More than 1,000 flights were cancelled at UK airports on Tuesday after a technical problem in Britain's air traffic control system disrupted operations across the country, flight tracking website Flightradar24 reported.
The technical issue caused disruption at multiple airports, triggering widespread travel problems for passengers across the UK.
Although flights continued to depart and British airspace remained open, the disruption caused widespread delays, with NATS later saying it had implemented a fix and that its systems were beginning to recover.
By evening, NATS said it had fixed the problem with its flight processing system. However, delays continued across 15 UK airports and beyond as airlines and airports worked to clear a major backlog of disrupted flights.
NATS initially said the problem had been traced to its flight processing system and that engineers were working to restore normal operations.
"We have identified that the issue was in our flight processing system. Our engineers are on site and working urgently to resume normal operations as quickly as possible," NATS said in a statement, as quoted by Reuters. "Flights are still departing and airspace is open, but recovery will take some time," it added.
Heathrow, Britain's largest airport, said it was coordinating with NATS to resolve the disruption. Flight-tracking website Flightradar24 said arrivals and departures were being regulated at airports across the London flight information region because of the technical problem.
The disruption quickly translated into significant delays and cancellations. FlightAware data showed that around 100 flights had been cancelled at Heathrow, while 367 were delayed.
Air India also warned passengers that its flights to and from the UK had been affected by the technical fault at NATS. In a post on X, the airline said it had been forced to divert, delay or cancel multiple flights scheduled to operate to and from UK airports. It added that the disruption could affect some of its other services as aircraft and crews were left out of position.
NATS subsequently announced progress towards restoring normal operations. "We have implemented a fix and our flight system is starting to recover," NATS said in a post on X.
