Satellite navigation interference has become an increasingly important concern for the maritime industry, prompting classification societies to consider how ships can better identify and respond to these threats. Japan-based ClassNK has taken a step in this direction by introducing a class notation recognising vessels equipped with systems that detect the effects of Global Navigation Satellite System (GNSS) interference.
The development reflects a shift in maritime cybersecurity discussions: beyond protecting onboard networks and digital systems, the industry must also consider the reliability of the information used to navigate a vessel.
Why GNSS Interference Matters
Modern ships depend heavily on satellite navigation for positioning and situational awareness. However, this dependency creates vulnerabilities that can be exploited through two distinct techniques.
GNSS jamming interferes with satellite signals, potentially depriving a vessel of reliable satellite-based positioning. Spoofing, meanwhile, manipulates the information received by navigation equipment, potentially presenting a false position without an immediately obvious loss of signal.
These incidents can complicate bridge operations, undermine confidence in navigational information and increase the workload of bridge teams. Their implications extend beyond individual navigation equipment, particularly when inaccurate positioning information affects other systems or operational decisions.
Reports of interference across the Baltic Sea, Black Sea, Middle East Gulf and East Asia illustrate why the issue deserves attention from shipowners, operators and maritime safety professionals.
ClassNK Introduces a Recognition Mechanism
Through Edition 1.1 of its Guidelines for Advanced Safety Measures, ClassNK has established a framework for evaluating onboard systems designed to detect the effects of GNSS interference and alert bridge teams.
The new notation provides a means of formally recognising relevant detection capabilities. It should not, however, be interpreted as a guarantee that a vessel can prevent spoofing, withstand jamming or maintain accurate satellite positioning during an incident. Its focus is on the capability to detect interference and notify the crew.
ClassNK has also clarified that IACS Unified Requirements E26 and E27 do not directly require protection against GNSS spoofing or jamming. This distinction is important because compliance with existing cyber resilience requirements should not automatically be taken as evidence that a vessel has adequate safeguards against GNSS interference.
Implications for Shipowners and Operators
ClassNK’s initiative reinforces the need to assess satellite navigation interference as a distinct operational risk. Shipowners should consider not only whether detection equipment is installed, but also whether bridge teams understand its alerts, know how to verify suspicious position information and can follow appropriate procedures when GNSS reliability is compromised.
Technical detection capabilities are only one part of the response. Operational preparedness, crew competence and the availability of alternative positioning and navigation methods also play important roles in maintaining safe operations during interference events.
For the maritime industry, the key question is no longer simply whether a ship’s digital systems meet applicable cyber requirements. It is also whether the vessel and its crew can recognise when navigational data may be unreliable and respond effectively.
ClassNK’s new notation is a relevant development in this evolving area. As GNSS interference continues to affect shipping, the assessment of detection capabilities may become an increasingly important consideration in maritime cybersecurity and navigational risk management.
