Plain English Meaning

Ice forming on the aircraft while flying through cold, moist air. It changes the shape of the wings, adds weight, and can block instruments or controls, making the aircraft harder or unsafe to fly.

Full Definition

The accumulation of ice on aircraft surfaces, typically caused by supercooled water droplets striking and freezing on the airframe, propeller, windscreen, or engine components during flight through visible moisture at temperatures at or below freezing. Icing degrades aerodynamic performance, adds weight, disrupts airflow, and can interfere with control surfaces, engine intakes, pitot- , and .