Nats air traffic control failures: Alexander demands accountability

Transport Secretary Heidi Alexander has said there “must be accountability” for the technology failures at Nats, the UK’s air traffic control provider, describing “successive Nats technology failures” as “totally unacceptable”. She was speaking to the Airports UK conference in London on Wednesday, according to Travel Weekly.

The comments matter to passengers, airlines and airport operators, all of whom were caught up in the fault on 8 September. Ms Alexander said she “was angry” at that failure and told aviation leaders: “Passengers deserve better. Your industry deserves better.”

UK airport delays and Nats system failures on 8 September

A preliminary report published by Nats on Friday said the 8 September incident was caused by a fault in the software that allocates codes to individual aircraft. The codes identify each aircraft on radar while it is airborne. Nats said the fault happened “in the space of a millisecond”, and more than 2,000 flights were cancelled, with disruption continuing into the following day.

The report said controllers at the London Area Control centre lost access to some live flight data and switched to fallback procedures. These included handing over aircraft to neighbouring air traffic control units manually, a task that normally happens automatically. As this raised controller workload, the number of aircraft allowed in the airspace was reduced “to maintain safety margins”.

Nats chief executive Martin Rolfe wrote that it was a software issue and not caused by incorrect actions by military or civil operators. Nats also said there was no evidence at this stage of a malicious actor or cyber-related activity. Airports including Heathrow, Gatwick, Manchester and Stansted were affected.

Transport Secretary demands Nats accountability

At the conference Ms Alexander said Nats had delivered its report and the Civil Aviation Authority had started its review. “I want to understand why we keep experiencing these problems,” she said. “Rest assured I’ll act without fear or favour.”

Responding to the preliminary report, she said it was “clear we need to urgently understand why this issue was not discovered and fixed before it caused chaos”. She has asked the CAA to check Nats’ findings and examine its investment plans for resilience, along with regulatory accountability. She previously told MPs she did not believe the problem was “unavoidable”.

The limits of her role are relevant. After a separate Nats fault in July 2025, the Department for Transport noted that the Transport Secretary has no direct control over Nats and no powers on staffing decisions, according to Yahoo News UK. Ryanair’s Neal McMahon has repeated calls for Mr Rolfe to resign, while Airlines UK said it is writing to Nats to demand compensation and a credible resilience plan.

Nats disruptions impact UK travel: how the incidents compare

Three Nats failures are now part of the public record, and the reported figures differ in kind. The table sets out what each source said.

Going by the minimum figures reported, about twelve times as many flights were cancelled on 8 September as in July 2025. The 2023 figure counts passengers rather than flights, so it cannot be compared directly. Mr Rolfe said the latest incident was not related to either earlier one, but easyJet chief executive Kenton Jarvis called them “repeated failures” that leave airlines as “insurer of last resort”.

What happens next

Nats said its own full report will be completed within 60 days, and the CAA’s independent review is due to be published within six months. Those two documents are the next points at which the cause, and any investment shortfall, should become clearer. Parliament is also considering the Civil Aviation Bill, which Ms Alexander listed among the work she wants to see through.

For passengers affected, the CAA previously said they were “unlikely to be entitled to compensation for delays or cancellations that were directly caused by the incident”. Airlines UK has said it wants compensation for airlines’ costs, and easyJet wants a “fair solution” so airlines are not left to pick up the bill.

Airport leaders also raised sharply higher business rates with the minister. She said “discussions remain ongoing” and that, with the Budget a fortnight away, there was a limit to what she could say.