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4 ALBERT EMBANKMENT LONDON SE1 7SR
Telephone: +44 (0)20 7735 7611 Fax: +44 (0)20 7587 3210
MSC.1/Circ.1657
28 November 2022
The Maritime Safety Committee, at its 106th session (2 to 11 November 2022), approved the revised Procedure for responding to DSC distress alerts by ships, as set out in the annex, prepared by the Sub-Committee on Navigation, Communications and Search and Rescue (NCSR), at its ninth session (21 to 30 June 2022).
This circular contains a procedure to be followed by radio personnel on board ships when responding to VHF, MF and HF distress alerts, in accordance with chapter IV of the International Convention for the Safety of Life at Sea, 1974. Flow diagrams 1 and 2 in the annex are recommended to be displayed on ships' bridges as A4 size posters.
Member Governments are invited to bring the annexed Procedure to the attention of seafarers and all other parties concerned.
This circular becomes effective on 1 January 2024, superseding COMSAR/Circ.25 as from that date.
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I:\CIRC\MSC\1\MSC.1-Circ.1657.docx
MSC.1/Circ.1657
Annex, page 1
This document provides a procedure for responding to VHF, MF and HF distress alerts, given in flow diagrams 1 and 2, which are recommended to be displayed on the ship's bridge as A4 size posters. It also provides the following guidance.
Radio personnel serving on ships should be made aware of the consequences of transmitting a distress call relay and of routeing a DSC distress alert relay to destinations other than coast stations (CS).
The number of unintended activations of DSC distress alerts and DSC distress alert relays creates extra workload and confusion for (M)RCCs and also causes delay in the response-time. The original distress alert from a ship in distress should not be disrupted by other ships, by transmitting a DSC distress alert relay.
Recommendation ITU-R M.541 on Operational procedures for the use of digital selective-calling equipment in the maritime mobile service identifies only two situations in which a ship would transmit a distress call relay (distress alert relay):
on receiving a distress alert on an HF channel, which is not acknowledged by a coast station within five minutes. The distress call relay should be addressed to the appropriate coast station (annex 1, paragraph 3.4.2 and annex 3, paragraph 6.1.4); and
on knowing that another ship in distress is not itself able to transmit the distress alert and the master of the ship considers that further help is necessary. The distress call relay should be addressed to "all ships" or to the appropriate coast station (annex 3, paragraph 1.4).
In no case is a ship permitted to transmit a DSC distress alert relay on receipt of a DSC distress alert on either VHF or MF channels.
Distress calls relay on HF channels should be initiated manually.
Compliance with operational and technical provisions above would prevent transmissions of inappropriate distress calls relay.
Recommendation ITU-R M.493 on Digital selective-calling systems for use in the maritime mobile service provides for "group calls" an address consisting of the characters corresponding to the station's maritime mobile service identity (MMSI) and a number of Administrations have already assigned a "group call" MMSI to their coast stations in addition to the coast station's individual MMSI.
MSC.1/Circ.1657
Annex, page 2
By multilateral agreements, a "group call" MMSI could be assigned to all coast stations of a specific region, e.g. an RCC area, and could comply with IMO's requirement without need of introducing further modifications to GMDSS equipment.
An alternative method to implement an "all coast stations" call without the need to modify Recommendation ITU-R M.493 could be to use the reserved MMSI worldwide as an address for all coast stations, in accordance with Recommendation ITU-R M.585 on Assignment and use of identities in the maritime mobile service. However, this solution is not applicable to MF or HF coast stations and would also require a modification of the set-up at each VHF coast station participating in the GMDSS.
It should be noted that on ships, distress alerts, distress acknowledgements and distress call relays can only be transmitted with the permission of the master of the ship.
The simplified flow diagrams 1 and 2 describe actions to be taken aboard ships upon receipt of distress alerts from other ships. Administrations distribute these flow diagrams widely to ships and training institutions.
Member Governments are invited to bring the above guidance and the attached flow diagrams to the attention of their shipowners, seafarers, coast stations, RCCs and all others concerned.
MSC.1/Circ.1657
Annex, page 3
ACTIONS BY SHIPS UPON RECEPTION OF A VHF / MF DSC DISTRESS ALERT
IS
THE ALERT ACKNOWLEDGED BY CS AND/OR RCC?
IS DISTRESS TRAFFIC IN PROGRESS?
IS THE DSC
DISTRESS CALL
CONTINUING?
IS
OWN VESSEL ABLE TO ASSIST?
ACKNOWLEDGE THE ALERT BY RADIOTELEPHONY
TO THE SHIP IN DISTRESS ON VHF CH 16 / 2 182 kHz
INFORM CS AND OR RCC
ENTER DETAILS IN LOG
RESET SYSTEM
VHF CH 16 / 2 182 kHz
DSC DISTRESS ALERT
IS RECEIVED
Note 1: Appropriate or relevant RCC and/or coastal station should be informed accordingly. If further DSC distress alerts are received from the same source and the ship in distress is beyond doubt in the vicinity, a DSC acknowledgement may, after consultation with an RCC or coastal station, be sent to terminate the call.
Note 2: In no case is a ship permitted to transmit a DSC distress alert relay on receipt of a DSC distress alert on either VHF channel 70 or MF channel 2 187.5 kHz.
CS = coastal station RCC = rescue coordination centre
MSC.1/Circ.1657
Annex, page 4
IS THE ALERT
ACKNOWLEDGED OR RELAYED BY CS AND/OR
RCC?
IS DISTRESS
COMMUNICATION IN PROGRESS ON ASSOCIATED RTF CHANNELS?
TRANSMIT DISTRESS ALERT RELAY ON HF TO COAST STATION AND INFORM RCC
IS
OWN VESSEL ABLE TO ASSIST?
ENTER DETAILS IN LOG
RESET SYSTEM
CONTACT RCC VIA MOST EFFICIENT MEDIUM TO OFFER ASSISTANCE
ACTIONS BY SHIPS UPON RECEPTION OF A HF DSC DISTRESS ALERT
HF DSC DISTRESS ALERT IS RECEIVED
HF DSC AND RTF | CHANNELS (kHz) |
DSC | RTF |
4 207.5 | 4 125.0 |
6 312.0 | 6 215.0 |
8 414.5 | 8 291.0 |
12 577.0 | 12 290.0 |
16 804.5 | 16 420.0 |
NOTE 1: If it is clear the ship or persons in distress are not in the vicinity and/or other crafts are better placed to assist, superfluous communications which could interfere with search and rescue activities are to be avoided. Details should be recorded in the appropriate logbook.
NOTE 2: The ship should establish communications with the station controlling the distress as directed and render such assistance as required and appropriate. NOTE 3: Distress alert relays should be initiated manually.
CS = coastal station RCC = rescue coordination centre