Definition
An engine instrumentation system that measures the temperature of the exhaust gases leaving an engine's cylinders or turbine section, using one or more thermocouples placed in the exhaust stream and displaying the reading on a cockpit gauge. In piston engines, it is used primarily as a fuel-mixture management tool, since exhaust gas temperature peaks at a specific fuel-to-air ratio. In turbine engines, it is a critical engine-limit indication used to monitor combustion temperature and protect the turbine section from overheating.
Plain English
A system that measures how hot the air coming out of the engine is, and shows that temperature to the pilot on a gauge. The reading helps the pilot adjust the fuel mixture in piston engines, or watch for dangerous heat in jet engines.
Context Anchor
Seen on engine instruments, especially during engine run-up, climb, cruise, and mixture adjustment in piston-engine aircraft.
Derivation
From 'exhaust gas' (the burned air and fuel leaving the engine) and 'temperature indicating' (showing how hot it is). The name describes exactly what the system does -- it shows the temperature of the exhaust gas.
Why Pilots Care
Monitoring this system helps detect mixture problems, cylinder issues, or overheating before they cause engine damage or failure.
Analogy
It works like putting a temperature probe in a hot air stream and showing the result on a gauge, except the hot air stream is the engine exhaust.
Intuition Check
Do not read this as a system that controls exhaust temperature. It only senses the temperature and displays it to the pilot.
Example Sentence 1
After leveling off in cruise, the pilot leaned the mixture slowly while watching the exhaust gas temperature indicating system until the needle reached its peak.
Example Sentence 2
A sudden drop on the exhaust gas temperature indicating system warned of a possible cylinder failure.