FAA Airline Transport Pilot (ATM)Aircraft Performance and Weight and BalanceHard
A twin-engine transport departs at a weight 9,600 lb above its maximum structural landing weight and must return immediately due to a medical emergency. The airplane's fuel jettison system dumps fuel at a rate of 1,200 lb per minute. Approximately how long must the crew jettison fuel to reach maximum landing weight, ignoring fuel burned during the jettison?
- A12 minutes
- B8 minutes
- C6 minutes
- D4 minutes
Show answer & explanationAnswer & explanation
Correct answer: B. 8 minutes
Divide the excess weight by the jettison rate: 9,600 lb ÷ 1,200 lb/min = 8 minutes. This calculation, ignoring normal fuel burn, gives the minimum jettison time needed to bring the airplane down to its maximum landing weight before landing.
Why the other options are wrong
- A. This overshoots, removing 14,400 lb, more fuel than necessary.
- C. This would only remove 7,200 lb, insufficient to reach max landing weight.
- D. This would only remove 4,800 lb, not the full 9,600 lb excess.
Fuel Jettison for Overweight Landing
A system on some transport aircraft that dumps fuel in flight to reduce weight to at or below maximum landing weight before an emergency landing.
- Jettison time = excess weight ÷ jettison rate (lb/min)
- Used when time/altitude permits, versus accepting an overweight landing
- Crews must also verify CG remains within limits as fuel is jettisoned
Memory trick: Divide the extra pounds by the pump rate to find your dump time.