When the flight data software says no | Letters

Martyn Thomas and David Griffiths on the air traffic control failure in August that led to more than 2,000 flight cancellationsFor a few years about 20 years ago, I advised the board of Nats, the air traffic control services provider, about software failures, including in NAS, its flight data processing system at that time (UK air traffic failure blamed on ‘extremely rare’ circumstances as CAA opens inquiry, 6 September). NAS was written in 1966 and had been heavily modified, but it