Definition
The act of servicing an aircraft with the wrong type of fuel for its engine — most commonly putting jet fuel (kerosene-based, such as Jet A) into a piston-engine aircraft designed for aviation gasoline (avgas), or the reverse.
Plain English
Putting the wrong kind of fuel in the airplane. Piston engines need avgas; turbine engines need jet fuel. Mixing them up is misfueling.
Context Anchor
Encountered during fueling, preflight inspection, fuel-sample checks, and review of fuel receipts or fuel placards near the filler caps.
Derivation
Built from the prefix 'mis-' (wrongly, badly) and 'fueling.' The prefix flags an error in the action — not just fueling, but fueling done incorrectly.
Why Pilots Care
Misfueling can cause rapid engine failure or seizure, often within minutes of engine start, creating an immediate safety emergency.
Intuition Check
Do not treat misfueling as simply “not enough fuel.” Misfueling means the fuel itself is wrong for that aircraft.
Example Sentence 1
After landing at an unfamiliar field, the pilot watched the fueling closely to prevent any chance of misfueling.
Example Sentence 2
Misfueling a piston aircraft with jet fuel will usually destroy the engine shortly after takeoff.