Definition
Jet A is a kerosene-based turbine engine fuel used primarily in civil aviation in the United States. It has a flash point of approximately 100 °F and a freezing point of −40 °C, and is intended for use in turbine (jet and turboprop) engines, not piston engines.
Plain English
Jet A is the standard kerosene fuel that turbine-powered aircraft burn. It is the fuel you put in jets and turboprops, and it is different from the gasoline used in piston aircraft.
Context Anchor
Seen in fuel grade discussions, aircraft fuel placards, fuel truck markings, fueling orders, and preflight checks around the fuel caps.
Derivation
The word 'kerosene' (the base of Jet A) comes from the Greek 'keros' meaning wax, reflecting its origin as a heavier, oilier petroleum fraction than gasoline. The 'A' simply designates the grade — Jet A is one of several turbine fuel grades (Jet A, Jet A-1, Jet B), each with slightly different properties.
Why Pilots Care
Using Jet A ensures proper engine operation and prevents fuel-related failures; the wrong grade can cause starting problems, flameouts, or damage.
Grounding Statement
JET A is the fuel from the jet-fuel truck, but the aircraft still has to be approved to use it.
Intuition Check
Do not assume JET A is only for large airline jets. Some propeller aircraft use JET A because their engines are turbine engines, while many smaller piston-engine airplanes must not use it.
Example Sentence 1
Before signing the fuel receipt, the captain confirmed the truck had delivered Jet A and not Jet A-1.
Example Sentence 2
The checklist requires verification that Jet A, not Jet A-1, is available at airports where freezing temperatures are possible.