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.
Plain English
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.
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.