Icing

Icing is the formation of ice on the aircraft when supercooled water droplets freeze on impact. It is most common in visible moisture such as cloud, rain or drizzle when the temperature is near or below freezing. Ice increases drag, reduces lift, can raise stall speed and may affect the propeller, engine intake, pitot static system and windshield. A pilot should avoid known icing conditions if the aircraft is not approved for them, use anti icing or de icing systems if installed, and change altitude or route if icing is encountered.