Another Cirrus down...

He clearly had made the decision to fly at those altitudes in a non-pressurized airplane beforehand. I'd think hard before I did that - and maybe he did. I don't think that itself is reckless.

The entire situation would have easily been preventable had he measured his O2 rate every few minutes. This is why I think people with the cavalier attitude of "I feel fine at 12,000', I haven't measured it, and see no need to" are unsafe. Hypoxia is not obvious; it really sneaks up on you, and you might not notice it at all.

Seems like a good advertisement for pulse oxymeters and their use....Also, if I ever got into a situation where I was flying at altitude and was unsure about my O2 state, I would put 10,000' into the AP, without worrying about ATC or anything else.

-Felix
 
I also cannot imagine flying at such an altitude without a pulse-ox.

I have also thought about the whole altitude-preset idea, but it presupposes the mental faculties necessary to recognize the need. Hypoxia is Not Nice.
 
SCCutler said:
I also cannot imagine flying at such an altitude without a pulse-ox.

I have also thought about the whole altitude-preset idea, but it presupposes the mental faculties necessary to recognize the need. Hypoxia is Not Nice.
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Very true. Time of useful consciousness at that altitude is about 3 minutes. I guess you would have to check every minute or so and have your co-pilot do the same. That just doesn't sound feasible....
 
sba55 said:
Very true. Time of useful consciousness at that altitude is about 3 minutes. I guess you would have to check every minute or so and have your co-pilot do the same. That just doesn't sound feasible....
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How about a pulse-ox worn constantly that sounds an aural alarm? Are there any out there?
 
http://en.wikipedia.org/wiki/Time_of_Useful_Consciousness

Looks like TUC at 12k for a reasonably fit individual would be 30 minutes or more. Seems reasonable to me. Hypoxia sucks, but it can be dealt with as long as you recognize your symptoms. Too many people who attempt flight at these altitudes have no concept of what can happen to them if the symptoms go unnoticed.
 
gprellwitz said:
A little more expensive, but not prohibitively so, especially if you're planning to fly at those altitudes. My only concern would being able to hear the alarm through the headset. Probably too much to ask for one with an audio output though, huh? :)
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Was wondering the same thing - bet someone makes something like this, could easily plumb into the audio panel.
 
gprellwitz said:
A little more expensive, but not prohibitively so, especially if you're planning to fly at those altitudes. My only concern would being able to hear the alarm through the headset. Probably too much to ask for one with an audio output though, huh? :)
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The other issue is being able to respond to the alarm. hypoxia really affects your ability to think. I have been in the altitude chamber a couple of times and the thing I remember most is how hard it was to think. Stuff would happen that we needed to react to, but I could not process what was happening and take meaningful actions all the time. The goal of that training was to recognize early symptoms and then take action. Once you are in the throes of hypoxia I think it may be too late.
 
Sad indeed.

As a relatively new owner of an airplane capable of these altitudes,
it's something I've been very aware of.

On the trip to OSH and back at FL200, and FL210 respectively, I think I checked every few minutes to make sure I still had O2 flow going, and also used the Pulse Ox every 5 to 10 minutes to ensure we were getting enough.

Something like that wrist band one, posted above, that could be worn all the time is something I might consider. Can't hurt wearing one for the whole flight.
It's scary how quickly and unnoticed hypoxia can sneak up on you, and isn't something to be taken lightly.
 
I wonder why he flew at such an altitude. The report doesn't mention weather - if I read it correctly.

One reason, with a turbocharged aircraft, might be to get the highest possible TAS; the sales brochures for the SR22 and turbo Mooneys like to give TAS figures at 25k :)

Was he using the standard cannula, or a mask?
I have done a fair bit of work with o2 stuff
http://www.peter2000.co.uk/aviation/oxygen/index.html
http://www.peter2000.co.uk/aviation/oxygen2/index.html

and while one can go to 20k with cannulas, and I know people who have, doing this requires constant and conscious attention to one's breathing. I use the Precise Flow demand regulator but even having maximum constant flow doesn't help very much at these altitudes. For example, before doing a long ATC readback, one wants to draw in a long deep sniff of oxygen. It is thus not something I would do with passengers, and a mask is really desirable. And this pilot was much higher.

If he was on a cannula at 25k then IMHO he would have been seriously struggling, at best. One just cannot draw in enough o2 via an open cannula.
 
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peter-h said:
I wonder why he flew at such an altitude. The report doesn't mention weather - if I read it correctly.

