PNT Update

UK Positioning, Navigation and Timing: Overview

As of March 2025, the UK’s Framework for Greater PNT Resilience, introduced in October 2023, continues to drive efforts to enhance Positioning, Navigation, and Timing (PNT) services. A significant milestone was achieved on 20 November 2024, when the National PNT Office, established within the Department for Science, Innovation and Technology (DSIT), collaborated with the Royal Institute of Navigation (RIN) to launch the world’s first best practice principles and checklist for resilient PNT. This initiative provides businesses with actionable guidance to mitigate risks and invest in robust PNT technologies, marking a global lead in standardizing resilience measures. Additionally, the 2025 National Risk Register, part of the National Security Risk Assessment (NSRA), reaffirmed the critical risk of PNT disruptions due to potential catastrophic Global Navigation Satellite System (GNSS) failures, underscoring the urgency of ongoing resilience efforts.

Introduction

PNT services are vital to the UK’s economy, security, and daily operations, supporting sectors such as finance, defence, transportation, telecommunications, and emergency services. PNT encompasses Positioning (determining location and orientation), Navigation (guiding movement between positions), and Timing (maintaining precise time from a global standard). Primarily delivered through GNSS, such as the US Global Positioning System (GPS), PNT is an “invisible utility” enabling communications, global supply chains, and activities like banking and broadcasting. The UK’s reliance on GNSS, however, exposes it to disruptions, prompting the government to prioritize enhanced PNT resilience.

Why PNT Matters

PNT underpins all 13 sectors of the UK’s Critical National Infrastructure (CNI), including energy, transport, and emergency services. It enables secure financial transactions, media broadcasts, and emerging technologies like autonomous vehicles and smart cities. The 2018 Blackett Review, Satellite derived Time and Position: A Study of Critical Dependencies, highlighted the risks of GNSS dependency, noting that disruptions from technical failures, space weather, or intentional interference could severely impact the economy and national security. The 2025 National Risk Register further emphasizes the need for robust contingency measures to address these vulnerabilities.

Government Framework for Greater PNT Resilience

The Framework for Greater PNT Resilience, a 10-point policy plan launched in October 2023, aims to reduce dependency on vulnerable GNSS signals, enhance resilience, and foster innovation. Building on the 2018 Blackett Review, the 2021 Integrated Review, and the UK Space Agency’s Space Based PNT Programme (SBPP), the framework remains a cornerstone of UK PNT policy. Its key components include:

1. National PNT Office

The National PNT Office, housed in DSIT, coordinates PNT policy and delivery across government. Launched post-2023 framework, it drives resilience by collaborating with stakeholders to address vulnerabilities and promote innovative solutions, as evidenced by the 2024 RIN collaboration.

2. PNT Crisis Plan

A cross-government PNT Crisis Plan is maintained to mitigate GNSS disruptions, identifying short-term solutions to ensure continuity of critical services, as informed by the 2023 RIN White Paper and 2025 National Risk Register.

3. National Timing Centre (NTC)

A proposed National Timing Centre, based on the National Physical Laboratory’s UTC(NPL) time scale, would provide resilient, terrestrial, and sovereign timing using advanced optical clocks. Supported by £14 million, this builds on the NTC R&D programme since 2020.

4. Ministry of Defence (MOD) Time

A proposed “MOD Time” system would ensure resilient timing for defence applications, leveraging NTC capabilities to enhance national security in contested environments.

5. Enhanced Long-Range Navigation (eLORAN)

A terrestrial, sovereign eLORAN system is proposed to provide backup positioning and navigation. In May 2023, Ofcom sought industry interest in eLORAN broadcast licenses, advancing implementation.

6. UK Satellite-Based Augmentation System (SBAS)

A UK Precise Point Positioning SBAS is under exploration to replace reliance on the European Geostationary Navigation Overlay Service (EGNOS), supporting high-accuracy positioning and GNSS integrity monitoring

7. Next-Generation PNT Technologies

Investments in quantum navigators and potential UK sovereign regional satellite systems aim to diversify PNT sources and bolster resilience against emerging threats.

