The Air Force is nudging closer to figuring out the problem with F-22 Raptor’s oxygen system that has caused pilots to experience dizzying hypoxia spells or blackouts that were behind last year’s grounding of the advanced fighter fleet.
“We are starting to believe that we are getting closer to the root cause” of the problem, Lt. Gen. Janet Wolfenbarger, the military deputy in the Air Force’s acquisition office, told a Senate committee Tuesday. She said progress has been made based on recent data but would not go further into what might be behind the incidents, saying it is still under evaluation.
“I am not ready to say yet that we are ready to declare a root cause,” she said.
The Lockheed Martin [LMT]-built F-22s were grounded in May 2011 after 14 pilots experienced the disorientating symptoms and since remained under investigation, even though the Air Force resumed flying the stealth jets in September.
The problem returned to the spotlight following a CBS 60 Minutes airing on Sunday that featured two pilots who said they have experienced the symptoms and refuse to fly. The whistleblower airmen also asserted several of their colleagues fear flying the plane or have also objected to taking to the skies in it.
Wolfenbarger conceded during the appearance before the Senate Armed Services Committee’s aviation subpanel that since the grounding was lifted, 11 cases of hypoxia-like symptoms have been reported by pilots, with severity varying on a case-by-case basis. She said that amounted to less than 0.1 percent of the flights.
Wolfenbarger insisted the airplanes are safe for the skies and added that steps have been taken to improve the Honeywell International [HON]-supplied Onboard Oxygen Generating System (OBOGS). Those changes range from educating pilots on the issue to making it easier for a pilot to yank a handle that triggers the emergency oxygen system, she said. She said pilots are encouraged to return to base immediately if they experience disorientation.
“We are determined to get to root cause,” she said.
OBOGS has also been the source of speculation behind an F-22 crash in Alaska in 2010, but the Air Force has attributed that incident to pilot error.