The U.K.'s air traffic control provider said Monday that it had "identified and remedied" an earlier technical issue which saw flights across the country disrupted.
In an afternoon update, the National Air Traffic Service said that it was now working with airlines and airports to manage the affected flights following warnings that passengers could face hourslong delays.
"We have identified and remedied the technical issue affecting our flight planning system this morning. We are now working closely with airlines and airports to manage the flights affected as efficiently as possible," NATS said in a statement issued at 3:15 p.m. London time.
"Our engineers will be carefully monitoring the system's performance as we return to normal operations," it added.
NATS did not provide further details on the cause of the issue or what flight restrictions remained in place.
Following the announcement that the glitch had been remedied, a spokesperson for London's Heathrow Airport said that flight schedules will remain "significantly disrupted" for the rest of the day and urged passengers to only travel to the airport if their flight is confirmed as still operating.
British Airways said that its schedule had been "severely disrupted" by the outage and noted that many flights — particularly short haul — may no longer be operating Monday.
Holiday travel disruption
The update follows earlier announcements from NATS, in which it said that a technical fault had disrupted its ability to automatically process flight plans and that air traffic control was instead being handled manually.
"We are currently experiencing a technical issue and have applied traffic flow restrictions to maintain safety," NATS said in a statement issued at 12.10 p.m. "Engineers are working to find and fix the fault."
In an update issued at 2.20 p.m., NATS said that the fault remained unresolved and that air traffic control was being handled manually for the time being.
"This morning's technical issue is affecting our ability to automatically process flight plans. Until our engineers have resolved this, flight plans are being input manually which means we cannot process them at the same volume, hence we have applied traffic flow restrictions," it said.
NATS first announced the disruption at 12.10 p.m. and clarified that "UK airspace is not closed" following reports on social media site X, formerly known as Twitter.
The issue with air traffic control was announced earlier by Scottish airline Loganair, which said on X that there was a "network-wide failure of UK air traffic control computer systems this morning."
Passengers were warned that they could face severe delays. It comes during the U.K.'s busy bank holiday travel period, with many people returning from summer holidays.
Flight tracking website Flightradar24 shared an image on X of live air traffic data at 12:35 p.m. London time.
In an accompanying statement, it said that U.K. airports, including Heathrow, appear to be "significantly limiting departures," although arrivals continue. It added that all of its most tracked flights are currently London arrivals.
Gatwick Airport, London's second-largest airport, said Monday afternoon that it was "seeing delays, and [flight] cancellations," while Luton Airport said the air traffic control issue was "affecting UK airspace, resulting in disruption to flights."
Meanwhile, Stansted Airport said it was "aware of a nationwide air traffic control issue that is affecting flights in and out of airports across the country."