What actions should the GMDSS radio operator take prior to any potential Distress situation?

(B). All of these answers are good operational practice and should be consistently done.

• Create a table or chart of all the DSC coast stations that might be used during the vessel's itinerary.

• Prepare a detailed Distress message file on both satellite & MF-HF SITOR (NBDP) equipment containing all information needed in a Distress so it will be available for last-minute editing.

• Ensure all LES choices are correct and then updated properly as the vessel transits different SAR jurisdictions.

For Distress, urgency, and safety communications, please see Code of Federal Regulations on
§ 80.1109 Distress, urgency, and safety communications.

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What information should be contained in a detailed Distress message that was NOT transmitted by an initial Distress "hot-key" alert?

(C). Vessel name & call sign, POB and all potential means to communicate with the vessel.

Send during initial Distress "hot-key" alert:

• Vessel position, course & speed and the nature of Distress.
• The distress vessel's IMN and position at the time of alert.
• Vessel name & call sign, distress vessel's IMN & vessel position.

For more details, please see US Coast Guard article on DSC DISTRESS

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Which GMDSS equipment is best suited to simultaneous long-range communications with an RCC/coast station and OSC vessels or SAR aircraft?

(D). MF-HF SSB transmitters using voice follow-on frequencies.

The HF (High Frequency) propagation of radio waves can reach up to several thousand miles due to ionosphere bounces as it operates on 3 MHz to 30 MHz band.

Then, the MF (Medium Frequency) transmission can be picked up a few hundred miles away, due to night time atmospheric layer changes, allowing bouncing from ionosphere.

During day, when energy absorbing lower layers are present, MF can be heard up to 200 miles away. MF operates on 300 kHz to 3000 kHz (3 MHz).

The SSB (single side band) signal concentrates all radio waves energy on a one side of the wave, usually the USB or upper side band, having the LSB or lower side band and the carrier signal suppressed. This allows a stronger voice propagation.

For great explanation with illustrations, please see Yacht.com article on Worldwide Communications via MF/HF marine SSB radio

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Which statement is NOT true regarding an Inmarsat Distress Alert?

(A). USCG coast stations will receive the alert and immediately notify the correct RCC.

For Inmarsat Distress Alert:

• The operator selection of LES will determine which associated RCC will receive the alert.

• If the operator selects an invalid or inoperative LES code the NCS for that service will intercept the call and reroute the alert.

• If the LES choice is not updated properly the Distress Alert might be routed to a non-optimum RCC, introducing delays and confusion into the Distress situation.

For more info, please see Inmarsat article on Safety

For overview of Inmarsat system, please see pdf Inmarsat Rescuenet Handbook and also Inmarsat's International Safetynet Handbook

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What are the best resources for researching and planning equipment setups and updates prior to any potential Distress situation?

(D). Inmarsat handbook, NGA Pub, 117 or ITU List of Coast stations.

See Radio Navigational Aids, Publication No. 117, NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY pdf Publication No. 117

See International Telecommunication Union (ITU) list List IV - List of Coast Stations and Special Service Stations The list has to be purchased.

Another source is the Mariland Nautical ITU List IV - List of Coast Stations and Special Service Stations, 2021 Edition (CD Only) The list has to be purchased.

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Which statement is true regarding Inmarsat "hot-key" Distress Alerts?

(A). The LES programmed by the watch officers into the Distress Alert Update menu determines which RCC will receive your initial Distress Alert.

The Land Earth Stations (LES) list should be entered for the voyage path so that in case of Distress Alert, it will be contacted.

For overview of Inmarsat system, please see pdf Inmarsat Rescuenet Handbook and also Inmarsat's International Safetynet Handbook

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