548 - 10/07 - Automatic Identification Systems (AIS) Errors - Worldwide

The UK Maritime and Coastguard agency (MCA) has issued Marine Information Note (MIN) number 298 warning of erroneous AIS transmissions, particularly with the NAUTICAST AIS.

Replacing MIN 243, this recent notice warns that a small number of the ACR/Nauticast AIS systems transmit a default MMSI (1193046). This has the potential, in certain circumstances, to cause 'target swap' with a possible consequence that more than one ship can appear as a single ship.

Stations undertaking ship contact pursuant to the requirements MIN231 (and its successor MIN 290) should be aware that the ship name may default to "Nauticast". In this event, it may be necessary to identify a ship by its position (latitude and longitude) and if that fails, to follow up at its next port.

The problem may be caused by the MMSI not being set when installed, or by the system memory reverting to default settings in the event of loss of power. The MCA notice contains manufacturer information on how to check and change your MMSI numbers.

Users of this system should check the operation of their AIS to assure that an MMSI has been correctly installed in the AIS. Check the condition of the memory backup battery periodically as follows:

· With the AIS powered up, check that the MMSI is entered into the AIS system

· Remove power from the AIS system for approximately two minutes

· Apply power to the system and check that the correct MMSI is present

· If step 3 shows the default MMSI of 1193046 then the memory backup battery is probably discharged and must be serviced.

Visit the MCA website for the full text of the notice


Source of information:

Maritime and Coastguard Agency of the United Kingdom



Staff Author