An integrated communication system which uses satellite and terrestrial radio communication to ensure that no matter the ship’s position in distress, assistance can be sent. GMDSS incorporates the Inmarsat and EPIRB satellite systems to improve the reliability and effectiveness of the distress and safety system on global basis. DSC-equipped marine radios are used for routine communications and for transmitting, acknowledging and relaying distress alerts. Other elements Of the GMDSS include:
- The coastal NAVTEX broadcast system,
- High seas SafetyNet broadcast system,
- The Search and Rescue Transponder (SART) for liferafts enhancing the radar visibility of small targets.
All passenger and cargo ships over 300 grt on international voyages have to carry satellite and radio communication equipment for sending and receiving distress alerts, maritime safety information and for general communication. The requirements were published in Chapter IV of SOLAS on Radio communications and were adopted in 1988. Entered into force on the 1st February 1992, they were fully implemented seven years later.