Definition
A fuel delivery system in which fuel flows from the fuel tanks to the engine by the force of gravity alone, without the use of a fuel pump. This arrangement is typical of high-wing aircraft, where the tanks sit above the engine, allowing fuel to descend through the lines under its own weight.
Plain English
The fuel runs downhill from the wing tanks to the engine on its own, because the tanks are higher than the engine. No pump is needed to push it.
Context Anchor
Seen in fuel system descriptions, especially on airplanes with wings mounted above the cabin.
Derivation
‘Gravity-feed’ describes the method: gravity does the feeding. The term is used because no mechanical assistance is required — the natural downward pull of gravity is enough to deliver fuel to the engine.
Why Pilots Care
Provides simple, reliable fuel delivery with fewer mechanical parts that could fail, common in training aircraft.
Analogy
Like water flowing from a rooftop tank down to a tap on the ground floor — no pump needed, the height difference does the work.
Intuition Check
Do not assume “gravity-feed” means fuel will always reach the engine automatically. It only works if there is usable fuel above the engine and the fuel path is open.
Example Sentence 1
The Cessna 172 uses a gravity-feed system, so fuel flows from the wing tanks to the engine without an electric or engine-driven pump.
Example Sentence 2
Before flight the pilot verifies that the gravity-feed system has no obstructions in the fuel lines from the wing tanks.