U.K. air traffic control operator says ‘technical issue’ briefly caused flight delays

Planes are parked at Terminal 5 at Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kin Cheung, file)

LONDON — A technical issue briefly grounded and diverted flights in Britain on Wednesday before engineers were able to restore the system, the air traffic control operator said.

Airports said it would take time for the disruption to clear, with many planes and crews out of position.

The National Air Traffic Service, or NATS, said the glitch happened at its control center at Swanwick, southwest of London, and required the service to limit the number of aircraft flying to ensure safety.

John Carr said it upended his flight to Norway for his brother’s wedding, where he is the best man and had to plan the rehearsal. He and a group of friends were having a meal in the Heathrow Airport when the departures monitor showed their flight had been canceled.

“I’m pretty gutted,” Carr said. “There was no warning from (the airport) or the airline that said it was cancelled. It’s rubbish. There’s nothing we can do.”

London’s Gatwick Airport said the issue affected outbound flights across the U.K. Some inbound flights were put into holding patterns or diverted.

Stansted, another London-area airport, said “many departures and arrivals” were affected and advised passengers to check with their airlines.

British Airways said the problem forced it to reduce the rate of flights from 45 an hour to 32 an hour, for a period of more than two hours.

About 20 minutes after issuing an initial alert, the agency said engineers had fixed the problem and that it was “in the process of restoring normal operations.”

Transport Secretary Heidi Alexander said “I am aware of a technical issue which impacted NATS’ operations causing travel disruption this afternoon.

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

The NATS system has suffered several software-related failures since it opened in 2002.

In August 2023, a glitch meant flight plans had to be processed manually, rather than automatically. Hundreds of flights were delayed or canceled at the height of the summer holidays and some 700,000 passengers affected.