Chaos at UK airports that led to cancellations and passengers stranded sparked by ‘software glitch’ – as delays continue

31 July 2025, 14:36

A software glitch was behind the air traffic outage that sparked chaos at UK airports as hundreds of flights were delayed or cancelled, officials have said, warning disruption could last days.

The software “glitch” left air traffic controllers confused about the airspace as the programme that is supposed to relay information to their screens broke down.

Bosses at the National Air Traffic Service (Nats), which runs UK airspace, immediately” put safety restrictions in place as the tech went down.

“This was a genuine software error and the back-up systems worked as they should. They run a different programme so there is no chance of the same issue happening twice,” a source told The Times.

Airports including Heathrow and Gatwick were affected by the outage, with travel hubs as far north as Edinburgh reporting that flights had been grounded shortly after 4pm UK time.

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Eurocontrol, the EU-wide air traffic control agency, reported that the London control area was “temporarily unavailable due to technical issues”.

As thousands of travellers faced cancellations, an update by NATS – a national air traffic control agency – provided more positive news, with the organisation stating that air traffic control systems are now “fully operational” shortly after 5pm.

Despite fully functioning radar systems, all airports have warned that travellers are set to face severe delays exceeding three hours to UK-bound airports.

There were calls today – made by Ryanair’s chief operating officer – for the head of the UK’s air traffic control company Martin Rolfe to resign in the wake of yet another ATC disaster.

There is no evidence that the technical issue was cyber related, they added.

One passenger, who was stranded aboard a London-bound flight at Italy’s Treviso airport in Venice, told LBC the captain had told passengers: “traffic control over London is blocked”.

Maps emerging online show the aftermath of the outage, with a cluster of aircraft gathered at London airports, leaving airspace across the south of England largely clear of air traffic.

Another passenger told LBC the pilot had warned that “a queue of flights” would be waiting to land when planes are eventually able to re-enter airspace.

Transport Secretary Heidi Alexander has said “continued disruption is expected” after the Nats radar failure on Wednesday.

“I am aware of a technical issue which impacted Nats’ operations causing travel disruption this afternoon,” the Cabinet minister posted on X.

“I have been informed systems have now been restored but continued disruption is expected, and passengers should check with individual airports for advice.”

Following the outage, airlines are demanding answers regarding the steps being taken by Nats to stop issues from happening again.

EasyJet’s chief operating officer David Morgan said: “It’s extremely disappointing to see an ATC failure once again causing disruption to our customers at this busy and important time of year for travel.

“While our priority today is supporting our customers, we will want to understand from Nats what steps they are taking to ensure issues don’t continue.”

A similar outage in August 2023 left more than 700,000 passengers affected by the cancellation of more than 500 flights at the UK’s busiest airports.