A volcano in Iceland erupted yesterday, spewing a gigantic cloud of dust in the air, and with the wind blowing from the northwest, it brought air traffic in the northern parts of Europe to a halt. Jet engines can be severely damaged by the glassy silicate in that volcanic dust, leading authorities to close airports and airspace in Britain, France, and most of northern Europe.
Such clouds can flame out jet engines, because those silicates have a melting point of between 600 and 800°C, while jet engine temperatures in flight are higher than 1,000°C. The tiny particles melt when they encounter the high temperature of the interior of a jet engine. When that liquid glass hardens as it flies out the back of the jet engine, it can gum things up and disrupt the engine's air flow.
That's exactly what happened to KLM flight 867 in 1989, where the Boeing 747's four engines suddenly stopped running after it passed through volcanic ash cloud, and dropped almost 2 miles before the pilots could restart them. It's no wonder aviation officials shut down airports and airspace until at least 1:00 AM on Friday.