Definition
The formation of ice on an aircraft caused by flight through visible liquid precipitation — such as rain, drizzle, or wet snow — at temperatures at or below freezing. The supercooled water droplets or partially melted snowflakes strike the airframe and freeze on contact, accumulating on leading edges, windscreens, antennas, and control surfaces.
Plain English
Ice that builds up on the aircraft when it flies through rain or wet snow in freezing conditions. The water hits the cold airframe and freezes there.
Context Anchor
Seen in weather briefings, pilot reports, and in-flight decisions about clouds, rain, snow, and freezing conditions.
Derivation
Icing comes from ice, meaning frozen water. Precipitation comes from a Latin idea meaning to fall or be thrown down; in weather, it means water falling from the sky. Together, the term points to ice forming because falling moisture is hitting the aircraft.
Why Pilots Care
This condition can produce rapid and severe ice accumulation that degrades lift, increases drag, and may lead to loss of control if not addressed promptly.
Grounding Statement
Picture cold rain striking a cold windshield and turning into a rough layer of ice instead of running off.
Intuition Check
Do not assume icing only happens inside clouds. If freezing rain, drizzle, wet snow, or sleet is hitting the aircraft, icing can occur in the precipitation itself.
Example Sentence 1
The pilot diverted after encountering icing in precipitation while descending through a layer of freezing rain.
Example Sentence 2
The preflight briefing warned of icing in precipitation below the overcast, prompting the pilot to activate the de-icing equipment early.