Overview
- A previously unknown software defect in a small part of the National Airspace System caused flight data corruption on September 8, forcing nationwide traffic restrictions for about six hours.
- The fault began when a manual request for an aircraft identification code was paused by a higher-priority message and then resumed incorrectly, producing corrupted outputs within a millisecond that affected subsequent flight data.
- Operations were restored the same evening but a backlog of cancellations and delays took more than two days to clear, with industry figures saying roughly 2,000 cancellations and over 300,000 passengers were affected.
- NATS says it has identified the bug, put immediate mitigations in place, is safety-testing a permanent software fix, and denies any link to the 2023 outage or military action.
- Transport Secretary Heidi Alexander has tasked the Civil Aviation Authority with an independent resilience review to report within six months and the incident has renewed scrutiny of NATS' backup systems and planned investment in resilience.