Around the globe, every country’s critical national infrastructures (CNI) is under threat. Whether it be climatic change or the security implications of rising geopolitical tension as identified within the recent Strategic Defence and Security review, now is the time to address the continued over-reliance on global navigation satellite systems (GNSS) that can be compromised by both natural phenomena and bad actors.
From emergency services to finance, chemicals to defence, food to health, transport to water, effective, resilient CNI underpins every aspect of life. These industries are highly dependent on the provision of accurate position and timing information – and often that provision is provided by GNSS as Prof. Aled Catherall, CTO at Plextek discusses…
The Quiet Threat
The chaos wrought by infrastructure failure in today’s interconnected world is highlighted far too frequently. In the UK, for example, a simple fire in one substation manages to take out the nation’s leading airport, London Heathrow, for an entire day or a faulty software update such as CrowdStrike affects an estimated 8.5 million companies globally, or a cyber-attack paralyses airlines, banks, hospitals, shops, and government services. When such incidents occur, questions are inevitably asked about resilience and redundancy of processes and procedures.
Such questions are increasingly being raised about our shared global (over)reliance on GNSS – which includes GPS, GLONASS, Galileo, and BeiDou – for the provision of time and position. The degradation of GNSS is simply far too easy to achieve, affecting both positioning accuracy and timing precision. While deliberate GNSS jamming is generally illegal, signal degradation or loss can still occur due to a range of factors — including malicious interference (such as the recent jamming that disrupted European Commission President Ursula von der Leyen’s aircraft), natural phenomena like solar flares, or satellite anomalies. For instance, in May 2025 a data-format change on GPS satellite PRN 37 triggered widespread “dual/complete GPS failures” across multiple aircraft.
Whilst the public widely recognises GNSS’s role in providing position data, its equally vital function in disseminating precise time often goes unnoticed. Precise timing is essential to many critical systems – from seamless handovers in broadcast and cellular networks to synchronised power grid operations, accurate financial trade timestamping, and reliable industrial controls. Many of these rely on sub-microsecond accuracy to function effectively.
Crucially, systems designed with sole dependence on GNSS for timing render them dangerously exposed. This risk is now well understood globally, where governments have begun to model and stress-test the economic consequences of outages.
Moreover, GNSS degradation for position and navigation proves equally disruptive, particularly for transport. As the primary source of position information for aircraft, ships, and vehicles, GNSS is vital. The vulnerability of CNI to GNSS degradation is gaining increasing recognition across the world. In fact, the UK government recently estimated that a GNSS outage for 24 hours would cost the UK economy over £1.4 billion. With this undoubtedly having similar or greater effects on other countries too, the effect of widespread satellite compromise could be catastrophic. And yet, despite awareness, discussion, and debate, vulnerability still exists. So, what can be done to provide resilience to GNSS degradation?
Building GNSS Resilience
Strengthening resilience starts with selecting GNSS receivers that support multiple constellations (GPS, Galileo, GLONASS, BeiDou) across a range of frequency bands (e.g., GPS L1, L2, L5). While not foolproof, this adds redundancy and makes deliberate jamming or spoofing more difficult. Complementing this, Controlled Reception Pattern Antennas (CRPAs) can reject signals from unwanted sources, further enhancing protection.
Highly stable atomic clocks provide critical timing hold-over for periods when GNSS is lost, while next-generation quantum technologies are also being explored for even more resilient timing and positioning.
A multi-layered approach, combining an appropriate set of diverse Position, Navigation and Timing (PNT) sources with multi-constellation, multi-band GNSS receivers and even CRPAs, is essential to ensure the continuity and integrity of critical civilian infrastructure in the face of GNSS disruption.
True GNSS resilience demands a diverse range of sources using different sensing modalities, coupled with an intelligent fusion algorithm capable of identifying when a PNT source is degraded and dynamically prioritising which sources to use and adjusting their respective weighting.
In addition, AI will likely play a key role in the next generation of high-performance data fusion solutions enabling multiple technologies to be deployed in tandem. Combined, these diverse PNT technologies provide the resilience and redundancy needed to ensure that timing and positioning remain accurate, even if one system fails, safeguarding critical infrastructure operations.
Cutting Costs Without Compromise
So, what is holding back routine implementation of GNSS resilience? Cost is, of course, a concern. A basic GNSS receiver is very cheap, but resilience is not. A GNSS receiver covering all constellations and bands, equipped with on-board intelligence to detect spoofing and discrepancies, costs more than a simple GNSS receiver. CRPA antennas are significantly more expensive than a basic on-chip antenna package. And complementary technologies such as inertial sensors and atomic clocks add further significant cost.
Therefore, it is imperative that global governments and industry alike accelerate its commitment to investing in cost-effective resilience, including standard deployments that support plug-and-play architectures, with standardised interfaces for PNT solutions. Rapid integration of third-party alternative PNT solutions can reshape the cost model, helping civilian and government organisations overcome a major barrier to protecting critical infrastructure. Robust simulation environments also enable infrastructure owners to test multi-layered approaches without heavy upfront investment. De-risking the investment in this way transforms accessibility and removes a further barrier to leveraging multiple PNT solutions. Cross-border collaboration here is key: multinational infrastructure projects, joint testbeds, and simulation environments allow owners to de-risk investment while also aligning standards globally.
Conclusion
The escalating frequency of disruptions underscores a critical global vulnerability in our interconnected world: the pervasive overreliance on GNSS for precise timing and positioning. The immediate and severe cascading consequences for CNI can lead to significant economic losses and jeopardise public safety. The often-unseen dependence on GNSS for timing presents a profound risk. While implementing robust resilience measures carries a cost, the escalating economic and societal costs of inaction are likely to be far greater.
Safeguarding critical infrastructure requires a shift to a multi-layered PNT approach – combining multi-constellation, multi-band GNSS with complementary alterative technologies like atomic clocks, inertial systems, and intelligent fusion algorithms. Governments and industries must work together to accelerate investment in cost-effective, plug-and-play solutions with standardised interfaces. Embracing this “system of systems” model is key to maintaining service continuity, mitigating GNSS vulnerabilities, and securing our future.