NATS said a software defect, not human error, caused the Sept. 8 UK air traffic disruption.
Why it matters: The incident disrupted airline schedules across the UK, with more than 2,000 flights canceled and hundreds of thousands of passengers affected. It also puts a spotlight on how quickly a small systems failure can cascade through critical aviation infrastructure.
- NATS said a defect in its flight data system caused the Sept. 8, 2026 disruption.
- The company said the vulnerable moment was "in the space of a millisecond."
- AP reported more than 2,000 flights were canceled and hundreds of thousands of passengers were affected.
- NATS said restrictions lasted about six hours and the backlog took more than two days to clear.
NATS said a software defect in its flight data system triggered the UK air traffic disruption on Sept. 8 after a manual aircraft-code request was paused and then resumed incorrectly, corrupting output and affecting later flight data updates. The company said the critical failure occurred "in the space of a millisecond" in its preliminary report. NATS published the preliminary report
Because controllers had reduced information, restrictions were imposed across UK airspace while the national system was restarted and flight data reloaded. NATS said those restrictions lasted about six hours and operations returned to normal that evening, though it took more than two days to clear the passenger backlog. The report details the recovery timeline
The impact on passengers was extensive. AP reported more than 2,000 flights were canceled and hundreds of thousands of travelers were affected. AP reported the cancellation figures
Transport Secretary Heidi Alexander said passenger safety was protected, but said regulators needed to understand why the problem was not found and fixed before it caused disruption. She asked NATS to complete a full investigation, and the UK Civil Aviation Authority was assigned an independent review of the incident and NATS' resilience plans.
NATS chief executive Martin Rolfe said the problem was unrelated to the major system outage in August 2023 and was not caused by military intervention or incorrect actions by civil or military operators.
By the numbers
- 2,000+ - Flights AP said were canceled.
- Hundreds of thousands - Passengers AP said were affected.
- About 6 hours - Length of the UK airspace restrictions, according to NATS.
Yes, but: NATS has said the disruption was brief in operational terms, but the passenger backlog lasted more than two days and regulators are still reviewing how the failure escaped earlier detection.
What's next: The UK Civil Aviation Authority is conducting an independent review, and NATS must complete a full investigation.