Topic: psychosomatic hypoxia (Pilots)

[Shadow Of A Doubt]

Remember I am not saying that the pilots who reported hypoxia are lying

But it has been suggested by others so I was commenting on that. Sorry if that wasn't clear.

[Citizen Skeptic]

Have any of you ever passed out? It's a very strange feeling and it's really tough to put together what happens once you start to lose consciousness. It's like very light anesthesia.

[Belgarath]

Ok, give me a bit to look into this.  What exactly is the question?

[Belgarath]

So the F-22 system is one I don't know a lot about.  Couple of points:

1) Is there such a thing as psychosomatic hypoxia?  Possibly, I've never heard of it in any training material that I've read.  I could essentially imagine a pilot getting a panic attack and attributing that to hypoxia.

2) The system in question basically strains out the nitrogen from the air to make the O2 partial pressure in the mid 90% range.  This system could fail in a manner that has no indication unless you're measuring the partial pressure of O2 at the mask.

3) You wouldn't need to measure a persons Blood O2 level if you could measure partial pressure of O2 at the mask and that would be a quicker (At least I think)

4) I have no idea what back-up systems they have in place. 8 seconds of useful consciousness is for a normal average human.  People who are in excellent physical health (as most fighter pilots are) would have a longer useful consciousness.  In our aircraft we basically have a few seconds to immediately place our oxygen masks on in the event of a pressurization failure.  The indication for us is instantaneous when the pressure rises above about 10000 feet MSL.

I can't really comment further without having a better understanding of how the system works, what detection systems exist and what backup systems exist.

[Desert Fox]

Ok, give me a bit to look into this.  What exactly is the question?

We have a F-22 that crashed apparent due to the oxygen system failing
That does not seem to be in question

There have been various news articles about pilots afraid to fly the plane because of feeling hypoxia and there are also claims of ground crews effected.

I met an F-22 pilot this weekend and asked him about it. He said that it was basically two reserve pilots that reported it and the media blew the whole situation out of proportion.   Stated that the F-22 is certified both for demonstration and operational status.  He added that they are monitoring the system. This was out of uniform and informally.

On another forum, I posted what he told me. A number of people argued that he is basically stating the government line and should not be believed.

What I was wondering is if the hypoxia experienced by the two reserve pilots could have been psychological and not caused by the equipment? I do know about the weird cause in the hospital  where a bunch of doctors and nurses became ill when that one woman died and one of the leading explanations is that it was psychological.

Also, have a photo

(click to show/hide)

[Belgarath]

This is kind of a different kind of aircraft without a pressurized cockpit providing the oxygen
The oxygen comes from a mask

Edit: I would like the opinion on a pilot on this
The reason why is that the media has all sorts of headlines
A pilot (of the aircraft) yesterday told me that everything is being blown out of proportions (off the record)
Problem is that it has been suggested by others that of course the pilot would lie

I think the pilots would have a strong incentive not to lie about a real problem like this!

As was stated, a pilot might experience ALL of the symptoms of hypoxia, but may not actually have hypoxia.  So he/she may not be lying about their experience, but may be mistaken as to the cause.

[Belgarath]

We have a F-22 that crashed apparent due to the oxygen system failing
That does not seem to be in question

Do not doubt this in any way.  The failure modes of this O2 system seem to be fairly insidious and if there isn't a warning fairly rapidly, the pilot could easily pass out and crash.

There have been various news articles about pilots afraid to fly the plane because of feeling hypoxia and there are also claims of ground crews effected.

Ok, the second bit is making my skeptical bullshit detector go off.  How the hell would ground crews get hypoxia, on the ground in the normal atmosphere!  That doesn't make a lot of sense.

I met an F-22 pilot this weekend and asked him about it. He said that it was basically two reserve pilots that reported it and the media blew the whole situation out of proportion.   Stated that the F-22 is certified both for demonstration and operational status.  He added that they are monitoring the system. This was out of uniform and informally.

On another forum, I posted what he told me. A number of people argued that he is basically stating the government line and should not be believed.

If there is one thing I know about military pilots, they ARE NOT known for stating the government line, especially out of uniform.

What I was wondering is if the hypoxia experienced by the two reserve pilots could have been psychological and not caused by the equipment? I do know about the weird cause in the hospital  where a bunch of doctors and nurses became ill when that one woman died and one of the leading explanations is that it was psychological.

All this system does is essentially grab the N2 out of the air and leave the O2 behind.  If we're supposing that the system is generating some sort of other gas such as CO (which can make you hypoxic) it would be detectable in the pilot's blood stream.  Based on what I know of these systems, I don't think that they could do anything like that. If they fail, they would just deprive the pilot of sufficient oxygen.

Could the SYMPTOMS they experienced be psychosomatic?  Certainly they could be.  It's very hard to tell one way or the other.

[Citizen Skeptic]

3) You wouldn't need to measure a persons Blood O2 level if you could measure partial pressure of O2 at the mask and that would be a quicker (At least I think)

Yeah, the change at the mask would be quicker but you'd have to assume that the O2 is getting to the hemoglobin.

[Belgarath]

3) You wouldn't need to measure a persons Blood O2 level if you could measure partial pressure of O2 at the mask and that would be a quicker (At least I think)

Yeah, the change at the mask would be quicker but you'd have to assume that the O2 is getting to the hemoglobin.

Well, I think that's an extremely safe assumption, UNLESS there is a failure mode where the mask produces CO.

[SkeptiKiwi]

I cannot imagine how a mask could be producing CO. They can cause retained CO2. It is my understanding that CO is only present as a product of incomplete combustion.

