when using cannulas over 18,000 feet.  seems like good advice.

-dan

[wombat]

@MikeOH The way I read it, 23.1447 is a certification requirement for the aircraft.    For me, as a pilot of the aircraft, I MUST abide by the POH (Example: Vne).   But while the POH offers some helpful information about cannulas, such as "The FAA Approved flow devices consist of..." and it also offers advice, "...information that should be observed when operating..." there is nothing in that text that is mandatory or prohibited.

What is mandatory is that for any time above 14,000 MSL the entire minimum flight crew must use supplemental oxygen.   But there is no language in part 91 about what equipment counts as supplemental oxygen.   So from my perspective, if you have a bunch of party balloons filled with oxygen in the cabin (Bad idea! Don't do this!!!) and breathe from them like you are making your voice squeaky with helium balloons, you have met the letter of the law.  (Again: Bad idea!  Don't do this!!)

[MikeOH]

@wombat

I think where the legality comes in is the AFM supplement for the, for example, Precise Flight oxygen system which states that it is only for up to 18,000 feet.  Now, that is for their INSTALLED system...portable systems, I can't yet find a legal requirement.

[wombat]

@MikeOH Mostly I agree with you, but I don't think it says there is a limitation.  It says "The FAA Approved flow devices consist only of.(blah, blah, blah)..that are calibrated and adjustable for altitude to supply oxygen to ...(paraphrasing) differnt types of cannulas (end paraphrasing) up to 18,000"  So they simply say they are calibrated up to 18,000' for cannulas, or masks for higher.

 

[MikeOH]

13 minutes ago, wombat said:

@MikeOH Mostly I agree with you, but I don't think it says there is a limitation.  It says "The FAA Approved flow devices consist only of.(blah, blah, blah)..that are calibrated and adjustable for altitude to supply oxygen to ...(paraphrasing) differnt types of cannulas (end paraphrasing) up to 18,000"  So they simply say they are calibrated up to 18,000' for cannulas, or masks for higher.

 

@wombat

I was only reading what I saw in the AFM Supplement for the PreciseFlight system that Lancecasper posted on page two of this thread.  It is my understanding that an AFM Supplement becomes a legal part of the POH which must be complied with.  As in, the fact they specifically call out the FAR.  I could be wrong on that (maybe some sections are not legally required?).

[Pinecone]

8 hours ago, LANCECASPER said:

FAR 23.1447 says that above 18,000 feet it must cover the nose and mouth.

https://www.govinfo.gov/content/pkg/CFR-2012-title14-vol1/pdf/CFR-2012-title14-vol1-sec23-1445.pdf

Does that apply to portable systems, as it says "if installed?"

[LANCECASPER]

Just now, Pinecone said:

Does that apply to portable systems, as it says "if installed?"

Again, principles apply here. Is it a human who is breathing the oxygen? The person’s lungs don’t know whether that oxygen is coming from a portable tank or a built-in system. The FARs can’t, don’t and never will cover every situation, but common sense, which is not that common, applies. 

[wombat]

@MikeOHI agree with you that the AFM is compulsory.  But the FAR they call out in the page Lancecasper posted is about aircraft certification, not about operation.  If you want to certify a oxygen dispensing unit, you must comply with 23.1447.  Otherwise, it doesn't apply.

 

And I'm only interested in the legal aspect of this.    Could I circle around above FAA headquarters at 18,001 feet, live-streaming myself on a cannula and not get busted?  Considering I have 17 other pilots in the aircraft each on independent oxygen systems with pressure masks and immediate access to the controls and whatnot to prove that it's actually 'safe'.

[Pinecone]

2 hours ago, LANCECASPER said:

Again, principles apply here. Is it a human who is breathing the oxygen? The person’s lungs don’t know whether that oxygen is coming from a portable tank or a built-in system. The FARs can’t, don’t and never will cover every situation, but common sense, which is not that common, applies. 

FARs are do not necessarily denote what is safe or not safe for each person or each system.

Many experts feel that the FAR requirements for the use of oxygen have no basis in physiology.

If the FAA wanted to, it could have worded the regulation to say any supplemental oxygen system, not limiting it to installed systems

[Will.iam]

