S

Sig600

Well Known Member
Anyone else read the article in this months AOPA about the Baron pilot killed by hypoxia? Was using a home brewed O2 system, and it got me thinking to the posts I've read on here, guys touting their use of home made systems. I never gave it a second thought until I read the article (sounds like a great idea for cruising high!!!). It goes into what exactly he used to build his system, and I realized just how complicated a true aviation O2 system is.

High altitude and hypoxia recognition training saved my life a while back at FL480, so be careful out there. This is one of those lessons we seem to keep learning over and over again in aviation. You only get once chance to screw it up.

As another learning point, I remember doing a basic demonstration in the altitude chamber back in basic. They tuned off the lights except one red light on the roof, and took us to 10,000. I didn't think much of it, as I used to fly a couple of light twins around between 12 and 15 all the time without O2 (yes I'm admitting that). After 15 minutes or so, they had us put our mask on and take a few breaths. After three breaths I seriously thought someone had turned the lights on. I never picked up on my vision degredation, and the results were scarey, at just 10K.
 
I read it. He was using a non-adjustable regulator AND he was using cannulas above 18K. Even if the regulator is non-altitude compensating, that's ok if you know the flow with flowmeters in series with the breathing apparatus in conjunction with a pulse oxymeter.
 
rocketbob said:
I read it. He was using a non-adjustable regulator AND he was using cannulas above 18K. Even if the regulator is non-altitude compensating, that's ok if you know the flow with flowmeters in series with the breathing apparatus in conjunction with a pulse oxymeter.
Click to expand...

He was found, still strapped into the seat, waring a mask. Pulse oxymeter was found in the wreckage, and he kept very detailed logs, and a journal.

The NTSB found the pilot strapped in the left front seat and wearing an oxygen mask.
Click to expand...

Link to the article.

http://www.aopa.org/asf/asfarticles/2011/sp0211.html

Regardless of what he had DONE, at the time he was doing everything right... minus using a homebrewed system. The hypoxia was slow, and he never recognized it.
 
Last edited:
Oh ok I missed that part, but it did mention that he wore cannulas above 18K because it was more comfortable. What it did say however, is he ran out of oxygen. Without an adjustable regulator and some sort of oxymizer in place no matter what, the bottle's gonna run out at some point, most people here are putting systems together that are efficient.
 
Last edited:
rocketbob said:
What it did say however, is he ran out of oxygen.
Click to expand...

Just like fuel. Ya gotta keep the quantity sufficient for the usage, no excuses. People still run perfectly good airplanes into the dirt on a regular basis because they neglected to monitor fuel supply, you can't fix stupid.
 
At 27,000 ft there is not much time to observe and make corrections to the O2 system...:(

He was a little higher than this...

Height: 8000m

Faculty Effect
Visual Skills Loss of consciousness in approx 4 minutes
Memory Loss of consciousness in approx 4 minutes
Reaction / Motor Skills Considerable confusion in approx 2.5 minutes
Personality Change Loss of consciousness in approx 4 minutes
Perception Often none until consciousness lost. Otherwise as above

From here -

http://www.altitudecentre.com/mountaineering/hypoxia.htm

This parachute link puts it a a little less time...

http://www.koyn.com/CloudDancer/articles/23KJump99.html

"The time of useful consciousness without supplemental oxygen at 23,000 is approximately 4 minutes."

Not much margin at those altitudes.

ADDED

At the heights we would normally be at, loss of conciousness is unlikely - still bad though...

Height: 6000m (about 19,000 ft)

Faculty Effect
Visual Skills Tunnelling of vision and more loss of colour perception
Memory Profound short term memory impairment
Reaction / Motor Skills Profound generalised reaction time slowing and error rate increase. Clumsy movements. Small chance of fits and loss of consciousness
Personality Change Frequent personality change. Volatility, judgement and insight impairment. Considerable disinhibition & loss of willpower
Perception Frequently none. Very obvious to others. Feeling drunk, unreal confused, uncoordinated “tingling pins & needles"
 
Last edited:
Oxygen Saturation

From the report:

The pilot kept an electronic journal where he wrote, according to the NTSB, ?He would attempt to fly high in an effort to get more efficiency from the engines, and would use the oximeter to monitor his blood oxygen levels. He stated that below 80-percent oxygen saturation, ?I notice a degradation of my cognitive ability.?

If you are using a pulse oximeter, anything below 90% should be cause for alarm, and take immediate action to correct the situation.
 
Agreed

80% O2 saturation is SERIOUSLY low. You get below 90% in a hospital, and they'll be oiling the wheels on the crash cart...
 
PCHunt said:
From the report:

The pilot kept an electronic journal where he wrote, according to the NTSB, He stated that below 80-percent oxygen saturation, ?I notice a degradation of my cognitive ability.?

If you are using a pulse oximeter, anything below 90% should be cause for alarm, and take immediate action to correct the situation.
Click to expand...

Having used O2 in my RV-6 for the past 13-years, I agree that anything below 90% does adversely effect your piloting skills. You need to increase O2 flow or descend.
 
