The U.S. Air Force has grounded its entire fleet of F-22 raptor fighters.
Officials are concerned how the jet provides oxygen to the pilot.
Since January, the aircraft already had been kept at altitudes under 25,000 feet during an ongoing investigation into a November crash.
Flying above that altitude could cause a pilot to black out from lack of oxygen and lose control.
According to an Air Force spokeswoman the stand-down affects all routine training and other missions.
Last summer, the raptor began replacing the older F-15′s being flown by the Hawaii Air National Guard.
See the original article at: KHON2 Developing Stories
