British air traffic control operator NATS said on Friday that a software defect last week disrupted air travel for hundreds of thousands of passengers.
The incident resulted in around 2,000 flight cancellations and several days of disruption, leaving airlines facing millions of pounds in costs as they worked to reposition aircraft and crews and process passenger refunds.
Media reported NATS chief executive Martin Rolfe as saying that the failure was caused by a problem in a small section of code within the organisation’s flight data system. He said the incident was unrelated to a similar disruption in 2023 and dismissed reports linking the outage to military intervention.
Rolfe also said aviation safety was not compromised at any stage. According to him, the software fault has been identified, and temporary measures have been introduced while a permanent solution undergoes safety testing before deployment.
Transport Minister Heidi Alexander, who had ordered NATS to submit a report on the incident and requested an independent review by the Civil Aviation Authority, described the disruption as unacceptable.
She said authorities needed to establish why the technical problem had not been detected and resolved before it caused widespread disruption, stressing the need to ensure the resilience of the UK’s critical infrastructure.
The latest outage came after a major NATS failure in August 2023 that caused widespread travel disruption and was estimated to have cost airlines about £100 million. Another technical problem in July 2025 resulted in roughly 150 cancellations.
NATS said the latest failure occurred when its system was processing an aircraft identification request and received a higher-priority request, causing the first operation to pause. The report noted that a difference of just one millisecond in the timing of the second request would have allowed the update to proceed normally.
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