Definition
A valve in a multi-engine aircraft fuel system that allows fuel from a tank on one side of the aircraft to be routed to an engine on the opposite side. When opened, it connects the left and right fuel systems so either engine can draw from either side's tanks.
Plain English
A valve that lets the left engine drink from the right tank, or the right engine drink from the left tank. Normally each engine feeds from its own side, but this valve opens a path between them when needed.
Context Anchor
Seen in multi-engine aircraft fuel systems, cockpit fuel controls, emergency procedures, and fuel management checklists.
Derivation
Cross' meaning across or from one side to the other, plus 'feed' meaning to supply. The valve literally feeds fuel across the aircraft from one side's tank to the other side's engine.
Why Pilots Care
Enables continued engine operation or balanced fuel consumption when one tank is low or unusable, directly affecting flight safety and range.
Analogy
Think of two water tanks with a pipe between them and a shutoff handle in the pipe. Opening the handle lets water move across to serve the other side; closing it keeps each side separate.
Intuition Check
Do not assume “cross-feed” means both tanks automatically share fuel evenly. It means the pilot or system has opened a path for fuel to feed across to another side or engine.
Example Sentence 1
After the right engine was shut down, the pilot opened the cross-feed valve so the left engine could draw fuel from the right wing tank.
Example Sentence 2
During the engine-failure procedure, the crew used the cross-feed valve to keep the operating engine running from the opposite wing tank.