Definition
Under ICAO usage, any machine that can derive support in the atmosphere from the reactions of the air other than the reactions of the air against the earth's surface.
Plain English
A machine that stays up by pushing against the air itself — not by riding on a cushion of air bouncing off the ground. This includes airplanes, helicopters, gliders, balloons, and airships, but excludes hovercraft.
Context Anchor
Seen in the Pilot/Controller Glossary when FAA material is using the international ICAO meaning of a term.
Derivation
The [ICAO] tag marks this as the International Civil Aviation Organization's wording. ICAO is the United Nations body that sets global aviation standards, so the definition is written to apply consistently across all member countries.
Why Pilots Care
The wording matters because it deliberately excludes hovercraft and similar ground-effect-only vehicles. For pilots flying internationally or reading ICAO documents, this is the legal definition of what counts as an aircraft.
Intuition Check
Do not assume aircraft means only airplane. In this context, it means any machine supported by the air in flight, unless it is supported only by air pressing against the surface below it.
Example Sentence 1
When filing an international flight plan, pilots must use the ICAO aircraft type designator that matches their specific make and model.
Example Sentence 2
ICAO rules require that an aircraft maintain flight without relying on ground effect.