The area within the radio telephone coverage range of at least one VHF coast station in which continuous DSC Ch70 Alerting is possible.
Sea Area A2
The area, (excluding Sea Area A1), within the radio telephone coverage range of at least one MF coast station in which continuous DSC 2187.5 kHz Alerting is available.
Sea Area A3
The area, (excluding Sea Areas A1 and A2), within the coverage of an INMARSAT geostationary satellite in which continuous alerting is available. This extends from latitudes 70 degrees North to 70 degrees South..
Sea Area A4
The area outside A1, A2 and A3. The Polar Regions, above 70 degrees North and below 70 degrees South.
