Maritime distress alerting system

The future development of a global maritime distress alerting system is discussed with particular emphasis on the possible role of satellite relays. The present maritime distress system, which is based on a complicated interlinking of several elements by means of telephone, morse code telegraphy or emergency position-indicating radio beacons (EPIRBs), is considered, and disadvantages related to the unreliability of radio propagation at the various frequencies employed are pointed out. The requirements established by the Inter-Governmental Maritime Consultative Organization for its Future Global Maritime Distress and Safety System, to be implemented around 1990, are then presented in relation to distress alerting methods and ranges, the identification of the unit in distress, the positioning of the unit in distress, search and rescue coordinating communications, on-scene communications, locating the unit in distress or its survivors, and preventive actions. The capabilities of geostationary and low polar orbiting communications satellites in meeting these requirements are discussed, with consideration also given to the use of satellite EPIRBs and a combined geostationary-polar orbiting satellite system.