LONDON: Flights at several British airports were delayed on Monday (Sep 21) due to an air traffic control failure, Britain's NATS air traffic control provider said, less than two weeks after a separate issue halted flights across the country.

Manchester, Glasgow and Belfast airports were experiencing delays, which NATS said were related to an issue at its Prestwick centre in Scotland, while London's Gatwick and City Airports said there would be some disruption.

British transport minister Heidi Alexander, who has been considering the future of NATS Chief Executive Martin Rolfe after repeated failures, said the problem had now been fixed, and systems were resuming.

"I know this will be deeply frustrating for passengers after the previous issue," she said on X.

Ryanair, Europe's biggest airline, said 25,000 of its passengers were facing delays as a result of Monday's issue and repeated its calls for Rolfe to resign.

Rival airline easyJet said it had cancelled some flights while British Airways warned its customers that they were likely to experience disruption on Monday.

NEW ISSUE BEHIND DELAYS

NATS said that Monday's delays were caused by a connectivity issue "unrelated to the issue two weeks ago", when about 2,000 flights were cancelled owing to a software defect, affecting hundreds of thousands of people. Cancellations on Monday had reached 24 by 8.58am GMT (4.58pm, Singapore time).

"Airports south of Manchester are broadly unaffected, however, flights heading north and flights departing Scottish airports are currently subject to some delay," NATS said in a statement.

A previous outage in August 2023 cost airlines 100 million pounds (US$134 million) and caused travel chaos. EasyJet said that Monday's disruption underlined weakness in the air traffic operator's systems.

"This, once again, calls into question the resilience of NATS' systems and demonstrates the need for firm actions to prevent these repeated failures," easyJet said.