Flight delays and cancellations were expected to continue into Wednesday at UK airports after another air traffic control failure kept planes grounded for hours, affecting hundreds of thousands of passengers.
At least 177 flights scheduled for Wednesday to and from UK airports had been cancelled, plane tracking site Flightradar24 said, “nearly all at London Heathrowâ€. More than 1,000 were cancelled by about 8pm on Tuesday.
The “technical issue†at the air traffic control services provider Nats caused Britain's third major stoppage in just over three years. Nats said on Tuesday evening: “This has been a very complex recovery and has created difficulties for the whole aviation network, from which it will take time to recover.â€
The breakdown started at about 1pm on Tuesday and affected departing flights at many of Britain's biggest airports including Heathrow, Gatwick, Manchester and Stansted. By the time Nats said it had fixed its flight processing system almost four hours later, most flights scheduled to depart were yet to take off. The disruption spread to include incoming flights to much of southern England.
Cancellations and delays continued through Tuesday evening, and British Airways said disruption would affect operations into Wednesday at least, with passengers offered free rebooking until Friday. Nats provides air traffic control services to 15 UK airports.
Ryanair said more than 65,000 passengers had been delayed and 50 flights cancelled. The knock-on effects hit flights across Europe, according to easyJet. Some inbound flights had to be held at airports abroad, said Eurocontrol, the European airspace co-ordinator.
London airports, as well as Manchester and Birmingham, were among the most directly affected. Flights to and from other airports around the UK, including Edinburgh and Belfast, were also disrupted. Heathrow said late on Tuesday that departures had resumed with disruptions but arrivals had been suspended for the rest of the night.
Nats initially announced at 1.46pm that it was “investigating a technical issue which is causing some disruption to flight departuresâ€. It later identified the problem in its flight processing system, and announced at 4.40pm that it was fixed.
A spokesperson said the fault was not the same as those that caused outages and mass disruption in 2023 and 2025. “We are continuing to work closely with our airline and airport customers on recovery. We apologise sincerely for the disruption to people's journeys today and they should continue to check with their airline.â€
The chief executive of Nats, Martin Rolfe, was scheduled to brief the transport secretary, Heidi Alexander, on Wednesday over the breakdown. Alexander will in turn address MPs in the Commons for the second reading of the civil aviation bill.
Rolfe expressed his “huge sympathies to everyone who has been caught up in today's disruptionâ€.
“We absolutely take responsibility for this,†he told Sky News. “We never want this sort of thing to happen. I completely understand how frustrating it is for passengers.â€
He claimed, however, “these things are relatively rareâ€.
“We resolved it to get back to our systems operating normally,†he added. “But of course, there's a huge amount of disruption that's now built up in the system.
“We're working very closely now with airlines and airports to try to work through the night to make sure that we can get as many people travelling as possible.â€
The air traffic control problems follow an “isolated event†a year ago that caused widespread disruption, and appeared less severe than the full grounding of flights in August 2023, which prompted a parliamentary inquiry.
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British Airways said that “the severity of the issue means there will be a significant knock-on impact for customers and colleaguesâ€.
“We were forced to cancel or divert more than 100 flights on Tuesday afternoon, inconveniencing tens of thousands of customers,†a spokesperson said.
“This incident was entirely out of our control and incredibly frustrating for our customers and colleagues, with aircraft and crews ending up out of place.â€
Airlines renewed calls for Nats to be overhauled.
Ryanair repeated its demand for Rolfe to resign. The airline's chief operating officer, Neal McMahon, said: “Families travelling on holiday, people travelling for work and thousands of visitors to the UK have once again paid the price for Nats' abhorrent failure.â€
He said the government should “stop making excuses for repeated Nats failures and appoint a new leader capable of running the UK ATC systemâ€.
Wizz Air said: “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.â€
Alexander, said: “I'm aware of a technical issue impacting flights at airports including Heathrow and Gatwick. Technicians have identified the issue and are fixing it as we speak. I know this will be frustrating for passengers and I'm sorry.
“I am seeking assurances that lessons will be learned and systems that support aviation are up to the job.â€
