What defines the GMDSS Sea Coverage Area A1?

• A. VHF-FM coastal area to approximately 20 miles offshore within radiotelephone coverage of at least one coast station with continuous DSC alerting capabilities
• B. Global satellite coverage for the entire ocean
• C. Inland river coverage up to 5 miles offshore
• D. Microwave line-of-sight coverage up to 10 miles offshore

Answer: (A)

The key idea is that Sea Coverage Area A1 is the zone where a vessel can rely on VHF communications with at least one coast station, with continuous DSC alerting. It’s defined by being within the radiotelephone range of a coast station on VHF-FM, typically up to about 20 miles offshore, where a coast station can automatically alert via DSC and handle voice calls. This makes A1 the near-shore, VHF-based coverage area.

The other options point to different concepts: global satellite coverage describes the farthest, satellite-based reach of the system; inland river coverage isn’t a sea-area designation; and microwave line-of-sight coverage isn’t how GMDSS sea areas are defined.