FAA Airline Transport Pilot (ATM)Aircraft Performance and Weight and BalanceMedium
During takeoff planning, a captain notices the runway is contaminated with standing water. How does this affect the accelerate-stop distance required (ASDR) compared to a dry runway?
- AASDR decreases because water reduces tire heat buildup during braking
- BASDR is unaffected since accelerate-stop distance depends only on airspeed
- CASDR increases because reduced tire-to-runway friction lengthens the stopping distance
- DASDR increases only if the takeoff is rejected below V1
Show answer & explanationAnswer & explanation
Correct answer: C. ASDR increases because reduced tire-to-runway friction lengthens the stopping distance
Standing water reduces the coefficient of friction between the tires and runway surface, degrading braking effectiveness and increasing the distance needed to stop after a rejected takeoff, thus increasing the accelerate-stop distance required.
Why the other options are wrong
- A. Reduced friction increases stopping distance, it does not decrease it.
- B. Runway surface condition is a major factor in braking performance, not irrelevant.
- D. ASDR always applies to the rejected takeoff scenario at or below V1, not conditionally exempted.
Accelerate-Stop Distance (ASD)
The total distance required to accelerate to V1 and then bring the airplane to a complete stop, factoring runway surface condition, weight, wind, and altitude.
- Contaminated runways (water, ice, snow) increase ASD
- Braking effectiveness depends on tire-runway friction
- ASD must not exceed the accelerate-stop distance available (ASDA)
Memory trick: 'Slick runway, slow stop (longer stop distance)'