Investigators also found Know evidence Statement that the takeoff may have been performed Hold with the elevator trim tab still set Being_in_operation for landing .

If the elevator trim tab had not been set Being_in_operation for takeoff this would have been exacerbated Cause_change_of_position_on_a_scale by the incorrect position of the centre of gravity and the aircraft would have been uncontrollable .

An investigation by the USAF determined Deciding that the crash was likely caused Causation by an improper stabilizer trim setting .

The investigation was unable to determine Deciding conclusively what had caused the horizontal stabilizer trim to be set Placing improperly , but theorized Coming_to_believe that the most likely cause was an aircraft system malfunction Motion .