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.
Plain English
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.
Context Anchor
Encountered during engine-power problems, especially in cool, damp conditions or when reviewing abnormal engine indications.
Derivation
Induction' comes from the Latin 'inducere,' meaning 'to lead in.' The induction system is the pathway that leads outside air into the engine. Induction icing is ice forming in that pathway.
Why Pilots Care
It can cause sudden engine roughness or power loss that requires immediate use of carburetor heat to restore normal operation.
Analogy
It is like trying to breathe through a straw that is slowly being squeezed shut. The engine may still run, but it cannot get the air it needs.
Grounding Statement
Picture cool, moist air entering the engine and ice forming inside the intake path until the engine can no longer breathe normally.
Intuition Check
Induction icing is not ice on the wings or windshield. It is ice in the engine’s air-intake path, where it can reduce engine power.
Example Sentence 1
After flying through wet snow for several minutes, the pilot noticed a slow drop in manifold pressure and suspected induction icing was blocking the air filter.
Example Sentence 2
Induction icing forms most readily when the outside air is cool and moist, even if no visible clouds are present.