Definition
The actual temperature of the undisturbed air mass through which an aircraft is flying, measured without any heating effect caused by the aircraft's motion through the air.
Plain English
The real temperature of the air outside the aircraft, as it would be if the aircraft were sitting still in it.
Context Anchor
Seen in aircraft performance planning, air data displays, and discussions of outside air temperature at altitude.
Derivation
Static comes from the Latin staticus, meaning 'standing still.' Here it refers to the air at rest relative to itself — not the air being compressed or heated as the aircraft pushes through it.
Why Pilots Care
Correct static air temperature values are required to compute true airspeed, density altitude, and engine performance limits.
Grounding Statement
If the airplane’s motion makes the temperature sensor read slightly warm, Static Air Temperature is the corrected value for the air outside.
Intuition Check
Static does not mean the air is not moving at all. Here it means the temperature of the outside air without the added warming caused by the aircraft moving through it.
Example Sentence 1
At cruise altitude the pilot noted a static air temperature of minus fifteen degrees Celsius before computing true airspeed.
Example Sentence 2
Static air temperature was used to convert indicated airspeed into true airspeed for the flight log.