Required Setting on Inmarsat-C MES due to I-4 Satellite Migration

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Required Setting on Inmarsat-C MES due to I-4 Satellite Migration

This is is to inform that FURUNO FELCOM 15 and FELCOM 18 Inmarsat-C users will be required to take necessary actions due to the transition of services via I-3 to I-4 Inmarsat satellites.

Once the migration has started, some vessels who are navigating specific area may lose synchronization with the satellite due to the change of coverage area by I-4 Satellite Migration. The right Ocean Region will then have to be selected MANUALLY in order to ensure that the antenna is pointed to the appropriate satellite. The procedure to manually select the right Ocean Region is as shown in the attached Appendix.


  • Distress Alert can be generated even under the “unsync” condition because automatic searching of/connection with an appropriate satellite is temporarily possible under such condition according to GMDSS regulations.
  • FURUNO Mini C FELCOM 16 and 19 (mainly used for SSAS), and FURUNO Fleet F77 terminals allow for an automatic selection of new Ocean Region just after the migration.


1) Migration Schedule

I-3 to I-4 migration Applicable Terminals Schedule
Atlantic Ocean Region West (AORW) I-3 to Americas (AMER) I-4 Fleet 77 30 April 2018 at 17:30 UTC
Inmarsat-C/Mini-C 09 May 2018 at 14:00 UTC
Pacific Ocean Region (POR) I-3 to Asia/Pacific (APAC) I-4 Inmarsat-C/Mini-C

Fleet 77

End Q2 2018 (planned)
Atlantic Ocean Region East (AORE) I-3 moved from 15.5W to 54W (I-3 F5 satellite) End Q3 2018 (planned)
Indian Ocean Region (IOR) I-3 to Alphasat EMEA I-4 End Q4 2018 (planned)


2) Applicable Products

  • FELCOM 15
  • FELCOM 18


3) Symptom

Some vessels, who are navigating applicable Ocean Region where the migration is planned, may lose the connection with the satellite. In this case, the caution message “Synchronization loss” will appear on those Inmarsat-C Terminals.

Step 1 Migration on 9th May, 2018 at 14:00 UTC
The vessels who are navigating the red-shaded area of
AORW (see the right map) on 09 May, 2018 at 14:00 UTC
will face the “Synchronization loss”.
AORE needs to be selected manually in this case.