Disruption to flights to and from Scotland and northern England because of the latest Icelandic ash cloud crisis will continue for the rest of the day.
British Airways cancelled all flights today to and from Glasgow, Edinburgh and Newcastle airports, and air traffic control service Nats listed the airports likely to be affected between 7pm today and 1am tomorrow.
As well as Glasgow, Edinburgh and Newcastle, Nats said Barra, Prestwick, Cumbernauld, Tiree, Carlisle and Durham Tees Valley airports could expect to see some services disrupted.
A number of airlines axed services to these destinations and more than 250 flights were cancelled across Europe following the eruption of the Grimsvotn volcano.
Irish carrier Ryanair sent up a test flight over Scotland and the carrier's chief executive Michael O'Leary said the flight proved there was "no volcanic cloud" over the country.
He said the Civil Aviation Authority (CAA) should "take their finger out of their incompetent bureaucratic backsides and allow the aircraft back into the skies over Scotland".
Mr O'Leary said the CAA's so-called "red zone" - an area of high-density volcanic ash - was "non-existent, mythical and a misguided invention".
But Transport Secretary Philip Hammond accused Ryanair of using "very inflammatory language".
Mr Hammond said: "If they (Ryanair) don't believe in the red zone modelling, it's up to them to put forward a safety case to their regulator, which is the Irish Aviation Authority."
The late-afternoon Nats statement, based on Met Office forecasts, suggested that high-density levels of ash would not spread further south than northern England.
But one set of travellers was taking no chances. The Barcelona football team, due to take on Manchester United at Wembley in the Champions League final on Saturday, brought forward their journey to London from Thursday to tonight.
Earlier, disappointed travellers had milled round Scottish airports in the hope of getting flights.
They had to contend with Scottish regional airline Loganair scrapping 38 flights. Other carriers that had to axe flights included easyJet, Flybe and Aer Lingus.
Ryanair said it had been "forced" to cancel all its flights to and from Scottish airports for the rest of today.
At Glasgow airport, Guy McKinven, from the Clyde Valley area, was attempting to travel with easyJet to Stansted to spend a week with his grandmother.
He said: "You see people shouting and getting upset, but there's nothing you can do.
"It is frustrating, but that's just the situation. EasyJet have been helpful and have told me I can have a refund for my flight.
Earlier Mr Hammond said: "This is the largest volcanic eruption in Iceland for at least 50 years. It is inevitable that a major event like this will cause some disruption.
"We are in a much better place this year because we have worked with airlines and regulators to build a regime that puts safety first, but with far more flexibility. We will not be imposing a blanket ban like the last government.
"Instead it is up to airlines to decide whether it is safe to fly in discussions with the CAA."
He went on: "We now have a graduated approach and over the last 12 months have been able to establish a safety case for planes being able to fly at much higher concentrations of ash than last year.
"Under last year's approach, we would now be seeing much more widespread disruption than we are experiencing today."
Mr O'Leary said: There's nothing over the skies of Scotland, there is no volcanic ash cloud over Scotland, there's no volcanic material over Scotland. Would the CAA please take their finger out of their incompetent bureaucratic backsides and allow the aircraft back into the skies over Scotland.
"It's not about picking up the tab for the debacle, it's about learning about the mess and the mismanagement of last year and not repeating the same bureaucratic bungling or mistakes that were made last year."
Mr Hammond responded by saying: "The radar track information suggests that the Ryanair aircraft that Mr O'Leary has been referring to that flew over Scotland this morning did not fly in any red zone, so in fact all he has done is confirm the CAA's own model, which showed there was no ash in the areas where that aircraft flew.
"We have a different solution from last year, and Ryanair have been involved with all the other airlines in discussions to arrive at that solution. We've now got a much more refined model.
"We know much more precisely where the cloud is and what the density of the cloud is and the airlines have much more discretion in making their own proposed operational plans, putting them forward to the CAA for approval."
Colin Brown, director of engineering at the Institution of Mechanical Engineers, said: "Airlines and the CAA should be using the Grimsvotn ash cloud to launch test flights to verify the theoretical modelling of how ash clouds disperse.
"More test flights should be taking place. It's only by flying up to these areas and measuring the amount of ash in the atmosphere, and the way it accumulates in engines, that work can be done to prevent disruption to air travel due to volcanic ash in the future."