Definition
Flight at speeds of Mach 5 or greater — that is, five or more times the speed of sound. At these speeds, airflow behavior changes dramatically: extreme aerodynamic heating, shock wave interactions, and chemical changes in the air around the aircraft become major design factors.
Plain English
Flying at five times the speed of sound or faster. At these speeds the air itself heats up violently against the aircraft, and the rules of normal high-speed flight no longer fully apply.
Context Anchor
Seen in high-speed aerodynamics, missile discussions, experimental aircraft, and spacecraft reentry.
Derivation
From Greek 'hyper' meaning 'over' or 'beyond,' combined with 'sonic' from Latin 'sonus' meaning 'sound.' Literally 'beyond sound' — but specifically far beyond it, well past the supersonic range.
Why Pilots Care
Hypersonic flight is outside the operating envelope of civil and almost all military aircraft, but the term appears in speed-regime discussions and shows where the supersonic range ends and a fundamentally different flight regime begins.
Grounding Statement
At hypersonic speed, the vehicle is moving so fast that the air ahead of it is squeezed and heated intensely instead of flowing smoothly around it.
Intuition Check
Hypersonic does not just mean “very fast.” In aviation, it means a specific speed range: about Mach 5 or higher, faster than supersonic flight.
Example Sentence 1
The space shuttle re-entered the atmosphere in a hypersonic flight regime, generating intense heat on its leading edges.
Example Sentence 2
Engineers study hypersonic flight to design vehicles that can cross continents in under an hour.