Definition
An aircraft system designed to remove ice that has already formed on critical surfaces such as wings, tail, propellers, or windshield. Deicing systems act after ice has accumulated, typically using inflatable rubber boots, electrical heating elements, or chemical fluids to break off or melt the ice.
Plain English
Equipment on the aircraft that gets rid of ice once it has built up on the surfaces.
Context Anchor
Seen in icing discussions, aircraft equipment lists, cockpit switches, and procedures for flight in or near freezing clouds or precipitation.
Derivation
From 'de-' (to remove) and 'icing' (the formation of ice). The prefix 'de-' comes from Latin, meaning 'down from' or 'away.' So 'deice' literally means to take ice away — which describes exactly what the system does after ice has formed.
Why Pilots Care
Ice changes airfoil shape, reduces lift, and increases drag; timely activation restores normal flight characteristics and prevents loss of control.
Intuition Check
Do not confuse deicing with preventing ice. A deicing system removes ice after it forms; an anti-icing system is meant to keep ice from forming in the first place.
Example Sentence 1
After picking up a quarter-inch of ice on the leading edges, the pilot activated the deicing system and watched the boots inflate to break the ice off.
Example Sentence 2
Before beginning the approach, the crew verified that the deicing system had cleared the wings of accumulated ice.