The shutdown of European airspace due to volcanic ash in April drew fierce criticism at a World Travel Market seminar on the airline industry.

Birmingham Airport chief executive Paul Kehoe complained: “The right decision was taken on the first day, but thereafter no one would take a decision. Our airport was a ghost town. We waited three days before the UK prime minister even said he would do something about it.”

Kehoe said the situation had only been resolved after British Airways chief executive Willie Walsh went up in an aircraft to test the restriction. He said: “Hopefully, we have learned from that and from the current experience in Indonesia, and we will not ground aircraft for six days again.”

Emirates president Tim Clark agreed: “There was clearly an over-reaction in closing airspace.”

Aer Lingus chief commercial officer Stephen Kavanagh stressed the cost of the shutdown to carriers in compensation to stranded passengers because of current denied-boarding regulations. He pointed out: “Once airspace re-opened we were looking at up to 100,000 passengers claiming expenses. The equity of that needs revisiting.”

However, Colin Matthews, chief executive of airport operator BAA saw two positive outcomes from the ash cloud. He said: “One successful aspect was that we avoided having thousands of people arriving at our airports with nowhere to go. We didn’t have any chaos.

“The shutdown also brought a degree of balance to the debate over the benefits and costs of aviation. The impact of grounding aircraft for six days astonished a lot of people.”