What is balanced field length in takeoff performance?

• A. The runway length required to both reach takeoff speed and clear an obstacle with one engine inoperative (for multi-engine).
• B. The total runway needed to taxi to the runway.
• C. The distance to stop after engine failure.
• D. The runway length for landing.

Answer: (A)

Balanced field length is the runway length that makes the takeoff distance with all engines operating equal to the distance required when an engine fails and you continue takeoff with the remaining engines. In practice, it’s the length needed to reach takeoff speed and to clear an obstacle under the normal takeoff scenario, and it’s also the length needed to achieve the same obstacle clearance under a one-engine-out scenario. This intersection defines the minimum runway length that can safely support either takeoff condition for a multi-engine aircraft. If the runway is shorter than this length, you can’t guarantee adequate performance for an engine-out takeoff; if longer, the runway supports both cases. The other options describe taxi distance, stopping distance after an engine failure, or landing distance, which are not what balanced field length measures.