Definition
The temperature of the exhaust gases as they leave the engine's cylinders, measured by a probe (thermocouple) placed in the exhaust stream. EGT is used as a reference for adjusting the fuel-air mixture, because the temperature of the burned gases changes predictably as the mixture is leaned or enriched.
Plain English
It's how hot the burned gases are when they exit the engine. Pilots watch this number to fine-tune how much fuel the engine is using compared to air.
Context Anchor
You will see EGT on engine instruments, especially during cruise power settings, mixture adjustment, and engine monitoring.
Derivation
“Exhaust” comes from older words meaning “to draw out” or “empty out.” In an engine, exhaust is the burned gas being carried out after combustion. That makes exhaust gas temperature the heat reading of the gases leaving the engine.
Why Pilots Care
Allows proper mixture adjustment for performance and efficiency while detecting conditions that can damage the engine.
Intuition Check
EGT is not the overall temperature of the engine. It is specifically the temperature of the gases leaving the engine through the exhaust system.
Example Sentence 1
After reaching cruise altitude, the pilot slowly leaned the mixture and watched the EGT rise until it peaked, then enriched slightly to set the desired power setting.
Example Sentence 2
A sudden drop in exhaust gas temperature on one cylinder indicated a possible spark plug or ignition problem.