Definition
Aircraft systems and devices designed to prevent the formation of ice on critical surfaces and components by being activated before ice begins to form. Common anti-icing equipment includes heated pitot tubes, heated stall warning sensors, heated fuel vents, electrically heated propellers or windshields, and weeping-wing systems that bleed a freezing-point-depressing fluid through small pores in the leading edges.
Plain English
Equipment turned on before ice forms to stop it from forming in the first place. It protects parts of the aircraft where ice would be dangerous, like the wings, propeller, windshield, and air sensors.
Context Anchor
Seen in aircraft systems descriptions, preflight checks, and procedures for flight near freezing temperatures, clouds, rain, or other visible moisture.
Derivation
From 'anti-' (Latin/Greek, meaning 'against' or 'preventing') and 'icing' (the formation of ice). The label is literal: equipment that acts against ice forming. This is what distinguishes it from deicing equipment, which removes ice that has already formed.
Why Pilots Care
Prevents loss of lift, increased drag, and engine power loss that can quickly make the airplane unflyable; allows continued safe operation instead of requiring immediate exit from icing conditions.
Intuition Check
Do not read “anti-icing” as the same thing as “deicing.” Anti-icing is mainly prevention or delay of ice buildup; deicing is removal of ice that is already present.
Example Sentence 1
Before climbing into the cloud layer, the pilot turned on the pitot heat and other anti-icing equipment.
Example Sentence 2
During the preflight, the instructor verified that the anti-icing equipment was operational and the fluid reservoir was full for the planned flight through known icing.