Section 697.9 - Facilitation of enforcement(a)General. See § 600.730 of this chapter.(b)Radio hails. Permit holders, while underway, must be alert for communication conveying enforcement instructions and immediately answer via VHF-FM radio, channel 16, when hailed by an enforcement officer. Vessels not required to have VHF-FM radios by the Coast Guard are exempt from this requirement.64 FR 68248, Dec. 6, 1999, as amended at 73 FR 67809 , Nov. 17, 2008