Total GNSS failure and suspected spoofing on passage to Port Said
At 0340 on 14 March a 300 m container ship is on passage from Piraeus to Port Said, steering 118° T at 18.5 kn, about 55 nm south-west of Cape Kormakiti. Wind is NE 4, sea slight, visibility 8 nm, and the charted current sets 085° at 0.9 kn. Both GNSS receivers lose lock within two minutes of each other. One then displays a position that jumps 11 nm to the north-east before reverting to 'no fix'; ECDIS drops to dead reckoning and sounds its position-integrity alarm. AIS now shows several targets on implausible courses, including one at 60 kn, and one target's reported position plots over your own ship. The ARPA shows a coaster bearing 020° relative at 9.5 nm with a CPA of 1.2 nm. The OOW, a newly promoted third mate, calls you. The paper chart folio is corrected to the current Notices to Mariners, the magnetic compass has a current deviation card, and both X-band and S-band radars are working. The company SMS requires notification of navigation equipment failure.
1. State your immediate actions and priorities for the first 15 minutes, with the reasoning behind the order in which you take them.
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Priority order: keep the ship safe from immediate hazard, then restore positional awareness, then record and report.
- Protect the navigation of the ship first. The coaster has a 1.2 nm CPA and own ship is at 18.5 kn with an unreliable position. Order the engine room to standby, switch to hand steering, and reduce speed if the CPA is unacceptable - do not wait for the fix to be recovered before reducing risk. A collision does not wait for the ECDIS.
- Call the master (already done by the 3/O) and inform the engine room/uMS alarm status.
- Treat all GNSS-derived data as suspect. Put ECDIS on DR using the last confirmed fix and the course, speed and current actually being made good. Do not 'correct' the DR to make it agree with the jumping GNSS position - that would propagate the error. Keep AIS transmitting but stop using AIS positions for collision avoidance; the 60 kn target and the target on top of own ship prove the data is corrupt.
- Build an independent picture with radar. Range and bearing to the coaster, plot it manually on the reflection plotter or paper plotting sheet, and confirm with both X-band and S-band sets.
- Fix the ship's position by terrestrial/radar methods (see next task) and transfer the fix to the paper chart, which becomes the primary navigational record until the receivers recover.
- Post an extra lookout, brief the bridge team, and note the time of failure, last confirmed fix, and every alarm in the bridge notebook and official log.
- Report: coastal state VTS/coast radio station, NAVTEX/NAV warning if the interference is affecting other traffic, company DPA, and note it for the next port. Spoofing is often deliberate - do not assume a receiver fault.
2. Describe how you will obtain and validate an independent position fix, and what cross-checks would give you confidence in it.
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Method - build two independent fixes and reconcile them.
- Radar fix (primary). Take range and bearing to three charted features with a good angle of cut - Cape Kormakiti, Cape Andreas to the east, and an off-lying islet, lighthouse or charted platform. Use the variable range marker on a long-range scale for range and the heading marker/EBL for bearing. Plot on the paper chart. A cocked hat of 0.3–0.5 nm or less at this range is acceptable; if the triangle is larger, check radar performance, identification of the features and compass error before accepting it.
- DR advanced from the last good fix. Last good fix plus 18.5 kn through the water on 118° T, plus the charted current 085°/0.9 kn, gives an expected position. Agreement within about 1 nm supports both.
- Echo sounder cross-check. Compare the sounding with the charted depth along the DR track, allowing for tide and for the fact that the echo sounder reads below the keel. A systematic offset of several metres means you are not where you think you are.
- Celestial and azimuth checks. At this latitude and time, a star fix or a meridian altitude of Polaris, plus a gyro error check by azimuth of a known body or by transit bearings, gives an entirely GNSS-independent position and confirms the gyro.
- Validation rule. Accept the fix only when radar, DR and sounding agree. If they do not, assume the least favourable case for safety - the position closest to danger - and set the planned passage accordingly.
Record each fix, its source and its estimated accuracy in the bridge notebook and on the chart.
3. What ECDIS and chart-related settings and records must you manage while the outage lasts, and what must be logged and reported?
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ECDIS integrity settings
- Confirm the ECDIS is displaying the correct datum (WGS 84) and that the paper chart is on the same datum. A datum offset after a change of position source is a classic source of error.
- Re-check safety contour, safety depth, shallow-water contour and safety depth for the ship's actual draught, plus the look-ahead distance. With a 300 m ship at 18.5 kn the look-ahead must match the stopping distance, not the default.
- Check whether the ECDIS can accept a manual/radar position source or a radar overlay; if so, select it rather than leaving the input on a failed GNSS feed. Never leave a 'dead' position feeding the ECDIS silently.
- Switch to the paper chart as the primary means of navigation, with the ECDIS as a monitoring aid, and record the decision.
Records
- Bridge notebook and official log: time of first alarm, the 11 nm jump and the 'no fix' event, the last confirmed fix (time, position, method), all fixes taken during the outage with their source, the speed and course changes made, and the master's attendance.
- Note the AIS anomalies factually, without speculation, in case of later investigation.
Reporting
- Notify the coastal state/VTS and, where the interference threatens other ships, request a NAV warning through the coast radio station or NAVTEX authority.
- Notify the company DPA under the SMS; retain the alarm logs and any screen captures as evidence.
- On arrival, arrange a receiver health check and update the passage plan and risk assessment with the lessons learned.