VHF DSC distress alert at anchor off Paradip: acknowledgement, relay and a DSC with no position
0230 local time. You hold the ROC and are alone on the bridge of a 4,500 GT container ship at anchor six nautical miles off Paradip. The VHF DSC controller on channel 70 sounds the distress alarm. The display reads: nature of distress, fire or explosion; MMSI 419xxxxxx, an Indian fishing vessel; position 20°12.4'N 086°47.1'E; time of position 2101 UTC, twenty-six minutes before the alert was received. Your own controller has never been interfaced to the GPS, so its position field shows the 'no position' default of 99°99'N 999°99'E. Channel 16 is silent, and no DSC acknowledgement has appeared from any coast station. A radar contact bearing 040° at 8 nm shows no navigation lights. Eight other ships are in the anchorage, two of them Indian Coast Guard vessels. Your master is asleep and the next watch is at 0600.
1. State your actions in the first five minutes, including whether and how you acknowledge and what you transmit.
Read the worked answer
Only a coast station transmits a DSC distress acknowledgement. A ship does not send a DSC ACK to another ship's alert; it acknowledges by radiotelephony on the associated frequency. In A1 on VHF, give the coast station a short interval - about five minutes - to acknowledge. Channel 16 is silent and no ACK has appeared, so you act.
- Do not silence and forget. Keep the alert stored or printed and note the UTC time of receipt.
- Acknowledge on channel 16 using the standard form: 'MAYDAY, 419xxxxxx, this is [own name, call sign, MMSI], received MAYDAY, position 20°12.4'N 086°47.1'E, nature fire or explosion, over.' Repeat until answered.
- Maintain a continuous listening watch on channel 16, keep the channel 70 DSC running, and offer a working channel.
- Call the Coast Guard. Address the ICG units in the anchorage on channel 16, and/or send a DSC individual call to the coast station, passing what you have received and that you are standing by.
- Call the master, start the main engine, and prepare boat and life-saving gear in case the vessel is sighted or assistance is requested.
The classic error is to leave channel 16 to 'go and look'. Do not break the communications link before the acknowledgement has been passed and the Coast Guard has the details.
2. Should you relay the alert, and how does the twenty-six-minute-old position change what you would do if tasked to assist?
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Relay only when it adds something.
- If the distressed station does not answer and no coast station acknowledges within a few minutes, transmit a MAYDAY RELAY on channel 16 addressed to all stations: 'MAYDAY RELAY, MAYDAY RELAY, MAYDAY RELAY, this is [own station], the following received from 419xxxxxx, position 20°12.4'N 086°47.1'E at 2101 UTC, fire or explosion, over.'
- The relay must say plainly that the position and time are twenty-six minutes old. Do not read them out as if current.
- A DSC distress relay is properly the coast station's function. For a VHF alert you can relay by voice, a voice relay to the coast station and to the Coast Guard vessels present is the clean route; do not clutter the DSC distress frequencies.
- If tasked to assist, the search datum is the 2101 UTC position, not the 0230 position. Apply set and drift for the elapsed time and work an expanding-square or sector search from that datum as directed by the on-scene coordinator. Use the SART response, lights, sound and visual lookout as the final guide, not the DSC figure.
- The dark radar contact at 040°, 8 nm is a lead, not proof. Verify before closing at speed in an anchorage with other ships around you; a fishing vessel showing no lights may equally be a darkened hull with nobody on board.
3. What does the blank position field mean for your own station, what would happen if you transmitted a distress alert now, and what must be done?
Read the worked answer
What it means: the controller is displaying the 'no position' default (99°99'N 999°99'E). It has never had a GPS feed, so it has no idea where the ship is.
If you pressed the distress button now: the alert would go out with your MMSI and a nature of distress but no position. The RCC would have to call you, or plot you by other means - and at 0230, with the VHF watch being kept by one person, it may get no answer. Minutes to tens of minutes are lost at exactly the wrong moment. A distress alert without a position is a materially degraded distress alert.
What is acceptable in the meantime
- Entering the position manually is a stopgap only. It must be updated at least every four hours and after every significant alteration, and it is only as good as the person typing it.
- The real fix is a NMEA feed from the GPS into the DSC controller, followed by a check that the displayed position and UTC match the GPS display.
Action at the next port: have the feed wired and verified, write the check into the radio log, and raise a defect report if the set cannot accept an input. WPC and classification surveys look at precisely this, and so will a port state control officer. Treat a DSC with no position input as a defective installation, not an inconvenience.