GMDSS

Global Maritime Distress and Safety System (GMDSS) is an internationally mandated framework of safety procedures, communications networks, and equipment intended to automate distress alerting and the coordination of search and rescue (SAR) at sea. It operates to ensure that ships in distress can quickly transmit their location, vessel identification, and other essential data to competent authorities and nearby ships, so that a rapid response can be organized.

GMDSS is established by the SOLAS (Safety of Life at Sea) convention and applies to ships on international voyages that meet certain tonnage or passenger-vessel criteria. It integrates multiple communication systems and services to provide redundant paths for distress and safety information, covering global sea areas through different technologies and networks. The system is designed to function even if some components fail, by routing alerts through available channels and authorities.

The equipment set typically required under GMDSS includes satellite communication gear (such as Inmarsat-based terminals or other recognized satellite data terminals), VHF and MF/HF radiotelephones with digital selective calling (DSC), a NAVTEX receiver for coast-wide navigational and weather warnings, a Search and Rescue Transponder (SART) for radar-based localization, and emergency position-indicating beacons (EPIRBs) operating on COSPAS-SARSAT 406 MHz. Additional elements may include SafetyNET for satellite-based safety messages and onboard operational procedures for maintenance and testing.

In practice, a distress alert is initiated via DSC or satellite networks, automatically or manually transmitted to the MRCC (Maritime Rescue Coordination Center), which coordinates SAR resources and disseminates safety information to ships and shore facilities as needed. Crews receive training and conduct regular tests to ensure readiness.