Icing (Structural)

The accumulation of ice on the external surfaces of an aircraft when flying through visible moisture (clouds or precipitation) at temperatures at or below freezing. Structural ice adds weight, disrupts the smooth airflow over the wings (reducing lift and increasing drag), and can block pitot tubes and static ports. The three types are clear ice (heavy, hard to remove), rime ice (rough and opaque), and mixed ice. Most training aircraft are not certified for flight into known icing conditions.