GMDSS

NATIONAL WEATHER SERVICE PARTICIPATION IN THE GMDSS

In February 1999, the Global Maritime Distress and Safety System (GMDSS) became the primary international means for disseminating Maritime Safety Information (MSI) to mariners. The goals of the GMDSS are to provide more effective and efficient emergency and safety communications and disseminate Maritime Safety Information (MSI) to all ships on the world's oceans regardless of location or atmospheric conditions. MSI includes navigational warnings, meteorological warnings and forecasts, and other urgent safety related information. GMDSS goals are defined in the International Convention for the The Safety Of Life At Sea (SOLAS) and affects vessels over 300 gross tons and passenger vessels of any size.

The National Weather Service participates directly in the GMDSS by preparing meteorological forecasts and warnings for broadcast via NAVTEX, HF Narrow Band Direct Printing (NBDP) and approved satellite providers SafetyNET and Safetycast.

The World Meteorological Organization (WMO) has developed a GMDSS Webpage which, as a first step, provides links to worldwide meteorological bulletins and warnings issued for the high seas via SafetyNet and SafetyCast. Click here for a transmission schedule for full GMDSS Service.

The NWS also offers other international communication services which provide weather, water and climate information to segments of the World Meteorological Organization (WMO) International community.

The U.S. Coast Guard Navigation and Vessel Inspection Circular (NVIC) 3-99 on GMDSS and EPIRB Equipment Requirements on Commercial Vessels is available in Acrobat (PDF) format. It replaces NVIC 9-93.

Operation of a shipboard radio installation requires a license and is regulated by the FCC. The exception to this is the Telecommunications Act of 1996 permits recreational boaters to have and use a VHF marine radio. For further information, see the FCC's Wireless Telecommunication Bureau's Maritime Mobile Service Webpage. Licensing is not normally required when receiving only. Learn more about GMDSS and other marine communication systems by visiting the U.S. Coast Guard Maritime Telecommunications Information webpage.

Under GMDSS regulations, reception of MSI is mandatory.

"While at sea, vessels must maintain radio watches for broadcasts of maritime safety information on the appropriate frequency or frequencies on which such information is broadcast for the area in which the ship is navigating." 47 CFR 80.1123(b).

Waivers for inoperative GMDSS equipment which can not be repaired prior to scheduled sailing should be requested of the FCC by phone or email to Ghassan Khalek (202-418-2771, gkhalek@fcc.gov, 202-418-2643(fax)) identifying other systems available, planned repair date, duration of next voyage, destination etc.

Also under U.S. GMDSS regulations,

"Ships must carry the most recent version edition of the IMO publication entitled GMDSS Master Plan of Shore Based Facilities". 47 CFR 80.1085(ii)(d). This document is available from the IMO. The FCC allows NGA Publication 117 to be carried as an alternative to the GMDSS Master Plan.

Refer to NGA Publication 117, which is updated through the Notice to Mariners, for the latest official listing of NAVTEX, SafetyNET and Safetycast broadcast schedules. 

The British Admiralty List of Radio Signals is an excellent reference source for GMDSS information.

All NWS marine forecasts rely heavily on the Voluntary Observing Ship (VOS) program for obtaining meteorological observations.

National Weather Service Marine Products via NAVTEX

NAVTEX is an international automated medium frequency (518 kHz) direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent marine safety information to ships. It was developed to provide a low-cost, simple, and automated means of receiving this information aboard ships at sea within approximately 200 nautical miles of shore. NAVTEX stations in the U.S. are operated by the U.S. Coast Guard. There are no user fees associated with receiving NAVTEX broadcasts. Within the U.S., there are no NAVTEX broadcasts on the alternate designated frequencies of 490 or 4209.5 kHz, however, the NAVTEX station in the Marianas (Guam) will temporarily broadcast on frequency 4209.5 kHz using B1 character while repairs are being made to the station which broadcasts on 518 kHz. 

Here is some detailed information about NAVTEX broadcasts from the US Coast Guard, including links to maps of coverage areas.

If you experience difficulties receiving weather forecasts via NAVTEX, it could be a transmission issue, equipment issue, or combination of both. Be certain your NAVTEX receiver has been properly programmed with proper NAVTEX station and subject identifiers. A minimum of 4 forecasts should be received daily. Both good and poor reception reports, stating your position, date/time(s), and make/model of your NAVTEX receiver to; COM-SMB-WATCH@uscg.mil and marine.weather@noaa.gov would be greatly appreciated.

NAVTEX is a major element of the Global Marine and Distress Safety System (GMDSS). For further information on NAVTEX, the GMDSS, and worldwide NAVTEX schedules, including coverage diagrams, visit the U.S. Coast Guard Maritime Telecommunications Information webpage.

