Plain English Meaning
A jet fuel that is a mix of kerosene and gasoline, used mainly in very cold places because it does not freeze as easily as standard jet fuel.
Full Definition
A turbine engine fuel that is a wide-cut blend of kerosene and gasoline, with a lower flash point and better cold-weather performance than Jet A or Jet A-1. It is used primarily in very cold climates because it remains fluid at extremely low temperatures, but its higher volatility makes it more flammable and harder to handle safely.
Context Anchor
Seen in fuel-system discussions, aircraft fueling procedures, and fuel grade markings for turbine-engine aircraft.
Derivation
Jet B sits in a family of turbine fuel grades (Jet A, Jet A-1, Jet B). The 'B' is simply a grade designator, not an abbreviation for a longer name. The 'wide-cut' character refers to the fact that it spans a wider range of distillation temperatures than straight kerosene, blending lighter (gasoline-like) and heavier (kerosene-like) components.
Why Pilots Care
It allows turbine engines to operate safely when ambient or fuel temperatures would cause JET A or A-1 to approach their freezing limit.
Intuition Check
JET B is not simply a newer or better version of Jet A. It is a different jet fuel grade, chosen mainly for very cold conditions and handled with extra care because it is more volatile.
Example Sentence 1
Operators flying in arctic regions sometimes use Jet B because it stays fluid at temperatures where Jet A would begin to freeze.
Example Sentence 2
Maintenance records noted that the aircraft had been operated on JET B during winter operations in northern Canada.