IMO has published the revised Iridium SafetyCast service manual

The International Maritime Organization has published MSC.1/Circ.1613/Rev.2, the revised Iridium SafetyCast service manual.

This revised circular was published on 5 July 2023 and supersedes MSC.1/Circ.1613/Rev.1, as of 1 July 2023.

The Maritime Safety Committee, at its 101st session (5 to 14 June 2019), approved the Interim Iridium SafetyCast service manual (MSC.1/Circ.1613), which provided information on Iridium's enhanced group calling service, for circulation to Member States as advance information.

Two Member States were invited to take account of the information contained in the manual when conducting system trials and tests.

The Committee, at that session, also established an IMO Enhanced Group Call Coordinating Panel for coordinating the development and use of the international satellite-based enhanced group calling service. The Panel's terms of reference and certification process are given in MSC.1/Circ.1635.

The Committee, at its 104th session (4 to 8 October 2021), approved the revised Interim Iridium SafetyCast service manual, (MSC.1/Circ.1613/Rev.1), which became effective on 1 January 2022.

The Committee, at its 107th session (31 May to 9 June 2023), approved the revised Iridium SafetyCast service manual, as set out in the annex, prepared by the Sub-Committee on Navigation, Communications and Search and Rescue (NCSR), at its tenth session (10 to 19 May 2023), and agreed that it should become effective on 1 July 2023.

Member States intending to use the Iridium SafetyCast service are invited to take account of the attached revised Iridium SafetyCast service manual.

General information

The Iridium SafetyCast service is a satellite-based service for the promulgation of MSI, navigational and meteorological warnings, meteorological forecasts, SAR related information, and other urgent safety-related messages to ships.

The Iridium SafetyCast service fulfills an integral role in the GMDSS developed by the International Maritime Organization (IMO) and incorporated into the 1988 amendments to the International Convention for the Safety of Life at Sea (SOLAS), 1974, as a requirement for ships to which the Convention applies.

This Manual describes the structure and operation of the Iridium SafetyCast service.

It is intended primarily for national Administrations and registered information providers, but may also be useful to the mariner who requires more operational information than is found in manufacturers' equipment manuals.

Iridium SafetyCast service

The Iridium SafetyCast service provides shipping with navigational and meteorological warnings, meteorological forecasts, shore-to-ship distress alert relays, SAR-related information, and other urgent information in accordance with SOLAS requirements.

It provides an automatic method of broadcasting messages to both fixed and variable geographical locations in all sea areas, including the means of disseminating MSI to coastal warning areas not covered by the International NAVTEX service.

It is suitable for use in all sizes and types of ships.

The Iridium SafetyCast service offers the ability to direct a message to a given geographical area.

The area may be fixed, as in the case of a NAVAREA/METAREA or coastal warning area; or it may be a user-defined area (circular or rectangular).

A user-defined area is used for messages, such as a local storm warning or a shore-to-ship distress alert relay, for which it is inappropriate to alert ships in an entire NAVAREA/METAREA.

Messages are submitted by registered information providers via an Iridium gateway.

Messages are broadcast according to their priority, i.e. distress, urgency or safety.

Aboard ships, messages are received by type-approved Iridium Ship Earth Station (SES) EGC receivers.


For more information, please see the document below (available only to subscribers):


IRIDIUM SAFETYCAST SERVICE MANUAL