Definition
In a turbine engine, the temperature of the gas measured between two stages of the turbine section, typically between the high-pressure and low-pressure turbine wheels. ITT is displayed on a cockpit gauge and is one of the primary engine limits the pilot must monitor during start, takeoff, and high-power operations.
Plain English
It is how hot the gas is at a point inside the turbine part of a jet or turboprop engine. The pilot watches this number to make sure the engine is not getting too hot.
Context Anchor
Seen on turbine-engine instruments, especially during engine start, takeoff, climb, and power changes.
Derivation
‘Interstage’ means ‘between stages.’ The turbine in a jet engine has multiple stages (wheels), and the temperature is sampled between them. The name simply tells you where the probe sits.
Why Pilots Care
Exceeding ITT limits can damage turbine blades and reduce engine life.
Intuition Check
ITT is not outside-air temperature, cabin temperature, or general engine warmth. It is a specific internal temperature reading from the hot gas path inside a turbine engine.
Example Sentence 1
During the start, the pilot kept a close watch on ITT to make sure it stayed below the published start limit.
Example Sentence 2
A rapid increase in ITT during climb prompted the crew to reduce power and troubleshoot.