The Furuno IC-305 Distress Alert / Received Call Unit is a critical, safety-compliant GMDSS interface component designed for installation on a vessel’s bridge. It acts as a remote signaling station for Furuno Inmarsat-C Mobile Earth Stations (MES), notably the FELCOM 15, FELCOM 16, FELCOM 18, and FELCOM 19 satellite systems.

Unlike the IC-306 (which is only a standard alarm notification unit), the IC-305 serves two critical functions: sending emergency distress signals outward to search-and-rescue networks and acknowledging incoming high-priority emergency alerts.

Operational Procedures

Because this unit connects directly to the ship’s emergency satellite transceivers, strict protocols govern its physical operation to prevent accidental activations:

• Initiating a Distress Alert: The operator must flip open the protective, transparent spring-loaded safety guard over the red [DISTRESS] button. The button must be held down continuously for at least 4 seconds. During this time, the internal lamp flashes rapidly; once the transmission successfully begins via the Inmarsat satellite network, the light shifts to a steady, solid red.

• Handling Incoming Alerts: When a priority message or urgent call is received by the baseline FELCOM terminal, the panel sounds an audible buzzer, and the [ALARM ACK] button illuminates. Pressing this button silences the onboard audio alert tone, signalling to the bridge team that the call has been acknowledged.