Definition
An engine instrument on a turbine engine that displays the temperature of the exhaust gases as they leave the turbine section. It provides an indirect indication of the temperature inside the turbine itself, which must be kept within published limits to avoid damaging the turbine blades and other hot-section components.
Plain English
A gauge that shows how hot the air is just after it leaves the turbine. Pilots watch it to make sure the engine is not running too hot.
Context Anchor
Seen on the instrument panel of turbine-powered aircraft, especially during engine start, takeoff, climb, and other high-power operation.
Derivation
The reading is taken at the outlet of the turbine — the point where exhaust gases exit after spinning the turbine wheels. Naming the gauge by its measurement location tells the pilot exactly what part of the engine the temperature reflects, and reminds them it is a downstream reading, not the actual internal turbine temperature.
Why Pilots Care
It alerts pilots to excessive heat that could damage turbine blades or other components and confirms the engine is operating within safe temperature limits.
Grounding Statement
The TOT gauge is a heat check on the engine at one of its hottest and most important points.
Intuition Check
TOT is not outside-air temperature and it is not oil temperature. It is the temperature of the hot gas leaving the turbine section of the engine.
Example Sentence 1
During start, the pilot watched the TOT gauge closely to make sure the temperature stayed below the limit shown in the engine manual.
Example Sentence 2
A sudden rise on the TOT gauge during cruise prompted the pilot to reduce power and investigate fuel flow.