Thousands of passengers face UK flight cancellations because of drifting ash from an Icelandic volcanic eruption.
Airports likely to be affected from 1300 to 1900 BST include Londonderry, Glasgow, Edinburgh, Prestwick, Durham Tees Valley, Newcastle and Carlisle, air traffic services company Nats said.
European air traffic controllers said 252 flights had been cancelled so far.
Ryanair said it had carried out a test flight over Scotland and challenged a ruling some flights should be grounded.The carrier said its one-hour flight at 41,000ft showed there was no visible volcanic ash cloud or evidence of ash on the airframe, wings or engines.
It claimed the “red zone” over Scottish airspace where ash has been classified “high-density” was a misguided invention by the Met Office and the Civil Aviation Authority (CAA).
Meanwhile, the UK’s emergency response committee, Cobra, will meet at 1530 BST to discuss the knock-on effects of the ash cloud