Definition
In aviation, power is the rate at which an engine does work, typically measured in horsepower. In a piston aircraft, power output is controlled primarily by the throttle (which sets manifold pressure) and, in constant-speed propeller installations, the propeller control (which sets engine RPM). Power determines how much thrust the propeller can produce and, together with pitch attitude, how the airplane climbs, cruises, or descends.
Plain English
How much work the engine is producing per unit of time. More power means the engine is doing more work, which the propeller turns into thrust to push the airplane forward, climb, or accelerate.
Context Anchor
Pilots use this meaning whenever they adjust the throttle during takeoff, climb, cruise, descent, approach, or landing.
Derivation
From Latin 'posse' meaning 'to be able.' In physics, power is the rate of doing work — not the work itself. That distinction matters in flying: a small engine running hard and a big engine loafing can both do the same job, but their power output at that moment is what determines performance.
Why Pilots Care
Correct power management directly controls climb rate, airspeed, fuel burn, and the margin above stall speed during critical phases of flight.
Analogy
Think of power like the amount of effort you ask from a car engine with the gas pedal. It is not the same as speed, but it strongly affects whether the vehicle speeds up, slows down, climbs a hill, or comes down a hill.
Intuition Check
Do not read “power” here as electrical power or personal authority. In this context, it means engine output selected by the pilot.
Example Sentence 1
On the takeoff roll, the pilot smoothly advanced the throttle to full power and confirmed the engine instruments were in the green.
Example Sentence 2
Reducing power smoothly allowed the airplane to descend at the desired rate without gaining excess speed.