Bridge Programs

4/9/2018: Inmarsat network migration impact on maritime distress and safety services

Editor’s note: This post was updated April 10, 2018 to reflect that Inmarsat will begin the migration 1400 UTC May 9, 2018 instead of April 16, 2018, as originally announced. For the latest information, visit the Inmarsat website provided in our blog post.

Inmarsat has announced that it will migrate Inmarsat-C, Mini C, and Fleet77 used for Global Maritime Distress & Safety System (GMDSS), Long Range Identification and Tracking (LRIT) and Ship Security Alerting Systems (SSAS) from their I-3 to their I-4 Network. This migration will begin 1000 UTC on May 9, 2018 and take approximately nine months to complete.

Inmarsat notified the IMO Sub-Committee on Navigation, Communications and Search and Rescue, at its fifth session Feb. 19-23, 2018, that they have developed a plan to migrate mobile satellite communication services. This plan includes the Inmarsat-C, SafetyNET, and Fleet 77 services, from the primary Inmarsat-3 satellites over to the Inmarsat-4 satellites within 2018.

The Inmarsat I-3 satellites are predicted to reach end-of-life between 2019 and 2020. These services must be migrated onto the I-4 satellites in order to ensure their continuity.

The details on the migration of the Inmarsat-C services for GMDSS can be found at It describes the impact of the migration and provides an overview on how to prepare for it. Inmarsat will periodically update this webpage as migration continues.

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 source documents, such as the Federal Register, Homeport and the Code of Federal Regulations. These documents remain the official source for regulatory information published by the Coast Guard.

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