Definition
A system that prevents ice from forming on the cockpit windscreen, keeping the pilot's forward view clear in icing conditions. On most general aviation aircraft this is done by spraying or pumping a freezing-point-depressant fluid (typically isopropyl alcohol) onto the outside of the windscreen. Larger and turbine aircraft commonly use electrically heated windscreen panels, while some use heated bleed air directed against the inside of the glass.
Plain English
Equipment that stops ice from building up on the front cockpit window so the pilot can still see out when flying in icy conditions.
Context Anchor
Seen in anti-ice and deice system descriptions, and on cockpit switches or checklists for aircraft equipped with a heated windscreen.
Derivation
Anti-' comes from Greek meaning 'against,' and 'ice' is the substance being prevented. So 'anti-ice' literally means 'against ice forming,' which distinguishes it from 'de-ice' systems that remove ice after it has already formed.
Why Pilots Care
Maintains forward visibility when flying through visible moisture at freezing temperatures, directly affecting the ability to continue safe flight or complete an approach.
Intuition Check
Anti-ice does not mean scraping off a thick layer of ice after it is already there. Here it means keeping the windscreen warm enough that ice is prevented from forming or sticking in the first place.
Example Sentence 1
Before entering the cloud layer, the pilot turned on the windscreen anti-ice to keep the forward view clear.
Example Sentence 2
During the preflight, the instructor confirmed that the windscreen anti-ice fluid reservoir was full for the winter flight.