It wasn't flight-worthy, it just hadn't crashed yet. If your jet stopped properly responding to controls and you had the opportunity to eject and probably not die rather than crash and almost certainly die, what do you think you would do? Also if it lost power, it would still fly for a bit because momentum and airfoils and physics and such, but not be transmitting its position because no power, which makes it kinda hard to track because like, y'know, stealth aircraft