Definition
Inflatable rubber sleeves bonded to the leading edges of wings and tail surfaces that expand and contract pneumatically to break off ice that has already formed. When activated, engine-driven pneumatic pressure inflates the boots, cracking the accumulated ice so that airflow carries it away; the boots then deflate and return flush with the airfoil shape.
Plain English
Rubber strips along the front edges of the wings and tail that puff up like a balloon to crack ice off, then flatten back down so the wing flies normally again.
Context Anchor
Seen in aircraft ice-protection discussions, especially for airplanes certified to fly in icing conditions.
Derivation
Deicing' means removing ice that has already formed (as opposed to 'anti-icing,' which prevents it from forming). 'Boot' is used in the older mechanical sense of a protective sleeve or covering fitted over something — like a rubber boot fits over a shoe. Together: a rubber sleeve that removes ice.
Why Pilots Care
Maintains lift and control authority when operating in icing conditions.
Analogy
A deicing boot works a little like flexing a thin rubber cover so a crust of ice cracks and falls away.
Grounding Statement
When ice starts building on the wing’s front edge, the boot swells briefly and breaks the ice loose from the surface.
Intuition Check
Do not read “boots” as anything related to shoes. In this aviation use, deicing boots are inflatable protective strips that remove ice; they are not an anti-ice system that keeps the surface warm all the time.
Example Sentence 1
After picking up a quarter-inch of rime ice on the leading edges, the pilot activated the deicing boots and watched the ice crack and shed into the slipstream.
Example Sentence 2
During preflight, the mechanic inspected the deicing boots for cracks or loss of flexibility.