Definition
The runway length declared available and suitable for the acceleration and deceleration of an aircraft aborting a takeoff. It is the runway length plus any stopway, measured from the start of the takeoff roll.
Plain English
The total distance you have to speed up for takeoff and then stop again if you decide to abort. It includes the usable runway plus any paved area beyond it that's strong enough to stop on.
Context Anchor
Seen in runway declared-distance data, aircraft performance planning, and takeoff planning at airports with published runway distance limits.
Derivation
The name describes the calculation directly: the distance available to accelerate (speed up) and then stop. 'Stopway' adds to runway length here because it's a paved area beyond the runway specifically built to support a stopping aircraft, even though it isn't usable for takeoff roll.
Why Pilots Care
Determines maximum allowable takeoff weight and whether a runway is long enough for a safe rejected takeoff.
Grounding Statement
Picture starting the takeoff roll, deciding to abort, and needing enough declared runway or approved stopping area ahead to bring the aircraft to a full stop.
Intuition Check
“Available” does not mean every bit of pavement you can see. It means the distance officially declared suitable for this specific takeoff-and-stop use.
Example Sentence 1
Before departure, the captain checked that the ASDA for runway 27 was sufficient for an accelerate-stop at their planned takeoff weight.
Example Sentence 2
With an engine failure after V1, the crew used the full ASDA to bring the airplane to a stop.