FAA Flight Instructor Airplane (FIA)Performance, Weight and BalanceMedium
An engineer analyzing a reciprocating-engine airplane's power curves determines that at 9,500 ft pressure altitude, the power required to maintain level flight exactly equals the maximum power available from the engine. This altitude represents the airplane's
- Aservice ceiling
- Babsolute ceiling
- Ccritical altitude
- Dmaximum operating altitude
Show answer & explanationAnswer & explanation
Correct answer: B. absolute ceiling
When power available equals power required, there is no excess power to climb, meaning rate of climb is zero — the definition of absolute ceiling.
Why the other options are wrong
- A. Service ceiling occurs where excess power still allows a 100 fpm climb, before power lines fully converge.
- C. Critical altitude concerns turbocharger boost limits, not the power-available/required intersection.
- D. Maximum operating altitude is a structural or pressurization limit, unrelated to this power analysis.
Power Available vs Power Required (Absolute Ceiling)
Excess power (power available minus power required) determines climb capability; where the two curves intersect, excess power is zero, defining the absolute ceiling.
- Excess power drives rate of climb
- Curves converge at absolute ceiling
- Service ceiling occurs slightly below, at 100 fpm excess capability
Memory trick: Where the lines meet, climbing is beat