Aviation Calcs

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Accelerate-Stop Distance Calculator

How much pavement does a constant-acceleration reject use? Enter a decision speed, how fast you get there, a recognition delay, and a braking deceleration, and this page adds the three pieces: distance to that speed, distance during the delay, and distance to stop. It is textbook kinematics, not a certified accelerate-stop distance, not a V1 from an AFM, and not a reason to depart on a runway that only “looks long enough.”

Speeds are treated as groundspeed. Acceleration and deceleration default to knots per second; you can instead enter the distance used to reach the decision speed, or a fraction of g. The default recognition time is 1 second — a round number, not a certification value.

Result

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Three distances: accelerate, recognize, stop

Under constant acceleration a to a speed V, the ground roll to that speed is saccel = V² / (2a) and the time is V/a. During a recognition delay tr the airplane is assumed to keep rolling at V, covering V tr. A constant deceleration d then stops it in V² / (2d). The educational accelerate-stop distance is the sum of those three pieces. An 80-knot decision speed at 4 knots per second, a 1-second delay, and an 8-knot-per-second stop uses about 2,160 feet — a useful order-of-magnitude check, not a dispatch number.

A published V1 and a Part 23 or Part 25 accelerate-stop distance are a different model: configuration changes, engine-out thrust, runway slope, wind, and braking condition all enter the AFM/POH chart. This page has none of that. Use the takeoff and landing distance calculator when you are correcting a POH baseline, and defer to the book for a reject decision.

Sources

Frequently asked questions

Is this a legal V1 or ASDR?

No. V1 and accelerate-stop distance come from the AFM or POH for the weight, flap setting, runway, and conditions of the day. This page is an educational kinematics check.

What recognition time should I use?

The default of one second is a round classroom number, not a certification reaction time. Try a longer delay if you want to see how sensitive the total is.

Does the calculation include wind or slope?

No. Speeds are treated as groundspeed on a level, still-air runway.