The Air Force grounded its entire F-22 fleet for seven months in May 2011 due to repeated cases of hypoxia. (Tech. Sgt. Michael Holzworth / Air Force)
A “very small number” of F-22 pilots have requested to not fly the U.S. Air Force’s Raptors following the grounding and unfruitful investigation into the oxygen problems plaguing the stealthy jet, the head of Air Combat Command said April 30.
The service has yet to identify a root cause for 11 unexplained hypoxia-related incidents, and the command has extended its investigation to looking at ground maintainers who have experienced oxygen-related problems in handling the jet, Gen. Mike Hostage said in a wide-ranging media briefing at Joint Base Langley -Eustis, Va.
There is a worry among pilots, Hostage said, but he does not see a reason to stand down. The briefing, in fact, came just days after the Air Force announced that a squadron of F-22s were headed to a deployment in southwest Asia. Officials on April 30 would not say where the F-22s were deployed from, or give additional details about their mission.
“The risk is not as low as I’d like it,” Hostage said of the deployed F-22s.
“This nation needs this airplane. I wish I had 10 times as many. It’s our best airplane,” he added.
The Air Force in May 2011 grounded its entire F-22 fleet for four months due to repeated cases of hypoxia. Maj. Gen. Charles Lyon, the director of operations for ACC, said that the F-22 has flown 12,000 sorties since September with 11 unexplained cases of hypoxia.
Since the grounding was lifted, pilots have taken extra precautions such as wearing a commercial pulse oximeter to measure the amount of oxygen in their blood and added a charcoal air filter to measure the amount of toxins in the air. The filters were recently removed, Lyon said, because analysis of more than 500 revealed no unhealthy amount of toxins post-flight.
ACC has directed all pilots to abort their mission and land the aircraft if they encounter any physiological problems, Hostage said. Since the directive was announced, which began after pilots were cleared to fly following the grounding, there has been an expected increase in incidents.
“We fully expect that we are going to have more incidents since we lowered the threshold,” Hostage said.
Hostage said the F-22 is back to flying long flights and at high altitude. The Raptors were contained to a lower ceiling immediately after the grounding was lifted.
A large task force, including engineers, doctors, physiologists, analysts and others, is continuing to try to determine a root cause. Lyon said he believes there is a root cause and that the service is narrowing down on it. Either pilots are not getting enough oxygen for some reason or toxins are either not being filtered or the aircraft is creating them, he indicated.
“The smoking gun is disassembled in a mosaic in front of us ... at some point we’re going to have the smoking gun assembled,” Lyon said.