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Acknowledgment of a dsc distress relay alert received from a coast station

Coast stations, after having received and acknowledged a DSC distress alert, may if necessary, retransmit the information received as a DSC distress relay call, addressed to all ships, all ships in a specific geographical area, a group of ships or a specific ship.

Ships receiving a distress relay call transmitted by a coast station shall not use DSC to acknowledge the call, but should acknowledge the receipt of the call by radiotelephony on the distress traffic channel in the same band in which the relay call was received, i.e. 2182 kHz on MF, channel 16 on VHF.

Acknowledge the receipt of the distress alert by transmitting the following by radiotelephony on the distress traffic frequency in the same band in which the DSC distress relay alert was received:

    1. "MAYDAY",

    2. the 9-digit identity or the call sign or other identification of the calling coast station,

    3. "this is",

    4. the 9-digit identity or call sign or other identification of own ship,

    5. "RECEIVED MAYDAY".

Acknowledgment of a dsc distress relay alert received from another ship

Ships receiving a distress relay alert from another ship shall follow the same procedure as for acknowledgment of a distress alert, given above.

Cancellation of an inadvertent distress alert (distress call)

A station transmitting an inadvertent distress alert shall cancel the distress alert using the following procedure:

    1. Immediately transmit a DSC "distress acknowledgment" in accordance with Recommendation ITU-R M.493, 8.3.1 e.g. with own ship's MMSI inserted as identification of ship in distress. (NOTE: This feature is not yet generally available on DSC-equipped radios)

    2. Cancel the distress alert aurally over the telephony distress traffic channel associated with each DSC channel on which the "distress call" was transmitted.

    3. Monitor the telephony distress traffic channel associated with the DSC channel on which the distress was transmitted, and respond to any communications concerning that distress alert as appropriate.

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Urgency Transmission of urgency messages

Transmission of urgency messages shall be carried out in two steps:

  • announcement of the urgency message,

  • transmission of the urgency message.

The announcement is carried out by transmission of a DSC urgency call on the DSC distress calling channel (2187.5 kHz on MF, channel 70 on VHF).

The urgency message is transmitted on the distress traffic channel (2182 kHz on MF, channel 16 on VHF).

The DSC urgency call may be addressed to all stations or to a specific station. The frequency on which the urgency message will be transmitted shall be included in the DSC urgency call.

The transmission of an urgency message is thus carried out as follows:

Announcement:

    1. tune the transmitter to the DSC distress calling channel (2 187.5 kHz on MF, channel 70 on VHF);

    2. key in or select on the DSC equipment keyboard:

      • All Ships Call or the 9-digit identity of the specific station,

      • the category of the call (urgency),

      • the frequency or channel on which the urgency message will be transmitted,

      • the type of communication in which the urgency message will be given (e.g. radiotelephony), in accordance with the DSC equipment manufacturer's instructions;

    3. transmit the DSC urgency call.

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