# Planes are having their GPS hacked. Could new clocks keep them safe?
## 2 March 2025

**As a Ryanair flight from London approached Vilnius, Lithuania, on 17 January, its descent was suddenly aborted. Just minutes from touching down, the aircraft's essential Global Positioning System (GPS) suffered an unexplained interference, triggering an emergency diversion.**

The Boeing 737 MAX 8-200 had already descended to around 850ft (259m) when the disruption occurred. Instead of landing, the plane was forced to climb back into the sky and divert nearly 400km (250 miles) south to Warsaw, Poland. Lithuanian air authorities later confirmed the aircraft had been affected by "GPS signal interference".

This was not an isolated incident. Over the last three months of 2024, more than 800 cases of GPS interference were recorded in Lithuanian airspace. Estonia and Finland have also raised concerns, accusing Russia of deploying technology to jam satellite navigation signals near Nato's eastern flank – though the country has denied that. Last March the then Defence Secretary, Grant Shapps, was on a plane that had its GPS signal jammed while flying close to Russian territory.

The threat of GPS jamming extends beyond aviation. Without GPS, our lives would grind to a halt: in 2017,  that systematic GPS jamming could bring the UK's financial, electricity and communications systems to a standstill.

## A new way of measuring time

The challenge can be compared to the invention of a portable clock for marine navigation by John Harrison in the 18th Century, which solved the so-called longitude problem, allowing a new era of trade and a golden age of exploration.

Three hundred years on, researchers are once again racing to perfect a new clock to solve the GPS problem – and the impact could be at least as transformative.

"History shows that each time we have an improvement in the ability to measure time, new applications follow to make things possible that people didn't dream of before," says Dr Helen Margolis, head scientist (time and frequency) of the UK's timing laboratories at the National Physical Laboratory (NPL) in south-west London.

In 1967, the world's timekeepers, an intergovernmental body called the General Conference on Weights and Measures, agreed to define time using atomic clocks, rather than by the Earth's rotation.

The switch transformed our world just as radically as Harrison's clock, laying the foundation for GPS and similar space-based systems. These provided precise timekeeping from atomic clocks on satellites, which allowed rapid and huge volumes of communications, computation, and transactions to be carried out everywhere in the world near instantaneously, as well as more precise navigation.



**John Harrison's marine clock revolutionised navigation, paving the way for global trade and exploration**

The search for a new portable alternative to GPS involves a field called quantum technologies, finding ways to manipulate atoms. Much of the buzz around the subject in recent years has been about the development of powerful quantum computers which, the narrative goes, will make our fastest supercomputers seem like abacuses by comparison.

But a quieter revolution to improve navigation and measurement of time has flown under the radar, and it is in this field that quantum technology is set to make its earliest impact, according to Prof Douglas Paul of the UK Hub for Quantum Enabled Position Navigation and Timing (QEPNT), which was set up last December by the government to develop these new devices.

"We are expecting to see some sort of navigation system within two to five years in the marketplace," he says. "So, some of these technologies are already quite advanced."

## The 'Time Lords'

Prof Paul and his quantum scientists are working with Dr Margolis and her fellow researchers at NPL, who have been given the "Time Lords" nickname by other horologists. In 1955, the NPL invented the first atomic clock of the sort that is used today, based on the frequency of radiation from an atom of the element caesium.

GPS and other satellite navigation systems reset their own clocks by touching base with these more accurate clocks on the ground. For the alternative to GPS, the scientists will need a new type of atomic clock that can eventually be miniaturised and robust enough to work in everyday situations, rather than the carefully controlled conditions inside a lab.

The NPL researchers are perfecting a so-called optical clock to achieve this, which is 100 times more accurate than the most accurate caesium clocks used today. It looks as if it might be part of Dr Who's Tardis and is stimulated with laser light rather than microwaves.

When optical clocks take over from caesium ones as the timepieces that determine Universal Coordinated Time (UTC), the way the passage of time is defined will also have to change, according to Dr Margolis.

"The international community has drawn up a road map for the redefinition of the second," she tells BBC News.

The NPL's immediate hope is to have a national network by 2030, connecting four atomic clocks across the UK that businesses can plug into for secure accurate timekeeping and for developing new innovative applications that harness ultra-fast time.

Eventually, critical systems in the UK in finance, telecommunications, energy, utilities and national security could switch over – though that would take longer. "To convert everything is at least a decade away, and probably significantly longer," says Prof Paul.

Yet the stakes are high, and the alternative this new technology offers is significant. "The US Department of Defence might decide to stop supporting GPS, it could be taken out in a conflict or by an accident," he says. "There is no guarantee GPS … will always be available. With all the jamming and spoofing , you cannot always guarantee you have an assured signal, so if you cannot get or trust the information then people will stop using it."



**In March 2024, the then Defence Secretary Grant Shapps experienced GPS jamming first-hand when his plane lost signal while flying near Russian territory**

While this type of research is taking place around the world, it's being led by the UK. When an aircraft with the technology on board , the then science minister Andrew Griffith described it as "further proof of the UK as one of the world leaders on quantum". According to the government, it was the first test of this type of technology in the UK on an aircraft in flight, and "the first such flight worldwide that has been publicly acknowledged".

By carrying a group of atoms cooled to -273C on the plane itself, rather than relying on an external signal, the technology can't be interfered with by jamming.

But the problem is that the equipment is still too large to be used routinely on planes.

Henry White, part of the team from BAE Systems that worked on the test flight, told BBC News that he thought the first application could be aboard ships, "where there's a bit more space".

Quantum clocks, gyroscopes and accelerometers are large, bulky and incredibly expensive, with an accurate quantum clock costing around £100,000. Yet military research is allowing the creation of smaller, better and cheaper systems.



**GPS jamming is disrupting British military operations in conflict zones like Ukraine, posing serious challenges**

GPS jamming is causing problems for the British military in conflict zones such as Ukraine. One of the main challenges faced by scientists at the government's Defence, Science and Technology Laboratory (DSTL) is making the sensitive technology work not just in the real world, which in the Navy's case is often in very choppy seas, but also in the harshest of environments; the battlefield, according to a lead researcher at the DSTL, who has to remain anonymous for security reasons.

"You are harnessing atoms," she points out.

"You have vibrations, you have pressure changes, you have temperature changes, and you have environments which have all of these different variables going on while you are trying to manipulate the properties of light. So, it's precision that is needed".

## Atomic clocks in our pockets

The ultimate aim for some of those working on this new technology is for each of us to have the equivalent of our own personal GPS system incorporated into our phones.

This would comprise a miniaturised optical clock as well as a tiny gyroscope, so we know which direction we are going in, and a device called an accelerometer, which will tell us how fast we are going.

QEPNT has been set up by the government to shrink the devices on to a chip, making them robust enough for everyday life and affordable for everyone.

That process isn't going to happen soon, though. "This is many decades away from happening for all critical national infrastructure across the UK," says Prof Paul.

Quantum clock researchers are facing exactly the same problems experienced by John Harrison when he was developing his portable marine clock in the 18th Century. Mr Harrison had to build a clock whose timekeeping was not affected by changes in temperature, pressure or humidity, and was able to function in a constantly moving ship – his greatest difficulty was to make it small.



**Organised criminals targeting tractor GPS systems**

Police say there has been "a significant increase" in GPS thefts over recent weeks.

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