CHAPTER 1. GMDSS COMMUNICATIONS

What is the Global Maritime Distress and Safety System (GMDSS)?

The primary function of GMDSS is to coordinate and facilitate Search and Rescue (SAR) operations, by both shore authorities and vessels, with the shortest possible delay and maximum efficiency. It also provides efficient urgency and safety communications, and broadcast of Maritime Safety Information (MSI) such as navigational and meteorological warnings, forecasts, andother urgent safety information. MSI is transmitted via NAVTEX, International SafetyNet on INMARSAT C, and some radiotelex services. GMDSS was fully implemented in 1999 for all commercial vessels exceeding 300 GRT.

What are the GMDSS operational details?

This is a system with worldwide communications coverage. It is achieved by using a combination of INMARSAT satellite communications and terrestrial systems. All of these systems have range limitations that have resulted in the designation of four sea areas, which defines communications system requirements.

What is Area A1?

Area 1 is within shore-based VHF radio range. Distance is in the range of 20-100 nm. Radio required is VHF operating on Channel 70 for DSC, and Channel 16 radiotelephone. EPIRB requiredis 406 MHz or L-band unit (1.6 GHz). A VHF EPIRB is required.Survival craft require a 9-GHz radar transponder and portableVHF radio (with Channel 16 and one other frequency).

What is Area A2?

Area 2 is within shore-based MF radio range. Distance is in the range of 100-300 nm. Radios required are MF (2187.5 kHzDSC) and 2812 kHz radiotelephone, 2174.5 NBDP, and NAVTEX on 518 kHz. Also needed are the same VHF requirements as Area A1. EPIRB required is 406 MHz or L-band (1.6 GHz). Survival craft requirements are the same as in Area A1.

What is Area A3?

Area 3 is within geostationary satellite range (INMARSAT). Distance is in the range of 70°N-70°S. Radios required are MF and VHF as above and satellite (with 1.5-1.6 GHz alerting), or as per Areas A1 and A2 plus HF (all frequencies). Survival craft requirements are the same as in Area A1.

What is Area A4?

Area 4 includes the other areas (beyond INMARSAT range). Distance north of 70°N and south of 70°S. Radios required are HF,MF, and VHF. EPIRB required is 406 MHz. Survival craft requirements are the same as in Area A1.

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