Airports chaos caused by 'software glitch' officials find - as Government orders further probe but dodges sacking under-fire NATS boss

An air traffic control system failure that led to thousands of flights being cancelled last week was caused by a software glitch, a preliminary report has found.The National Air Traffic Services (NATS) probe into the chaos on September 8 said it was caused by a 'software defect' in a small part of its systems.The software which experienced issues usually allocates codes to individual aircraft automatically when manual requests are made, NATS said.The codes are used to identify flights on radar while they are airborne.But the meltdown, which saw hundreds of thousands of passengers suffer cancellations or nightmare delays, was not caused by any 'incorrect actions', the NATS report added.In response to the preliminary report, Transport Secretary Heidi Alexander said she had ordered the Civil Aviation Authority (CAA) to review NATS' findings.The Cabinet minister had given under-fire NATS boss Martin Rolfe a week to report back on the reasons for the grounding of more than 2,000 flights, having previously said she did not believe the issue was 'unavoidable'. She has so far dodged calls by airlines, including Ryanair and WizzAir, for a major overhaul of NATS and the removal of Mr Rolfe over repeated failures. Hundreds of thousands of passengers suffered disruption due to the 'technical issue'Passengers at Heathrow, Gatwick, Manchester and Stansted were all impacted by last week's fault, which caused flights both in and out of the UK to be axed.Writing in the report, Mr Rolfe said that at this stage he could confirm the incident was not related to a outage in 2023 or a radar issue in July last year.'I can also confirm that it was a software issue and not caused by any incorrect actions by either military or civil operators,' he said.Mr Rolfe apologised again to travellers who were affected by the incident, as well for the challenges it caused to the aviation industry.'This was a software issue in a specific part of our flight data system, that we have traced to a small subsection of coding,' he added.'The issue has been identified and mitigation is in place while a permanent fix is safety tested and deployed.'Mr Rolfe promised a 'major incident report' would be completed within the next two months following a full investigation.'Our primary focus, and the primary accountability under our licence, is the safety of all air traffic using UK airspace,' he continued.'We will always do what is necessary to preserve that. That can mean placing restrictions to limit air traffic, as we did on 8 September; we do not do that lightly, and we deeply regret the inconvenience it caused to so many people.'In response to the preliminary report, Ms Alexander said: 'The disruption we saw last week was completely unacceptable and I know how frustrating it was for passengers, airlines and airports.'I have now received NATS' report and, while I am pleased to see that the safety of passengers was protected, it's clear we need to urgently understand why this issue was not discovered and fixed before it caused chaos.'I have therefore tasked the CAA with conducting an independent review to check NATS' findings and investigate their investment plans to enhance resilience in the future, along with regulatory accountability.'It is crucial that our national infrastructure is fit for the future, and this Government will make sure the aviation sector is as resilient as possible, so passengers can get to where they need to be.'The CAA report is due to be published within six months. Last July, a 'radar-related issue' caused an air traffic control failure which disrupted thousands of passengers and forced the cancellation of more than 160 flights.In August 2023, more than 700,000 passengers suffered disruption when flights were grounded at UK airports when NATS suffered a technical glitch while processing a flight plan.