CAA Launches Independent Review of NATS Air Traffic Failure

The UK Civil Aviation Authority has announced an independent review into the September 8, 2026 NATS system failure that caused widespread flight disruptions. The CAA set out the scope of this review on September 25, 2026, focusing on the technical incident that delayed, cancelled, or diverted more than 2,000 flights. Transport Secretary Heidi Alexander ordered the investigation following the major failure.

Scope of review covers systemic infrastructure challenges

The review will assess whether NATS has a credible and deliverable approach to renewing critical air traffic management infrastructure for the coming decade. It will examine the organization's capability, capacity, and leadership. The investigation will scrutinize NATS' strategy for modernizing critical operational systems and the adequacy of its business continuity arrangements.

It will also evaluate the effectiveness of the CAA's own regulatory oversight. The review aims to determine if the regulator had sufficient visibility of risks to critical systems and whether its supervision encouraged adequate investment and contingency planning. NATS' ownership structure and its influence on investment and system renewal will be considered.

Review examines multiple system failures and lessons learned

The primary incident under review occurred on September 8 at NATS' Swanwick centre. A preliminary report published by NATS on September 18 traced the cause to a previously unidentified software defect. The fault was triggered in the processing of a manual aircraft squawk-code request when a second, higher-priority request arrived within a one-millisecond window, causing data corruption.

Normal operations resumed about six hours after the initial failure, though cancellations and delays persisted into the following day. NATS has introduced an interim mitigation while a permanent fix undergoes safety testing. The review will also analyze a separate incident on September 21 at the NATS centre in Prestwick. A connectivity fault there affected a flight data processing system, prompting traffic restrictions across parts of Scotland, Northern Ireland, and northern England. While the two failures had different causes, the Prestwick incident will inform the broader review.

Previous recommendations inform current review framework

This new investigation will examine the implementation of 34 recommendations from a prior independent review. That earlier review was commissioned after a major NATS flight-planning failure in August 2023, which affected approximately 700,000 passengers. By June 2026, the CAA had confirmed all 34 recommendations were either completed or incorporated into its ongoing regulatory work.

The current review will assess NATS' implementation of these past recommendations. It will also seek lessons from international best practice on system resilience and recovery. The process will involve hearing evidence from NATS, airlines, airports, passenger groups, and other stakeholders.

The CAA will deliver an initial report by the end of January 2027. A final report is due by March 8, 2027.