Figure 1.

The characteristic profile of a parabolic flight maneuver. At standard cruising altitude (about 12,000 ft) the aircraft is pulled up at a 47° angle, inducing a gravito-inertial acceleration (GIA) of 1.5–1.8 g, after which the engine’s thrust is limited to compensate air-drag, entering a phase of free-fall comparable to 0 g, and hence, weightlessness. This phase is completed by another phase of hypergravity before returning to 1 g again. After an initial test parabola, the maneuver is repeated a total of 30 times with 3–5 min breaks between parabolas and a longer (about 8 min) break after the 16th parabola.