Definition
A cockpit-operated valve that controls which fuel tank (or tanks) supplies fuel to the engine. The pilot sets it to a specific tank position (e.g., LEFT, RIGHT, BOTH) or to OFF to shut off fuel flow entirely.
Plain English
A switch or knob in the cockpit that lets the pilot choose which fuel tank the engine draws from, or shut the fuel off altogether.
Context Anchor
Seen during preflight checks, normal tank management in flight, and engine-failure or emergency checklist actions.
Derivation
Fuel means material burned to make power. Selector comes from the idea of choosing one option from several. Valve comes from an old word for a moving flap or door. Together, the term points to a control that opens the chosen fuel path and closes or limits the others.
Why Pilots Care
Correct selection prevents engine failure from fuel starvation or contamination; in emergencies it ensures the engine receives usable fuel from the best available tank.
Analogy
It is like a water control that chooses which tank or pipe feeds the pump. The pump can only use the source the selector is actually connected to.
Intuition Check
Do not assume fuel on board automatically reaches the engine. The fuel selector valve must be positioned so fuel can flow from the intended tank to the engine.
Example Sentence 1
Before starting the engine, the pilot moved the fuel selector valve to BOTH and confirmed fuel pressure was in the green.
Example Sentence 2
Before starting the engine the student confirmed the fuel selector valve was set to the fullest tank as required by the checklist.