The Old System and the Need for Improvement

The old maritime distress and safety system as defined in chapter IV of the International Convention for the Safety of Life at Sea (SOLAS), 1974 in force prior to 1 February 1992 was based on the requirements that certain classes of ships, when at sea, keep continuous radio watch on the international distress frequencies assigned in accordance with the ITU Radio Regulations and carry radio equipment capable of transmitting over a minimum specified range. The master of any ship at sea should, on receiving a signal that a ship or aircraft or survival craft is in distress, proceed with all speed to the assistance of the persons in distress, informing them that he is doing so. Since the minimum specified range of communications provided by the required shipborne equipment is 100-150 nautical miles, assistance to a ship in distress could generally be rendered by other shipping in the vicinity of an incident, which means that the old system is primarily intended for ship-to-ship operation. However, in accordance with the ITU Radio Regulations, coast stations open to public correspondence are required to maintain a continuous watch during their service hours on the distress frequencies.

The old system includes two major manually operated sub-systems:

- The Morse telegraphy system on 500 kHz for all cargo ships of 1600 tons and over and all passenger ships. Since Morse competence is essential to the operation of this system, a Morse-qualified radio officer is required on all ships having radiotelegraph installations.

- The radiotelephony system on 2182 kHz and 156.8 MHz (VHF Ch 16) for all cargo ships of 300 tons and over and all passenger ships, which provides common distress communications for all ships, subject to the 1974 SOLAS Convention.

It has been proven difficult to make any significant progress in the communication arrangements for a ship in distress when it is beyond the range of medium frequency coast radio stations, although various measures have been implemented to improve the situation.

Introduction of modern technology, including satellite and digital selective calling techniques, enables a distress alert to be transmitted and received automatically over long range and irrespective of meteorological and interference conditions.

 

Basic Concepts of the GMDSS

The Basic concept of the Gmdss is that search and rescue authorities ashore as well as shipping in the immediate vicinity of the ship, or persons in distress will be rapidly alerted to a distress incident so they can assist in a coordinated research and rescue operation with the minimum delay. The system also provides for urgency and safety communications and the promulgation of maritime safety information (navigational and meteorological warnings and forecasts and other urgent safety information). In other words, every ship is able, irrespective of the area in which it operates, to perform those communication functions, which are essential for the safety of the ship itself and of other ships operating in the same area. To this end each Government Contracting to the amendments to the 1974 SOLAS Convention concerning Radiocommunications for the GMDSS undertake to make available appropriate shore-based facilities for space and terrestrial radio communications services, as recommended by the International Maritime Organization, and all ships, while at se, must be capable of:

a) transmitting ship-to-shore distress alerts by at least two separate and independent means, each using a different radio-communication service;

b) receiving shore-to-ship distress alerts;

c) transmitting and receiving ship-to-ship distress alerts;

d) transmitting and receiving search and rescue coordinating communications;

e) transmitting and receiving on-scene communications;

f) transmitting and receiving signals for locating;

g) transmitting and receiving maritime safety information;

h) transmitting and receiving general radiocommunications from shore-based radio systems or networks;

i) transmitting and receiving bridge-to-bridge communications.

 

Recognizing that the different radio sub-systems incorporated in the GMDSS system have individual limitations with respect to the geographical coverage and services provided, the equipment required to be carried by ships is determined in principle by the ship’s area of operation, which is designated as follows:

Sea area A1 – an area within the radiotelephone coverage of at least one VHF coast station in which continuous DSC (digital selective calling) alerting is available, as may be defined by Contracting Government;

Sea area A2 – an area excluding sea area A1 within the radiotelephone coverage of at least one MF coast station in which continuous DSC (digital selective calling) alerting is available, as may be defined by Contracting Government;

Sea area A3 – an area excluding sea areas A1 and A2 within the coverage of an Inmarsat geostationary satellite in which continuous alerting is available; and

Sea area A4 – an area outside areas A1, A2 and A3.

In all areas of operation the continuous availability of alerting is required.

 

GMDSS Basic Equipment

All ships to which the 1974 SOLAS Convention, as amended in 1988, applies are required to carry the GMDSS radio equipment, depending on the se areas in which they operate.

One of the basic principles on which the GMDSS carriage requirements is based is a functional requirement to ensure the capability of transmitting ship-to-shore distress alerts by at least two separate and independent means. The capability of performing other communications functions is also required. There are specific carriage requirements for ships according to the sea area(s) in which they operate.

Carriage requirements for GMDSS radio equipment can be summarized as follows:

· 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;

· All ships will carry equipment for receiving MSI broadcasts.