An area beyond A1 and A2 within coverage of an Inmarsat geostationary satellite, covering most ocean areas between latitudes 70°N and 70°S.
Quick facts
Frequency
406 MHz
In practice
For most deep-sea trades the Inmarsat terminal — typically an Inmarsat-C, Fleet 77, or Fleet Broadband terminal — provides the primary distress and safety communication link, as well as commercial voice and data services. Officers must understand the Inmarsat distress button function, the system's automatic GPS position update capability, and the limitations of the geostationary satellite link at high latitudes where the satellite elevation angle becomes very low. GMDSS General Operator Certificates are required for operators of satellite communication equipment in Sea Area A3 vessels. Maintenance testing of the Inmarsat SES, EPIRB, SART, and HF radio is required under SOLAS IV/15.
Regulatory detail & full definition
GMDSS Sea Area A3 is defined as the ocean area, excluding Areas A1 and A2, within the coverage of an Inmarsat geostationary satellite system in which continuous alerting is available — broadly the ocean between latitudes 70°N and 70°S. Vessels operating in A3 must carry all A2 equipment plus either an Inmarsat ship earth station capable of two-way communications and DSC or an HF radio installation with DSC capability, providing a choice between satellite and radio-based distress paths. A 406 MHz EPIRB registered to the ship is mandatory.
For most deep-sea trades the Inmarsat terminal — typically an Inmarsat-C, Fleet 77, or Fleet Broadband terminal — provides the primary distress and safety communication link, as well as commercial voice and data services. Officers must understand the Inmarsat distress button function, the system's automatic GPS position update capability, and the limitations of the geostationary satellite link at high latitudes where the satellite elevation angle becomes very low. GMDSS General Operator Certificates are required for operators of satellite communication equipment in Sea Area A3 vessels. Maintenance testing of the Inmarsat SES, EPIRB, SART, and HF radio is required under SOLAS IV/15.