Definition
A cockpit instrument that displays the temperature of the exhaust gases leaving the engine cylinders, used by the pilot to lean the fuel/air mixture for best efficiency. A probe in the exhaust pipe senses temperature and the gauge shows the result, typically in degrees or as a needle position relative to a peak value. As the mixture is leaned, EGT rises until it reaches a peak, then falls if leaning continues; the pilot uses this peak as the reference point for setting the mixture according to the aircraft's operating handbook.
Plain English
An instrument that shows how hot the gases coming out of the engine are. The pilot watches this number while adjusting the fuel/air mixture to find the best setting.
Context Anchor
Seen in piston-engine aircraft during engine operation, especially when adjusting the mixture control in climb, cruise, or descent.
Derivation
Exhaust comes from an older word meaning to draw out or empty. In an engine, exhaust is the burned gas pushed out after power is made. Gauge comes from a word meaning a measuring rod or standard, which fits because the instrument measures temperature; it does not control it by itself.
Why Pilots Care
Helps the pilot set the correct fuel mixture to protect the engine from overheating or detonation while improving fuel economy.
Grounding Statement
Picture the engine breathing out hot burned gas; the EGT gauge shows how hot that outgoing gas is.
Intuition Check
Do not read the EGT gauge as a direct measure of the whole engine’s temperature. It measures exhaust gas temperature, which is useful for mixture setting and trend monitoring.
Example Sentence 1
In cruise, the pilot slowly pulled the mixture back and watched the EGT gauge climb until it reached its peak.
Example Sentence 2
A sudden drop on the EGT gauge after leaning warned the pilot that one cylinder had lost ignition.