In 1979, a group of experts drafted the International Convention on Maritime Search and Rescue, which called for the development of a global search and rescue plan.  This group also passed a resolution calling for the development of a Global Maritime Distress and Safety System (GMDSS) to provide the communication support needed to implement the global search and rescue plan.  

This system, which the world's maritime nations - including the United States - have implemented, is based upon a combination of satellite and terrestrial radio services and has changed international distress communications from being primarily ship-to-ship-based to primarily ship-to-shore-based (Rescue Coordination Center).  

For more information download a GMDSS Inspection Checklist.