Heidi Alexander said the Civil Aviation Authority will check their findings after a UK air traffic control outage NATS traced to a software defect that corrupted flight data in a millisecond. The failure began on Tuesday 8 September and left flights across the UK facing six hours of disruption.
Alexander said the regulator would move to urgently understand why this issue was not discovered and fixed before it caused chaos. The outage disrupted hundreds of thousands of passengers, and the backlog of travel disruption took more than two days to clear.
Martin Rolfe and the restart
Martin Rolfe said, “The issue has been identified and mitigation is in place while a permanent fix is safety tested and deployed.” He added, “I would like to apologise again, very sincerely, to everyone who was affected last week.” Rolfe also said, “It’s our job to get people where they want to go, quickly and without delay and we are devastated when that goes”.
The sequence of failures shows how fast the system moved from an apparent recovery to a full shutdown. Engineers were told at 10.02am that the link between the national airspace system and the London area control system had dropped. By 10.06am, the system had apparently recovered with no operational impact, but the same issue returned at 12.30pm and a major incident was declared.
Tuesday 8 September timeline
After the repeat error, the link between the national and London airspace management dropped again at 12.32pm. Nats began restricting flights at 12.45pm as the system kept glitching, the system failed completely at 1.32pm, and airlines were advised of restrictions at 1.40pm. Between 2.50pm and 4.09pm, Nats rebooted the system, and full operations resumed at 7.30pm.
The software fault appeared when a manual request for an aircraft code was being processed and another request paused it. When processing resumed, the defect meant the system did not resume correctly and the output was corrupted. That left the immediate question Alexander named: why the problem was not caught before the outage spread across the UK and beyond.
Civil Aviation Authority review
Alexander said the Civil Aviation Authority would now check Nats’ findings and look at its plans. The episode was the third major air traffic control failure in the UK since summer 2023, according to Ryanair, which also demanded Rolfe’s dismissal. For passengers whose trips were caught in the disruption, the key operational point is that the system has resumed, but the regulatory review and the permanent fix process are still under way.
