Millisecond software error caused UK air traffic outage, Nats says

A millisecond software error caused a significant outage in the UK's air traffic control system on Tuesday, leading to the grounding of thousands of flights and widespread disruption. National Air Traffic Services (Nats), the public-private partnership body responsible for air traffic control, issued an alert shortly after 1pm when passengers began seeing delays at major airports like Heathrow and Gatwick.

An hour and a half later, Nats announced the issue in its flight processing system had been identified and fixed, with systems recovering. However, the recovery took longer than anticipated, and Nats issued a further statement at 7:30pm, offering an unreserved apology to the growing number of stranded passengers at airports including Bristol, Birmingham, and Manchester.

This incident brings to mind previous disruptions. In July of the previous year, hundreds of flights were impacted by a radar-related failure. Two years prior, during the August 2023 bank holiday, an outage of the flight plan processing system resulted in nearly 1,600 cancelled flights, affecting 700,000 passengers and costing the industry approximately £100 million. Nats' investigation into that incident revealed issues with slow desktop PCs and a lack of available workstations, as well as the complexity of its system architecture making up-to-date mapping difficult.

Nats has stated that Tuesday's system failure was not the same as the 2023 incident. Despite Nats' investment of £3.3 billion in infrastructure and technology since 2001, aviation experts have expressed concerns about a perceived lack of investment in air traffic control systems, warning that this week's incident may not be an isolated event. Nats CEO Martin Rolfe has faced calls to resign but stated he accepts responsibility.