GMDSS Sea Areas

For the needs of the G.M.D.S.S applications, sea areas have been world widely characterized as:

Sea Area A1.

Within the radiotelephone coverage of at least one VHF coast station in which continuous DSC alerting is available. Such an area could extend typically 20- 50 nautical miles from the coast station.

Sea Area A2.

An area, excluding sea area A1, within the radiotelephone coverage of at least one MF coast station in which continuous DSC alerting is available. Such an area approximately extends 50- 400 m from the coast station.

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. This area lies from 70º North and South.

Sea Area A4.

An area outside sea areas A1, A2, A3. This is essentially the polar regions, north and south of about 70º of latitude, but excludes any other areas.