Definition
The temperature of the ambient air surrounding the aircraft, measured by a probe mounted on the airframe and displayed in the cockpit, typically in degrees Celsius. It is used as an input for performance calculations, density altitude, true airspeed computation, and icing assessment.
Plain English
The temperature of the air around the aircraft right now, shown on a gauge in the cockpit.
Context Anchor
Seen on cockpit temperature displays, performance charts, weather discussions, and instrument-flying references that use temperature as an input.
Why Pilots Care
OAT is required for density altitude, true airspeed, and engine performance calculations.
Intuition Check
Do not read OAT as cabin temperature or the temperature of a sun-warmed aircraft surface. It means the air temperature outside the aircraft, as representative of the surrounding air as the sensor can measure.
Example Sentence 1
Before takeoff, the pilot checked the OAT to calculate density altitude and confirm the runway was long enough for departure.
Example Sentence 2
Lower OAT values increase true airspeed for any given indicated airspeed.