18 September 2026 | 18:56

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A software fault lasting “one millisecond”, not an act of sabotage as initially suspected, caused the disruption to flights across the UK on 8 September, grounding thousands of aircraft, a preliminary investigation by Nats has concluded. Nats, the UK’s main air traffic control service provider, found that the software defect compromised flight data and its updates, forcing restrictions on air traffic to ensure safety.

The fault affected only flights managed by the London area control centre, but nationwide restrictions were required to allow the National Airspace System (NAS), which underpins UK airspace management, to be safely restarted. Nats said the investigation ruled out a hostile cyberattack or deliberate sabotage.

The technical problem led to the cancellation of around 2,000 flights and disrupted hundreds of thousands of journeys, raising concerns about Nats’ systems and prompting calls for the resignation of its chief executive, Martin Rolfe. Rolfe said the issue was “a software problem in a specific part of our flight data system, which we traced to a small subsection of the code.” He added that the fault had been identified and corrective measures implemented while a permanent fix is tested and deployed.

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