Equipment to be duplicated for area A3 vessels

GMDSS ships operating in A3 areas are required to provide the following duplicated equipment:

  • Two complete VHF installations (including DSC), and either;
  • Two complete Inmarsat C systems and one MF radio system, or;
  • One complete Inmarsat C system and one complete MF/HF radio system (including a scanning DSC receiver and NBDP equipment).

Many GMDSS ships opt for the latter option (1 Inmarsat C and one MF/HF DSC system), on cost grounds. Unfortunately, this has proven to be one of the underlying causes of the present extremely high false alerting rate on some GMDSS systems.