Air traffic controller blames a millisecond-software glitch for flight cancellations

A preliminary report says a software defect lasting a “millisecond” triggered the cancellation of more than 2,000 flights in and out of the United Kingdom on Sept. 8, snarling airports for days. NATS, the provider formerly known as National Air Traffic Services, said the issue was in the National Airspace System, which assigns codes that let controllers identify flights on radar. The report pointed away from human error and clarified that the software glitch, not military or civil operator actions, led to the decision to cancel. NATS chief executive Martin Rolfe said mitigation measures are in place while a permanent fix is being tested and deployed. Transport Secretary Heidi Alexander ordered a full investigation and an independent review by the Civil Aviation Authority, noting she wants answers on why the problem wasn’t found earlier.