AFTER TRAVELING ABOUT 1,000 FT ON ITS TAKEOFF ROLL, THE AIRCRAFT WAS SEEN BY WITNESSES AS BEGINNING ITS ROTATION. TOWER PERSONNEL REPORTED THEY COULD SEE THE BELLY OF THE AIRCRAFT. THE AIRCRAFT ROLLED LEFT, ITS LEFT WING CONTACTED THE RUNWAY, AND IT CONTINUED TO AN INVERTED POSITION. THE AIRCRAFT SLID DOWN THE RUNWAY AND THEN VEERED OFF ON TO THE GRASS ON THE NORTH SIDE OF THE RUNWAY. THE AIRCRAFT CAME TO A REST, INVERTED, ABOUT 100 FT OFF THE RUNWAY AND ABOUT 1,380 FT FROM THE LOCATION WHERE THE TAKEOFF ROLL BEGAN. THE AIRCRAFT OPERATING HANDBOOK INDICATED THE NORMAL TAKEOFF DISTANCE TO THE POINT OF ROTATION AND LIFTOFF SHOULD BE BETWEEN 1,350 AND 1,400 FT. THIS DISTANCE WAS COMPUTED USING THE AIRCRAFT'S WEIGHT AND THE REPORTED WEATHER AT THE TIME OF THE ACCIDENT. A DEPARTING BOEING 737 WAS CLEARED FOR TAKEOFF ABOUT 5 MINUTES PRIOR TO THE ACCIDENT AIRCRAFT'S TAKEOFF ROLL ON THE OPPOSITE RUNWAY. THE WINDS WERE CALM.