Longstanding rules governing air safety have been changed today in a move that will allow more transatlantic flights to go ahead and planes to fly closer to ash clouds during the Iceland volcano crisis.

But passengers still face long delays for transatlantic flights in and out of Europe because of the continuing ash plume from the Eyjafjallajokull volcano.

Irish airline Aer Lingus said yesterday that the current safety testing model being used by Europe's regulators and air traffic controllers was unsuitable and they called for an alternative safety system using specialist, possibly military, aircraft to monitor ash levels in much the same way that US authorities carry out hurricane watches.

Aer Lingus chief executive Christoph Mueller told the press the system of tracking volcanic ash primarily through a centre at the U.K. Met Office 'has been proven inaccurate several times and we have lost confidence in its reliability.'

'It is now impossible to continue with it and we believe volcanic ash predictions thousands of miles away from the original eruption need to be treated differently,' he added.

'Europe has little or no experience in this area, whereas the Federal Aviation Authority (FAA) in the US has been monitoring airspace around a number of active volcanos for decades.'

'We propose that specialized aircraft, including possibly military aircraft, equipped with appropriate measurement devices be deployed around the Atlantic rim as a part of a European initiative in order to respond swiftly and decisively to any approaching ash cloud.'

However the Met Office said results from its 'tested and proven' models had been compared with, and were consistent with, those of advisory centers in France and Canada.

The Civil Aviation Authority (CAA) the UK safety regulator, revealed it had received 20 reports from airlines over smells in cabins and possible ash on wings or in engines since flights resumed three weeks ago.

Irish budget carrier Ryanair has reported two incidents from Sunday to the Irish aviation authorities. These involved traces of volcanic ash being found in two aircraft using Belfast City airport.

On Tuesday 7.10 A.M. flight from the same airport to Stansted was forced to return to Belfast soon after takeoff because crew reported an 'acrid smell' in the cabin.

The airline said the plane landed normally and passengers disembarked as usual by using the aircraft steps. The plane was returned to service after checks.

More transatlantic flights to go ahead