NASA parabolic maneuvers: C-9B Flight Trajectory for zero-g training

NASA's Reduced Gravity Research Program made it possible for scientists to study human responses to simulated weightlessness. The reduced-gravity aircraft flies an up-and-down parabolic pattern. This provides about 30 seconds of hypergravity (1.8 to 2.0 g) as the plane climbs to the top of the parabola. Once the aircraft starts to tip over the top of the parabola to descend toward Earth, the aircraft experiences about 25 seconds of microgravity (zero-g). A typical flight conducted 30 to 40 parabolic maneuvers over the Gulf of Mexico. KIAS = knots indicated air speed. (Source: NASA Reduced Gravity Research Program. Because of the poor quality of the original, the figure has been recreated with modified labeling by Dr. Douglas J Lanska.)