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Emergency Communication

Emergency communication includes distress, urgengy and safety messages. These messages have absolute prioriy over other radio communication. Today, emergency communication is initiated with the appropriate "all stations" calling procedures using communication equipment with Digital Selective Calling capability, which is an essential part of the Global Maritime Distress and Safety System. After the appropriate alerts have been sent over the DSC channels, voice communication as described in the following will be conducted on the appropriate distress channels.

Code of Conduct during a Distress Situation

After a distress situation has been made public on one of the distress and calling channels, the following rules should be respected:
  • Distress calls have absolute priority over all other communications on that frequency, and the word MAYDAY commands immediate radio silence, which should continue until it is seen that communication has been properly established between the station in distress and a responsible Search-and Rescue (SAR) authority, and appropriate assistance is being provided.
  • Similarly PAN-PAN urgency communications have priority over all other communications except distress calls.
  • If any station monitoring a distress or urgency message becomes aware that a coast station or Search-and-Rescue (SAR) authorities either have not received the message, or having received it cannot establish contact with the originator, that station has a responsibility to contact the SAR authorities and/or the originator and offer assistance - possibly in the form of a relay station - which may entail remaining in the area.
  • After receiving a distress call, all transmission should be terminated. All vessels having knowledge of distress traffic, and which cannot themselves assist, are forbidden to transmit on the frequency of the distress traffic. They should, however, listen and follow the situation until it is evident that assistance is being provided. Routine communication may be resumed after hearing an "Silence Fini" message indicating that the distress situation has been relieved.

Distress Communication

A vessel is in distress when a crew member or the vessel itself are in grave and imminent danger, which cannot be averted and requires immediate assistance. The distress signal is the word "Mayday" and is to be used only on the authority of the captain or person responsible for the vessel.

Exemplary situations allowing highest priority distress communication:

  • a person overboard situation has occurred
  • the vessel is sinking, with flooding not under control
  • the vessel is on fire, with fire not under control
  • the lives of all onboard is threatened by grounding, capsizing, ...

After the distress alarm has been sent to all the radio stations in the vicinity by the DSC controller (alerting all the receiving DSC stations by optical and acoustical signals), the distress voice communication is conducted on VHF channel 16 (156.8 MHz) or on MF 2182 kHz according to the following procedures:

1. Distress Call

After having transmitted the distress alarm, the vessel requiring help will send a distress call "to all stations" including information on it's position, the nature of distress, which kind of assistance is expected. To obtain best possible understandability, this information is sent in a fixed formatted Distress Call. This format ensures that vital information is communicated in a clear and concise way.

Radio stations receiving a distress call, must immediately stop all communication on channel 16 and continue to listen and record the distress communication. Distress alarms sent over DSC will also be stored in the memory of the receiving DSC controller and may contain additional information such as position, time and nature of distress.

2. Distress Acknowledge Message

After receiving a distress alarm, allow at least 5 Minutes of time for the coast stations or the Search-and-Rescue stations to prepare suitable actions. Should a distress call appear to remain unanswered after this period of time, then any vessel able to reply should acknowledge the distress call even if it is not in a direct position to assist.

This Distress Acknowledge message will also be communicated in the shown format.

Every effort should then be made to relay the distress message to a Search-and-Rescue or Coast Guard authority in order that further action can be taken to assist the vessel in distress.

3. Distress Relay Call

If a vessel or coast station receives a distress call and feels that further assistance is necessary, or a distress message has only been received (and acknowledged) by a vessel not in a position to assist, the "Distress Relay Call" may be used to re-transmit the received distress call. Also in situations in which a vessel in distress is unable to transmit a distress call for itself, a vessel in the vicinity may initiate a distress alarm on behalve of the vessel in distress using this "Distress Relay Call".

Note, that DSC radio equipment stores all incoming DSC alerts automatically. In the case that such an alarm has to be relayed, the stored distress call can be re-transmitted (to all stations or selectively to the nearest coast station) using the digital DSC channel. In this case no voice communication as described above is conducted. However, if the vessel in distress has no DSC equipment it may be interested in hearing a voice message in which the Distress Relay is reported. In this case, the vessel in distress is addressed directly with a "Distress Relay Call".

4. Silence

Control of all distress traffic is primarily the responsibility of the station in distress. However, this responsibility is usually handed off to a Maritime Rescue Coordination Centre (MRCC) by the distress vessel as they are in a better position to coordinate communication, and impose silence on any station that may be interfering with distress traffic.

All vessels who are aware of the existence of a distress situation and are not in a position to be of assistance are forbidden to transmit on any frequency being used for distress traffic and / or search and rescue related activity.

Having been made aware that a distress situation exists, the coordinating radio station will normally make use of the signal "Silence Mayday" to impose radio silence on Channel 16. This indicates that distress traffic is being passed on that channel and that it is not to be used for any traffic that is of less than distress priority.

If the distress situation is relieved, the station in distress (or an involved search and rescue station) may want to end the ongoing distress condition that imposes radio silence on the distress channel. Therefore, as soon as normal communication can be resumed on the distress channel, the coordinating radio station will make an announcement to this effect on the distress channel in use with the call "Silence Fini".

5. Cancellation of a false Distress Alarms

In the DSC system, false distress alarms may easily be transmitted by accident and should be cancelled immediately with the "Cancel Distress" message.
After detection of the erroneously transmitted distress alert, immediately reset the DSC controller to prevent an automatic re-transmission of the false distress alert!

Urgency Communication

An urgency situation exists if a crew member or the vessel itself require urgent help, without being in immediate danger. The urgency signal is "Pan Pan".

Exemplary situations allowing urgency communication:

  • the vessel's engine is disabled and she is dragging her anchor down onto a lee shore;
  • a yacht is dismasted with the hull integrity not affected
  • urgent medical assistance for a crew member is required

The urgency communication will be initiated using a DSC urgency alarm sent to all stations in the vicinity of the station requiring help. Additionally, a "Urgency Call" may be broadcast on the distress channel with the indication of a working channel on which the details of the urgency call will be repeated. The shift to a working channel is required to keep the distress channel clear for higher priority communication.

An urgency call must not be acknowledged, but if a station is in a position to give assistance an "Urgency Reply Call" may be conducted.

After the urgency situation has been relieved, the initiating station should report this on the distress channel with an "Urgency Finished Call".

Safety Communication

The safety signal is "Securité" and indicates that an important message concerning the safety of shipping will follow. Such messages usually originate ashore, but they can be used by ships at sea to report a navigational hazard.

Exemplary situations allowing safety communication:

  • a drifting or unlit lightbuoy
  • an unmarked and uncharted obstacle (e.g. floating containers)
  • a gale warning or an ice warning

Safety communication has lower priority than distress and urgency communication. Therefore, the transmission of a safety alarm on the DSC calling channel, will include a working channel on which the "Safety Call" will be transmitted.
If no DSC equipment is available, the transmission of the "Safety Call" may be announced on the distress and calling channel together with the working channel(s) on which it will - subsequently - be transmitted.

Cover  <<  Sail Away  <<  Marine Radio Communication  <<  . .>> Data Transmission last updated: 22-Feb-2008