The National Weather Service issues a series of forecast products specifically tailored to fit the broadcast ranges of the U.S. Coast Guard NAVTEX transmitters on the CONUS and Puerto Rico. The NAVTEX forecast products are a blend of the existing offshore marine forecasts and coastal marine forecasts, however, the inshore portion of these forecasts contain less detail than available in the coastal forecasts. Mariners can continue to obtain NWS coastal marine forecasts by other means including NOAA Weather Radio, USCG VHF Voice, NOAA telephone recordings and the Internet.  The U.S. has no NAVTEX coverage in the Great Lakes, though coverage of much of the Lakes is provided by the Canadian Coast Guard. 

SITOR (NBDP) is similar in many respects to NAVTEX but does not offer all of the same functionality such as avoiding repeated messages.

A Listing of NWS Marine Products Broadcast via U.S. Coast Guard NAVTEX is available.

For a complete listing of NWS marine text products (with links) visit the NWS Production Schedule for Marine Text Products webpage.

Refer to NGA Publication 117, which is updated through the Notice to Mariners, for the latest official listing of U.S. Coast Guard and worldwide broadcast schedules. The British Admiralty List of Radio Signals is an excellent reference source for NAVTEX and GMDSS information.

All NWS marine forecasts rely heavily on the Voluntary Observing Ship (VOS) program for obtaining meteorological observations.

National Weather Service Products via Inmarsat-C SafetyNET II

The NWS began using SafetyNET II services from Inmarsat operationally on January 22, 2024. SafetyNET II is a part of the Global Maritime Distress and Safety System (GMDSS), is the new generation international broadcast and automatic reception service for Maritime Safety Information. SafetyNET II is an enhancement to the current SafetyNET system, and provides a user-friendly, interactive web interface for Maritime Safety Information Providers to create their Maritime Safety Information messages and delivered them simultaneously over multiple Inmarsat networks, including Inmarsat C, Mini C and Fleet Safety.

A SafetyNET II User Guide and API Manual can be downloaded here.  

InMarsat migrated its older satellites to newer ones in 2018. The SafetyNet Migration Guide is here.

See NGA Publication 117 and the U.S. Coast Guard Maritime Telecommunications Information webpage for a complete description of SafetyNET II and the GMDSS as well as worldwide schedule information. The British Admiralty List of Radio Signals is an excellent reference source for SafetyNET II and other GMDSS information.

The National Weather Service prepares high seas forecasts and warnings for broadcast via SafetyNET II for two ocean areas four times daily. These areas are known as METAREA IV and METAREA XII and cover much of the western North Atlantic and the eastern North Pacific Oceans. Click here for a map of METAREAS around the world.

These broadcasts are prepared cooperatively by the Ocean Prediction Center, National Hurricane Center, Honolulu Forecast Office and National Tsunami Warning Centers. See table below for broadcast schedule.

All NWS marine forecasts rely heavily on the Voluntary Observing Ship (VOS) program for obtaining meteorological observations.

The table below indicates which Inmarsat satellite users can tune into to get products for METAREAs IV and XII. Inmarsat has satellites which overlap regions of the globe so knowing which satellite to tune into is important to get specific products for areas IV and XII.

National Weather Service Products via Iridium SafetyCast

Iridium SafetyCast is an internationally adopted, automated satellite system for promulgating weather forecasts and warnings, marine navigational warnings and other safety related information to all types of vessels and is part of the Global Maritime Distress and Safety System (GMDSS). There are no user fees associated with receiving SafetyCast broadcasts. 

The NWS began its operational phase with Iridium's SafetyCast on 6/12/2023. Additional resources for using Safetycast can be found here.

See NGA Publication 117 and the U.S. Coast Guard Maritime Telecommunications Information webpage for a complete description of SafetyCast system and the GMDSS as well as worldwide schedule information. The British Admiralty List of Radio Signals is an excellent reference source for SafetyCast and other GMDSS information.

The National Weather Service prepares high seas forecasts and warnings which are broadcast via SafetyCast for two ocean areas four times daily. These areas are known as METAREA IV and METAREA XII and cover much of the western North Atlantic and the eastern North Pacific Oceans. Click here for a map of METAREAS around the world. The NWS also prepares Tropical Cyclone and Tsunami Bulletins for broadcast when they are relevant to METAREAs IV and XII. 

These broadcasts will be prepared cooperatively by the Ocean Prediction Center, National Hurricane Center, Honolulu Forecast Office and National Tsunami Warning Centers. Below is a listing of NWS products broadcast by SafetyCast. SafetyCast does not have overlapping satellite coverage in METAREAs IV and XII so a specific satellite is not necessary for proper reception.  

All NWS marine forecasts rely heavily on the Voluntary Observing Ship (VOS) program for obtaining meteorological observations.