Definition
A weather phenomenon code used in aviation weather reports and forecasts to indicate the presence or forecast of aircraft icing conditions, where supercooled water droplets freeze on contact with an aircraft's airframe, propeller, or engine intakes.
Plain English
A short code that means 'icing' — that is, ice forming on the aircraft as it flies through cold, moist air.
Context Anchor
Seen in coded pilot weather reports during weather briefings, preflight planning, and in aviation weather displays.
Derivation
From the English word 'ice,' shortened to 'IC' as a two-letter weather code. The leading slash is a formatting convention used in PIREPs and weather products to introduce a coded element.
Why Pilots Care
Icing can reduce lift, increase drag, and affect aircraft performance and safety.
Intuition Check
/IC is not a forecast by itself. It is the icing part of a pilot report, based on what a pilot observed.
Example Sentence 1
The PIREP included /IC at 8,000 feet, so the pilot requested a lower altitude to stay clear of the icing layer.
Example Sentence 2
The briefer noted /IC moderate mixed in the area forecast discussion.