Global Maritime Distress and Safety System Sea Areas

GMDSS sea areas serve two purposes: to describe areas where GMDSS services are available, and to define what GMDSS ships must carry. Prior to the GMDSS, the number and type of radio safety equipment ships had to carry depended upon its tonnage. With GMDSS, the number and type of radio safety equipment ships have to carry depend upon the areas in which they travel. GMDSS sea areas are defined by governments.

In addition to equipment listed below, all GMDSS-regulated ships must carry a satellite EPIRB, a NAVTEX receiver (if they travel in any areas served by NAVTEX), an Inmarsat-C SafetyNET receiver (if they travel in any areas not served by NAVTEX), a DSC-equipped VHF radiotelephone, two or more VHF handhelds, and a search and rescue radar transponder (SART).

Sea Area A1

An area within the radiotelephone coverage of at least one VHF coast station in which continuous digital selective calling (ch70) alerting and radiotelephony services are available, as defined by the International Maritime Organization.

The United States now has Sea Area A1 service as shown in Rescue 21 Distress System Coverage.   Formal declaration of Sea Area A1 is in process.

Sea Area A2

An area, excluding Sea Area Al, within the radiotelephone coverage of at least one MF coast station in which continuous DSC (2187.5 kHz) alerting and radiotelephony services are available, as defined by the International Maritime Organization. GMDSS-regulated ships travelling this area must carry a DSC-equipped MF radiotelephone in addition to equipment required for Sea Area A1.

The United States has no Sea Area A2 service.  The US Coast Guard 2 MHz infrastructure is closed effective 1 August 2013. 

Sea Area A3

An area, excluding sea areas Al and A2, within the coverage of an INMARSAT geostationary satellite in which continuous alerting is available. Ships travelling this area must carry either an Inmarsat F77, B or C ship earth station, or a DSC-equipped HF radiotelephone/telex, in addition to equipment required for an A1 and A2 Area. Clicking on the image below willl open a new browser window and show an enlarged 48KB image.

Sea Area A4

The area outside that covered by areas A1, A2 and A3 is called Sea Area A4 Area. Ships travelling these polar regions must carry a DSC-equipped HF radiotelephone/telex, in addition to equipment required for areas A1 and A2.

GMDSS Radio Equipment Required for U.S. Coastal Voyages

GMDSS-mandated ships operating off the U.S. coast must fit to Sea Areas A3 (or A4) unless they remain restricted to within Rescue 21 VHF range of shore.  Radiocommunications equipment onboard such ships must be fitted to Sea Area A1regardless of where they operate.

Search and Rescue Areas

These show the nation or rescue coordination center responsible for coordinating distress emergencies which occur in these areas. Search and rescue areas are still undefined in many ocean regions.

United States Search and Rescue Area

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Atlantic Search and Rescue Area

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