UK MCA tells maritime sector to plan for operating without reliable GNSS

The UK Maritime and Coastguard Agency published Marine Guidance Note MGN 719 (M+F), "Operating in GNSS Denied and Degraded Environments", on 1 October 2026. It reports a marked rise in jamming and spoofing, especially around the Black Sea, the Baltic, the Gulf and parts of East Asia, so satellite positioning is no longer available everywhere.

The note lists exposed shipboard systems (ECDIS, AIS, autopilots, dynamic positioning, gyrocompasses, GMDSS), shore systems such as vessel traffic services and port management, timing-dependent networks, and survey-grade GNSS and RTK equipment. Stakeholders are encouraged to map their dependencies, set up interference detection, verify position independently and drill alternatives such as radar fixing, visual and celestial navigation and dead reckoning. The guidance is advisory. It cites a 2023 government study putting a seven-day outage at £1.5bn, including £1.309bn for ports. A UK eLoran backup is planned for timing in 2028 and full capability in 2030.

Why it matters: GNSS interference now affects survey-grade RTK, timing networks and port systems as well as ships' navigation, so geospatial and marine operators need to audit dependencies and fallbacks. Resilience planning like this is a template other coastal states may follow.