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Aug. 1, 2012—
Maj. Gen. Charles Lyon, Air Combat Command's director of operations and head of the Air Force's ongoing F-22 task force investigation, said he is confident the Air Force has finally figured out what has been causing hypoxia-like symptoms among some F-22 pilots.

"We determined with confidence the source of the unexplained physiological incidents resides in the F-22 cockpit," Lyon told reporters during a July 31 briefing in the Pentagon. He reiterated comments made by Chief of Staff Gen. Norton Schwartz that "there is no smoking gun," saying instead service officials have identified a combination of factors as the cause.

More specifically, officials discovered that a quick-connection valve on the pilots' upper pressure garment has been allowing these vests to inflate under "normal" flight conditions, causing the vests to act as "corsets" that constrict pilots' breathing, said Lyon. These vests were designed only to inflate when pilots encountered increased G forces or rapid decompression at high altitudes in order to help the pilots breathe under those stressing circumstances and protect their lungs, he said.

As a result, the Air Force stopped using the upper pressure garment in early June as it continued testing the valve. Lyon showed reporters a new prototype valve during the briefing and said it is designed to offer increased tension in the hopes of preventing the vest from inflating at the wrong times.

Officials expect to begin testing the new valve in about a month, and Lyon said he expects the F-22 fleet would be "completely outfitted" with it by year's end.

He identified other contributors to the hypoxia-like symptoms as leaky oxygen hoses connected to the vests and an air filter meant to keep out chemical and biological agents.

Service officials have ruled out contamination of the F-22s's oxygen system as a potential cause, said Lyon.

Schwartz last week
announced that the Air Force, based on guidance from Defense Secretary Leon Panetta, would lift in phases the flight restrictions on the F-22s that have been in place as a safety measure.

Before all the restrictions are lifted, the Air Force must implement the remaining
recommendations made by the Air Force Scientific Advisory Board, review the results of an independent analysis by NASA, and change out a finger-mounted pulse oximeter that measures the pilot's oxygen level in favor of a helmet-mounted one that is expected to be more effective, said Lyon.

The AFSAB made a total of eight recommendations and the service has already implemented five, he said. Officials now are focused on incorporating an independent oxygen sensor in the cockpit to alert pilots of their oxygen concentration. That effort is about 89 percent complete, noted Lyon.

"When we finish those three things this fall . . . we'll go back to Secretary Panetta and show him where we are and we'll start reducing that tether on local sorties," said Lyon of some of the flight restrictions. 

Altitude restrictions on the F-22s will be lifted once issues with the faulty valve are ironed out, he noted.

It's not clear how much it will cost to make all these fixes, although Lyon said it would definitely be in the "millions" of dollars.

The Raptor community has flown almost 8,000 sorties and accumulated more than 10,000 flight hours in the F-22 since the last hypoxia-like incident on March 8, said Lyon.

"Let me be clear, there will be physiological incidents in the future in the F-22 and in other aircraft. That goes with the territory of high-performance fighter aircraft and flight operations," he said.

He added, "What gave the Air Force grave concern last year when we stood down the fleet was the unexplained nature of the incidents. . . . We now have an explanation and the incident rates are decreasing."