One reason, with a turbocharged aircraft, might be to get the highest possible TAS; the sales brochures for the SR22 and turbo Mooneys like to give TAS figures at 25k :)

Was he using the standard cannula, or a mask?
I have done a fair bit of work with o2 stuff
http://www.peter2000.co.uk/aviation/oxygen/index.html
http://www.peter2000.co.uk/aviation/oxygen2/index.html

and while one can go to 20k with cannulas, and I know people who have, doing this requires constant and conscious attention to one's breathing. I use the Precise Flow demand regulator but even having maximum constant flow doesn't help very much at these altitudes. For example, before doing a long ATC readback, one wants to draw in a long deep sniff of oxygen. It is thus not something I would do with passengers, and a mask is really desirable. And this pilot was much higher.

If he was on a cannula at 25k then IMHO he would have been seriously struggling, at best. One just cannot draw in enough o2 via an open cannula.
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I understood that the cannulas aren't allowed above 18K in the US. The packaging on the cannulas I have states something about for use below 18,000'.

And Scott's point about being able to correctly respond while under the effects of hypoxia is a good one. I was paying attention to the 3 minutes of useful consciousness at FL25 previously referred to in the thread by Felix.
 
Do you have a reference for cannulas being banned > 18k?

As far as I have been able to find out, the only applicable regs are those concerning fitted oxygen systems (which a turbo SR22 would probably have as standard) in which case the usage restrictions are defined in the Flight Manual Supplement.

For portable systems, I am not aware of any regulations.
 
peter-h said:
For portable systems, I am not aware of any regulations.
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Neither am I. I can't get above 96% with cannulas above 16,000' no matter the flow rate, so I use masks above that. When I went to the Air Force for some altitude chamber training, I got to use their masks. Those, especially on emergency forced breathing, definitely get your saturation up to 100% :P
 
A quick search of the FARs gave me this...

FAR 23.1447 (c)
(c) If certification for operation above 18,000 feet (MSL) is requested, each oxygen dispensing unit must cover the nose and mouth of the user.
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A pal of mine took his Lanceair up to 18K feet just to say he'd done it. There was a kink in the line and he went very hypoxic. Had it not been for his rather copious medical knowledge and his luckily realizing what was going on I doubt he'd still be here.
 
I often fly about 15,000 on longer trips. I use an oximeter w/oxysaver canulas (or masks very high up). At 16,000 and 17,000, you have to be concious of your breathing and oxy saturation because the canulas are barely adequate. Above 17,000 for more than a few minutes, I need a mask.

I also find that the flow-meters on the oxy tubes do not accurately reflect the amount of oxy flow that's necessary at higher altitudes.
 
A quick search of the FARs gave me this...

FAR 23.1447 (c)
Quote:
(c) If certification for operation above 18,000 feet (MSL) is requested, each oxygen dispensing unit must cover the nose and mouth of the user.
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which starts off by saying

If oxygen dispensing units are installed..

so this reg applies to fitted oxygen systems, not portable oxygen systems.

It would be very unusual, for Part 91, to see a regulation concerning a portable item.
 
peter-h said:
which starts off by saying

If oxygen dispensing units are installed..

so this reg applies to fitted oxygen systems, not portable oxygen systems.

It would be very unusual, for Part 91, to see a regulation concerning a portable item.
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So maybe not regulatory for a portable unit (I don't know; as I said, it was my "understanding"), but based on the postings above this, it seems like a Really Good Idea to use masks above 18,000'!
 
I'm trying to do my best not to start crying again while reading this thread (since you all are talking about events that killed a friend of mine), so if any of this comes across as rude, I apologize in advance: There's a damn good reason why you should not use a cannula above 18,000 regardless of a fixed or portable system. Actually I would argue for >12,000' but that's just because I know the particulars of oxygen delivery systems pretty well since I have a background as a respiratory therapist. Even with someone healthy and at or near sea levels, if the person is hyperneic (taking very deep breaths), rapid breathing or mouth breathing- both of which are common in hypoxic individuals- the effect of a cannula upon the FiO2 (fraction of inspired oxygen) is going to be minimized simply as a function of dilution.

and while one can go to 20k with cannulas
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That is something I would consider to be on my list of bonehead moves.

How about a pulse-ox worn constantly that sounds an aural alarm? Are there any out there?
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I would look at one of the larger ones we use in hospital. They are pretty comparable in cost to a lot of the ones I've seen peddled directly to pilots. I am actually purchasing a used one for myself. The one I have in mind is about 8" W x 6" D x 2" H but I've seen much smaller ones and there are adhesive ("Band-Aid") probes that you help keep the probe in place on your finger. One of my friends is

My only concern would being able to hear the alarm through the headset. Probably too much to ask for one with an audio output though, huh?
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Some of the ones we use in the hospital setting you can hear the damn thing through a closed door. Also it is not uncommon for them to have a flashing display of some sort (light or the screen) to alert personnel to silenced alarms etc.
 