I also agree that a ride in an altitude chamber is worth the time & money to find what your unique hypoxic symptoms are as they are as varied as intoxication symptoms are. In fact intoxication is like hypoxia it’s just chemical blocking the brain of oxygen instead of partial pressures. If you can’t get a chamber ride the next best thing is to go up in an aircraft that has another pilot flying on oxygen and you take your mask / cannula off and experience the effect that way. Another important piece of equipment IMO is the oximeter since it reports a reading every second which is better than the apple watch which takes 15 seconds to get a reading but that’s better than nothing ir if you forget to bring your oximeter on a flight. Now the oximeter as was previously mentioned earlier in this thread is delayed and that even depends on the bodies function at the moment but is easy to check and you can even show yourself by putting an oximeter on and hold your breath. At first it will stay constant but as you continue to hold your breath you will see the oxygen level start to drop. Right about the time your lungs are screaming for air about a minute and 30 seconds my oxygen level starts diving through the 80’s but what is really interesting is when i take the first breath, i start to feel better but the oxygen reading actually continues to drop about 5 more points lower (my personal record is 77) but then jumps back up 15 points and on the next breath goes back to 98 or 99. So i can see that the blood that has the fresh oxygen in it still has to be pumped out to the limbs and to the hand and fingers before the oximeter picks up the new levels but it still takes time for that new oxygenated blood to be pumped out to the body. 
i think the easy to identify hypoxia is when the flow of oxygen is stopped instantly as you pickup on the change to the body like when you bank an airplane quickly. But when the flow of oxygen is slowly lowered like a small leak develops or your climbing higher and you need more oxygen than at the lower level it like a slow turn in IMC if you don’t check your instruments you don’t realize your into a banked turn. So my oximeter is like my ADI for imc or a friend at a party that takes your keys away, an instrument to tell me if there is a slow situation developing that I can’t sense on my own because just like when you are drunk you overestimate your abilities to drive a car and you can’t make rational decisions, hypoxia can give you that same feeling.  The oximeter can warn me if I’m getting into that situation. 
Also just bad posture and shallow breathing can bring my numbers down. If i sit upright and take deeper fuller breaths i can improve my numbers on average by 5 points but that can get tiring pretty quickly. 
i also learned everybody is a little different in their readings. My daughter that’s 11 years old holds 97 at 10,000ft easy where I’m at 91 or 92 but that’s just my age working against me. I can get to 97 if i situp and deep breathe but I’m still very cognizant at 91. In fact before i tested my daughter on that flight i thought my oximeter was broken or it wasn’t reading my finger well. Only when it showed 97 to 99 on my daughter did i realize it’s not broken im just old enough that my lungs are not as efficient as they used to be.  
i also took the oximeter on the airlines and when you are at 39,000ft the cabin altitude is at 8,500ft and i would take my reading which would fluctuate on any given day between 89 to 95 but i had other pilots that had readings as low as 80! And they were unaware they were that low. Now it could be the oximeter giving a false reading but after sampling a few dozen people and having them go on oxygen and the numbers always went up to 98 or 99 i have come to the realization that some people just are able to operate at a lower oxygen saturation level than others or maybe they are mildly hypoxic and just don’t know it. Maybe they are smokers? Who knows, but i think only after you establish your base line can you recognize when you need oxygen and how much to keep your levels. So take lots of readings to find out what is low for you. 
 

oh almost forgot, as your O2 levels go down, at least for me, my heart rate goes up, i assume the body’s way to try and compensate for the low levels. (This does not happen when i hold my breath just the opposite) but when breathing normally and up in altitude, if my pulse rate goes up i check my oximeter and sure enough my O2 is down.  The heart rate is like a cheap proxy for O2 levels and another warning sign to me my body is being deprived of oxygen. 

Edited April 23, 2023 by Will.iam
More info

[ilovecornfields]

5 hours ago, Will.iam said:

In fact intoxication is like hypoxia it’s just chemical blocking the brain of oxygen instead of partial pressures.

I’m curious to know where you obtained that information.

[Austintatious]

This is a good thread... I have a few pennies to toss in.

 

First off, If you are going high and using oxygen, you are really missing out if you don't have a pulse demand system such as Mountain High.  Not only does it conserve oxygen to a degree you will not believe if I tell you, but it adds what I consider a large margin of safety. The unit will sound an alarm if you are not breathing oxygen.  

I have had my O2 system fail on me at FL210... well, fail may be a bit harsh, but what happened was that my elbow knocked my scott connector (before I had the MH system)  loose and I stopped receiving oxygen.  I noticed pretty quickly,  hypoxia for me feels miserable so there is no going off into a euphoric la la land for me.  This is obviously different for different people.  This is why I feel the MH system adds so much safety, you miss ONE breath and an alarm will go off, you cannot ask for better awareness of your O2 intake.   

As far as how high is safe:  That probably varies for everyone.  I am comfortable with FL210 and I will explain why.  Having been in an altitude chamber, I know what it is like at FL250 and it is MUCH more rapid onset of symptoms and you will find yourself in bigger trouble a lot faster than at 210. 

Looking at the TUC chart

So, by staying at FL210 or lower I have 10 min.... go to FL250 and you drop to 3-5min.  And believe me, the 5 min is for the youngsters.  More than likely if you are 30 or older it will be closer to 3 min.

Now, keep in mind, if you found yourself at FL250 with a failed O2 system and symptoms of hypoxia (which you will feel IMMEDIATELY) , you dont need to get down to only FL 180, you are ALREADY hypoxic, you need to get much lower, probably 12,500 or less.  So you have 12,500 feet to lose and you need to do it pretty quickly. 

I can pop speed brakes and reduce power a few inches and come down at about 1500 FPM at the yellow arc.  That will take 8.3 min to get down to breathable air.... IMHO this is simply not fast enough.  So, from FL250 if I have an 02 failure I need to be making a large reduction in power and getting that rate to more like 3000 FPM which will get me to 12.5 in 4 min.   This is certainly achievable, however I now put my engine at risk of shock cooling.  Or at the very least subject it to large rapid changes in CHT which is also not good. 

I don't want a failure of my 02 system to be a major event.  If I limit myself to FL210, I start with 10 min of Useful consciousness,  which in itself is plenty of time to 1: see if the problem can be solved, say by plugging the scott connector back in!  and  2.  begin a much more normal descent down to breathable air.

You give up about 8 knots staying at 21 vs 25.     Over A full tank of fuel that gives 5 hours of cruise flight, this is less than 15 extra min of flying.