'Software issue' caused UK flight chaos this month: Operator

LONDON: An air traffic control outage that affected hundreds of thousands of passengers last week was caused by a "software issue", the UK's National Air Traffic Services (NATS) said on Friday (Sep 18).

The issue sparked travel chaos, causing more than 2,000 flights to be cancelled and widespread delays over two days across major UK airports.

"This was a software issue in a specific part of our flight data system, that we have traced to a small subsection of coding," Martin Rolfe, chief executive of NATS said in a statement.

"The issue has been identified and mitigation is in place while a permanent fix is safety tested and deployed," he added.

The disruption affected more than 330,000 passengers over two days, said industry body Airlines UK, with 155,000 travellers having their flights cancelled while around 180,000 experienced delays.

In a preliminary report published on Friday, NATS said the software defect had happened in a small part of the National Airspace System, which "underpins the management of UK airspace".

"It was a software issue and not caused by any incorrect actions by either military or civil operators," Rolfe confirmed in the report.

Most of the cancelled flights were to and from London Heathrow, one of Europe's busiest airports, according to aviation analytics firm Cirium.

Gatwick, Liverpool, Birmingham and Edinburgh airports were also affected, while Dublin airport said it had cancelled dozens of flights.

Last week's travel chaos followed a technical glitch in July last year that saw scores of flights to and from the UK cancelled, prompting anger from airline chiefs.

Britain suffered its worst air systems failure in years in 2023, with more than 700,000 passengers affected after hundreds of flights were delayed or cancelled.

Rolfe on Friday confirmed that the latest incident was not related to those in 2023 or 2025.

Transport Secretary Heidi Alexander last week ordered an independent review to establish the cause and ensure systems "get passengers to where they need to be".