FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsHard
A performance chart shows a sea-level, standard-temperature takeoff ground roll of 600 feet for a light sport airplane. The chart notes that ground roll increases by 10% for each 1,000 feet increase in density altitude. If the departure airport has a density altitude of 3,000 feet and there is no wind, what is the approximate takeoff ground roll?
- A780 feet
- B900 feet
- C600 feet
- D660 feet
Show answer & explanationAnswer & explanation
Correct answer: A. 780 feet
A density altitude of 3,000 feet represents three 1,000-foot increments, each adding 10%, for a total increase of 30%. Ground roll = 600 × 1.30 = 780 feet.
Why the other options are wrong
- B. Incorrect — overstates the increase, applying roughly 50% instead of 30%.
- C. Incorrect — ignores the density altitude adjustment entirely.
- D. Incorrect — applies only a 10% increase instead of the required 30%.
Density Altitude Effect on Takeoff Distance
Takeoff performance charts often show ground roll increasing by a fixed percentage for each increment of density altitude, reflecting reduced engine power and lift in less dense air.
- Higher density altitude increases required takeoff distance
- Percentage increases are typically given per 1,000-foot increments on charts
- Wind, weight, and runway surface also affect actual takeoff distance
Memory trick: Each 1,000 feet of density altitude tacks on another 10%