FAA Flight Instructor Airplane (FIA)Performance, Weight and BalanceMedium
A pilot's POH shows a takeoff ground roll of 800 ft at a gross weight of 2,000 lb. FAA guidance indicates that a 10% increase in gross weight produces approximately a 20% increase in takeoff distance. What is the estimated takeoff ground roll at a gross weight of 2,200 lb?
- A840 ft
- B880 ft
- C960 ft
- D1,024 ft
Show answer & explanationAnswer & explanation
Correct answer: C. 960 ft
The weight increase from 2,000 to 2,200 lb is a 10% increase. Applying the rule that a 10% weight increase yields about a 20% increase in takeoff distance: 800 ft × 1.20 = 960 ft.
Why the other options are wrong
- A. This reflects only a 5% increase, not the correct 20% relationship.
- B. This reflects only a 10% increase, matching the weight change rather than the distance change.
- D. This overstates the increase, applying nearly 28% growth instead of 20%.
Weight Effect on Takeoff Distance
Because takeoff distance depends on the square of liftoff speed, small increases in gross weight cause disproportionately larger increases in required takeoff distance.
- A 10% weight increase ≈ 20% more takeoff distance
- Relationship is roughly squared, not linear
- Heavier weight also reduces climb performance
Memory trick: Ten becomes Twenty — weight up 10%, distance up 20%