UPDATE 1 — UK air traffic control outage caused by software defect, says operator

(Adds quote from NATS and Transport minister) LONDON, Sept 18 (Reuters) — British air traffic control operator NATS said on Friday an outage which affected hundreds of thousands of passengers last week was cause by a software defect. NATS CEO Martin Rolfe said the shutdown was not related to a problem in 2023 which also caused widespread disruption, nor was it linked to military intervention — as reported by some media outlets last week. He added that safety was at no point compromised during the incident. "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." Transport minister Heidi Alexander said the disruption was "completely unacceptable", adding that "we need to urgently understand why this issue was not discovered and fixed before it caused chaos". "It is crucial that our national infrastructure is fit for the future," she said in a statement. (Reporting by William James, editing by Sarah Young) ((sarah.young@thomsonreuters.com; +44 20 7542 1109; Reuters Messaging: sarah.young.thomsonr