The drifting ash cloud from the Eyjafjallajokull volcano that erupted in Iceland earlier this week is still causing massive flight delays that could get worse by the end of Friday, with 17,000 flights likely to be canceled across the continent. Why is it so threatening and could it happen in the U.S.? Aviation expert Clive Irving on the rare force of nature.
Travelers are facing the greatest ever disruption of international air travel. In an unprecedented emergency all flights to and from the United Kingdom and western Scandinavia were grounded Thursday by a gigantic cloud of ash drifting south eastward from the Icelandic volcano eruption. The ripple effects of this grounding extend across the world—28,000 flights have been cancelled and airports are filling up with stranded travelers.
Nothing is more lethal to a jet engine than ingesting this kind of ash—it’s like putting sugar or sand in the gas tank of a car.
For days forecasters had been watching the course of this cloud. Few people realized that what seemed one of nature’s great entertainments, hot lava melting a glacier, had the potential to paralyze Europe’s entire air traffic system.
And then, because of a switch in the high altitude prevailing winds over the north Atlantic, the accumulated and intensifying ash cloud began to head in the direction where it could most disrupt human life: The British isles, Scandinavia, and western Europe.
Why was it so threatening?
Well, just as human lungs can choke on the fine particulates in volcanic ash, so can jet engines. In fact, nothing is more lethal to a jet engine than ingesting this kind of ash. It’s like pouring a fine mist of hot metal into the system. In this case, silicate in the ash melts as it hits the hot turbines of the engine and shuts it down.
Imagine putting sugar or sand in the gas tank of a car. Not only does the engine stop but it’s a complete write-off. That’s why thousands of planes are now sitting on the tarmac with their engine intakes capped.
What is extraordinary about Thursday’s emergency is the rare combination of a volcanic eruption, winds at jet stream height that coincide precisely with the cruise altitude of jets, and the location of the eruption so close to one of the most densely flown pieces of sky in the world.
Until now, Southeast Asia has been the place where volcanic ash and airline routes have intersected. The closest call involving volcanic ash came in 1982 when two big jets flew through ash from the Galunggung volcano in Indonesia and all four engines on each plane seized up. In both cases, after diving to a lower altitude clear of ash, the captains were able to restart their engines. The pilot of one of these planes, a British Airways 747, told the BBC Thursday that although he was able to get the engines running again they were badly damaged and his emergency landing was hairy—the engines had to be scrapped.
Mount Pinatubo in the Phlippines which produced the second largest eruption of the 20th century in 1991 and changed the summer climate of the northern hemisphere with a high altitude ash cloud for a year or more was in a location where airline routes could be altered to avoid the cloud without major disruption. It did, however, have the effect of closing down a significant U.S. military location, Clark Air Base, and the U.S. military never returned there.
In the U.S., the volcano most threatening to airline routes is Mount St. Helens, but it has never had anything like the impact of Thursday’s phenomenon.
Just how long European air lanes will be closed by the Icelandic cloud is in the hands of the elements. As long as it’s up there, nothing can fly. Depending on the course the cloud takes, it could move into southern Europe and the Mediterranean and similarly devastate air travel there. A British meteorologist said today that the cloud might, in fact, stall or even make a turn to the west, leaving it as a continuing threat. Apart from the disruption of travel, the economic cost of it all is incalculable—in lost travel, hotel cancellations, tourists who will never turn up, and business meetings canceled.
The last time anything approaching this happened was the grounding of all flights in U.S. air space after 9/11 and it took the airline industry a long while to recover from that. In this case, of course, the cloud will eventually dissipate, but it will never be forgotten.
Note: The original version of this story has been updated with additional information and new details.