The accumulation of airframe ice. Rough, milky, opaque ice formed by the instantaneous freezing of small supercooled water droplets. A glossy, clear, or translucent ice formed by the relatively slow freezing or large supercooled water droplets. A mixture of clear ice and rime ice.
Ice becomes perceptible.
Rate of accumulation is slightly greater than the rate of sublimation. Immediate flight diversion is necessary. This will help the controller to confirm an aircraft identity or to identify an aircraft. It is used to immediately distinguish one displayed beacon target from other beacon targets. At some airports, obstructions or other factors require the establishment of nonstandard takeoff minimums, departure procedures, or both to assist pilots in avoiding obstacles during climb to the minimum en route altitude.