How does altitude affect engine power in a typical fixed-wing single-engine?

• A. Higher altitude reduces air density, which reduces engine power output and performance.
• B. Higher altitude increases engine power due to cooler air.
• C. Altitude has no effect on engine power.
• D. Lower altitude reduces engine power due to denser air.

Answer: (A)

Altitude reduces air density, which directly lowers engine power output and overall performance in a typical fixed-wing single-engine aircraft. The engine’s power depends on how much air—specifically, how much oxygen—can be drawn into each intake cycle. As you climb, the air becomes thinner, so fewer air molecules reach the cylinders, less fuel can be burned efficiently, and horsepower drops. The propeller also loses efficiency in thinner air, which compounds the reduction in thrust and climb performance. Cooler temperature at altitude doesn’t compensate for the loss in density, so power falls as altitude increases. Closer to the ground, with denser air, more power is available.