Marine Safety Information Bulletins

MSIB: Worldwide Navigational Warnings Service

The Coast Guard has issued Marine Safety Information Bulletin (MSIB) 05-21 to provide a brief overview of the Global Maritime Distress and Safety System (GMDSS) Worldwide Navigational Warnings Service.

On 30 August 2020, a report that Over 50 warships were involved in Russian Navy exercises that surprised Alaska trawlers. Although many fishing in the area were caught by surprise, a warning of the planned exercise was broadcast by satellite to shipping over the Global Maritime Distress and Safety System (GMDSS) Worldwide Navigational Warnings Service on 19 August, five days prior to the start of the exercise.


The International Maritime Organization, in cooperation with the International Hydrographic Organization and World Meteorological Organization, established a worldwide navigational warnings service to ships. Twenty-one navigational and meteorological areas (NAVAREAs and METAREAs) were established with responsibility for coordination and broadcast assigned regionally to various countries. In the U.S, the National Geospatial-intelligence Agency (NGA) was assigned responsibility for NAVAREAs IV and XII. Similarly, the National Oceanic and Atmospheric Administration is responsible for METAREA IV and XII. Most NAVAREAs alsopost their navigational warnings online.

GMDSS Navigational Areas (NAVAREAs)

Ships fitted with an inexpensive GMDSS Inmarsat-C or Iridium LT-3100S ship earth station will receive these international NAVAREA and METAREA warnings, as well as alerts from rescue coordination centers. These satellite terminals can also transmit distress alerts and communicate with rescue coordination centers globally. The five Arctic NAVAREAs and METAREAs XVII through XXI are fully covered by Iridium.

Please send questions concerning this Marine Safety Information Bulletin to USCG Spectrum Management and Communications Policy Division (CG-672) at HQS-SMB-CG-672@USCG.MIL or to the Coast Guard Navigation Center’s “Contact Us” page by selecting ”Maritime Telecommunications” as the subject.

This blog is not a replacement or substitute for the formal posting of regulations and updates or existing processes for receiving formal feedback of the same. Links provided on this blog will direct the reader to official publications, such as the Federal Register, Homeport and the Code of Federal Regulations. These publications remain the official source for regulatory information published by the Coast Guard.

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