Text in force at 23-63: from 23-0, effective 1 Feb 1965.
(a) Each riding (anchor) light required for a seaplane or amphibian, 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 the maximum unbroken light practicable when the airplane is moored or drifting on the water.
(b) Externally hung lights may be used.
29 FR 17955 · Source