GMDSS sea areas and radio survey (SOLAS IV, 2024)

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The Global Maritime Distress and Safety System (GMDSS) is built on one promise: wherever a ship is, she can raise the alarm ashore by at least two separate and independent means, and the rescue coordination centre can talk back. Since 1 January 2024 that promise is delivered under a completely new text of SOLAS Chapter IV, adopted by resolution MSC.496(105). “Inmarsat” has disappeared from the convention, Iridium can now provide GMDSS services where the flag accepts it, and HF radio telex is no longer a GMDSS requirement.

Radio equipment that sits quietly on the bridge for years is exactly the equipment that fails when it is finally needed. In 2024 the Tokyo MOU recorded 1,244 radio communication deficiencies, and “absence or failure of the proper operation of the radio equipment for distress and safety communication” is on the IMO list of grounds for detention. This lesson explains the sea areas, what each requires, and what happens during the radio survey.

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In this lesson

Try it: Where does each requirement first appear in SOLAS Chapter IV?
In plain words
In detail
What the rules say
Flag and class notes
Key numbers
What inspectors find
Questions people ask
Quiz: 5 questions

Sources

1 IMO Resolution MSC.496(105), Amendments to the International Convention for the Safety of Life at Sea, 1974 (adopted 28 April 2022, in force 1 January 2024), annex, new text of chapter IV, regulations 2, 4, 7 to 13, 15, 16 and 18. https://www.amsa.gov.au/sites/default/files/2023-11/resolutions_mscresolutions_res.msc_.496105_230713_050220-1.pdf
2 IMO Resolution A.1207(34), Survey Guidelines under the Harmonized System of Survey and Certification (HSSC), 2025, annex, general part paragraphs 4.4.1 and 5.11, and part 4 (Cargo Ship Safety Radio Certificate), paragraphs (RI) 4.1.1 to 4.1.4 and (RP) 4.2. https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2034-Res.1207%20-%20SURVEY%20GUIDELINES%20UNDER%20THE%20HARMONIZED%20SYSTEMOF%20SURVEY%20AND%20CERTIFICATION%20(HSSC),%202025%20(Secretariat).pdf
3 Indian Register of Shipping, Technical Circular No. 030/2023, Amendments to SOLAS Chapter IV (Radiocommunications). https://www.irclass.org/technical-circulars/amendments-to-solas-chapter-iv-radiocommunications/
4 IACS Unified Requirement Z17, Procedural requirements for service suppliers, annex 1, section on firms engaged in surveys, inspections and testing of radio communication equipment (text read: Rev.11, 2015; check the current revision on the IACS website). https://iacs.org.uk/
5 Tokyo MOU, Annual Report on Port State Control in the Asia-Pacific Region 2024, Tables 7 and 14. https://www.tokyo-mou.org/wp/wp-content/uploads/ANN24-1.pdf
6 IMO Resolution A.1206(34), Procedures for port State control, 2025 (adopted 3 December 2025), appendix 2, section 5, item 9; appendix 7, paragraph 5.1.4.5; appendix 12, item 6. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/AssemblyDocuments/A.1206(34).pdf

Free awareness training. Al Safwan Marine is not an approved training provider, so no certificate is given, and these courses are not a qualification. They don't replace STCW training, manufacturer training or the certification technicians need for this work. The manufacturer's manual and your flag's rules always come first.

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