LONDON — Hundreds of flights across the United Kingdom were grounded on Tuesday, September 8, 2026, after a critical software fault in National Air Traffic Services' (NATS) flight processing system triggered widespread delays and cancellations at key travel hubs, including London Heathrow, Gatwick, Stansted, and Manchester.

System Failure and Timeline

The disruption began around 1:00 PM BST when NATS identified a technical issue within its flight processing system—the core software responsible for processing flight plans and airspace tracking data.

By mid-afternoon, NATS engineers pinpointed the fault and began working on a fix, which was successfully implemented around 4:40 PM. Although NATS confirmed the system was fully restored by 7:34 PM BST (18:34 GMT), the several-hour outage created a massive operational backlog that caused significant knock-on delays extending into Wednesday.

Scale of the Disruption

Flight-tracking metrics indicate that over 1,000 flights operating to and from UK airports were canceled on Tuesday, with some estimates placing the total closer to 1,300.

Tens of thousands of passengers were stranded or delayed. Ryanair reported that more than 50 of its flights were canceled, leaving over 65,000 of its passengers facing delays of up to eight hours. The outage also extended beyond domestic and European routes, affecting long-haul international flights, including connections to and from India, and causing ripple effects across European airspace.

Official Response and Industry Reaction

NATS issued an apology for the severe disruption, clarifying that flight safety was never compromised during the incident, though it warned that restoring normal schedules would be a complex and lengthy process. Transport Secretary Heidi Alexander confirmed the resolution of the technical issue and extended an apology to affected travelers.

The incident has reignited heavy criticism regarding the resilience of the UK's aviation infrastructure. Mark|ing the third major air traffic control system failure in three years, airlines and aviation leaders are now renewing calls for a comprehensive overhaul of the national air traffic control system.