Text in force at 29-59: from 29-0, effective 1 Feb 1965.
(a) Each riding light required for water operation must be installed so that it can--
(1) Show a white light for at least two 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.
29 FR 16150 · Source