LONDON (AP) — A technical issue disrupted flights in and out of Scotland, Northern Ireland and the north of England on Monday.

NATS, formerly known as National Air Traffic Services, said in a statement that its engineers are continuing to investigate the issue at its Prestwick center in Scotland. It said airports south of Manchester, including those in and out of London, are “broadly unaffected” though flights heading north and flights departing Scottish airports are currently subject to some delay.

NATS said the disruption is unconnected with the software glitch that led to the cancellation of over 2,000 flights in and out of the United Kingdom two weeks ago. The chaos prompted mounting calls for its chief executive Martin Rolfe to stand down.

EasyJet said the latest flight disruption “once again, calls into question the resilience of NATS’ systems and demonstrates the need for firm actions to prevent these repeated failures.”

And British Airways said it is “disappointing” that some customers may experience disruption after “yet another technical fault” involving NATS.

The U.K. government owns 49% of NATS, making it the largest shareholder and giving it a veto over key decisions. Airlines, airports, investors and employees own the remaining shares in the public-private partnership.

The Associated Press