Electronic Navigation and GNSS Resilience
Multi-band, multi-constellation, RAIM, authentication and CRPA may mitigate GNSS risk but do not guarantee a valid fix during jamming or spoofing: plausibility checks and independent sources remain necessary.
Operational Explanation
Jamming may deny the signal and spoofing may produce plausible but false PNT. RAIM checks measurement consistency, not universal authenticity; multi-band and other technologies improve resilience only within their limits. Decisions must be performance-based and tied to equipment actually installed.
Regulatory Reference
SOLAS V/19 and applicable performance standards; joint IMO/ICAO/ITU statement on GNSS interference. Equipment manuals, bridge procedures and SMS define degraded/denied-PNT response.
PNT means positioning, navigation and timing. Two agreeing displays may receive the same erroneous GNSS data: check input provenance. AIS and integrated systems may also depend on GNSS. Dead reckoning accumulates error; check whether an inertial system still receives corrections from the suspect sensor before treating it as independent. MCA MGN 379: electronic navigation and cross-checks.
If position is doubtful, call the master, apply degraded-navigation procedures and reassess route, speed and margins. Manage sensors and automation according to the manual and SMS; restore inputs only after independent verification, not merely when an alarm disappears. MCA: sensor limitations and backup arrangements.
Scope of Application
Every ship dependent on GNSS for position, velocity or time. Technological mitigations are not universal SOLAS requirements for every ship and area.
Procedure / How to Complete It
- Know capabilities, inputs, alarms and failure modes of installed equipment.
- Monitor time/position jumps, speed/course anomalies, sensor disagreement and plausibility.
- Check against available radar and visual/celestial fixes; soundings and dead reckoning are supporting checks with their own limits, not automatic independent fixes.
- On degradation isolate suspect inputs and enter the ship-specific denied-PNT procedure.
- Record and report interference through applicable Company, coastal and navigational-warning channels.
Practical Example
A RAIM-enabled receiver gives no alarm but radar ranges and soundings disagree: the team does not declare GNSS valid; it moves to independent checks and degraded procedure.
What Typically Goes Wrong
Promising accurate position with L1/L2/L5 during complete interference or making multi-band/RAIM universally mandatory.
Common Mistakes Mistake Library
| Mistake | Consequence | How to Avoid It |
|---|---|---|
| Promising accurate position with L1/L2/L5 during complete interference or making multi-band/RAIM universally mandatory. | Incorrect operational decision or regulatory status | Use the primary reference and ship-specific procedure |
What the PSCO Checks
Operational Tips
- Treat each technology as mitigation, not guarantee.
- Protect GNSS-dependent time inputs too.
- Periodically exercise independent methods prescribed by the SMS.
Preparation checklist
- Capabilities/limits known
- Alarms and disagreement monitored
- Independent fixes available
- Denied-PNT procedure ready
- Suspect inputs manageable
- Reporting defined
FAQ
Related Topics
Last substantive revision of this page: 15 September 2026 · page fingerprint cd07cac3ef2c