This aircraft is used to train astronauts in zero-g maneuvers, giving them about 25 seconds of weightlessness out of 65 seconds of flight in each parabola. During such training, the airplane typically flies about 40–60 parabolic maneuvers
During such parabolic flight an aircraft flies a trajectory that provides freefall for up to 40 seconds. Parabolic flight generates freefall by following a trajectory wherein the acceleration of the aircraft cancels the acceleration due to gravity along the aircraft vertical (z) axis.
