LONDON: A software defect corrupted flight data “in the space of a millisecond”, triggering a six-hour UK air traffic control outage that caused widespread cancellations and delays, National Air Traffic Services has said.
The failure on September 8 disrupted hundreds of thousands of passengers and created congestion that took more than two days to clear.
According to Nats’ preliminary report, the first error occurred at 10am when a software defect affected the National Airspace System, which assigns identification codes to aircraft.
Engineers initially believed the system had recovered. However, the link between national and London airspace management failed again at 12.32pm, prompting Nats to declare a major incident.
Software Error Corrupted Flight Data
Nats said the problem occurred while the system processed a manual request for an aircraft code. Another request temporarily interrupted the process, and when processing resumed, the software defect generated corrupted output that affected subsequent flight-data updates.
Controllers consequently performed some tasks manually while Nats restricted flights. The system failed completely at 1.32pm before engineers conducted a series of reboots.
Full operations eventually resumed at 7.30pm.
Nats chief executive Martin Rolfe apologised and said mitigation measures were in place while engineers safety-tested a permanent fix. He stressed that passenger safety was never compromised.
CAA Launches Independent Review
Meanwhile, Transport Secretary Heidi Alexander described the disruption as “completely unacceptable” and questioned why authorities had not identified the defect earlier.
She instructed the Civil Aviation Authority to independently examine Nats’ findings, investment plans and measures for improving resilience. The CAA expects to publish its review within six months.
Furthermore, Airlines UK said carriers would seek compensation from Nats for costs resulting from the disruption and demanded stronger investment to prevent a single technical failure from again causing nationwide aviation disruption.
