Parabolic flights are short investigations that are used to test microgravity and reduced gravity. The tests are used to train astronauts before departure to space and to test equipment before instruments are used in space.
These flights are done on specially designed aircraft. The campaigns typically consist of three flights. There are 30 parabolas flown at a time, and during two of the flights, the gravity is increased in 20-second intervals. This happens prior to and following the reduced-gravity interval. Parabolic flights are the only sub-orbital carriers that can medically observe and test humans under reduced gravity circumstances. These tests are valuable for physicists because of the hands-on training experience.