THE IRISH Aviation Authority has modified how it assesses the risk posed to aircraft from volcanic ash.
The authority had refined its safety model on the basis of data from test flights and the analysis of more than 300,000 flight hours from airlines operating around the ash plume over the last month.
The revised restrictions are due to be issued in the coming days. Eamonn Brennan of the authority told RTÉ radio's Morning Irelandthe authority had "been talking to aircraft engine manufacturers about the safety tolerance levels in order to enhance how we handle the disruption to airline traffic".
The remodelling of risk criteria would depend on the aircraft and engine type but would reduce the no-fly zone restrictions, which are based on ash density, he said.
The authority sent up an ash measurement flight from Weston Aerodrome yesterday and no ash was found, the authority’s Martin Towey said.