Definition
The mixture control position in which the maximum amount of fuel is delivered to the engine relative to the air entering the carburetor or fuel injection system. This is the standard setting for takeoff, climb, and most operations at low altitude where the air is dense.
Plain English
The mixture knob or lever pushed all the way in, telling the engine to use the most fuel. It's the normal setting when flying at lower altitudes.
Context Anchor
Seen in piston-engine heat management, takeoff and landing checklists, climbs, and any procedure that tells the pilot to set the mixture full rich.
Derivation
Full' means all the way, and 'rich' refers to a fuel-air mixture that has a high proportion of fuel. A 'rich' mixture has more fuel relative to air; a 'lean' mixture has less. So 'full rich' means the mixture control is set to deliver the most fuel possible.
Why Pilots Care
It supplies extra fuel to absorb heat and prevent detonation during high-power operations.
Grounding Statement
Picture the mixture control pushed fully forward: the engine is receiving its richest normal blend of fuel and air, which often helps carry heat away during high-power operation.
Intuition Check
Full rich does not mean “best power in every situation.” It means the mixture control is at the maximum-fuel end of its normal range; the correct setting still depends on the aircraft procedure and operating conditions.
Example Sentence 1
Before takeoff from the sea-level airport, the pilot set the mixture to full rich and advanced the throttle.
Example Sentence 2
Returning the mixture to full rich while entering the traffic pattern ensured adequate engine cooling for landing.