Definition
A kerosene-based turbine engine fuel used in most civilian jet and turboprop aircraft in the United States, with a freezing point of -40°C or lower. It is designed for use in turbine engines and must never be used in piston aircraft engines, which require aviation gasoline (avgas).
Plain English
Jet-A is the standard fuel for jet and turboprop airplanes. It is a type of kerosene, not gasoline, and only goes into turbine-powered aircraft.
Context Anchor
Seen on fuel trucks, fuel order forms, fuel caps or placards, and in the airplane’s operating handbook when checking the approved fuel type.
Derivation
The 'Jet' refers to jet (turbine) engines. The letter 'A' designates this specific grade in a family of jet fuels, distinguished from Jet A-1 (used internationally, with a slightly lower freezing point) and Jet B (a wide-cut fuel used in very cold climates). The lettering simply marks different specifications, not quality.
Why Pilots Care
Using the correct fuel prevents engine damage and ensures reliable turbine operation.
Intuition Check
Do not assume JET-A means “any jet fuel” or that the “A” stands for aviation. Here, JET-A means one specific grade of turbine fuel approved for certain aircraft.
Example Sentence 1
The line crew confirmed the placard read Jet-A before fueling the King Air's tanks.
Example Sentence 2
Jet-A remains fluid at low temperatures, making it suitable for high-altitude flights.