UK Air Traffic Outage Cost the Economy £33m, and It Was Not a Cyber Attack

A major IT failure at the UK's National Air Traffic Services (NATS) in September was not caused by a cyber incident, yet it still cost the economy tens of millions of pounds. The Cyber Monitoring Centre (CMC) published a report on November 4 estimating the cost at around £33m, with 70 domestic organisations affected. Its modelled range reaches £42m, reflecting the cost to UK airlines, airports, ground operations and tour operators of 1152 flight cancellations, plus significant delays and diversions.

Including overseas airlines, the cost could reach £76m based on 1800 cancelled flights, although the impact on other non-UK organisations was not assessed. The CMC estimated that 450,000 passengers faced cancellations or delays of more than two hours. Almost all of the cost fell on airlines and other organisations rather than on NATS itself.

The CMC said the outage came from a previously unknown defect in legacy software of the National Airspace System, when a routine request for an aircraft identification code and a higher-priority system message collided within about one millisecond. The report compared the event to the 2024 CrowdStrike failure, noting that a fault in one critical technology can cause widespread disruption. It also said the new Cyber Security and Resilience Bill would do little to prevent a similar incident, though it may improve incident reporting and oversight.