NATS publishes preliminary report on technical incident of 8 September

Share on Facebook Share on Twitter Share on LinkedIn Copy link to clipboard Home Media Centre News NATS publishes preliminary report on technical incident of 8 September NATS, the UK’s major provider of air traffic services, has today published a preliminary report into the events which led to widespread disruption to travellers earlier this month. This initial report was requested by Heidi Alexander, Secretary of State for Transport. It describes what caused the problem and its resolution, with a full report to follow. Martin Rolfe, Chief Executive Officer, confirmed that this incident was unrelated to the major system outage in August 2023. He also dismissed speculation that it was caused by military intervention. “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 said. “The issue has been identified and mitigation is in place while a permanent fix is safety tested and deployed.” The preliminary report reveals that the incident on Tuesday 8 September was caused by a software defect in a small part of the National Airspace System (NAS), which underpins the management of UK airspace. The software in question allocates codes to individual aircraft when manual requests are made; these are usually allocated automatically. These codes are used to identify flights on radar when they are airborne. While a manual request for an aircraft code was being processed, the system received a message for a higher priority activity which resulted in the aircraft code request being paused. When processing of the aircraft code request resumed, the software defect meant it did not resume correctly and the resulting output was corrupted, and affected some subsequent flight data updates. This happened in the space of a millisecond. With reduced information available to controllers, restrictions were put in place to limit air traffic to maintain safety. Although the software issue only affected flights in the London Area Control centre – higher level flights operating mainly above 24,500ft – the restrictions had to be placed across the UK so that the NAS could be restarted and flight data reloaded. Restrictions were in place for some six hours and while NATS operations returned to normal the same evening, it took more than two days for the backlog of passenger disruption to be cleared, with hundreds of thousands of passengers’ travel plans disrupted. Mr Rolfe said: “I would like to apologise again, very sincerely, to everyone who was affected last week. It’s our job to get people where they want to go, quickly and without delay and we are devastated when that goes wrong. However, our primary role is to keep our skies safe, and everyone who flies through them. At no point last week was safety in question.” Over the past 10 years, NATS has invested well over one billion pounds in systems and technology, and we will soon submit plans to the Civil Aviation Authority to invest a further billion pounds by the end of 2033. Read the report Read the preliminary report here Media Centre News Blog Altitude ELEVATE Photos & videos Reports NATS Press Office 01489 615 945 (09:00-17:00 Monday-Friday) 01489 445 699 (outside of standard office hours) [email protected] Share on Facebook Share on Twitter Share on LinkedIn Copy link to clipboard Home News NATS publishes preliminary report on technical incident of 8 September UK Flights Press releases NATS publishes preliminary report on technical incident of 8 September 18 Sep 2026 18 Sep 2026 Air Traffic Control overlooked as career option by 1 in 4 jobseekers 01 Sep 2026 01 Sep 2026 Operation Blue Skies Takes Off: Landmark Oceanic Airspace Trial to Test AI-Driven Contrail Avoidance 18 Aug 2026 18 Aug 2026 July hots up with record traffic levels 12 Aug 2026 12 Aug 2026 Visit media centre Follow @NATS on X Reports & downloads Annual Report Aviation Index 2026 Modern Slavery Statement Pay Gap Report Responsible Business Report Tax Strategy Related websites Aeronautical Information Service (AIS) Airspace Change Organising Group (ACOG) Civil Aviation Authority (CAA) NATS Customer Gateway (restricted) Searidge Technologies Help & support Quick links Assisted Flight Plan Exchange (AFPEx) Contingency PIBS Non-Standard Flight applications Wind farm pre-planning applications Contact us X Facebook LinkedIn Instagram YouTube