NOTE: As Mach values are largely temperature-dependent (outside air), the value presented above is representative of an object traveling at sea-level (15C / 59F). The speed of sound increases as ambient temperatures increase making the speed represented by Mach 1 variable. The Subsonic regime is up to 609 mph while Transonic flight is achieved between 609 and 914 mph. Supersonic flight occurs at 915 to 3,806 mph. Hypersonic speeds are experienced between 3,806 and 7,680 mph.