[ This aircraft is used to train astronauts in zero maneuvers, giving them about 25 seconds of weightlessness out of 65 seconds of flight in each parabola. During such training the airplane typically flies between 40-60 parabolic maneuvers. In about two thirds of these flights, this motion produces nausea due to airsickness, especially in novices, giving the plane its nickname. — Wikipedia entry on reduced gravity aircraft, a.k.a. “The Vomit Comet“, photo courtesy kwc under a Creative Commons License