Definition
The horizontal distance a helicopter can travel over the ground during an autorotation after an engine failure, measured from the point of failure to the touchdown point. It depends on altitude above the ground at the time of failure, airspeed, wind, gross weight, and rotor RPM management.
Plain English
How far a helicopter can glide along the ground after the engine quits, using only the spinning rotor to control the descent down to landing.
Context Anchor
Used in helicopter emergency procedures and performance planning when judging whether a landing area is within reach after power loss.
Derivation
From 'auto-' (self) and 'rotation.' In an autorotation, the rotor keeps turning on its own, driven by air flowing up through it as the helicopter descends, rather than being driven by the engine. The 'distance' part is simply how far forward the helicopter travels during that descent.
Why Pilots Care
Determines whether a suitable landing site remains reachable after engine failure.
Grounding Statement
If the engine quits, autorotational distance is the forward ground distance available while the helicopter descends to land.
Intuition Check
Do not read “autorotational distance” as how far the rotor itself spins. It means the distance the helicopter travels over the ground while in autorotation.
Example Sentence 1
At 1,500 feet above the ground with a headwind, his autorotational distance was just enough to reach the open field ahead.
Example Sentence 2
Higher airspeed at entry increased the autorotational distance available for the forced landing.