Definition
The combined volume of air and fuel delivered to an engine's cylinders for combustion, expressed as a ratio of the mass of air to the mass of fuel. In a piston aircraft engine, this ratio is adjusted by the pilot using the mixture control to match the changing density of air at different altitudes and power settings.
Plain English
The blend of air and fuel that is fed into the engine to be burned. The pilot can change how rich (more fuel) or lean (less fuel) that blend is.
Context Anchor
Seen in piston-engine operation, engine troubleshooting, carburetor and fuel-injection discussions, and when using the cockpit mixture control.
Derivation
Mixture comes from the Latin word miscere, meaning “to mix.” That helps because this term is about the actual mix of two things the engine needs: air and fuel.
Why Pilots Care
An incorrect ratio causes power loss, overheating, detonation, or excessive fuel consumption, directly affecting engine reliability and flight safety.
Intuition Check
Do not think of air-fuel mixture as just “air plus fuel.” In aviation, it means the proportion between them, and that proportion affects how the engine runs.
Example Sentence 1
As he climbed through 5,000 feet, the pilot leaned the air-fuel mixture to compensate for the thinner air.
Example Sentence 2
The technician adjusted the air-fuel mixture at idle to eliminate engine roughness before releasing the aircraft.