A study by icelander and danish scientists in nano particles (cited in the Proceedings of the National Academy of Sciences 26 April 2011) shows that the Civil Aviation Authority's decision to stop all flights in Europe during the awakening of the Eyjafjallajökul Volcano was justified. In april 2010 this ban on flights had been attacked by some aviation specialists. The reason for it were fears that ashes were hazardous for aircrafts. The interruption in air traffic was the longest that ever happent since World War II : almost 100 000 flights were canceled in 11 european countries leaving 10 millions passengers stranded. Net loss for airlines was estimated around 1.5 and 2.5 billion euros.
According to the scientists, 'the first ash particles sent in the air by the explosion were very thin, hard and as sharp as splinters from a crushed glass bottle. Later volcanic ashes had a higher granularity but were also dangerous'. They have estimated that if a plane ever crossed such an ash cloud at high speed, its hull would have been severely abraded and the cockpit windshield might have been totally opacified. Moreover, very thin ashes might have melted in reactors and formed clusters in the coldest parts increasing the risk of a failure.
The scientist conclude that the Civil Aviation Authorities made the right choice.
This study enables them to evaluate the level of threat that any kind of volcanic ash represents. They have created reliable analysis models and protocols. It is also worth noting that the properties of volcanic ash can change when the eruption is very long.
Source : translated from Le Figaro