Distress and Safety Communications
When we speak of Distress traffic we want to include all messages relating to the immediate assistance for a ship in distress as well as any Search and Rescue (SAR) communications and those on-scene communications. These communications should be conducted on the designated frequencies.
As would be expected Distress traffic has absolute priority over all other communications. We as GMDSS Radio Operators are required to monitor and copy in the station log all the traffic even if the ship is not directly involved, until it is clear that no assistance is required. No transmissions are to be made until all distress traffic has been cleared and you are given permission to resume normal traffic.
The radio telephone distress signal is spoken as MAYDA Y. And in the radiotelegraph method (includes NBDP, SITOR) the distress signal is SOS
Another form of traffic we should be aware of is the Urgency TRAFFIC, this signal indicated that the calling station has a very urgent message to transmit concerning the safety of a ship, aircraft, or other vessel, or some person on board a vessel or within sight. The Urgency signal is PAN PAN (pronounced "pon pon") and the telegraphic (includes NBDP, SITOR) signal is XXX.
A third traffic category is called Safety traffic. This would indicate to the mariner that the station sending the signal is preparing to transmit a message concerning the safety of navigation or giving important meteorological warnings. The radio telephone safety signal is Securite (Secur-a-tay). The telegraphic signal (includes NBDP, SITOR) would be TTT (three "T')
One might use this signal to indicate a hazzard effecting other shipping. Suppose you are leaving a dock and there is a bend in the river and ships in the bend of the river could not observe your ship as you back into the channel. A security message could be send on VHF to alert another ship out of sight that your ship is entering the channel.
In the US we generally use channel 13 to pass this information on to the ships in the area.
The transmitting of a distress alert should include the ships positions its identity, the problem, the ships course and speed, time of the transmitting of the alert. And of course, the type of assistance needed.
The distress alerting is intended to inform a SAR (Search and Rescue) organization that the ship is in distress. This would normally be directed to the Rescue Coordination Center (RCC). The alert will also notify other ships in the immediate area of the ship in distress. Shore/Ship distress alerts will inform ships about distress incidents as appropriate to their position.
Sometimes when an operator becomes aware of another mobile unit in distress, action must be taken to initiate and transmit a distress relay. When the mobile unit in distress is not in a position to transmit a distress alert or when the master of a ship not in distress determines that further assistance is needed, they them will do a distress relay. However, these ships doing the relay must indicate that they are themselves not in a distress situation.
On some of the GMDSS radio equipment there is a automatic distress relay programmed in the radio set. The Coast Guard is recommending that all these automatic relay devices be disabled.
The US Coast Guard recommends that all automatic distress reply from the equipment be disconnected.
The distress alert sent via Satellite(the COSPAS-SA TSART system) will be acknowledged by an RCC ashore. Ship stations may acknowledge distress alerts transmitted by Digital Selective Calling (DSC), but such acknowledgment is deferred several minutes to allow an RCC time to respond.
When we acknowledge Distress Alerts via Radiotelephone we should use the following format:
1.The distress signal MAYDAY.
2.The call sign (said three times) and name of the vessel sending the Distress.
3.The words THIS IS.
4.The call sign of the station acknowledging receipt of the distress alert spoken three times.
5.The words RECEIVED MAYDAY.
When we acknowledge a Distress Alert via NBDP (Narrow band
direct printing), we should stay with this method:
1. The distress signal MAYDAY.
2. The call sign and name of the vessel sending the Distress.
3. The word DE meaning "this is"
4. The call sign of the station acknowledging receipt of the distress alert.
5. The signal RRR MAYDAY
All ship board station receiving a distress alert must inform the Master or person responsible for the ship of the contents of any distress alert as soon as possible.
It is important the ship station should defer acknowledgment of a distress alert for a short period of time. This will allow the receipt and acknowledgment by a coast station. If a ship acknowledges receipt for a distress alert must, as soon as possible, inform a RCC via coastal radio station or via INMARSAT.
Ships that acknowledge receipt for distress alerts must, as soon as possible, inform a RCC via a coastal radio station or via INMARSAT. If the ship receives the distress alert via High Frequency radio then there should be a wait of 3 - 5 minutes before relaying the alert, IF there is no acknowledgment by a coastal station. It should be noted that you may receive the HF signal on one frequency and the coastal station may receive the alert on another frequency and due to propagation of the radio waves, you may not be able to hear the acknowledgment of the coast station.
If the Distress Alert is received via Medium Frequency (MF) on 2187.5 KHz then if you do not hear an acknowledgment within the 3 - 5 minute period you could then acknowledge the alert via radio on 2182 KHz.(SSB). If this attempt is unsuccessful the acknowledgment should be attempted using DSC on 2187.5 KHz.
If the Distress alert is received via VHF (using DSC on Channel 70 [156.525 MHz]), the VHF radio will, by the action of the DSC system, tune the receiving radio to Channel 16. The acknowledgment, by radiotelephony, will then be sent on Channel 16 (156.800 MHz). (As all VHF radios have been switched to Channel 16.) If there is no response to the acknowledgment then an acknowledgment could be sent on Channel 70 via DSC. It might be noted that some VHF station cannot acknowledge distress alerts on Channel 70.
