CAT.IDE.H.145 Radio altimeters

(a) Helicopters on flights over water shall be equipped with a radio altimeter capable of emitting an audio warning below a pre-set height and a visual warning at a height selectable by the pilot, when operating:

(1)  out of sight of the land;

(2)  in a visibility of less than 1500 m;

(3)  at night; or

(4)  at a distance from land corresponding to more than three minutes at normal cruising speed.