Definition
A cockpit instrument that displays the temperature of the gases flowing between the turbine wheels of a turbine engine, measured by thermocouples placed in the gas path between stages of the turbine section. It is used to monitor engine operating temperature against published limits during start, acceleration, and continuous operation.
Plain English
A gauge that shows how hot the gases are between the spinning turbine wheels inside the engine, so the pilot can make sure the engine is not running too hot.
Context Anchor
Seen on turbine-powered aircraft during engine start, takeoff, climb, and any power change where engine temperature limits must be watched.
Derivation
Interstage means 'between stages.' A turbine engine has multiple turbine wheels (stages) stacked behind the combustion section, and the temperature is sampled in the gas stream between them — hence interstage.
Why Pilots Care
High or rapidly rising ITT readings warn of potential turbine damage, compressor stall, or fuel control issues that require immediate power reduction.
Grounding Statement
When fuel is added and the turbine is producing power, the ITT gauge shows whether the heat inside the engine is staying within a safe range.
Intuition Check
Do not read ITT as outside air temperature or general engine warmth. It is a temperature reading from a specific hot-gas location inside a turbine engine.
Example Sentence 1
During engine start, the pilot kept a hand near the fuel cutoff and watched the ITT gauge for any sign of a hot start.
Example Sentence 2
A sudden increase in ITT prompted the crew to reduce throttle and investigate possible engine damage.