Definition
In a split-shaft/free turbine engine, the lower of two ground idle settings, used during normal ground operations to reduce fuel consumption, noise, and propeller thrust while keeping the engine running and ready for taxi or shutdown.
Plain English
The slower of two idle speeds the pilot can select on the ground. The engine is still running steadily, just at a lower RPM than the higher idle setting.
Context Anchor
Seen in turbine airplane procedures involving the condition lever or engine controls during engine start, taxi, and shutdown.
Why Pilots Care
Reduces noise, propeller wear, and the chance of sucking debris into the engine while on the ground.
Intuition Check
Low idle does not mean the engine is off or barely working enough to be unsafe. It means the engine is running at the lower of its approved idle settings.
Example Sentence 1
After engine start, the pilot left the power lever at low idle while completing the after-start checklist.
Example Sentence 2
With the engine at low idle the propeller turned slowly enough for safe ground handling.