ASDA (Acceleration Stop Distance Available) is defined as which of the following?

• A. the length of the takeoff run available plus the length of the clearway
• B. the length of the takeoff run available plus the length of stopway (if stopway provided)
• C. the length of the runway plus the length of stopway
• D. the length of the takeoff run available plus the length of stopway and clearway (if provided)

Answer: (B)

ASDA is the distance available to perform an abortive takeoff—the space you have to accelerate to decision speed and then stop if you decide to abort. It is calculated as the Takeoff Run Available plus the Stopway length, but only if a Stopway is provided. If there is no Stopway, ASDA equals the Takeoff Run Available. The Stopway is an extra paved area beyond the runway end intended specifically for decelerating an aircraft in an aborted takeoff. Clearway is not included in ASDA, since it serves a different purpose for takeoff performance and obstacle clearance, not for stopping within the available distance.

So, if TORA is used and a Stopway exists, ASDA increases by the Stopway length; if not, ASDA remains the same as TORA.