Definition
An ice protection system that uses inflatable rubber boots bonded to the leading edges of the wings and tail. When ice accumulates, the boots are inflated with air pressure, expanding to crack and shed the ice, then deflate so the surface returns to its normal aerodynamic shape.
Plain English
Rubber strips on the front edges of the wings and tail that puff up with air to break ice off, then flatten back down.
Context Anchor
Seen in icing discussions, aircraft equipment descriptions, and procedures for aircraft that use deicing boots on the wing or tail.
Derivation
Pneumatic comes from the Greek 'pneuma,' meaning breath or air. The system is called pneumatic because it works by pumping air in and out of the boots.
Why Pilots Care
Ice buildup on the tailplane can produce sudden nose-down pitching moments; the system removes that ice to preserve pitch control and prevent an uncommanded stall.
Grounding Statement
Picture a rubber strip on the front of a wing swelling for a moment, cracking the ice layer, and then flattening again.
Intuition Check
Do not assume a pneumatic deicing system prevents ice from forming. It removes ice after some has accumulated; a system that prevents ice formation is an anti-icing system.
Example Sentence 1
After picking up ice in the climb, the pilot activated the pneumatic deicing system and watched the boots inflate along the wing leading edges.
Example Sentence 2
Preflight checks confirmed the pneumatic deicing system was cycling normally before entering known icing conditions.