Definition
An ice-prevention system that uses heat to keep selected aircraft surfaces — typically wing leading edges, engine inlets, and tail surfaces — warm enough that ice cannot form on them in flight. The heat source is usually hot bleed air drawn from the engine compressor and routed through ducts inside the leading edge, though some systems use electrical heating elements or heat from engine exhaust.
Plain English
A system that warms parts of the aircraft so ice never gets a chance to stick in the first place.
Context Anchor
Seen in aircraft ice-protection system descriptions, maintenance manuals, and operating procedures for flight in cold moisture where ice can form.
Derivation
Thermal comes from the Greek 'thermē', meaning heat. Anti- is Latin for 'against'. Together: heat used against ice. The name tells you both the method (heat) and the goal (preventing ice).
Why Pilots Care
Keeps wings, propellers, and engine inlets free of ice so lift, thrust, and control remain normal in icing conditions.
Analogy
It is similar to a car windshield defroster: heat is applied to keep the surface clear instead of waiting for ice to cover it first.
Grounding Statement
Picture warm air moving inside a wing leading edge so the metal skin stays above freezing while the airplane flies through cold moisture.
Intuition Check
Thermal anti-icing is not the same as deicing. Anti-icing prevents ice from forming; deicing removes ice that has already formed.
Example Sentence 1
Before climbing into the clouds, the crew turned on the wing thermal anti-icing system.
Example Sentence 2
During the inspection the technician verified that hot air was flowing through the thermal anti-icing ducts on the horizontal stabilizer.