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More hypoxia incidents have occurred since the F-22 returned to the skies

The USAF's premiere air superiority fighter, the F-22 Raptor, had a rough year in 2011. There were several incidences of pilots exhibiting hypoxia-like symptoms that led to the aircraft being placed on stand-down for months while an investigation took place into the possible causes of the issue.
 
Fingers were pointed at the onboard oxygen generation systems and the OBOGS failure was thought to have contributed to the fatal crash of a Raptor pilot in 2010. That fatal crash was instead ruled pilot error.
 
On January 13, a report from the Pentagon's top tester was published on the grounding of the F-22 Raptors last year. According to the report, the Raptor stand-down last year was due to "suspected contamination problems with the aircraft environmental control system and associated onboard oxygen generation system from later April through late September 2011."
 
The report was penned by chief operational tester J. Michael Gilmore and confirms that toxins entering the cockpit of the F-22 had cause over twelve incidents that were similar to hypoxia. The USAF lifted the grounding before a hard answer to the cause of the problems was found. Since the grounding was lifted, the Raptors in the fleet have flown over 6,000 times. Defense News reports that more incidents of the hypoxia-like symptoms have occurred despite the precautions put into effect to install charcoal filters and have pilots wear pulse oximeters.
 
[Source: Lockheed Martin] 

Air Force spokeswoman Jennifer Ferrau said, "There have been approximately 90 events of interest and 15 are being investigated for potential physiological incidents -- 8 involving pilots and 7 involving aircraft maintenance personnel. This translates to a 1.8 percent event rate since the return to flight in September."
 
In USAF parlance an "event of interest" is an indication of a malfunction in a system or a data point that has not caused hypoxia-like symptoms. A "physiological event" is one that has produced hypoxia symptoms.
 
Ferrau said, "Any event involving hypoxia-like symptoms may be categorized by Air Force Instructions as a physiological incident following an investigation."

Source: DefenseNews



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RE: The smoking gun that wasn't loaded
By bug77 on 1/17/2012 5:15:25 AM , Rating: 2
The way I read that, is test-pilots are most likely trained for such incidents. In this case, the pilot failed to initiate an emergency dive that would have saved both the pilot and the plane.

These are planes in their test phase after all. You can't just sit behind a desk designing a plane until it's 100% and then test it. It's just not possible.


By BZDTemp on 1/17/2012 5:43:57 AM , Rating: 2
Since the pilot is sitting inside the plane and not out in open air it's not sure an emergency dive for breathable air would have worked. Remember this is not about lack of oxygen in the breathing system but about all sort of gasses that should not be in the air feed to the pilot.


By cjc1103 on 1/17/2012 7:33:13 AM , Rating: 4
Then F-22 has in fact passed the test phase and is operational. The last F-22 production fighter has been rolled out, and no more will be made. Having said that, there are obviously still problems that need to be worked out. The onboard OGS using engine bleed air was state of the art, and supposed to reduce the need for support and maintenance. Instead, it has turned into the achilles heel of the aircraft. How embarassing for the Air Force, their front line fighter can't fly because of this. I doubt it would be easy, or even possible, to retrofit an old-style liquid oxygen system to the F-22. I hope the F-35 has a better oxygen system.


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