A second failure of Britain’s air traffic control in two weeks left more than 200 flights canceled in the United Kingdom on Monday, according to aviation analytics firm Cirium.

Provider NATS (National Air Traffic Services) blamed the fault on a connectivity problem at its Prestwick centre in Scotland, and maintains it is unrelated to the September 8 software failure that led to more than 2,000 flights being canceled. Ryanair called for the resignation of NATS chief executive Martin Rolfe and said more than 25,000 of its passengers would be affected; Jet2 demanded “action, accountability and proper resilience”.