47 CFR § 80.179 - Unattended operation.
The following unattended transmitter operations are authorized:
(a) EPIRB operations when emergency conditions preclude attendance of the EPIRB transmitter by a person.
(b) Automatic use of a transmitter during narrow-band direct-printing (NB-DP) operations in accordance with § 80.219.
(c) Automatic use of a transmitter during selective calling operations in accordance with § 80.225.
(d) Automatic use of a transmitter when operating as part of the Automated Maritime Telecommunications System (AMTS), an automated multi-station system for which provisions are contained in this part, or an automated public coast station.
(e) Automatic use of a VHF transmitter to send brief digital communications relating to the condition or safety of vessels while moored when all of the following conditions are met:
(1) The equipment must be using DSC in accordance with ITU-R M.493-13 and ITU-R M.541-9 (both incorporated by reference, see § 80.7), as modified by this section.
(2) Sensors must automatically activate the transmitter only under one or more of the following conditions:
(i) Fire, explosion;
(v) Listing, in danger of capsizing;
(vii) Disabled and adrift; and
(viii) Undesignated condition related to ship safety.
(3) The “ROUTINE” DSC category must be used.
(4) Communications must be selectively addressed to an individual station.
(5) Transmitter output power must not exceed one watt.
(6) The call must employ a fixed format and must be in conformity with Recommendation 493 as follows:
(7) Such transmissions are permitted only on channel 70 and the transmitter must be inhibited automatically whenever there is another call in progress on Channel 70.
(8) The call sequence for any one alarm must not be repeated until after an interval of at least five seconds. Further repetition is permitted only after intervals of at least fifteen minutes each. Repetitions following fifteen-minute waiting intervals must not exceed three.