Coast Guard Issues Marine Safety Alert

Coast Guard Headquarters NewsThe Coast Guard issued the following Marine Safety Alert today.

Mariner’s Safety Endangered when VHF Radio Distress Alerts by Digital Selective Calling lack location and identification information.

United States Coast Guard Marine Safety Alert 04-11
September 1, 2011
Washington, DC

As the Coast Guard’s new marine radio network Rescue 21 becomes operational throughout the U.S., rescue centers can now receive instant distress alerts from commonly used DSC-capable VHF marine radios.  However, approximately 90% of VHF DSC distress alerts received by the Coast Guard do not contain position information, and approximately 60% do not contain a registered identity.   The Coast Guard cannot effectively respond to a DSC distress alert sent from such a radio.

This means that search and rescue efforts may normally be suspended when:

  •  no communications with the distressed vessel can be established,
  •  no further information or means of contacting the vessel can be obtained from other sources, and
  • no position information is known.


  • Ensure any information originally provided is updated as changes occur. FCC regulations require that DSC-equipped radios “use MMSIs assigned by the Commission or its designees” (47 CFR 80.103(b)).
  • THEN Interconnect your radio to a GPS receiver using a two-wire NMEA 0183 interface on all DSC-equipped marine radios and on most GPS receivers.  Instructions should be provided in the radio and GPS operators manual.  Further information is provided and will be routinely updated in

Developed by the Spectrum Management and Telecommunications Policy Division (CG-652), United States Coast Guard Headquarters, Washington, DC. Questions should be directed to Mr. Russell Levin at (202) 475 3555 or

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