Hypersonic flight is flight through the atmosphere below altitudes of about 90 km (56 mi) at speeds greater than Mach 5, a speed where dissociation of air begins to become significant and high heat loads exist. Speeds over Mach 25 have been achieved below the thermosphere as of 2020. [citation needed]
Hypersonic vehicles are able to maneuver through the atmosphere in a non-parabolic trajectory, but their aerodynamic heat loads need to be managed.