67.30-10—Sound signals.
(b)
Sound signals required by paragraph (a) of this section must have rated range of at least one-half mile, unless the District Commander prescribes a greater rated range, not to exceed 2 miles.
(c)
The owner of the structure shall operate the sound signal required by paragraph (a) of this section whenever the visibility in any direction is less than 3 miles, unless the District Commander establishes a greater or lesser distance of visibility, not to exceed 5 miles.
(1)
Authorized by the District Commander under the provisions of Subpart 66.01 of this subchapter; and