Plain English Meaning

Ice building up in the pipe that feeds outside air into the engine, choking off the engine's air supply and causing it to lose power.

Full Definition

Ice that forms in the engine's air intake system, restricting or blocking the flow of air into the engine. It typically forms on the air filter, intake screen, or intake duct walls when the airplane is flown in visible moisture (rain, wet snow, clouds) at temperatures near or below freezing. Reduced airflow into the engine causes a loss of power, rough running, and in severe cases, engine stoppage.

Context Anchor

Encountered during engine-power problems, especially in cool, damp conditions or when reviewing abnormal engine indications.