I have used Denitrogenation systems and they required a compressor to force the air (at about 300psi) through the molecular sieve or membrane that removes some of the N, the system I used only produced enriched gas at up to 40% O2.

If the compressor was poorly maintained or the wrong type of oil used then you could get CO produced but inline detectors are not rare in such systems. I'd be amazed if they did not have them in flight systems.

[Citizen Skeptic]

3) You wouldn't need to measure a persons Blood O2 level if you could measure partial pressure of O2 at the mask and that would be a quicker (At least I think)

Yeah, the change at the mask would be quicker but you'd have to assume that the O2 is getting to the hemoglobin.

Well, I think that's an extremely safe assumption, UNLESS there is a failure mode where the mask produces CO.

Well, fwiw, it would be cheaper to use an oximeter to measure what you actually want than to stick a gas detector in the mask. It's not that easy to measure the partial pressure of O2 in a gas.

[Citizen Skeptic]

I'm guessing it's just that "new plane smell."

http://defensetech.org/2012/05/09/f-22-ground-crew-suffered-hypoxia-like-symptoms/

Fresh on the heels of yesterday’s announcement by the Air Force that it thinks the hypoxia-like symptoms suffered by F-22 Raptor pilots may be caused by the jets high-altitude performance, reports are emerging that ground crew are also suffering from similar ailments when they stand near the jet while it’s engines are running. Interesting.
 
At least five ground maintainers complained of illness between September and December, Air Combat Command spokesman Lt. Col. Tadd Sholtis said in an Air Force Times article that hit the newsstands Monday. The maintainers grew sick after breathing in ambient air during ground engine runs, a congressional aide told Air Force Times.
 
I imagine that the service is looking at the rates of sickness for ground crew of other jets to make sure that the Raptor maintainers are actually suffering from something unique to the stealth jet. If they are, it seems to indicate that the problem is indeed related to contaminates emanating from the plane rather than a lack of oxygen getting to the pilots during flight. Just yesterday, one of the Air Force’s top acquisitions officials, Lt. Gen. Janet Wolfenbarger told Senators that the service suspects that the F-22’s  On-Board Oxygen Generating Systems (OBOGS) are either feeding the pilots contaminated air or aren’t giving them enough air to breath. She added that the problem may be related to the extreme altitudes that Raptors routinely execute high-G maneuvers in. Needless to say, this latest news puts an interesting twist on that claim.
 
Apparently, F-22 ground crew have been issued canisters designed to take air samples whenever they feel the onset of hypoxia.

And this one...

http://pogoblog.typepad.com/pogo/2012/05/pilots-arent-guinea-pigs-ground-the-f-22-until-dangerous-oxygen-problem-resolved.html

Two elite pilots that came forward to CBS's "60 Minutes" saying that they refuse to fly the F-22 Raptor because of potentially deadly oxygen-system problems have dramatically changed their positions, according to the Daily Press's HRMilitary.com. The pilots are claiming, through their attorney, that they are now willing to fly the aircraft because the Air Force recently removed a charcoal filter which may have been causing the health issues.
 
If you think this sounds fishy, you’re not the only one. There have been multiple reports that the Air Force appears to be attempting to intimidate the pilots who spoke out. The about-face shouldn’t quell growing evidence that an unknown problem or problems is making the F-22 too unsafe for pilots to fly. According to Air Force Times, the problems are even affecting maintainers who work on the plane.
 
The pilots, who despite the health allegations have consistently praised the F-22, should not be blamed for possibly fearing for their livelihoods and changing their public opinions. However, after multiple groundings, validated reports of pilot health and safety problems, a fatal crash due to a malfunction, and now these new reports—it’s time to say enough is enough. The F-22, which has yet to be used in a combat zone—like Iraq, Afghanistan and Libya—should be grounded until we know exactly what’s causing the dangerous health and safety problems.
 
“This is a classic case of the Air Force putting hardware before people, and generals sacrificing pilots in order to avoid embarrassment” Pierre Sprey, who co-designed the F-16 and the A-10 jets, told POGO.
 

[SkeptiKiwi]

It's not that easy to measure the partial pressure of O2 in a gas.

I respectfully disagree.

It is very easy and routinely done with high accuracy in Rebreathers as I described in my earlier post.

Now reliably is a different matter and this leads to a requirement of at least three sensors in a breathing loop with a voting logic to "vote out" a faulty sensor if the system is automatic.

[Citizen Skeptic]

It's not that easy to measure the partial pressure of O2 in a gas.

I respectfully disagree.

It is very easy and routinely done with high accuracy in Rebreathers as I described in my earlier post.

Now reliably is a different matter and this leads to a requirement of at least three sensors in a breathing loop with a voting logic to "vote out" a faulty sensor if the system is automatic.

Pulse oxymeters are very reliable. The problem with gas measurements is calibration and are sensitive to altitude/depth. Pulse oximeters don't require calibration at any altitude. You can make a pulse oximeter for $10. How much are those rebreather jobbies?

EDIT: I just want to comment that this is what I love about this forum. Where else can you have a discussion about hypoxia, rebreathers, f22's, oximetry and spectroscopy?

[SkeptiKiwi]

Well yes they are very expensive (mine cost around $16,000). Calibration is only required about once per week and a wrist computer displays the mV output as PPO2 on a wrist display.

PPO2 is just that the partial pressure of O2. No adjustment is needed to be made for depth or altitude. FO2 is where it gets tricky as 21% is not the same thing physiologically at 30,000 feet as it is at sea level (PPO2 = ATA*FO2). But of course you no doubt were more than aware of that.