Volcanic Ash Grounds Airliners

How volcanic ash grounded almost every jet in Europe

A volcano in Iceland erupted yesterday, spewing a gigantic cloud of dust in the air, and with the wind blowing from the northwest, prompted aviation authorities to shut down airports in Britain, France, Scandinavia and other parts of Europe on Thursday. Jet engines can be severely damaged by the glassy silicate in that volcanic dust.

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.

On December 15, 1989, this happened when clouds of ash from an eruption at Mt. Redoubt Volcano in Alaska nearly caused a Boeing 747 jetliner (KLM Flight 867) carrying 231 passengers to crash land after losing power to all four engines.

As the crew of KLM Flight 867 struggled to restart the plane's engines, "smoke" and a strong odor of sulfur filled the cockpit and cabin. For five long minutes the powerless 747 jetliner, bound for Anchorage, Alaska, with 231 terrified passengers aboard, fell in silence toward the rugged, snow-covered Talkeetna Mountains (7,000 to 11,000 feet high). All four engines had flamed out when the aircraft inadvertently entered a cloud of ash blown from erupting Redoubt Volcano, 150 miles away. The volcano had begun erupting 10 hours earlier on that morning of December 15, 1989. Only after the crippled jet had dropped from an altitude of 27,900 feet to 13,300 feet (a fall of more than 2 miles) was the crew able to restart all engines and land the plane safely at Anchorage. The plane required $80 million in repairs, including the replacement of all four damaged engines.

DVICE

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