Global Maritime Distress and Safety System (GMDSS)

What is the GMDSS?

The Global Maritime Distress and Safety System (GMDSS) is an international maritime system developed by the International Maritime Organisation(IMO) and forms part of the SOLAS regulations.GMDSS makes use of the terrestrial and satellite technology and ship-board radio-systems for ensuring immediate, automated, alert to the shore based communication and rescue authorities in event of receiving a distress call from a ship in distress.In addition it also alerts ships in the immediate vicinity to the ship in distress.As per the requirement of the GMDSS, all ocean-going passenger ships and cargo ships of 300 gross tonnage and upwards, engagaging in international voyages must be equipped with radio equipment which comply to the international standards as per the guidelines of the system. 
The GMDSS was adopted by the International Maritime Organization (IMO),being the international organisation responsible for the ships safety and the prevention of marine pollution.The GMDSS became fully effective on 1st February, 1999 as by this date all the ships coming uder its preview had to compulsorily comply with the GMDSS requirements in SOLAS.The GMDSS was adopted by means of amendments to the International Convention for the Safety of Life at Sea (SOLAS), 1974. The amendments, contained in Chapter IV of SOLAS on Radiocommunications, were adopted in 1988 and entered into force on 1 February 1992 but provided for a phase-in period until 1 February 1999.
Implementation of the GMDSS requirements is the responsibility of the Government of respective country, to ratify the GMDSS requirements into their concerned maritime national laws. Which also means that individual shipowners are also responsible for ensuring their ships meet GMDSS requirements, since they must obtain certificates from their flag State certifying conformity with all relevant international regulations.

How does the system work ?

On receipt of a distress call from a ship in distress,the search and rescue authorities ashore, as well as ships in the immediate vicinity, will be immediately alerted through satellite and terrestrial communication systems so that they can immediately assist in a coordinated search and rescue operation with minimum delay, in providing the necessary assistance to the ship in distress.

How does the GMDSS help in distress situations?

Ships fitted with GMDSS equipment are safer at sea - and more likely to receive assistance in the event of a distress - because the GMDSS provides for automatic distress alerting and locating when a radio operator does not have time to send out a distress call. The GMDSS also requires ships to receive broadcasts of maritime safety information which could prevent a distress from happening, and requires ships to carry satellite emergency position indicating beacons (EPIRBs), which float free from a sinking ship and alert rescue authorities with the ship's identity and location.
What equipments/systems do ships need to have onboard to comply with GMDSS requirements?
In order to comply with the regulations ships will require specific items of equipment for operation in designated areas:
Sea area A1: ships will carry VHF equipment and either a satellite EPIRB,or a VHF EPIRB.
Sea area A2: ships will carry VHF and MF equipment and a satellite EPIRB.
Sea area A3: ships will carry VHF, MF, a satellite EPIRB and either HF or satellite communication equipment.
Sea area A4: ships will carry VHF, MF and HF equipment and a satellite EPIRB.
Additionally, all ships will also have to be equipped to receive Marine Safety Information (MSI) broadcasts and have continuous scanning ability of all HF safety frequencies with automatic printing ability of MSI messages. A Navtex receiver will also have to be on board to continuously monitor 518 kHz with programming capability to be selective of message category.Ships will also be required to have a ‘Radar Transponder' (SART) and two way radios for designated use with survival craft.
The vessel must also have at least one radar set capable of operating in the 9 GHz band.Terminals to provide the above requirements are available.
Inmarsat A This offers the use of voice, data, facsimile and telex based communications.Inmarsat C This is a smaller unit and offers text and data messaging at reduced speed.Both terminals provide world coverage with the exception of the extreme polar regions.
The oceans are divided into four sea areas:
- Area A1 Within range of VHF coast stations with continuous DSC alerting available (about 20-30 miles)

- Area A2 Beyond area Al, but within range of MF coastal stations with continuous DSC alerting available (about l00 miles)

- Area A3 Beyond the first two areas, but within coverage of geostationary maritime communication satellites (in practice this means Inmarsat). This covers the area between roughly 70 deg N and 70 deg S.

- Area A4 The remaining sea areas. The most important of these is the sea around the North Pole (the area around the South Pole is mostly land). Geostationary satellites, which are positioned above the equator, cannot reach this far.

For example,coastal vessels only have to carry minimal equipment if they do not operate beyond the range of shore-based VHF radio stations, but they may carry satellite equipment. However, some coasts do not have shore-based facilities, so although the ship is close to shore, the area counts as Area A2 or A3. Ships which do go beyond Sea Area A1 have to carry MF equipment as well as VHF - or Inmarsat satellite equipment. Ships which operate beyond MF range have to carry Inmarsat satellite equipment in addition to VHF and MF. Ships which operate in area A4 have to carry HF, MF and VHF equipment.    


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