premise: As the flight United 93 left Newark the crew nonmember were tragically unaware of the hijacking of American 11 and if they had been they could have prevented their own hijacking by keeping the plane grounded and double-checking for safety .
hypothesis: As the flight United 93 left Newark the crew members were tragically unaware of the hijacking of American 11 and if they had been they could have prevented their own hijacking by keeping the plane grounded and double-checking for safety .