Air traffic disruptions that grounded thousands of flights across the UK last week were caused by a software defect in the national control system that corrupted flight data in the space of a millisecond, according to the report published by National Air Traffic Services on Friday.
The failure led to a six hour outage and more than 2,000 cancelled flights, affecting hundreds of thousands of passengers. Some travellers slept on airport floors, while others were left stranded overseas as airlines scrambled to reschedule. The BBC reports that NATS published its findings into the incident on Friday afternoon.
The scale of the disruption was remarkable given how brief the underlying fault appears to have been. A defect measured in millionths of a second cascaded into one of the worst weeks for British air travel in years, a reminder of how little slack sits inside critical national infrastructure.
Ministers were not satisfied with the answer. They said the report still left questions unanswered and that they needed to urgently understand why the issue was not discovered and fixed before it caused chaos, the Guardian reports.
The Civil Aviation Authority will conduct an independent review of the findings, looking at NATS resilience and regulatory accountability. That review matters for every airline operating in the UK, and for the businesses that depend on predictable air links for freight and passengers.
Aviation analysts say the episode will sharpen scrutiny of software assurance across the sector. Control systems are safety critical, and the industry standard is to test them accordingly. Where a single defect can idle an airport network for half a day, the question regulators will press is whether the testing regime matched that standard.
NATS has not indicated when further detail on the defect itself would be published. The CAA review will set out its own timetable later.