Definition
On a split-shaft (free turbine) turboprop engine, the elevated ground-idle speed setting at which the gas generator runs faster than low idle, providing increased airflow, hydraulic pressure, electrical generation, and bleed air without producing significant propeller thrust. It is typically selected on the ground for warm-up, cool-down, accessory operation, or before takeoff to ensure the engine is ready to respond quickly to power demands.
Plain English
A faster ground-idle setting that keeps the engine spinning quickly enough to run accessories and respond promptly when the pilot adds power, without the propeller pulling the airplane forward much.
Context Anchor
Pilots encounter high idle when using the condition lever or idle control in turbine airplane operations, especially before takeoff, landing, or any phase where quick power response is important.
Why Pilots Care
Provides faster throttle response and stable accessory operation during taxi, reducing the risk of slow acceleration or compressor issues when power is needed suddenly.
Grounding Statement
At high idle, the engine is not making takeoff power; it is simply being kept at a faster ready speed.
Intuition Check
High idle does not mean high power. It means a higher minimum idle speed, so the engine is more ready to respond.
Example Sentence 1
After starting the engine, the pilot moved the condition lever to high idle to bring the generator online and warm the engine before taxi.
Example Sentence 2
After engine start, high idle was selected to bring oil temperature up faster before applying takeoff power.