Definition
Aircraft systems designed to prevent the formation of ice on critical surfaces and components by being activated before ice begins to accumulate. They protect areas such as wing leading edges, propellers, windshields, pitot tubes, static ports, fuel vents, and engine inlets, typically using heat (electrical, bleed air, or exhaust), heated fluids, or chemical fluids that lower the freezing point of water on the protected surface.
Plain English
Equipment switched on ahead of time to stop ice from forming on the aircraft in the first place, rather than removing it after it has built up.
Context Anchor
Seen in aircraft systems, winter operations, icing-condition procedures, and checklists for equipment such as wings, propellers, windshields, engine inlets, and air-data sensors.
Derivation
Anti-' comes from the Greek for 'against' or 'before' -- the same root used in words like 'antibiotic' and 'antifreeze'. Combined with 'ice', it captures the system's purpose: to act against ice before it forms, not after.
Why Pilots Care
Prevents loss of lift, increased drag, and blocked engine inlets that can lead to loss of control or forced landing.
Analogy
It is like using a car’s windshield defroster before the glass becomes covered with ice; the goal is to stop the ice from taking hold in the first place.
Intuition Check
Anti-ice does not mainly mean removing ice after it has already built up. In aviation, anti-ice means preventing ice from forming on the parts the system protects.
Example Sentence 1
Before climbing into the cloud layer at the freezing level, the pilot turned on the anti-ice systems for the wings and propeller.
Example Sentence 2
During the winter preflight the instructor verified that all anti-ice systems were functioning.