Guidance

Safety Bulletin 30 – EPIRBs coded with the maritime user protocol: the vessel MMSI must start with a valid country code (232-235)

Updated 16 August 2022

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August 2022

The Maritime & Coastguard Agency informs owners and operators that distress alerts from Emergency Position-Indicating Radio Beacons (EPIRBs) using the Maritime User Protocol (and coded with an MMSI that does not start with a valid country code) will be processed as invalid and discarded or delayed by the Cospas-Sarsat system.

Summary of issue

Recently the International Cospas-Sarsat Programme has become aware of EPIRBs coded using Maritime User Protocol with an MMSI of ‘9’. In such cases the Cospas-Sarsat system processes a distress alert as invalid and discards or delays them.

The MMSI starting ‘9’ may result from coding;

  • a daughtercraft MMSI which starts ‘98’; or,
  • where the EPIRB has an AIS beacon, encoding the beacons AIS identity, starting ‘97’ in place of a ships MMSI

When using the Maritime User Protocol, UK EPIRBs must code the MMSI starting 232, 233, 234 or 235 that was issued to the vessel by Ofcom. For daughtercraft, the coded MMSI must be that of the parent vessel.

Note: ‘97’ is intended only for the identity message of the AIS transmitter and not for the 406 MHz EPIRB transmitter.

Actions to take

No 406 MHz EPIRB should be programmed using 98 or 97.

  • The EPIRB may be coded with a serial identity (rather than an MMSI identity), using Serial Location Protocol or Serial User Protocol as stated in MGN 665.
  • For an EPIRB of a daughtercraft associated with a parent ship, if an MMSI is used as the EPIRB identity, the MMSI should be the MMSI of the parent ship, or an MMSI specifically assigned to the craft (with a country code of 232-235). Note: there is a separate programming field that provides for separate numerical values to distinguish different EPIRBs aboard the parent ship and various associated daughtercraft.
  • New ‘second-generation’ EPIRBs have a message field for a complete nine-digit MMSI that is separate from the EPIRB’s country code field. These EPIRBs also have a separate field specifically to match the ‘974’ AIS identity for EPIRB-AIS devices. Therefore, the issues raised above should not occur on these EPIRBs provided the fields are coded correctly. Noting that the country code used must still be a valid MID.

Owners are responsible for the registration of EPIRBs as per MGN 665.

https://cospas-sarsat.int/en/documents-pro/system-documents

Documents within C/S T.000 refer to beacon coding. (T.001, T.018, T.021 & T.022)

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