Improvements to be added over F-22 oxygen problem

(CBS News) A new valve to regulate oxygen flow to a pilot's inflatable vest could be the fix to help F-22 pilots overcome their feeling of disorientation due to lack of oxygen (or hypoxia), while flying, CBS News has learned.

Correspondent David Martin reported Tuesday that Gen. Charles Lyon, the head of the task force investigating the cause of hypoxia in F-22 pilots, gave a briefing today which restated the Air Force's belief that they have identified the problem that was causing pilots to lose oxygen.

Lyon believes the Air Force has found the cause -- an inflatable vest which was restricting the pilots' breathing -- and the fix -- a new valve that regulates the flow of oxygen to the vest. The new valve begins testing next month and should be installed by the end of the year.

Right now, pilots are flying without the vest, which restricts them to altitudes below 44,000 feet. Once the valve is installed the F-22 will be able to go to its maximum altitude of more than 50,000 feet.

New oxygen sensors are also being installed on the aircraft. Once they are, the current flight restriction that restricts F-22s to within 30 minutes of a landing field will be lifted. (They were suspended to allow a deployment of F-22s to Japan last week which required them to fly at distances an hour and a half from a landing field.) That will probably be sometime this fall.

Martin had previously reported on the issue for "The CBS Evening News" on July 13. At the time, the F-22 was on a very short leash. After first being grounded, the world's most sophisticated and expensive jet fighter is flying again, but limited to flights within 30 minutes of a landing field.

The reason: A mysterious problem that without warning has caused pilots to suffer hypoxia - become disoriented from lack of oxygen. Over the past 10 months, says Col. Kevin Robbins, commander of the First Fighter Wing at Langley Air Force Base in Virginia, there have been 11 incidents of hypoxia.

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"No one has gotten to the point where they're completely, where they're delirious. They're still able to function, still able to bring the aircraft back safely," Col. Robbins says.

CBS News correspondent Martin had experienced hypoxia first hand in an F-22 simulator as Maj. Tom Massa reduced the flow of oxygen to his mask. It is like being dizzy.

When it got too bad, Martin pulled the emergency oxygen, and only then did he realize how far downhill his ability to function had gone. When he thought his simulated flight was going straight and level, he was actually continuing to climb.

The real F-22 can pull 9 Gs, subjecting the pilot to a force nine times the weight of gravity.

One standard piece of equipment is an inflatable vest. It provides chest counter-pressure during rapid decompression.

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Technical Sgt. Scott Bender helped Martin into a vest and hooked him up to an oxygen machine with the instructions: "Don't panic." The vest inflated to protect Martin's lungs from exploding at high altitude, but it also made it harder to breathe.

Centrifuge tests revealed that the vest - which was supposed to improve the pilot's chances of survival - was actually a hazard.

"The vest was inflating every time you pull G's in the aircraft and then staying inflated which was making it more difficult to take air," Col. Robbins says.

After months of dissecting every inch of the plane's complex oxygen system, Lyon, the man in charge of the investigation, believes he has solved the mystery of the F-22: It's the vest.

F-22 pilots no longer wear the vest, but as a result are not allowed to fly above 44,000 feet. Even without the vest, there have been two cases of pilots running short of oxygen, although Lyon said those were mechanical malfunctions unrelated to the hypoxia mystery. Until Lyon can convince Defense Secretary Panetta he really has solved the mystery, the F-22 will remain on a short leash.

Below, watch the original "60 Minutes" report on the F-22's oxygen deprivation issues