Distress priority applies to grave and imminent danger to a ship or a person requiring immediate assistance. After DSC, give the appropriate voice distress call and message: identity, position/time, danger, assistance required, people involved and useful details. PAN-PAN and SÉCURITÉ serve urgency and safety. Medical danger to a person may justify MAYDAY even when the ship is safe.
For a received VHF/MF DSC alert, listen on channel 16/2182 kHz for five minutes and follow the current IMO response flowchart. Do not send an all-ships DSC relay. For HF, inform a coast station/RCC after an unacknowledged alert and relay by DSC only if instructed. False alerts require active cancellation on the relevant service; switching off alone is insufficient. Use available means and the master's authority without delaying necessary help.
Classify the danger
Choose the priority word from the facts. ITU Radio Regulations Article 32 defines a distress alert or call as a signal that a mobile unit or person faces grave and imminent danger and requires immediate assistance. PAN-PAN marks urgency; SÉCURITÉ introduces safety information. The words are operational categories, not levels of drama. A medical emergency may concern a person even when the vessel remains afloat and manoeuvrable.
Build the follow-up
After a digital alert, prepare the voice or other follow-up using the applicable equipment procedure. A clear message identifies the station, states position and its UTC time, describes the danger, names the assistance required, identifies people at risk, and adds details that help rescue. Keep the data concrete: “Fire in the engine room; two persons injured; require immediate evacuation” gives the listener more to act on than “we have trouble.”
- 1Confirm the priority from the scenario facts.
- 2State identity, position, and the time attached to that position.
- 3Describe the danger and its consequences.
- 4State the help required and people involved.
- 5Listen, answer, and update when the situation or position changes.
| Category | Example in a study scenario | Required reasoning |
|---|---|---|
| Distress | Fire threatens people and immediate help is needed | Why would delay endanger life? |
| Urgency | A serious medical situation needs prompt advice | Why is immediate rescue not yet established? |
| Safety | A hazard needs broadcasting to navigators | Who needs the warning and through which service? |
Own, received, and accidental alerts
For an own VHF or MF distress alert, complete the applicable voice follow-up and maintain the required listening and coordination. For a received HF DSC distress alert, listen on the associated radiotelephony frequency. If no coast-station acknowledgement or distress communication is heard within five minutes, inform a coast station or RCC; relay the received alert only if instructed, under the master’s authority. Do not broadcast an all-ships DSC relay simply because a screen displayed an alert. VHF/MF response and HF relay are different branches; the medium matters.
The current source is MSC.1/Circ.1657/Rev.1, dated 6 July 2026. It covers ships responding to VHF, MF, and HF DSC distress alerts. Use that revision for the full flow, including listening, acknowledgement, relay, and coordination decisions.
A false alert must be dealt with promptly through the applicable service and equipment procedure. Stop the unintended transmission where possible, notify the appropriate RCC or coast station, and record the event. Powering down by itself is not a complete cancellation path.
Reason through a medical case
A crew member is deteriorating rapidly while the ship is safe. First ask whether the person faces grave and imminent danger and requires immediate assistance. If yes, distress treatment may be justified for the person. If the facts call for urgent medical advice without that threshold, PAN-PAN may fit. The category follows the facts supplied by the scenario and the responsible authority's procedure; never infer it from the ship's condition alone.
Sources: ITU Radio Regulations 2024, Articles 32.9–32.10; IMO MSC.1/Circ.1657/Rev.1; IMO MSC.514(105) index.
Official references · 2026-09-09
ITU RR Articles 32–33, Resolution 349 · MSC.1/Circ.1657/Rev.1 (2026-07-06)
Apply what you learned
In a closed simulation, a medical case is worsening but the vessel is safe. A received DSC alert from another ship appears on the exercise console.
Which two decisions must stay separate?
Suggested answer: Classify the medical facts independently, and handle the received alert using the current response procedure.
Why this works: The ship's safety does not settle the person's distress status, and the received alert does not justify an improvised relay. Each branch needs its own facts, authority, and record.
Continue with guided radio exercises.
Practise in the radio simulatorKey Takeaways
Distress means grave and imminent danger requiring immediate assistance; urgency and safety have different purposes.
A useful follow-up message preserves identity, position and time, danger, assistance required, people involved, and helpful details.
The current MSC.1/Circ.1657 revision controls responses to received DSC distress alerts.
False-alert handling requires prompt notification through the applicable authority and equipment procedure.
Common Mistakes
Choosing MAYDAY because a situation sounds serious without testing the published distress definition.
Using an outdated DSC flow instead of MSC.1/Circ.1657/Rev.1.
Assuming powering down alone cancels an unintended alert.
Test Your Knowledge
Practise this topic and review the explanation for each answer.
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