Air traffic control issue disrupts flights at major UK airports

The cancellation of more than 1,000 flights and ‌delays to hundreds more renew scrutiny of NATS three years after a flight-plan processing failure caused even more widespread disruption.

As passengers waited for information in departure halls across the country on Tuesday, airlines questioned whether the country's air traffic control system was fit for purpose.

NATS said at 1834 GMT that the issue, which had impacted its flight data processing system, had been resolved. It had earlier said that "safety was not compromised."

"Recovery from today’s system issue has taken longer than we had hoped. Our system issue is now resolved, we are operating normally and working as hard as possible to clear the backlog of flights," NATS said on X.

The traffic control provider later said in an update on X that it would take time to recover from the disruption, adding that "this ⁠has been a very complex recovery and has created difficulties for the whole aviation network".

CEO Martin Rolfe told Sky News that NATS had not "fully done the investigation" to find the reason behind the technical issue that caused the disruption.

"We don't have an idea yet of exactly what went wrong," Rolfe said.

Flights delayed and cancelled 

According to data from flight-tracking website Flightradar24, 1,300 flights to and from UK airports were cancelled on Tuesday. Another 177 flights had been cancelled for Wednesday, nearly all of them at Heathrow, the country's largest airport, it added.

Heathrow said at 2019 GMT that arrivals to the airport had been suspended for the remainder of Tuesday, and while departures had resumed, the disruption was expected to continue.

Earlier, data on flight-tracking platform FlightAware said some 490 departures were delayed at six airports, including Heathrow, Gatwick, London City, Luton, Edinburgh and Bristol as of 1518 GMT. Some 525 arrivals at those six airports were either cancelled or delayed, the website data showed.

At Heathrow, 38 of 661 scheduled arrivals had been cancelled or were unable to operate, according to aviation analytics company Cirium. British Airways was the most affected carrier at the airport, cancelling 16 of 333 scheduled departures.

"The severity of the issue means there will be a significant knock-on ‌impact for customers ⁠and colleagues," British Airways said in a statement.

Europe's traffic-filled skies 

Air traffic control is a tightly timed system in Europe's extremely busy skies.

Aviation analyst John Strickland said the consequences of even a relatively short outage can be severe because delays quickly cascade through tightly scheduled airline networks.

"A few hours of outage may on the face of it sound limited but the impact is enormous when a substantial number of airports across the UK are affected," Strickland said.

Ryanair said around 150,000 of its passengers had been affected by delays of up to eight hours and that it had cancelled more than 200 flights, and called on NATS Chief Executive Martin Rolfe to resign.

"How many more failures do ⁠passengers have to suffer before overpaid failure NATS CEO, Martin Rolfe, accepts responsibility for his repeated mismanagement and resigns?" Ryanair Chief Operating Officer Neal McMahon said.

NATS did not immediately respond to a request for comment on McMahon's statement.

Wizz Air also called for urgent reform of the air traffic control provider, saying airlines, passengers and airports should not continue to bear the consequences of recurring system failures.

"A critical national infrastructure provider should not repeatedly bring the aviation system ⁠to a standstill. NATS is simply not fit for purpose in its current form," Wizz Air said.

Britain's aviation regulator said it would expect NATS to share a full report of Tuesday's incident.

The Civil Aviation Authority said it would then consider whether any further steps need to be taken to secure the reliability of the UK's air traffic control system.

In 2024, the CAA said NATS needed to review its contingency plans for ⁠outages after the automatic processing of flight plans had malfunctioned a year earlier, causing chaos across Britain's airports.

Airline bosses said that outage had cost them over £100 million ($135.49 million) in refunds and compensation.

In July last year, a radar-related technical issue in Britain's air traffic control system disrupted flights for over four hours at major airports in London and elsewhere, including Heathrow.