After over twenty years flying low altitude, 172 s SuperCub etc, we got our RV-10 flying last summer. We have a long way to go before thinking about supplemental oxygen. Having not even seen a supplemental system installed other than at air show exhidits can some one discribe how one is used? Or where to look for such information. How does a pulse oxymeter work? Does it take a blood sample like diabetics, pick your finger(I would doubt)?
Someone can place my post in another thread if this is not the place for it, as I don't want to hyjack this one, but I thought a lot of knowledgeable pilots would be following this thread.
Ron
 
A pulse oxymeter is just a little clip that goes on your finger. It shines an LED light through your finger and through PFM figures out your pulse and oxygen saturation. A great tool no doubt, but high altitude hypoxia training is invaluable.
 
90%?

I wish one of our physicians would weigh in here on the Oximeter thing... A few here have said anything below 90% saturation is bad and I would love to see the official source for that. It would seem to me to depend on lot on one's age, physical condition, etc.

Dr's... are you there?
 
I read that article and it was both sobering and enlightening.

You don't know what you don't know. I've often thought about building my own but I'm sticking with a MH system in the 10.

Phil
 
OK, why did this thread open with 'be afraid if you home-build an oxygen system', citing someone who crashed while using one, without mentioning that the guy ran out of oxygen?

Isn't that a bit like saying 'don't fly with mogas' because someone ran out of gas while flying on mogas?

Or the NTSB citing as the cause of an accident that 'the pilot failed to maintain altitude' without mentioning the failure of the single engine that was powering the plane?

I started reading expecting to learn useful info that I didn't already know. I doubt that there's anyone here that thinks it's ok to fly at 20K+ feet & run out of oxygen.

Charlie
 
O2 sats

I am a Family Practitioner not a pulmonologist.
I also fly below the need for oxygen and have never measured a Pulse ox in the air but FWIW:

normal ground based values are 97-99.
With age and particularly copd we often see folks down in the 80s.
I think the requirement for medicare to cover home O2 is 88 or below at rest.
Oximeter accuracy degrades rapidly with lower values.

Maxwell
 
Yup!

rv7charlie said:
OK, why did this thread open with 'be afraid if you home-build an oxygen system', citing someone who crashed while using one, without mentioning that the guy ran out of oxygen?

Isn't that a bit like saying 'don't fly with mogas' because someone ran out of gas while flying on mogas?

Or the NTSB citing as the cause of an accident that 'the pilot failed to maintain altitude' without mentioning the failure of the single engine that was powering the plane?

I started reading expecting to learn useful info that I didn't already know. I doubt that there's anyone here that thinks it's ok to fly at 20K+ feet & run out of oxygen.

Charlie
Click to expand...

What Charlie Said!

Don't just read the headlines........... there's always more to the story!
 
Pulse OX

First, you got to be careful with a pulse-ox. It mesures hemoglobins in the blood, but will give you a false reading in the presence of CO. I've had fire victims with a pulse ox in the nineties but actual blood gasses MUCH lower. Also, you get what you pay for, the one piece finger clamps always read lower for me. In the street, anyone with a reading below mid 90's gets oxygen therapy. It does depend on your circulation, heavy smokers will read lower (we'll put the sensor on the earlobe to get a better reading on them) All Info FWIW.
 
O2 in altitude

Looking back at my notes from the physiological training I took at CAMI in OKC it says 90% saturation at 10k is normal. As others mentioned your night vision acuity does go down dramatically but it is not lethal. I remember taking pulse ox readings flying at 8k and seeing levels of 88%. After sitting upright and a couple of deep breaths later I was back in the low 90s.
 
chart

I attached the chart I used for reference. This came out of the CAMI Aerospace Physiology handbook.

o2chart.jpg
 
Anaemia and hypoxia

Just as a data point I had a bout of hypoxia years ago at a cabin altitude of 8500'. I didn't know what was wrong - severe headache, confused, couldn't add two numbers together. At the time I was FE on a DC8. Told the boss I needed to lie down. By the time we had landed I felt fine again. It was days later before I figured it out. I had recently gotten over mononucleosis and had been feeling fine for quite a while so figured I could go back to work. Wrong move. It would have been a different story in a single pilot aircraft.
 
I had a bit of a wake up call coming back from last fall's Badlands fly-in. I was at 9500' so I figured I'd check my pulse / ox and maybe put on O2 since it usually makes me feel a bit better on long trips if I'm above 8500' or so. I told my 20 something year old daughter, (she would kill me if I told) that she should put it on too. When she asked why, I thought I'd teach her a lesson and clipped the pulse ox meter on her and you can guess what it told us. I never considered myself as even middle aged until then. She took this pic as a reminder. I had to listen to her teasing all the way home. I'm 54. Without O2 I was in the very low 90's 92-93 and she was 97 - 98. Believe me I checked and rechecked.

Of course you learn all this in your flight training. I just didn't need it thrown in my face. :( On second thought, maybe I did. :eek:

Anyway, this oxygen thing is very serious business!

IMG_0772.JPG
 
You must log in or register to reply here.