A view inside T5 at Heathrow airport following an after an air traffic control (ATC) fault caused major disruption. Photo / Getty Images
Summer holidaymakers are facing days of travel chaos after an air traffic control failure grounded flights across the UK.
Airspace across Britain was closed on Wednesday afternoon because of a radar issue that disrupted hundreds of flights.
While the breakdown was fixed within the hour, the knock-on effects from hundreds of delays and diversions – as well as at least 155 cancellations – are expected to last for days.
Nats [National Air Traffic Services], the air traffic control company responsible for Britain’s skies, refused to rule out hostile foreign action as the cause of the failure, fuelling calls for an “urgent investigation” into possible malign interference.
But it said there was “no evidence” the cause was “cyber-related”.
The system failure came at the peak of the summer holiday season and before the busiest day of the year for commercial flights, which falls on Friday.
Heidi Alexander, the Transport Secretary, said “continued disruption is expected” and urged passengers to “check with individual airports for advice”.
Aviation expert John Strickland warned that holidaymakers could face days of chaos because airlines were already stretched thin during the summer getaway period.
“In the absolute worst case, this could knock on for the next few days because pretty much all airline fleets are being used at full tilt right now,” he said.
However, affected travellers are unlikely to be eligible for compensation because the incident was out of the control of airlines, that would otherwise pay.
The outage came just four months after a fire at a single electricity substation closed Heathrow for nearly 24 hours.
Passengers were left on the tarmac at airports across the UK, including Heathrow, Birmingham, Gatwick, Stansted and Cardiff, while arriving planes were sent to destinations in Europe such as Amsterdam, Paris and Brussels.
In Edinburgh, a group of 40 French holidaymakers were left stranded after two flights to Paris were cancelled, while tourists in Faro told the Telegraph that flight attendants were handing out water to cope with delays in the Portuguese heat.
Virgin Atlantic apologised to affected passengers while British Airways said the problem was “affecting the vast majority of our flights”, with at least half a dozen flights diverted.
A BA source said: “We don’t know what caused this yet but it appears to have been a radar issue and Nats are responsible for the radar, so you have to say the buck stops with them.”
The Telegraph understands that the air traffic control system shut down when radar systems at Nats’ Swanwick area control centre in Hampshire stopped displaying flights at around 2.30pm, forcing controllers to stop accepting new arrivals into UK airspace.
All flights on the ground bound for UK airports were immediately stopped from taking off, while those which were airborne but outside British skies were ordered to divert elsewhere.
Flights which were preparing to land in the UK when the failure happened were able to do so safely because it only affected Nats’ upper airspace unit, which does not handle individual airports’ operations.
Domestic flights were able to continue operating during the outage provided they stayed below 24,500 feet, the Telegraph understands.
That is because the outage was limited to the Swanwick centre, which only controls flights above that height.
Nats came under fire for the failure, which came two years after an engineer who was working from home struggled to fix a four-hour outage. The failure forced the cancellation of thousands of flights around the world, disrupted 700,000 passengers’ journeys and cost airlines, travellers and others an estimated £100 million ($224.3m) in total.
On Wednesday, Ryanair called on Martin Rolfe, Nats’ chief executive, to resign after claiming “no lessons had been learnt” from the 2023 meltdown.
Neal McMahon, Ryanair’s chief operating officer, said: “It is outrageous that passengers are once again being hit with delays and disruption due to Martin Rolfe’s continued mismanagement of Nats.
“Yet another ATC system failure has resulted in the closure of UK airspace, meaning thousands of passengers’ travel plans have been disrupted.
“It is clear that no lessons have been learnt since the August 2023 Nats system outage and passengers continue to suffer as a result.”
He called on the Transport Secretary to “act without delay to remove Martin Rolfe and deliver urgent reform of Nats’s shambolic ATC service, so that airlines and passengers are no longer forced to endure these preventable delays caused by persistent Nats failures”.
Air traffic control bosses confirmed on Wednesday afternoon that service had been restored but refused to answer any queries about the root cause or Rolfe’s future with the company.
In a statement, Nats said: “Our engineers have now restored the system that was affected this afternoon. We are in the process of resuming normal operations in the London area.
“We continue to work closely with airline and airport customers to minimise disruption. We apologise for any inconvenience this has caused.”
Sir Ed Davey, the Liberal Democrat leader, called for a Government inquiry into whether Nats fell victim to a foreign hack.
He said on Wednesday: “It is utterly unacceptable that after a major disruption just two years ago, air traffic control has once again been hit by a technical fault.
“The Government should launch an urgent investigation to ensure the system is fit for purpose, including ruling out hostile action as a cause.”
A Department for Transport spokesman said: “While passengers should continue to check with individual airports for advice, Nats have confirmed their systems are now fully operational and flights are returning to normal.
“We are working closely with Nats to understand the cause of the technical issue and the implications for the resilience systems in place.”