8. Infrastructure Resilience

The framework promotes resilient GNSS receiver chips, holdover clocks, and potential legislation to mandate minimum PNT resilience standards for CNI sectors.

Economic and Strategic Impact

The framework addresses vulnerabilities while positioning the UK as a PNT innovation leader. By fostering skills, industry collaboration, and R&D, it supports economic growth and aligns with the 2023 UK Science and Technology Framework’s vision of a science and technology superpower by 2030. Resilient PNT systems are critical for autonomous vehicles, digital twins, and 5G networks, ensuring global competitiveness.

Conclusion

The UK’s Framework for Greater PNT Resilience strengthens critical infrastructure and drives economic opportunities. Recent advancements, including the National PNT Office’s 2024 best practice principles and ongoing NTC and eLORAN proposals, demonstrate progress toward a secure PNT ecosystem. For further details, visit www.GOV.UK.

Tracking the world’s forests: how the ESA’s Biomass mission will work The European Space Agency (ESA) is set to launch its ambitious Biomass mission later this month. The mission will map the world’s forests to provide the very first comprehensive measurements of forest biomass at a global scale. It will find out how forests are changing, and further our understanding about their role in the carbon cycle. The satellite is scheduled to lift off on April 29 aboard a Vega C rocket from the ESA’s Korou spaceport in French Guiana. What will the Biomass mission do? All life on Earth, from smallest microbes to gigantic California Redwoods, is carbon-based. As such, carbon is the element that makes life as we know it possible. But Earth does not gain or lose carbon. The element only moves between the atmosphere, living organisms, Earth’s crust and soil, and the oceans. This process is known as the carbon cycle, of which forests are an essential part. This is because forests store massive amounts of carbon — scientists estimate that they absorb around 16 billion metric tonnes of carbon dioxide (CO2) per year, and currently hold 861 gigatonnes of carbon in their soils and vegetation. Unfortunately, data on forest biomass — the mass of organic matter in forests — are severely lacking on a global scale. This fundamentally limits our understanding of the state of the forests, and their impact on the carbon cycle (and climate). The Biomass mission aims to bridge this knowledge gap. The mission will allow scientists to more accurately measure how the distribution of carbon in the planet is changing, as humans continue to cut down trees, and increase CO2 levels in the atmosphere. In 2023, Earth lost 3.7 million hectares of tropical forests, equivalent to losing around ten football f ields worth of forest land every minute, according to a report by the World Resources Institute. “This forest loss produced roughly 6% of estimated global CO2 emissions in 2023,” the report said. Simonetta Cheli, director of Earth Observation Programmes for the ESA, told The Observer, “We need to know the health of our tropical forests… We need to know the quality and diversity of its vegetation and the amount of carbon stored there. To get that information we are going to create 3D images of them — from the top of the forest canopy to the roots of its trees.” Beyond forest monitoring, the Biomass mission will also observe the movement of ice sheets in Antarctica, and generate digital models of terrains covered by dense vegetation. How will the Biomass mission monitor forests? To fulfil its objectives, the mission will use a synthetic aperture radar (SAR) to map the Earth’s surface. Notably, the satellite, which is f itted with a massive 12-m antenna, will be the f irst in space to use a long-wave P-band SAR. It will thus be able to penetrate dense forest canopies to assess how much carbon is stored on the floor and in the branches of the trees, and to assess how these levels are changing over time. Note that as a general rule, shorter wavelengths of electromagnetic radiation penetrate matter less than longer wavelengths. Shaun Quegan, a researcher at Sheffield University (England) and head of the Biomass science team, told The Guardian: “What the mission will do, effectively, is weigh the forests it studies… We know half that weight must be made up of carbon. So we are going to be able to weigh the carbon content of the world’s… forests from space and, crucially, work out how much these are changing over time. We will then know the balance of carbon that is flowing to and from the atmosphere. That is enormously important.”