Definition
An ice-prevention system that pumps alcohol — typically isopropyl alcohol — onto vulnerable surfaces such as propeller blades, windshields, or carburetors before ice can form. The alcohol mixes with water on the surface, lowering its freezing point so it cannot turn to ice at the prevailing temperature.
Plain English
A system that sprays alcohol onto parts of the aircraft to stop ice from forming there. Alcohol mixed with water freezes at a much lower temperature than water alone, so ice cannot take hold while the alcohol is flowing.
Context Anchor
Seen in aircraft equipment descriptions, winter operations, and preflight checks for airplanes equipped with alcohol-based ice protection.
Derivation
"Anti-icing" means preventing ice from forming, as opposed to "de-icing" which removes ice after it forms. The distinction matters: this system is used before ice appears, not to break it off afterward.
Why Pilots Care
Prevents vibration, thrust loss, and engine damage caused by ice accumulation on critical surfaces during flight.
Grounding Statement
Picture alcohol-based fluid being fed onto a cold propeller blade or windshield so moisture has a harder time freezing there.
Intuition Check
Alcohol here does not mean drinking alcohol. It means an alcohol-based anti-icing fluid used by the aircraft. Anti-icing means helping prevent ice from forming; it is not mainly for removing a heavy ice buildup after it is already there.
Example Sentence 1
Before climbing into the cloud layer where icing was forecast, the pilot switched on the alcohol anti-icing system to protect the propeller.
Example Sentence 2
During the preflight inspection the mechanic verified that the alcohol reservoir for the anti-icing system was full.