Definition
The position of the mixture control that fully cuts off fuel flow to the engine, stopping combustion. Moving the mixture control to idle cutoff leans the fuel-air mixture to zero, which shuts the engine down without using the ignition switch.
Plain English
It is the setting of the mixture control that turns off the fuel supply to the engine, causing the engine to stop running.
Context Anchor
Seen in engine shutdown procedures and in emergency or rejected-takeoff checklists when the pilot needs to secure the engine.
Derivation
Combines 'idle' (the lowest stable engine speed) with 'cutoff' (complete interruption of flow); the phrase describes the mixture control setting that halts fuel delivery even when the throttle is at idle.
Why Pilots Care
Using this position ensures the engine stops completely and prevents residual fuel from reaching a hot engine, reducing the risk of fire or unintended restart.
Intuition Check
Do not confuse idle cutoff with normal idle. Normal idle keeps the engine running at low power; idle cutoff stops fuel flow and shuts the engine down.
Example Sentence 1
After taxiing to the ramp, the pilot pulled the mixture to the idle cutoff position to shut down the engine.
Example Sentence 2
During an engine fire checklist, the first action was to move the mixture control to the idle cutoff position to stop fuel supply.