Definition
A fuel system arrangement on multi-tank or multi-engine airplanes that allows fuel from one tank (or one side of the airplane) to be routed to an engine on the opposite side, or to any selected engine. It is used primarily to manage lateral fuel imbalance or to continue feeding a running engine after the loss of an engine on the other side.
Plain English
A valve setting that lets fuel from one tank feed an engine on the other side of the airplane, so you can even out fuel between the wings or keep an engine running if its normal tank is unusable.
Context Anchor
Seen in fuel-system descriptions, cockpit fuel selector use, abnormal procedures, and multi-engine airplane operations.
Derivation
‘Crossfeed’ is a plain compound: ‘cross’ (over to the other side) and ‘feed’ (supplying fuel). The name describes exactly what the system does — it feeds fuel across to the other side of the airplane.
Why Pilots Care
Allows balancing fuel loads between tanks or supplying an engine when its primary tank is unusable due to pump failure, contamination, or exhaustion.
Intuition Check
Fuel crossfeed does not usually mean pouring fuel from one tank into another tank. It means routing fuel so an engine can use fuel from another tank or side.
Example Sentence 1
After securing the left engine, the pilot selected crossfeed so the right engine could draw fuel from the left main tank.
Example Sentence 2
With the left fuel pump inoperative, the pilot used fuel crossfeed to keep the left engine running from the right tank.