Definition
Inflatable rubber sleeves bonded to the leading edges of wings and tail surfaces that, when alternately inflated and deflated by engine-driven air pressure, flex the rubber to crack and shed accumulated ice.
Plain English
Rubber strips along the front of the wings and tail. They puff up and deflate to break ice off the airplane in flight.
Context Anchor
Used on aircraft equipped for flight in icing conditions, especially when discussing anti-icing and deicing equipment, preflight checks, and in-flight ice removal.
Derivation
Pneumatic comes from the Greek pneuma, meaning 'air' or 'breath' — the boots work by being inflated with air. 'Boot' is used in the everyday sense of a protective covering that fits over something, like a boot over a foot. Together: an air-powered protective covering for the leading edges.
Why Pilots Care
Ice on the leading edges destroys lift and control; the boots restore clean airflow so the airplane can continue to fly safely in icing conditions.
Intuition Check
Do not picture footwear. In this context, a boot is a protective rubber covering on the airplane. Pneumatic means it works by air pressure, not by heat or electricity.
Example Sentence 1
After picking up a quarter-inch of ice in the climb, the pilot cycled the pneumatic boots and watched the ice break away from the leading edges.
Example Sentence 2
During the preflight inspection the pilot verified that the pneumatic boots showed no cracks and the inflation valves operated normally.