More than 250 flights were cancelled at Heathrow and Gatwick airports on September 18, 2026, due to an air traffic control outage affecting the United Kingdom’s aviation network. Additional disruption extended to Liverpool, Birmingham, Edinburgh, and Dublin airports.
Cause of Outage and System Failure
The outage was caused by a software defect in a specific subsection of the flight data system operated by NATS, the UK’s air traffic control service provider. CEO Martin Rolfe explained that a timing conflict between a flight identification code request and a higher priority request paused the first, triggering backup protocols.
Operational Impact and Delays
Backup protocols required manual handovers of flights, reducing air traffic
capacity and creating knock-on delays across the network. NATS resolved the issue under controlled conditions while continuing limited service. The disruption forced cancellations and delays that rippled through multiple airports.
Airline Cancellations and Passenger Disruption
British Airways cancelled or diverted more than 100 flights, while Ryanair cancelled over 50 flights, affecting tens of thousands of passengers. Ryanair’s Chief Operations Officer Neal McMahon cited the repeated failures of the air traffic control system and called for Martin Rolfe’s resignation. The disruptions caused delays significant enough to postpone an Arsenal football team news conference scheduled in London.
Official Responses and Industry Context
NATS CEO Martin Rolfe stated, “This was a software issue
in a specific part of our flight data system that we have traced to a small subsection of coding. The issue has been identified and mitigation is in place while a permanent fix is safety tested and deployed.” UK Transport Minister Heidi Alexander described the disruption as “completely unacceptable” and ordered an independent Civil Aviation Authority review, saying, “It is crucial that our national infrastructure is fit for the future.”
The incident is unrelated to the August 2023 outage, which affected more than 700,000 passengers and cost airlines £100 million, nor to a radar fault in July 2025 that caused
150 cancellations. The 2023 failure resulted from duplicate waypoint names that forced the system into fail-safe mode. This latest failure underscores continuing challenges in UK air traffic control systems.
