In response to concerns that volcanic ash ejected during the 2010 eruptions of Eyjafjallajökull in Iceland would damage aircraft engines,[2] the controlled airspace of many European countries was closed to instrument flight rules traffic, resulting in what at the time was the largest air-traffic shut-down since World War II.[3] The closures caused millions of passengers to be stranded not only in Europe, but across the world. With large parts of European airspace closed to air traffic,[4][5][6] many more countries were affected as flights to, from, and over Europe were cancelled.