DSC distress alert with no follow-up voice message
While on watch in GMDSS Sea Area A2, the radio operator receives a DSC distress alert on VHF Ch 70 from a nearby fishing vessel about 12 nautical miles away. The alert is not followed by a distress message on Ch 16. No coast station acknowledgment is heard. The vessel is a 1,600 GT cargo ship with a VHF DSC and MF/HF installation. The master is asleep, and the OOW is alone on the bridge. Visibility is good, sea calm.
1. What are the radio operator's immediate actions on receiving the DSC alert?
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Immediate actions are to log, listen, and inform-not to transmit a DSC acknowledgment. The operator should:
- Record the time, the distressed vessel's MMSI, position, and nature of distress from the DSC alert.
- Not acknowledge the alert by DSC; ship stations do not acknowledge DSC distress alerts in that way.
- Switch to the associated radiotelephone channel (Ch 16) and listen for a distress message or coast station acknowledgment.
- Inform the master and keep the OOW briefed; the OOW must maintain navigation and lookout.
- Plot the fishing vessel's position and assess whether the cargo ship is the nearest station able to assist.
Reasoning: The absence of a follow-up voice message may mean the fishing vessel's crew is incapacitated, the radio has failed, or the alert is false. The correct first move is to establish whether the distress is real and whether a coast station is handling it, while preserving the ship's own navigational safety.
2. When, if at all, should the operator acknowledge or transmit a MAYDAY RELAY?
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Acknowledgment and relay are conditional, not automatic. If no coast station acknowledgment is heard within about 5 minutes, the operator may acknowledge the distress by radiotelephony on Ch 16 and attempt to contact the fishing vessel. A MAYDAY RELAY is justified when:
- The distress is confirmed or strongly indicated, and
- No coast station or other station is handling it, or the distressed vessel cannot communicate.
A relay should identify the relaying station, give the distressed vessel's details, and state what assistance is being provided. If a coast station acknowledges and takes control, the cargo ship should not relay; it should keep silence on the distress traffic and stand by for instructions.
Reasoning: The 12-nautical-mile range and calm sea make direct VHF contact plausible, so a short listening and calling period is better than immediate wide-area relay. Premature relay can clutter the frequency and interfere with a coast station that is about to answer.
3. What should the operator do if no one answers and the fishing vessel appears to be in trouble?
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If no one answers, the operator should treat the situation as a probable distress and move from monitoring to assistance. Actions:
- Inform the master, who must decide whether to divert; the cargo ship is close enough to assist without undue risk.
- Transmit a MAYDAY RELAY or a distress message as appropriate, including the fishing vessel's position and the cargo ship's intention.
- Maintain a listening watch on Ch 16 and, if fitted, monitor the fishing vessel's MF/HF distress frequency.
- Prepare for rescue: keep a lookout, rig rescue equipment, and brief the crew.
- Log all transmissions, times, and responses.
Reasoning: A DSC alert without voice contact is not automatically false. The operator should not ignore it merely because the follow-up message is missing. At the same time, the OOW remains responsible for the cargo ship's navigation; assistance must be given without creating a collision or grounding risk.