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.