On watch: receiving a distress alert
1The lesson in plain words
A distress alert reaches your bridge. Call the master, note the details, listen first, and follow the IMO flow diagram rather than pressing buttons.
First minutes
When a distress alert or call reaches the bridge, the officer of the watch (OOW) acts at once: call the master, note the time, the casualty's identity, position and nature of distress, and plot that position against your own. DSC means digital selective calling; an RCC is a rescue coordination centre.
VHF or MF DSC alert
For a very high frequency (VHF) or medium frequency (MF) DSC alert, follow the six steps below. Keep the MSC.1/Circ.1657/Rev.1 flow diagram on the bridge.
What not to do
Do not acknowledge a DSC distress alert by DSC unless a coast station or RCC tells you to. Never send an all ships DSC distress relay after receiving a VHF or MF DSC alert: it floods the system and confuses the rescuers. Only the master can permit a distress alert, acknowledgement or relay from your ship.
HF alerts
For a high frequency (HF) alert, listen on its voice channel for 5 minutes. If a coast station or RCC has acknowledged or relayed the alert, or distress traffic is in progress, contact the RCC to offer help if you can assist. If neither applies, inform a coast station or RCC by suitable means; send a DSC relay only if instructed. Avoid unnecessary traffic if distant or others are better placed. Log the details.
Relaying for others
You may need a Mayday relay when the casualty cannot alert for itself, for example after you see red flares or hear a weak voice call, and the master decides more help is needed. Address it preferably to one coast station or RCC. Then keep a continuous watch and log every message.
2Step by step
OOW actions on a VHF or MF DSC distress alert
- 1
Call the master, record the time, casualty's identity, position and nature of distress, and plot the position.
The master authorises transmissions; recording and plotting start immediately.
- 2
Listen on channel 16 or 2182 kHz for 5 minutes.
A coast station or RCC normally acknowledges first and takes control.
- 3
If acknowledged or distress traffic is underway, check whether you can assist. If able, acknowledge by voice and inform a coast station or RCC.
This branch checks your ability to assist. If unable, keep watch.
- 4
If there is no acknowledgement or distress traffic and DSC alerts continue, acknowledge by voice and inform a coast station or RCC.
A continuing unacknowledged alert needs a coordinated response.
- 5
If there is no acknowledgement or distress traffic and alerts have stopped, inform a coast station or RCC.
Silence does not show that the emergency is over.
- 6
Log the details and reset the system, keeping watch.
Keep a record and remain ready for further distress traffic.
3Key data
- Guidance
- MSC.1/Circ.1657/Rev.1 (2026); flow diagrams posted on the bridge
- First listening
- 5 minutes on channel 16 or 2182 kHz
- DSC acknowledgement
- Only if a coast station or RCC tells you to
- All-ships DSC relay
- Never, after a VHF or MF DSC alert
4Key points
- 1
Call the master, record and plot promptly; monitor channel 16 or 2182 kHz for 5 minutes before voice acknowledgement.
- 2
VHF/MF: if acknowledged or distress traffic is underway, check ability to assist; if able, reply by voice and inform RCC.
- 3
No acknowledgement or distress traffic: continuing alerts need a voice reply and RCC report; stopped alerts need an RCC report.
- 4
No DSC acknowledgement unless told, and never an all-ships DSC relay after a VHF or MF alert.
- 5
HF: inform an RCC, relay only on its instruction; log everything.
5Frequent mistakes
Wrong: Press the DSC acknowledge button at once so the casualty knows you heard.
Right: Listen first; acknowledge by voice if needed. A DSC acknowledgement is sent only when a coast station or RCC tells you to.
Wrong: Relay the DSC alert to all ships so everyone hears it.
Right: Never send an all-ships DSC relay after a VHF or MF alert; inform a coast station or RCC instead.
6Practice case & exam keys
At 0310 your VHF DSC sounds a distress alert from a fishing vessel 9 miles away, nature 'flooding'. After 5 minutes on channel 16 you hear no acknowledgement or distress traffic and the alert repeats. Your ship can assist; the master is coming to the bridge.
Show the answer
Having already called the master, recorded the details and plotted the position, acknowledge by voice on channel 16 with the master's permission. Inform the coast station or RCC by the quickest means. Do not send a DSC acknowledgement unless directed, or an all-ships DSC relay. Log subsequent actions and keep watch.
Exam keys
- MSC.1/Circ.1657/Rev.1: procedure for responding to DSC distress alerts by ships.
- VHF/MF: listen for 5 minutes, then follow the flow diagram's acknowledgement and reporting branches.
- No DSC acknowledgement unless directed; never an all-ships DSC relay after a VHF or MF alert.
- Only the master authorises distress alerts, acknowledgements and relays.
Finish this unit
When you've read it, answer three questions. Get all three right to finish the unit; opening the page alone doesn't count.
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