SteveinMichigan said:
I'm trying to do my best not to start crying again while reading this thread (since you all are talking about events that killed a friend of mine), so if any of this comes across as rude, I apologize in advance: There's a damn good reason why you should not use a cannula above 18,000 regardless of a fixed or portable system. Actually I would argue for >12,000' but that's just because I know the particulars of oxygen delivery systems pretty well since I have a background as a respiratory therapist. Even with someone healthy and at or near sea levels, if the person is hyperneic (taking very deep breaths), rapid breathing or mouth breathing- both of which are common in hypoxic individuals- the effect of a cannula upon the FiO2 (fraction of inspired oxygen) is going to be minimized simply as a function of dilution.
[...]
I would look at one of the larger ones we use in hospital. They are pretty comparable in cost to a lot of the ones I've seen peddled directly to pilots. I am actually purchasing a used one for myself. The one I have in mind is about 8" W x 6" D x 2" H but I've seen much smaller ones and there are adhesive ("Band-Aid") probes that you help keep the probe in place on your finger. One of my friends is [????]


Some of the ones we use in the hospital setting you can hear the damn thing through a closed door. Also it is not uncommon for them to have a flashing display of some sort (light or the screen) to alert personnel to silenced alarms etc.
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Steve, Thanks! Sorry again on the loss of your friend. I'm hoping that we can take something good out of it, like this education.

Do you have a source for those that is available to non-medical professionals?
 
Do you have a source for those that is available to non-medical professionals?
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Find a physician to sign a letter of authorization which is what I had to do to get the company to sell me one, even though I have a license to practice as an RT. I think most MDs would be amenable to this sort of thing if you explained your reasoning. Once you get the letter, you can generally just contact a local medical supply company (or find one online) and order the pulse ox that way without too much fuss.
 
SteveinMichigan said:
Find a physician to sign a letter of authorization which is what I had to do to get the company to sell me one, even though I have a license to practice as an RT. I think most MDs would be amenable to this sort of thing if you explained your reasoning. Once you get the letter, you can generally just contact a local medical supply company (or find one online) and order the pulse ox that way without too much fuss.
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Hey Dr. Bruce, how about it? :)
 
smigaldi said:
The other issue is being able to respond to the alarm. hypoxia really affects your ability to think. I have been in the altitude chamber a couple of times and the thing I remember most is how hard it was to think. Stuff would happen that we needed to react to, but I could not process what was happening and take meaningful actions all the time. The goal of that training was to recognize early symptoms and then take action. Once you are in the throes of hypoxia I think it may be too late.
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Most people are still lucid at sats of 85-90% (I deal with this daily in healthcare, and many are mentally functional even lower - though they are quite sick)

Considering your target is above 90% this isn't as difficult as it seems
 
gprellwitz said:
Steve, Thanks! Sorry again on the loss of your friend. I'm hoping that we can take something good out of it, like this education.

Do you have a source for those that is available to non-medical professionals?
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Ebay. There are plenty of ebay stores selling new equipment.

If its on aircraft spruce I doubt you need a prescription there either.
 
I would not trust any piece of medical equipment I find on Ebay.

If its on aircraft spruce I doubt you need a prescription there either.
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It's not really a "presciption needed" issue (so far as I am aware), just that a lot of reputable suppliers are loathe to sell medical equipment to people just looking to get one because of the issue of liability (putting it into the hands of someone who doesn't know how to use or troubleshoot it). Technically you need a prescription for nasal cannulae but it isn't something many places pay attention to.

Most people are still lucid at sats of 85-90% (I deal with this daily in healthcare, and many are mentally functional even lower - though they are quite sick)
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+1
 
Actually I would argue for >12,000' but that's just because I know the particulars of oxygen delivery systems pretty well since I have a background as a respiratory therapist
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It appears that you are dealing with some very unfit people. Which might well make sense, since healthy people are much less likely to end up in a hospital respiratory unit. But would any of them make it through the FAA Class 3 in that condition?

I have flown at high altitude with many people and have never seen anything like this. By far the worst I saw was one (IMHO very unfit and overweight) pilot who complained of seriously blurred vision at 12k, having previously said that he doesn't need oxygen ;) Immediately after he put on the cannula, he was fine and his blood o2 (I use the $300 Nonin meter) tested around 93%.

But flying at 25k is a whole different thing...
 
gprellwitz said:
How about a pulse-ox worn constantly that sounds an aural alarm? Are there any out there?
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Mine has alarms that are configurable.

