Definition
A turbine engine system that prevents ice from forming on the engine inlet, inlet guide vanes, and other critical components by directing hot compressor bleed air to those surfaces. It is designed to be turned on before icing conditions are encountered, not to remove ice that has already formed.
Plain English
A system that pipes hot air from inside the engine onto the parts at the front of the engine to keep ice from forming there.
Context Anchor
A pilot encounters engine anti-ice in turbine airplane checklists, cold-weather procedures, and operations in cloud, rain, snow, or other moisture near freezing temperatures.
Derivation
"Anti" means "against" or "before," and "ice" is the hazard. The name reflects the system's purpose: acting before ice forms, rather than removing it after the fact. This is what separates it from de-ice systems, which remove ice already present.
Why Pilots Care
Prevents ice ingestion that can damage compressor blades, cause engine surge, or lead to flameout.
Intuition Check
Do not read engine anti-ice as a general engine heater. Its job is to protect specific engine surfaces from ice buildup, mainly where incoming air could carry ice into the engine.
Example Sentence 1
Before descending into the cloud layer near freezing, the crew turned engine anti-ice on.
Example Sentence 2
With engine anti-ice active, bleed air warmed the inlet lips and kept ice from forming on the spinner.