Accelerate-Stop vs Accelerate-Go Distance
Multi-engine takeoff planning is not only about whether the airplane can get airborne. It also asks what happens if an engine fails during the takeoff roll or shortly after liftoff.
Accelerate-stop distance
Accelerate-stop distance is the distance required to accelerate to the applicable decision or failure point, recognize the problem, reject the takeoff, and bring the airplane to a stop under the assumptions used by the manufacturer.
Accelerate-go distance
Accelerate-go distance describes the distance required to continue the takeoff after an engine failure at the specified point and reach the defined height or condition using the remaining engine. Not every light twin publishes the same type of accelerate-go data, so the POH/AFM must be checked rather than assuming a number exists.
Why the two numbers matter
A runway can be long enough for a normal two-engine takeoff and still provide poor margins for a rejected takeoff or engine-out continuation. Temperature, pressure altitude, weight, wind, runway condition and obstacles can all change the result.
Light twins and decision making
Small training twins do not automatically have airline-style balanced-field performance. A pilot should know the airplane's actual published performance, available runway, obstacle environment and the operator or instructor's takeoff briefing before departure.
Common oral-exam question
What is the difference between accelerate-stop and accelerate-go? Accelerate-stop answers how much distance is needed to reject and stop after accelerating to the specified failure point. Accelerate-go addresses continuing the takeoff after the failure under the published assumptions.
Related study
Review single-engine service ceiling, VMC vs VYSE, zero sideslip, and the aircraft performance reference.
Where the definitions come from
The FAA Airplane Flying Handbook glossary defines accelerate-go distance using a specified engine-failure speed and continued takeoff on the remaining engine. Certification definitions rely on stated test conditions; they do not supply a generic number for every light twin. Use the current POH/AFM performance charts for the airplane you fly.
For the broader multi-engine discussion, see the multi-engine study hub.