Flight delays and cancellations at UK airports are expected to continue until Wednesday after another air traffic control glitch grounded planes for several hours, affecting hundreds of thousands of passengers.
At least 177 flights scheduled for Wednesday to and from UK airports were cancelled, plane tracking website Flightradar24 said, “almost all at London Heathrow”. More than 1,000 events were canceled around 8 p.m. Tuesday.
A “technical problem” at air traffic control provider Nats was the third major shutdown in the UK in three years. Nats said on Tuesday night: “This has been a very challenging recovery which has created challenges for the entire aviation network from which recovery will take time.”
The crash began at around 1pm on Tuesday and affected departing flights at many of the UK’s major airports, including Heathrow, Gatwick, Manchester and Stansted. By the time Nats said it had fixed its flight processing system nearly four hours later, most scheduled flights had not yet taken off. The disruption spread to include incoming flights across much of southern England.
Cancellations and delays continued into Tuesday evening, with British Airways saying the disruption would impact operations through at least Wednesday, with passengers being offered free rebookings until Friday. Nats provides air traffic control services at 15 UK airports.
Ryanair said more than 65,000 passengers were delayed and 50 flights were cancelled. EasyJet said the side effects were affecting flights across Europe. Some incoming flights had to be diverted to airports abroad, said Eurocontrol, Europe’s airspace coordinator.
London, Manchester and Birmingham airports were the hardest hit. Flights to and from other UK airports, including Edinburgh and Belfast, were also disrupted. Late on Tuesday, Heathrow said flights had resumed intermittently, but arrivals had been suspended for the remainder of the night.
The Nats initially announced at 1:46 p.m. that they were “investigating a technical issue that is causing some flight departure disruptions.” The company later discovered a problem in its flight processing system and announced at 4:40 p.m. that it had been fixed.
The spokesperson said this fault is different from those that caused outages and widespread outages in 2023 and 2025. “We continue to work closely with our airline and airport customers on recovery efforts. We sincerely apologize for the disruption to people’s travel today and they should continue to check with their airline.”
Nats CEO Martin Rolfe was due to brief Transport Minister Heidi Alexander about the breakdown on Wednesday. Alexander, in turn, will speak before deputies of the House of Commons in the second reading of the bill on civil aviation.
Rolfe expressed his “tremendous sympathy for everyone affected by today’s turmoil.”
“We are absolutely responsible for this,” he told Sky News. “We never want something like this to happen. I fully understand how upsetting this is for passengers.”
However, he stated that “such things are relatively rare.”
“We have resolved this issue to return our systems to normal operation,” he added. “But, of course, now a huge number of violations have accumulated in the system.
“We’re working very closely with airlines and airports right now to try to operate throughout the night and ensure we can get as many people traveling as possible.”
The air traffic control problems followed an “isolated event” a year ago that caused widespread disruption and appeared less severe than the complete grounding of flights in August 2023, prompting a parliamentary inquiry.
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British Airways said the “severity of the issue means it will have a significant impact on customers and colleagues.”
“We were forced to cancel or reroute more than 100 flights on Tuesday afternoon, causing inconvenience to tens of thousands of customers,” the spokesperson said.
“This incident was beyond our control and incredibly frustrating for our customers and colleagues as aircraft and crews were stranded.”
Airlines have renewed calls for a major overhaul of the Nats.
Ryanair repeated its demand for Rolfe’s resignation. The airline’s chief operating officer Neil McMahon said: “Families traveling on holiday, people traveling for work and thousands of visitors to the UK have once again paid the price for the abject failure of the Nats.”
He said the government should “stop making excuses for the repeated failures of the National Security Service and appoint a new leader capable of managing the UK’s air traffic control system.”
Wizz Air said: “A provider of critical national infrastructure should not have to repeatedly shut down the aviation system. Nats is simply not fit for purpose in its current form.”
Alexander said: “I am aware of a technical issue affecting flights at airports including Heathrow and Gatwick. Technicians have identified the issue and are fixing it right now. I know this will be frustrating for passengers and I am very sorry.”
“I want assurance that lessons will be learned and that the systems that support aviation will be up to the task.”