Global Maritime Distress and Safety System

The Global Maritime Distress and Safety System (GMDSS) is a worldwide system for automated emergency signal communication for ships at sea developed by the United Nations' International Maritime Organization (IMO) as part of the SOLAS Convention. It is a set of safety procedures, types of equipment, and communication protocols used for safety and rescue operations of the distressed ships, boats, and aircraft.

Source: Wikipedia — Global Maritime Distress and Safety System (CC BY-SA 4.0)