Ryanair has demanded the re-opening of Scottish airspace after the airline operated a one-hour "verification flight" that it says confirmed there was no volcanic ash in the airspace.
Ryanair operated the flight up to 41,000 feet in Scottish airspace this morning. The aircraft took off from Glasgow Prestwick, flew to Inverness, on to Aberdeen and down to Edinburgh.
The UK's Civil Aviation Authority had earlier declared a temporary danger area over Scotland from 1am to 1pm.
However, Ryanair said its flight this morning found no visible volcanic ash cloud or any other presence of volcanic ash and that its post-flight inspection "revealed no evidence of volcanic ash on the airframe, wings or engines".
In a statement, the airline said: "The absence of any volcanic ash in the atmosphere supports Ryanair’s stated view that there is no safety threat to aircraft in this mythical 'red zone' which is another misguided invention by the UK Met Office and the CAA."
Ryanair said it had also received written confirmation from both its airframe and engine manufacturers that it is safe to operate in these so called “red zones” and that "in any event, Ryanair’s verification flight this morning also confirms that the “red zone” over Scotland is non-existent".