Definition
A kerosene-based turbine engine fuel used primarily in international civil aviation, with a freezing point no higher than -47°C and a flash point of approximately 38°C. Jet A-1 is the standard jet fuel specification used outside the United States and is suitable for long-range and high-altitude operations where very low temperatures are encountered.
Plain English
A type of jet fuel made from kerosene that stays liquid at very cold temperatures. It is the standard jet fuel used in most countries outside the United States.
Context Anchor
Seen in fuel grade discussions, aircraft fuel placards, fueling orders, and aircraft operating documents for turbine-powered aircraft.
Derivation
‘Jet’ refers to jet (turbine) engines. ‘A-1’ is a specification grade — the ‘-1’ distinguishes it from standard Jet A by its lower freezing point, making it more suitable for long, cold flights at high altitude.
Why Pilots Care
Correct fuel choice prevents gelling or freezing at altitude, ensuring reliable engine operation and avoiding in-flight fuel system problems.
Intuition Check
Do not read “A-1” as meaning “best” or “premium.” Here it is a specific fuel grade with specific properties, especially a lower freezing point than Jet A.
Example Sentence 1
The flight crew confirmed the aircraft was refueled with Jet A-1 before departing on the transatlantic leg.
Example Sentence 2
The FBO offered JET A-1 instead of Jet A because the overnight temperatures were forecast to drop well below standard limits.