NAVTEX silence before a tropical storm warning
On passage 150 nm off the coast, your 12,000 GT vessel has had no NAVTEX printout for 30 hours. The receiver is switched on, tuned to 518 kHz, and the display shows 'all stations' selected and message types '01-99'. A tropical storm warning is forecast for your area within 24 hours. The Inmarsat-C terminal display says 'logged in', but the EGC/SafetyNET indicator is not shown and the printer has been out of paper since yesterday. The master asks whether the NAVTEX silence is normal and how you will receive the storm warning. The vessel carries an Inmarsat Fleet terminal for voice but no weather facsimile. The NAVTEX antenna is a short whip on the bridge roof; the coax connector was replaced last month. You are in a NAVTEX coverage area that normally broadcasts navigational and meteorological warnings in English.
1. Diagnose the possible reasons for the NAVTEX silence and list the checks you would make before declaring the receiver defective.
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Thirty hours of silence is not proof that the receiver is healthy. First check that the receiver is on 518 kHz international, that the correct NAVTEX station or 'auto' station selection is used, and that message types include 01 (navigational warnings), 02 (meteorological warnings) and 04 (SAR). If a specific station has been selected and the vessel has moved out of its coverage, no messages will appear. Check the display/printer, audio, power, and antenna: a short whip with a corroded or partly open coax connector can give no messages while the receiver still lights up. Check the station schedule/coverage and whether other ships are receiving. Silence can be normal in a quiet area, but with a tropical storm warning expected, assume a fault until proved otherwise. Do not change frequency randomly; 490 kHz is national-language and 4209.5 kHz is an additional NAVTEX frequency, but 518 kHz is the normal international English service.
2. How should you obtain the missing MSI and verify it, without misusing distress or urgency communications?
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Use Inmarsat-C SafetyNET: confirm the terminal is logged in and that EGC/SafetyNET reception is enabled and not filtered, set the correct position area (NAVAREA or circular area), and reload paper or use the display. If the Inmarsat-C EGC is unavailable, use the Inmarsat Fleet voice terminal to call MRCC or a coast radio station and request the latest MSI/forecast; monitor VHF Ch16 for coastal warnings and ask another ship to relay if necessary. A weather query is routine or urgency traffic, not distress; do not send a DSC distress alert or MAYDAY for a forecast. Record the source, time and content of the warning. If the storm warning threatens the vessel, inform the master immediately so route and speed can be adjusted.
3. What should be recorded and when should the matter be escalated?
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Log the time the silence was noticed, all checks made, the source and time of any MSI obtained, and the actions taken. Raise a defect report for the NAVTEX receiver/antenna and arrange repair at the next port; if the receiver is required for the area, note the reduced capability in the SMS. If no MSI can be obtained and the storm is a real threat, ask MRCC for advice and consider diverting or delaying. Do not falsify the radio log by writing that a broadcast was received when it was not. On arrival, have the antenna and coax tested and the receiver performance checked.