Definition
The maximum power an aircraft reciprocating engine is approved to produce continuously during normal operation, excluding takeoff. METO horsepower is lower than takeoff horsepower and represents the highest power setting the engine can sustain without time limits.
Plain English
The most power the engine is allowed to make for as long as you want, not counting the brief extra power used for takeoff. Takeoff power is higher but only allowed for a short time; METO power is what the engine can keep producing safely.
Context Anchor
Seen in engine specifications, aircraft operating limitations, and power-setting discussions for piston aircraft engines.
Derivation
METO stands for 'Maximum Except Take-Off.' The phrase tells you exactly what it means: the maximum allowed, except during takeoff (when a higher, time-limited setting is permitted).
Why Pilots Care
It sets the continuous power reference for climb and cruise, protecting engine life while delivering reliable performance.
Intuition Check
Do not read “except takeoff” as “not related to takeoff at all.” It means this is the maximum continuous power rating for operations other than the separate, often time-limited, takeoff power rating.
Example Sentence 1
The engine's takeoff rating is 450 horsepower, but its METO horsepower is 400, so the pilot reduces power after the initial climb.
Example Sentence 2
The maintenance manual requires an engine to sustain METO horsepower for extended periods during ground runs and flight tests.