eyjafjallajökull ash trail extends >1000km

This is the visual image from space of the reason why tens of thousands of people are stranded across Europe in airports. For a second day, planes have been forbidden to take off from most of Europe’s major airports due to volcanic ash in the atmosphere.

This precautionary measure is aimed at avoiding the near disaster (I heard on the radio correctly or incorrectly but nonetheless demonstrating the danger) when an aircraft lost power in all four engines as it flew through an ash cloud during the eruption of the Phillipines’ Mount Pinatubo in June 1991. Fortunately, the plane regained power before it hit the ground and tragedy avoided.

The current problem in Europe is a result of two coincidential events. Firstly, the eruption of Iceland’s Eyjafjallajökull volcano. The manner in which the eruption is occuring underneath the glacier creates large amounts of pressure. As well, the cold glacier creates an environment where magma cools rapidly, forming small particles. Combined, these two elements cause extreme amounts of ash to be ejected into the atmosphere.

As coincidence has it, the prevailing winds are blowing this ash in the direction of the United Kingdom and Scandanavia. Unfortunately for travellers, as long as the current weather conditions prevail and the volcano continues to erupt, flights are not likely to resume in the short term.

Why not fly through the ash?

Volcanic ash cannot be detected by aircraft systems. The ash causes abrasion damage to both the and interior of the engine, that is the turbines and fan blades. Since the engine operates at temperatures in excess of 700°C, the risk is that the ash will melt and block the cooling holes within the engine. The overheating results in the engine shutting down. Longer term, accumulation of sulfur deposits in the engine has been attributed to loss of engine power. As well, the sulfur has been attributed to fading paint and crazing of windows. (Source: The 1991 Pinatubo Eruptions and Their Effects on Aircraft Operations)

(image from NASA’s Earth Observatory)


4 responses to “eyjafjallajökull ash trail extends >1000km

  1. I would just like to clarify that there were NO instances of an aircraft losing power to all four engines as a result of the ’91 Pinatubo eruptions, however there were two instances of a single engine failure (a DC10 and a 742). Pinatubo did result in several instances of engine damage, including to one 743 which required all 4 engines to be replaced, but this was did not occur in the air.

    Loss of power to all four engines of a 747 in mid-flight has occurred before though, in ’82 to a BA 742, Speedbird 9, which few though the ash from the eruption of Mount Galunggung in Indonesia, (the same ash led to 3 engines being shut down on a SIA 747 a bit over two weeks later) and in ’87 to a KLM 744, Flight 867, which flew though the ash from Mount Redoubt.

  2. Regardless of the facts, its still dangerous 😛 but as the airlines have been arguing, it’s probably safe to take off during the “gaps”, but some of them don’t want to risk it. Your diagram kinda makes the ash cloud look like a hat!

  3. What gaps? Show me the gaps! I thought ash would be blown by the wind, so how can these gaps be fixed?

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