The 2010 eruptions of Eyjafjallajkull are a series of major volcanic events at Eyjafjallajkull in Iceland. Thick clouds of ash from a volcano eruption in Iceland continue to drift across the continent. The ash clouds include particles of rock, glass and sand that pose a serious threat to aircraft. Volcanic ash, which consists of the pulverised rock and glass created by the eruptions, can jam aircraft machinery if a plane flies through the plume, shutting down the engines. Ash can also be sucked into the cabin itself, contaminating the passengers' environment as well as damaging the plane's electronic systems. There is a risk of engine failure because of the ash. The problem with aircraft radar is that it is designed to pick up clouds of moisture and it won't detect ash.

If a jet plane is flying through air densely contaminated with volcanic ash, there is risk of ingested ash eroding the front blades, melting in the combustion heat, and

re-freezing sticking to the rear blades, affecting performance and perhaps stopping the engine Moreover, the ash may sandblast the outside of the plane, including making

windows opaque and damaging instruments.

A vast, high-altitude cloud of volcanic ash continued to spread over northern Europe on Friday as airspace and Europes busiest airports remained closed and thousands of

flights and millions of passengers around the world from North America to Asia were affected.
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This weired pronouncing volcano stopped almost all air traffic in Europe. Its ash covered almost whole Europe creating a nightmare for air travelling. Ash particles could damage parts of an airplane so they grounded all planes in most of Europe causing travel mess to all over the world.
Check these cool pics in http://www.boston.com/bigpicture/2010/04/more_from_eyjafjallajoku ll.html