20075291126550741.gif


However, while I can certainly hear it over the engine regardless of ANR status, at 25K it's going to be more of a matter of reaction. 10K in the autopilot as Felix suggests would be one good idea (provided you're in an area where 10K is sufficiently AGL!).

Also, it seems that there can be variations in O2sat sufficient to make the alarm go off briefly fairly often - "Crying wolf" doesn't help either, especially when it comes to making good decisions with limited brain function. :no:
 
It sounds like this guy just ran out of O2 after one leg with two people and half a leg with one. Does the SR-22 have an installed system? If so, what's its capacity? How many man-hours is that? And I, too, would like to know if he was using a mask or cannula.

BTW, until you've really experienced hypoxia, you just don't really know what it does to you. Even with a pulse oximeter, you could forget to check it, or misinterpret it, or just not care what it says during an insidious onset like depletion of the bottle. See http://www.faa.gov/pilots/training/airman_education/aerospace_physiology/ for how you can get that training in the altitude chamber.
 
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It appears that you are dealing with some very unfit people. Which might well make sense, since healthy people are much less likely to end up in a hospital respiratory unit. But would any of them make it through the FAA Class 3 in that condition?
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The reason I said that is based on some mountaineering medical research where there is evidence that persons who are not living at elevations <5,000 ft tend to be more likely to develop hypoxic symptoms as well as acute mountain sickness, high altitude pulmonary edema and high altitude cerebral edema unless they are given an slow acclimatization of a few days to allow their bodies to adjust. Flying through the mountains or simply at high altitude in an unpressurized aircraft is probably the most dramatic way to blow past that.

Actually you would be surprised the number of people I wind up seeing that are simply on prophylactic oxygen post-operatively for broken ankles, etc. Most of my patients are mobile, talkative (in fact, there are a couple I can't get to shut up most of the time) and in pretty good health. BTW, there is no "respiratory unit" (at least not in most hospitals in the US). We cover the whole hospital from the ICU to the general wards to the ED. The reason I mentioned what I was trained to do is because we are given an extensive knowledge of how the body works when it's functioning normally under a wide variety of circumstances so I am more than able to adequately judge the effects of altitude exposure on technically healthy individuals.

A lot of people- especially here (a glorious 800 feet above mean sea level)- are not adapted to high altitude conditions. It's well documented in the literature that
most of them will experience altitude-related symptoms (albeit usually mild) simply if you take them to Colorado and get them at 5,000 feet. This includes clouding of judgment, headaches, malaise, lack of energy, inability to concentrate, irritability, etc.

Also have you taken a look at some of our fellow pilots? They aren't exactly in the best shape to begin with and a lot of us have undiagnosed cardiac issues and are smokers which both predispose to increased severity of cases.
 
I can tell you for sure that acclimitization is real. When I first moved from 500 MSL to 4300 MSL, I could not initially run as far or as fast. Two years later, I went back to 500 MSL, and ran the fastest 10K I'd ever done.
 
Ron Levy said:
It sounds like this guy just ran out of O2 after one leg with two people and half a leg with one. Does the SR-22 have an installed system? If so, what's its capacity? How many man-hours is that? And I, too, would like to know if he was using a mask or cannula.
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IIRC, Cirrus MANDATES that IF you use oxygen in their planes, it MUST be the system they provide.
 
SteveinMichigan said:
Find a physician to sign a letter of authorization which is what I had to do to get the company to sell me one, even though I have a license to practice as an RT. I think most MDs would be amenable to this sort of thing if you explained your reasoning. Once you get the letter, you can generally just contact a local medical supply company (or find one online) and order the pulse ox that way without too much fuss.
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You don't need that. It's a class 2 medical device, sold without Rx.

There is actually some evidence based on the oxygen hemoglobin dissociation curves that those acclimated to 5K-11K fare better up to about 15K but then fall off HARDER than the nonacclimatized.

Does't really matter, though, you feel fine until you don't realize how un fine you really are. REALLY. It is also physiologically impossible to get enough O2 to function at FL 25 from any cannula system. Actually at 25K you should be in a Scott type tight fitting no-leak 100% mask.

But you would never glean that from "Flying 2.0" (see Cirrus website).
 
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Incidentally, is there a mask whose microphone can be used in an aircraft which is wired for the Bose-X (Lemo) aircraft power connectors?

I have the jacks as well but I don't think one can have the headset plugged in AND plug a mask mike into the mike jack socket.

The cheap masks have a hole in the side where you poke the headset mike but they are not comfortable. And not sealed, of course.
 
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