1257. Aircraft observations.

1257.     Aircraft observations.

Special observations must be made and reported by all aircraft whenever the following conditions are encountered or observed:

  1.  

    (1)     moderate or severe turbulence1;

  2.  

    (2)     moderate or severe icing2;

  3.  

    (3)     severe mountain wave3;

  4.  

    (4)     thunderstorms, without hail, that are obscured, embedded, widespread or in squall lines4;

  5.  

    (5)     thunderstorms, with hail, that are obscured, embedded, widespread or in squall lines5;

  6.  

    (6)     heavy dust storm or heavy sandstorm6;

  7.  

    (7)     volcanic ash cloud7; or

  8.  

    (8)     pre-eruption volcanic activity