Definition
A system installed on an aircraft that prevents the formation of ice on critical surfaces and components by heating them or by applying a fluid before ice has a chance to form. Anti-icing systems are activated before entering icing conditions and are distinct from de-icing systems, which remove ice after it has already accumulated.
Plain English
Equipment that stops ice from forming on the aircraft in the first place, rather than removing it once it has built up. It is turned on before flying into conditions where ice could form.
Context Anchor
You will see this term in aircraft systems descriptions, winter operations, preflight planning, and checklist items for flight in cold, moist conditions.
Derivation
The prefix 'anti-' comes from Greek, meaning 'against' or 'preventing.' An anti-icing system works against ice forming at all, which is what separates it from a de-icing system, where 'de-' means 'remove.'
Why Pilots Care
Ice reduces lift, increases drag, and can block engine air intakes; the system removes that hazard before it becomes dangerous.
Grounding Statement
Supercooled water droplets in clouds freeze on contact with the cold metal surfaces of the airplane.
Intuition Check
Anti-icing does not mean “ice removal after the fact.” It means preventing or limiting ice buildup before it becomes a problem. It also does not automatically mean the aircraft is approved to fly in all icing conditions.
Example Sentence 1
Before entering the cloud layer, the pilot turned on the anti-icing system to keep ice from forming on the wing leading edges.
Example Sentence 2
During the walk-around, the instructor confirmed that the anti-icing system lights were green on the panel.