The IMO defines GMDSS as the basic concept of GMDSS is that search and rescue authorities ashore, as well as shipping in the immediate vicinity of the ship in distress, will be rapidly alerted to a distress incident so that they can assist in a co-coordinated SAR operation with the minimum delay. The system also provides for agency and safety communications and the promulgation of Maritime Safety Information (MSI) - navigational and meteorological warnings and forecasts and other urgent safety information to ships. In other words, every ship is able, irrespective of the area in which it operates, to perform those communication functions which are essential for the safety of the ship itself and of other ships operating in the same area.

Components of GMDSS
GMDSS consists of several different safety systems based around different communications technologies. These include DSC, NAVTEX and INMARSAT.

The Global Maritime Distress and Safety System (GMDSS) forms Chapter IV of the SOLAS (Safety Of Life At Sea)Convention and was introduced in stages between 1993 and 1 February 1999. Its creation marked the biggest change to maritime communications since the invention of radio.

Requirements
Full operation of the Global Maritime Distress and Safety System (GMDSS) is planned for February 1st 1999. Under IMO legislation, all passenger vessels had to be fitted with the necessary equipment by 1995, and all vessels over 300grt to be GMDSS equipped by the 1st February deadline. National administrations are also being encouraged to provide the necessary shore based infrastructure in sufficient time.

Benefits
Under the GMDSS, all Distress and Safety communication will be automated and watchkeeping on traditional voice and Morse code frequencies become history. At the press of a button, a ship can send its identity, position and nature of distress by either satellite or terrestrial communication. It will then be up to a shore based Rescue Co-ordination Centre (RCC) to alert vessels in the area to go to the aid of the casualty. This co-coordinating role of the RCC is a new one. Under the SOLAS 1974 system, ships in the area were required to monitor for distress alerts and then respond directly. The GMDSS now makes this the responsibility of the RCC.

GMDSS also changes the nature of Routine and Safety Radio operation. These become fully automatic, enabling ship’s officers with a General Operator’s Certificate (GOC) to deal with all incoming and outgoing ship’s radio communication. It will no longer be necessary to sail with a specialist radio officer.