Software Defect Caused UK Air Traffic Control Failure, NATS Says

Software Defect Caused UK Air Traffic Control Failure, NATS Says

The UK’s National Air Traffic Services NATS has confirmed that a software defect caused the air traffic control system failure that disrupted flights across the country earlier this month, resulting in thousands of cancellations and delays. NATS said the incident on September 8 was traced to a small section of code within its flight data system. The failure led to restrictions being imposed on air traffic for about six hours as controllers worked to maintain safe operations. According to NATS’ preliminary investigation, the affected software is responsible for allocating identification codes to aircraft when manual requests are made. The system encountered a higher-priority task while processing one of those requests. When it resumed the original process, a software defect caused it to restart incorrectly, producing corrupted data that affected subsequent flight information updates. NATS said the problem occurred within a fraction of a second. The loss of reliable flight information forced air traffic controllers to restrict the number of aircraft using UK airspace.Although the technical issue was confined to flights operating through the London Area Control Centre, NATS said restrictions had to be applied across the UK while the system was restarted and flight data reloaded. The immediate technical problem was resolved the same evening, but the disruption continued for more than two days as airlines worked to restore aircraft, crews and schedules. Hundreds of thousands of passengers had their travel plans disrupted. NATS Chief Executive Martin Rolfe said the incident was unrelated to the major air traffic control outage of August 2023. He also rejected speculation that the latest failure had been caused by military intervention“This was a software issue in a specific part of our flight data system,” Rolfe said, adding that the defect had been identified and measures were being taken while a permanent fix undergoes safety testing. NATS said that, despite the widespread disruption, aviation safety was not put at risk during the incident. The organisation said restrictions were introduced precisely to maintain safe operations while the system was being recovered.Rolfe apologised to passengers affected by the disruption and said NATS was working to ensure the underlying systems become more resilient. The company said it has invested more than £1 billion in systems and technology over the past decade and plans to submit proposals to the Civil Aviation Authority for another £1 billion in investment through 2033. NATS said its preliminary report will be followed by a full investigation.