A technical failure in the UK's air traffic control system caused widespread flight delays and cancellations at major airports, disrupting the plans of hundreds of thousands of passengers. National Air Traffic Services, or NATS, said the problem began at about 1 p.m. local time on September 8, affecting airports including Heathrow, Gatwick, Manchester and Stansted. Disruption continued into September 9 as airlines worked through the resulting backlog.

More than 1,000 flights had been canceled by Tuesday evening, while flight-tracking service Flightradar24 reported at least another 177 cancellations scheduled for Wednesday, most involving London Heathrow. NATS said its flight-processing system was fixed about four hours after the problem began, but the disruption had already created a large backlog that continued to affect departures and arrivals.

Airlines were also dealing with the wider impact. British Airways said disruption would continue into Wednesday and offered affected passengers free rebooking, while Ryanair said more than 65,000 passengers had experienced delays and that 50 flights were canceled. EasyJet reported knock-on effects across Europe, with some inbound services forced to remain at airports outside the UK.

The incident has renewed concerns over the reliability of Britain's air traffic control infrastructure. NATS chief executive Martin Rolfe apologized to affected passengers and said the company was working with airlines and airports to restore normal operations. The disruption was the third major UK air traffic control incident in just over three years. Ryanair and Wizz Air have called for changes to NATS, while Britain's Civil Aviation Authority has requested a full report on the incident to determine whether further action is necessary.