A report into the failures that caused chaos in the UK’s National Air Traffic System last summer has been published.

The interim report, produced by the an independent panel for UK’s CAA has found that the August Bank Holiday meltdown, caused by a bug in the NATS IT system, was made worse by a failure to plan for and run practice drills in case of such and event. It also found that communication about the blackout was terrible, with some airlines learning about it through mainstream news channels.

Other uncomfortable findings in the report include staff, including system engineers, were away for the Bank Holiday and that the true number of passengers was seven times higher than mentioned in NATS’ initial findings.

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Jeff Halliwell, Chair of the Independent Review Panel, said: “This interim report sets out the Panel’s work so far in understanding the root causes of the incident; the effectiveness of communications between NATS, other parts of the aviation sector, and the consumers; and the underpinning regulatory regime.

“In developing the interim report, the Panel has engaged with a wide range of stakeholders to ensure the final report reflects a diverse range of perspectives”.

“In order to produce effective recommendations, the Panel has further lines of enquiry it is exploring in order to build a better understanding of how the aviation system can improve.”

The regulator estimates that over 700,000 passengers were impacted, including 300,000 people by cancellations, 95,000 by long delays of over three hours, and a further 300,000 by shorter delays.