Transport Secretary Heidi Alexander told MPs on Wednesday afternoon that she does not believe the air traffic control failure that has caused two days of disruption at Heathrow was "unavoidable", going further than the government's earlier comments on the fault.
Addressing the Commons, Alexander said: "A four-hour air traffic outage yesterday left hundreds of thousands of passengers facing cancellations, diversions, and delays... I would like to apologise wholeheartedly to passengers for this disruption." She said Nats chief executive Martin Rolfe had told her the outage was caused by a technical issue at the organisation's Swanwick control centre, and that a cyber attack could be ruled out, but added: "I do not believe this issue was unavoidable," according to the BBC and the Standard, which both reported her Commons statement.
Beyond the internal Nats investigation, which has one week to report back, Alexander said she has separately asked the Civil Aviation Authority to carry out an independent review of the incident, due to report to her within six months. She also raised "consumer redress issues" and said there had to be "tough questions about resilience of Nats systems", the BBC reported.
Heathrow, Nats' busiest customer airport, bore the brunt of the knock-on disruption through Wednesday alongside Gatwick, Manchester and Stansted, after Tuesday's four-hour outage in the system that processes flight plans nationally. Aviation analytics firm Cirium said more than 300 flights had been cancelled or failed to take off by 3pm Wednesday, taking the two-day total affected to more than 2,000, the Standard reported. British Airways, Heathrow's largest carrier, said the fault forced it to cancel almost 550 flights, affecting more than 85,000 passengers, and called the disruption "entirely out of our control". The Standard reported passengers at Terminal 5 sleeping on the floor with their luggage overnight as they waited for rebooking.
Airlines UK, which represents UK carriers, wrote to Alexander to "register serious concerns" over what it called Nats' third major system failure in three years, with chief executive Tim Alderslade arguing airlines currently "pick up the bill for the mistakes of others" and calling for the Civil Aviation Bill to address accountability. Nats has had two previous major failures: a 2023 August bank holiday shutdown that hit 700,000 passengers, and a smaller 2025 outage that caused 150 cancellations.
Ryanair and Wizz Air have called for Rolfe to resign, though Downing Street has said it retains confidence in him pending the investigations.
What this means for your journey: if your Heathrow flight was cancelled or delayed by this fault, keep evidence of costs incurred and check your airline's rebooking and compensation options, since ministers have flagged passenger redress as a live issue. If you're heading to the airport while schedules are still settling, see our /parking/ and /public-transport/ guides for up-to-date options.