Module 18 - Signals & Communications
DSC Distress Alerts
Digital Selective Calling (DSC) sends an electronic distress alert from the VHF set. A DSC distress alert normally includes the vessel MMSI, position if the radio is connected to GNSS, time, and the selected nature of distress. It alerts coastguard stations and DSC-equipped vessels in range.
The red distress button is not a replacement for the voice call. On receipt of a DSC acknowledgement, or after about 15 seconds, transmit the spoken MAYDAY call and message on VHF Channel 16 unless the crew are unable to do so. The spoken message gives the human detail that rescuers need: position, problem, assistance required, people on board, and other useful information.
- DSC sends an electronic distress alert
- MMSI identifies the vessel
- Position is included if GNSS is connected
- Follow DSC distress alert with a voice MAYDAY on Channel 16
- Cancel accidental alerts immediately and inform the coastguard
Watch for this: Check during pre-passage set-up that the VHF has a valid MMSI and live position input. A DSC set with no position data is much less useful in an emergency.
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