Thin air, less power.
Thin air carries less oxygen for combustion, so a piston engine loses power as density altitude rises. Pick your aircraft and a density altitude — get yours from the density altitude calculator — to see the horsepower you actually have. New to it? Read what is density altitude?.
Thin air carries less oxygen for combustion, so a piston engine loses power as density altitude rises. Pick your aircraft and a density altitude to see the horsepower you actually have. First compute it with the density altitude calculator (or the pressure altitude calculator on a standard day).
Educational estimates only — not for flight planning, dispatch, or weight-and-balance. Always fly the numbers in your POH and current official weather.
A normally-aspirated piston engine loses power roughly in proportion to air density — about 3% per 1,000 ft of density altitude (Gagg–Ferrar). At 8,000 ft density altitude a 180 hp engine makes closer to 135 hp. Turbocharged engines hold rated power up to a critical altitude, then fall off the same way.
Yes. Jet engines produce thrust, not horsepower, and thrust falls as you climb because thinner air means less mass flow through the engine — roughly with the ambient pressure ratio, so a turbofan at FL400 may make only about a third of its sea-level static thrust. Turboprops produce shaft horsepower and are usually flat-rated to a critical altitude, then lose power as density falls.
DensityAlt is a set of free, no-signup aviation calculators. Explore the rest: