Section 27.1399 - Riding light(a) Each riding light required for water operation must be installed so that it can- (1) Show a white light for at least two nautical miles at night under clear atmospheric conditions; and(2) Show a maximum practicable unbroken light with the rotorcraft on the water.(b) Externally hung lights may be used.Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27-2, 33 FR 964, Jan. 26, 1968