GMDSS
OVERVIEW
An Overview of the Global Maritime Distress & Safety System
Since the invention of radio at the end of the 19th Century, ships
at sea have relied on Morse code, invented by Samuel Morse and first
used in 1844, for distress and safety telecommunications. The need
for ship and coast radio stations to have and use radiotelegraph
equipment, and to listen to a common radio frequency for Morse encoded
distress calls, was recognized after the sinking of the liner Titanic
in the North Atlantic in 1912. The U.S. Congress enacted legislation
soon after, requiring U.S. ships to use Morse code radiotelegraph
equipment for distress calls. The International Telecommunications
Union (ITU), now a United Nations agency, followed suit for
ships of all nations. Morse encoded distress calling has saved thousands
of lives since its inception almost a century ago, but its use requires
skilled radio operators spending many hours listening to the radio
distress frequency. Its range on the medium frequency (MF) distress
band (500 kHz) is limited, and the amount of traffic Morse signals
can carry is also limited.
Over fifteen years ago the International Maritime Organization
(IMO), a United Nations agency specializing in safety of shipping
and preventing ships from polluting the seas, began looking at ways
of improving maritime distress and safety communications. In 1979,
a group of experts drafted the International Convention on Maritime
Search and Rescue, which called for development of a global search
and rescue plan. This group also passed a resolution calling for
development by IMO of a Global Maritime Distress and Safety System
(GMDSS) to provide the communication support needed to implement
the search and rescue plan. This new system, which the world's maritime
nations, including the United States, are implementing, 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 ship-to-shore (Rescue Coordination
Center) based. It spelled the end of Morse code communications for
all but a few users, such as Amateur Radio. The GMDSS provides for
automatic distress alerting and locating in cases where a radio
operator doesn't have time to send an SOS or MAYDAY call, and, for
the first time, requires ships to receive broadcasts of maritime
safety information which could prevent a distress from happening
in the first place. In 1988, IMO amended the Safety of Life at Sea
(SOLAS) Convention, requiring ships subject to it fit GMDSS equipment.
Such ships were required to carry NAVTEX and satellite EPIRBs by
1 August 1993, and had to fit all other GMDSS equipment by 1 February
1999. US ships were allowed to fit GMDSS in lieu of Morse telegraphy
equipment by the Telecommunications Act of 1996.
The GMDSS consists of several systems, some of which are new, but
many of which have been in operation for many years. The system
will be able to reliably perform the following functions: alerting
(including position determination of the unit in distress), search
and rescue coordination, locating (homing), maritime safety information
broadcasts, general communications, and bridge-to-bridge communications.
Specific radio carriage requirements depend upon the ship's area of operation, rather than its tonnage. The system
also provides redundant means of distress alerting, and emergency
sources of power.
The GMDSS consists of many separate systems which are being implemented
in a coordinated and agreed-upon manner. Some of these systems are
discussed on the following page.
To see the publication How
to Conduct an Inspection of a Fishing Vessel Radio Installation
For Compliance with the Fishing Vessel GMDSS Waiver go
to the FCC's website.
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