Definition
An ice protection system that uses heat to prevent ice from forming on critical aircraft surfaces such as wing leading edges, engine inlets, and propellers. Heat is supplied either by hot bleed air ducted from the engine compressor, by exhaust heat exchangers, or by electrical heating elements embedded in or beneath the surface. The heat keeps the protected surface above freezing so that supercooled water droplets cannot adhere and freeze.
Plain English
A system that warms key parts of the aircraft so ice cannot form on them in the first place.
Context Anchor
Seen in aircraft system descriptions, preflight checks, and operating procedures for flying near freezing temperatures when clouds, rain, or other moisture may be present.
Derivation
Thermal comes from the Greek thermos, meaning heat. Anti- is Latin for against, and ice is the substance being prevented. Together: using heat to work against ice forming.
Why Pilots Care
Ice on wings or engines reduces lift and power; this system keeps surfaces clear to maintain safe performance and control.
Grounding Statement
The basic idea is simple: keep the surface warm enough, and ice has a harder time sticking or forming there.
Intuition Check
Do not read anti-ice as the same thing as deice. Anti-ice is mainly used to prevent ice from forming; deice is mainly used to remove ice after it has formed.
Example Sentence 1
Before climbing into the cloud layer at the freezing level, the pilot turned on the thermal anti-ice system to protect the wing leading edges and engine inlets.
Example Sentence 2
During the instrument flight, the crew monitored the thermal anti-ice system to ensure the engine inlets stayed clear.