content: The F-22 had 2 different issues with their oxygen system.  The one caused the crash of that Elmendorf AFB plane in Alaska.  The system detected a fire and shut down and the pilot slammed the jet into the terrain trying to twist around and turn his emergency system on.  The other issue was the hypoxia and "Raptor cough."  The Air Force told us both issues were resolved, but that seems unlikely now.