Definition
A safety device in a combustion-type aircraft heating system that automatically shuts the heater off when internal temperatures exceed a safe limit. It protects against fire and damage caused by a malfunctioning heater, and once tripped, it typically requires manual reset on the ground after the cause has been investigated.
Plain English
A switch that automatically turns the cabin heater off if it gets too hot, so the heater cannot become a fire hazard.
Context Anchor
Seen in aircraft cabin heating system descriptions, especially for fuel-burning heaters used to warm cabin air.
Why Pilots Care
Prevents heater overheating that could cause fire or system failure while maintaining safe cabin temperatures.
Intuition Check
Do not think of the overheat switch as a control used to make the cabin warmer. It is a safety device that reacts when the heater reaches an unsafe temperature.
Example Sentence 1
The cabin heater quit working halfway through the flight, and after landing the mechanic found that the overheat switch had tripped.
Example Sentence 2
During preflight the mechanic verified that the overheat switch would protect the heating system from excessive temperature.