Definition
Aircraft equipment designed to manage structural ice. Anti-ice systems are turned on before ice forms and prevent it from accumulating on protected surfaces. Deice systems are activated after ice has already formed and remove it from the protected surfaces. Common methods include pneumatic boots, heated surfaces (electrical or bleed air), weeping-wing fluid systems, and heated pitot tubes and windshields.
Plain English
Equipment on the aircraft that either stops ice from forming or breaks it off once it has. Anti-ice is preventive and runs before ice appears. Deice is corrective and is used after ice has built up.
Context Anchor
Seen in instrument flying, icing discussions, aircraft equipment descriptions, and checklist procedures for cold-weather flight.
Derivation
The prefix 'de-' means to remove or reverse, so 'deice' literally means 'remove ice.' 'Anti-' means against or before, so 'anti-ice' means 'against ice forming in the first place.' The prefixes themselves carry the timing difference between the two systems.
Why Pilots Care
Correct selection and use preserves aircraft performance and control when flying in icing conditions.
Analogy
A car windshield gives a simple comparison: scraping ice off after it forms is like deicing, while using heat early to keep the glass clear is like anti-icing.
Grounding Statement
Picture an airplane in cold clouds: anti-ice is used to help keep ice from building up, while deice is used to shed ice that has already attached.
Intuition Check
Do not treat “deice” and “anti-ice” as interchangeable. Deice means remove existing ice; anti-ice means prevent or reduce new ice.
Example Sentence 1
Before entering the cloud layer at the freezing level, the pilot turned on the anti-ice systems to keep the wings and propeller clear.
Example Sentence 2
After noticing ice on the wings the crew relied on the deice and anti-ice systems to restore normal flight characteristics.