icing

The formation of a deposit or layer of ice on solid objects, as a consequence of the impact of supercooled liquid water drops or droplets. It is the leading cause of aviation accidents in the world, ahead of turbulence in its different forms. In Aeronautics, special attention is paid to this occurrence in flight, for which cloud areas and levels where icing may become dangerous are forecast. Depending on the size and quantity of freezing water droplets an aircraft encounters as it passes, crossing a cloud, the rate of ice accumulation on sensitive areas of its structure will be greater or lesser, and this will dictate the maximum time that aircraft can safely fly within that cloud environment. In the most extreme cases (severe icing), ice accumulation is so rapid (> 50 mm in 5 minutes) that the aircraft's anti-icing systems are unable to remove it, with the resulting risk to flight safety.