The UK government warns about the risks associated with degradation and denial of global navigation satellite systems (GNSS) and identifies measures maritime stakeholders can apply to strengthen resilience and protect operational safety.
The UK Maritime and Coastguard Agency (MCA) has published a new guidance titled MGN 719 (M+F) Operating in GNSS denied and degraded environments, issued on October 1, 2026.
Maritime stakeholders are invited to recognise that GNSS-derived information may be susceptible to disruption and assess whether appropriate resilience measures are required.
Recent years have seen a marked increase in reports of GNSS interference worldwide, particularly in the Black Sea, Baltic Sea, Gulf region and parts of East Asia. Such interference may take the form of jamming (where signals are blocked or degraded), or spoofing, (where false position information is presented to users).
As vessels, ports and maritime services become more dependent on satellite-derived PNT information, disruption from jamming, spoofing or signal loss can affect navigation, traffic management and other critical systems.
The guidance makes clear that maritime stakeholders must be prepared to operate safely when satellite-derived PNT services become degraded, unreliable or unavailable and are encouraged to ensure that personnel remain proficient in alternative means of maintaining operations.
A wide array of potentially affected shipboard navigation systems is enumerated by the agency, encompassing electronic chart display and information systems (ECDIS), GNSS receivers, integrated bridge systems (IBS), automatic identification systems (AIS), radar systems using GNSS inputs, track control systems and autopilots, dynamic positioning (DP) systems, voyage planning and route monitoring systems, gyro compass’, GMDSS, and pilot portable units (PPUs).
On shore-based and traffic management systems, vessel traffic services (VTS), port management information systems, pilotage management systems, search and rescue coordination systems, long range identification and tracking, automated logistics systems, fleet management and asset tracking systems, are likewise flagged as exposed.
The guidance is directed at a broad group described in the document as maritime stakeholders. It highlights that resilience and operational safety may be enhanced by adopting the measures outlined by the agency; the MCA does not set out mandatory requirements in this notice.
The financial consequences are substantial. Referencing prior UK government studies, the MCA calculates that a seven-day GNSS outage might cost Britain’s maritime sector £1.5bn, with £1,309m of that total attributable to port operations and £183m to shipping.
The MCA invites operators, ports, harbour authorities and service providers to assess and understand their dependencies on PNT services and take proportionate action to strengthen resilience against degradation or denial events.
For those seeking the full text and the MCA’s formal advice, the published guidance can be found here.
