The Economist tells why so little is known about the effects of erupting volcanoes on air travel and their potential long-term effects.
Northern Europeans will not forget the name Eyjafjallajokull in a hurry, even if they may have trouble pronouncing it. Monday April 19th marked a fifth day of jet-free skies over a huge swathe of the continent as a result of the eruption of the Icelandic volcano, which began pumping significant quantities of ash into the sky last Wednesday. That fine volcanic ash could pose a risk to jet engines, which have cut out in the past after exposure to similar volcanic material. Many of Europe's busiest airports remained out of action.
As the volcano's eruption subsided-for now, at least-Britain's National Air Traffic Service said on Monday afternoon that airspace in Scotland and parts of northern England would reopen on Tuesday morning, with the the rest of Britain possibly cleared for flying later in the day. After European Union transport ministers agreed to begin easing flight restrictions, the Dutch authorities said Schiphol airport in Amsterdam would reopen on Monday night. Earlier, Norway, Sweden and Finland had allowed a few mainly domestic flights to operate. The civil-aviation authorities had come under strong pressure from European airlines, several of whom had conducted successful test flights in the supposed danger zone. However, the engines of a Finnish military jet did suffer considerable damage as a result of breathing in the ash.
Although the situation looked more promising by Monday evening, there was still no clear answer as to how long the disruption might last. 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. Furthermore, there is no way of telling what concentration of ash the test aircraft were flying through. The best source of information for the moment is a theoretical model of where the cloud might be, taking into account the prevailing wind and other weather conditions. One interesting wrinkle is that studies of natural disasters tend to be paid for by insurance companies. As volcano eruption is deemed to be an uninsurable risk, there are few studies to turn to.