During a parabolic aircraft flight, test pilots fly the aircraft along a flight path that resembles an ideal ballistic curve. From horizontal flight, the aircraft first gains momentum at full thrust and then pulls up steeply. At this point, the people and devices on board the aircraft experience a force of 1.8 times the Earth’s standard gravitational acceleration, pulling them towards the floor of the aircraft.
The pilot then throttles the engines back, and weightlessness ensues for a period of 20 to 22 seconds, during which there is only a residual acceleration of about one percent of the Earth’s gravitational pull. As the pilot pulls the aircraft out of its steep descent, hypergravity occurs for another 20 seconds. The aircraft then returns to horizontal flight for a period of one minute, during which the Earth’s normal gravitational pull returns.
Credit: Gilles Le Barzic.