And though several European airlines conducted successful test flights in the danger zone, the engines of a Finnish military jet suffered considerable damage as a result of breathing in the ash.
For one thing, the European Aviation Safety Agency says that there is currently no consensus as to what is an acceptable level of ash in the atmosphere.
首先欧洲航空安全局表示：大气中可接受水平的灰尘标准目前尚无定论。
3
Mr Obama has been forced, because of the ash cloud, to fly to London tonight for the next part of his European tour.