Flight chaos for hundreds of thousands was caused in ‘millisecond’ by software error

Error first occurred at 10am but major incident was not declared until 12.30pm, says report

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A software defect in part of the UK's air traffic control system corrupted flight data in the space of a millisecond", leading to a six-hour outage and mass airline cancellations and delays across the UK last week, National Air Traffic Services has said.

But ministers said the Nats report into the incident still left questions unanswered, saying they needed to urgently understand why this issue was not discovered and fixed before it caused chaos".