Definition
Two related causes of engine power loss involving fuel supply. Fuel exhaustion is the condition in which the airplane has consumed all usable fuel on board, leaving none available to the engine. Fuel starvation is the condition in which usable fuel remains on board but is not reaching the engine, typically due to an empty selected tank, a closed or mispositioned fuel selector, a failed fuel pump, contamination, vapor lock, or another delivery problem.
Plain English
Exhaustion means the tanks are dry — the airplane has burned all its fuel. Starvation means there is still fuel on board, but it isn't getting to the engine for some reason, like the selector being on an empty tank or a pump failing.
Context Anchor
Encountered in engine-failure and emergency-landing discussions, especially when reviewing preventable causes of power loss.
Derivation
Exhaustion comes from Latin exhaurire, 'to draw out completely' — the tanks have been drawn dry. Starvation comes from Old English steorfan, 'to die,' later meaning to be deprived of something needed. The engine isn't out of fuel; it's being deprived of it.
Why Pilots Care
Correct identification tells the pilot whether switching tanks or other in-flight actions can restore power or whether a true fuel emergency exists.
Analogy
It is like the difference between a water bottle being empty and a full water bottle with the cap still closed. In one case, the supply is gone; in the other, the supply exists but is not reaching you.
Intuition Check
Do not treat exhaustion and starvation as the same thing. Exhaustion means the usable fuel is gone; starvation means fuel may still be aboard but is not reaching the engine.
Example Sentence 1
The accident report concluded the engine quit due to fuel starvation — the left tank ran dry while the right tank still held twelve gallons, but the selector was never switched.
Example Sentence 2
Fuel starvation stopped the engine even though the tanks were half full because the fuel selector was on an empty tank.