A technical failure of the UK’s air traffic control system that has caused widespread flight chaos was avoidable, according to the Transport Secretary. Heidi Alexander told the Commons she had ordered an independent investigation by the aviation watchdog into the system operated by Nats, which went down for four hours on Tuesday. More than 2,000 flights have been cancelled as disruption continued for a second day with passengers stuggling to fly out of and into the UK. After meeting with the boss of Nats, Martin Rolfe, Alexander said a cyberattack could be ruled out, but she added: “I do not believe this issue was unavoidable.” Nats has apologised for its third major technical fault in three years.
Alexander said she discussed with Rolfe how Nats, which is 49% owned by the government, “responded to resolve and minimise the disruption as quickly as possible”. She said there had to be “tough questions about resilience of Nats systems”, adding: “We also need to think about consumer redress issues.” Earlier on Wednesday the government said it had confidence in Rolfe, who has led Nats for 11 years as airlines such as Wizz Air and Ryanair called for him to step down. Nats has been asked to investigate the incident and report back in one week. But Alexander said she has also asked the Civil Aviation Authority to conduct an independent review and present an update in six months’ time.
Airlines UK, which represents the country’s carriers, said it had written to Alexander to “register serious concerns over yesterday’s technical failure at Nats – the third major system failure in three years – which has caused major disruption across the UK’s aviation network”. Airlines UK’s chief executive Tim Alderslade, said: “The result is a system where airlines pick up the bill for the mistakes of others, while the organisations responsible face little or no financial consequence. “Accountability should sit where responsibility lies and the Civil Aviation Bill offers the opportunity to address this.” It is not the first time disruption has blighted Nats’ control system. In 2023, a computer shutdown over the August bank holiday weekend caused chaos for 700,000 passengers.
It took an engineer, who had been unable to correct the fault from home, three hours to get to work. There was another, smaller Nats outage in 2025, which caused 150 cancellations. Nats is a public-private partnership, with the government holding the majority stake. The rest is split between a group of UK airlines including BA, easyJet and Virgin Atlantic as well as Heathrow and Nats staff.
Nats first confirmed it was investigating a “technical issue” at 13:46 BST on Tuesday, “which is causing some disruption to flight departures”. The glitch occurred at Nats’ Swanwick Centre in Hampshire, where one of its two air traffic control centres are. The other is in Prestwick, Ayrshire. Around 90 minutes later, it said it had identified that the issue was with its flight processing system.
This processes flight plans and other operational information used by controllers to manage air traffic. It continually updates flight information as aircraft progress through UK airspace, helping controllers maintain a safe and orderly flow of traffic. By 19:30, Nats said the system issue had been resolved and it was working to clear the backlog of flights. However, by Wednesday evening, the number of flights that had been cancelled or failed to take off since the fault first emerged had grown to more than 2,000, according to flight analytics firm Cirium.
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