Definition
Aircraft systems designed to remove ice that has already formed on critical surfaces such as wings, tail, propellers, and windshields. Common methods include pneumatic boots that inflate to crack and shed ice, electrically heated elements, and fluid weeping systems that release a freezing-point depressant. Deice systems are activated after ice accumulation is detected, in contrast to anti-ice systems which are turned on beforehand to prevent ice from forming.
Plain English
Equipment on the aircraft that gets rid of ice once it has built up on places like the wings or propeller. The pilot turns it on after ice has formed, and the system breaks it off, melts it, or pushes it away.
Context Anchor
Seen in aircraft equipment descriptions, icing discussions, and preflight planning for flight in cold, moist conditions.
Derivation
‘Deice’ combines the prefix ‘de-’ (Latin, meaning ‘remove’ or ‘reverse’) with ‘ice.’ Literally: to take ice off something. The prefix is the same one used in ‘defrost’ or ‘deplane,’ and it signals that the action happens after the thing is already there.
Why Pilots Care
Accumulated ice changes wing shape, reduces lift, and can block controls; removing it restores normal flight characteristics.
Intuition Check
Do not treat deice and anti-ice as the same thing. Deice systems remove ice after it forms; anti-ice systems help 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 deice boots and watched the ice crack and shed away from the wing.
Example Sentence 2
Preflight checks confirmed that the propeller deice systems were operating before the winter flight.