What are the three types of structural icing?

The classification of structural icing includes the types known as Clear, Mixed, and Rime icing. Clear icing forms when supercooled water freezes upon contact with an aircraft's surface, creating a glossy, clear ice layer. This type of icing can significantly increase aerodynamic drag and weight. Mixed icing occurs when a combination of both clear and rime ice is present, usually resulting from varying sizes of water droplets in different temperature zones. Rime icing is characterized by small, opaque ice crystals formed when supercooled large droplets freeze on impact, typically occurring in colder conditions and resulting in a more granular surface.

Understanding these categories is essential for pilots and crew to identify risks and manage flight conditions effectively. Other combinations mentioned in the incorrect choices do not accurately reflect the established classifications recognized in aviation safety guidelines.