GMDSS stands for Global maritime Distress and Safety System.
It was established in 1959. From then till now, we have seen the system advance from Radiotelegraphy to Maritime Satellite communication.
This is as a result of the efforts the International Maritime Organization (IMO) has put in the enhancement of Safety of Life at sea and in the exploration of advancements made in the radiocommunication technology.
The International Telecommunication Union also played a major roles in its advancement.
THE BASIC CONCEPT OF THE GMDSS
The basic concept of the GMDSS is that search and rescue authorities ashore, as well as ships in the immediate vicinity of a ship in distress, can be rapidly alerted to a distress incident so that they can assist in a coordinated SAR operation with the minimum delay.
In other words, the GMDSS is a system that allows a ship in distress to rapidly send a distress alert to search and rescue authorities ashore and to ships in its vicinity so that they can assist in a coordinated search and rescue operation as quick as possible.
The system is not only meant for distress alerting. The system also provides a platform for ‘urgency and safety communications and the promulgation of maritime Safety information (MSI) – navigational and meteorological warnings and forecasts and other urgent safety information to ships.’
For the sake of the GMDSS system, the sea as large as it is, is divided in four areas. They are
- Sea area A1
- Sea area A2
- Sea area A3
- Sea area A4
This can be said to be the ‘areas of operation for the GMDSS’.
THE FUNCTIONS OF THE GMDSS
The GMDSS majorly provides a means of communication. Therefore we can ask instead – what are the communication functions of the GMDSS. They include-
- GENERAL RADIO COMUNICATIONS
- BRIDGE TO BRIDGE COMMUNICATIONS
- DISTRESS ALERTING
- SEARCH AND RESCUE CO-ORDINATING
- PROMULGATION OF MARITIME SAFETY
- ON SCENE COMMUNICATION
GENERAL RADIO COMUNICATIONS.
This is communication between a ships and shore based communications network with respect to the management and operation of the ship. These shore based networks may include port operations, pilot stations, signal stations etc.
BRIDGE TO BRIDGE COMMUNICATIONS.
This is inter-ship safety communication. Generally, communication between ships are carried out using the VHF radiotelephone.
A Distress alert is a ‘rapid and successful reporting of distress incident to a unit which can provide or co-ordinate assistance. Distress incidents can include a vessel under attack, a vessel sinking, a vessel running aground etc. it has to be done rapidly because there is limited time during such incidents.
The GMDSS allows alerting to be carried out between ship to shore, ship to ship and shore to ship.
A distress alert can be carried out manually using radio communication equipments or automatically with equipments like the EPIRB which is automatically activated when a vessel sinks and the SART. For mor information on the SART CLICK HERE
SEARCH AND RESCUE CO-ORDINATING COMMUNICATION.
This is mostly communication between Rescue co-ordination centers and any on scene co-ordinator in the area where the distress alert originated.
PROMULGATION OF MARITIME SAFETY INFORMATION.
Maritime safety information are navigational warnings, meteorological warnings and forecast and other urgent maritime related information that are needed by ships for safe navigation and operations.
The GMDSS provides ships with this information using the international NAVTEX service on the frequency 518 kHz and ships recieved through the NAVTEX reciever.
It also provides broadcasts through Inmarsat enhanced group call (EGC) also known as the International SafetyNET system. This system is for ships that navigate beyond the coverage of the NAVTEX.
As the name implies, it involves finding a ship in distress or finding its survivors or survival crafts. This locating function is made possible by the SART. The SART is a search and rescue locating device carried by the ship or survivors in distress. For mor information on the SART CLICK HERE. The EPIRB is also important in this regard.
ON SCENE COMMUNICTION.
This is communication between the ship in distress and the unit providing assistance to the ship. It is usually carried out using designated distress and safety frequencies n the MF and VHF radio telephony.
THE GMDSS COMUNICATION SYSTEM AND EQUIPMENTS.
Generally, the GMDSS communications system comprises of two elements. The satellite communications and the Terrestrial communications. The GMDSS equipment are grouped into these two elements.
The satellite communication is the most important element as it provides a wider means of communication. The satellite system we have for now are the INMARSAT system and the COSPAS-SARSAT system.
The Inmarsat system uses geostationary satellites to provide a means of distress alerting and a capability for two way communications using email, fax, data transmission and radiotelephony. It also provides the MSI broadcasts. It provides all of this for ships that carry the following equipment-
Inmarsat fleet F77
Inmarsat Fleet broadband
Inmarsat Global Xpress
Inmarsat EGC (Enhanced Group Call) receiver
The Cospas-Sarsat system uses a polar orbiting satellite together with a geostationary satellite system. It provides one of the main means of distress alerting. It is able to determine the identity and position of the ship in distress or its survivors if the ship is fitted with an EPIRB.
The DSC is the basic equipment for distress alerting and safety communication in terrestrial communication. A DSC control unit is suited with the following-
HF radio equipment – The HF is for long range service. It is available even in areas not covered by satellite communications. Designated frequencies for this service are in the 4, 6, 8, 12 and 16 MHz bands.
MF radio equipment– The MF is for medium range service. Designated frequencies includes 2187.5 kHz for distress alert and safety call, 2182 kHz for distress and safety traffic.
VHF radio equipment– the VHF is for short range service. Designated frequencies includes 156.525 MHz (channel 70) for distress alert and safety calls using DSC, and 156.MHz (channel 16) for distress and safety traffic and general communication.
Other GMDSS equipment carried onboard ships includes-
SART (Search and Rescue radar Transponder). For more on the SART CLICK HERE and the NAVTEX receiver.
The following equipment are not part of the GMDSS communication system, but they have similar characteristics and are associated with other GMDSS equipment. They are
AIS (Automatic identification system) For more information on the AIS CLICK HERE
SSAS (ship security alert system)
LRIT (long range identification and tracking).
For more information on the GMDSS see the IMO GMDSS MANUAL.