The European Union has drawn up new guidelines for dealing with volcanic ash to curb disruption to travelers, the EU's aviation safety body said on Friday.
The rules will give more flexibility to national air traffic controllers and will involve the creation of a European crisis coordination center to ensure a smoother response to emergencies like the ash scare which grounded flights in April.
Fears that ash blown southwards from an erupting Icelandic volcano could clog up engines and cause planes to crash led to a six-day shutdown of Europe's busiest air corridors in mid-April, stranding millions and inflicting heavy losses on airlines.
The European Aviation Safety Agency said it had agreed new rules with the European Commission and Eurocontrol air traffic management agency for assessing the risk of contamination.
"The joint measures will offer member states greater flexibility in deciding how to manage their airspace, allowing for less flight disruption while still ensuring the highest level of safety," Cologne-based EASA said in a statement.
Under the new rules airspace will be divided into four zones instead of three at present, using maps updated every six hours.
The additional "grey" zone will allow flights under certain conditions, offering more discretion for local decision-makers.
The creation of an additional category will provide more options for controllers and allow some airspace to remain open where it might have been closed, even when it is deemed safe to fly.
Airlines have criticized Europe for overreacting to the ash scare by imposing blanket shutdowns across much of the region's airspace and some are pressing for financial compensation.
Regulators such as Britain's Civil Aviation Authority have said they were forced to rely on restrictive earlier guidance from engine makers and acted to put public safety first.