Definition
A cockpit instrument that displays the temperature of the ambient air outside the aircraft, typically measured by a probe mounted on the airframe where it is exposed to the free airstream. The reading is used by the pilot to assess conditions affecting engine performance, density altitude, carburetor icing risk, and true airspeed calculations.
Plain English
A small gauge in the cockpit that tells the pilot how hot or cold the air is outside the aircraft.
Context Anchor
Seen on the instrument panel and in discussions of carburetor ice and induction-system icing risk.
Why Pilots Care
Pilots use OAT readings to calculate density altitude, true airspeed, and to assess the risk of carburetor icing.
Intuition Check
Do not assume the OAT gauge shows the temperature inside the cockpit or inside the engine. It shows the temperature of the air outside the aircraft, which may be different from air after it enters the engine system.
Example Sentence 1
Before takeoff from the high-elevation airport, the pilot checked the OAT gauge to calculate density altitude.
Example Sentence 2
A drop in the outside air temperature (OAT) gauge reading indicated a higher likelihood of icing conditions.