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)