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Iceland Volcano's Ash Grounds European Air Travel
Ch_Omega writes "From the article at CBSNews: 'An ash-spewing volcano in Iceland emptied the skies of aircraft across much of northern Europe on Thursday, grounding planes on a scale unseen since the 9/11 terror attacks. British air space shut down, silencing the trans-Atlantic hub of Heathrow and stranding tens of thousands of passengers around the world. Aviation officials said it was not clear when it would be safe enough to fly again and said it was the first time in living memory that an ash cloud had brought one of the world's most congested airspaces to a standstill.'"
The BBC says "Safety group Eurocontrol said the problem could persist for 48 hours," and the Deccan Herald describes some of the effects on the ground in the volcano's home turf: "In Iceland, hundreds of people are fleeing rising floodwaters as the volcano under the glacier Eyjafjallajokull erupted yesterday again, for a second time in less than a month."
The trouble with ash and aircraft is that, at the high temperatures found in jet engine combustion chambers, ash turns into a delightful material extremely similar to molten glass(you also have the less immediately dramatic; but still annoying, problem of having the ash particles basically sandblasting the surface of the aircraft).
Best case scenario: some rather expensive repairs, including replacing scratched glass and engine parts(or even entire engines).
Worst case scenario: Fiery death.
It's not nearly as complicated as it seems, "fjalla" means mountain and "jokull" glacier so a native would read it more like "the glacier of the mountain Eyja" or "Eyja Mountain Glacier". But like the Scandinavian and German language they build one long word out of it.
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The ash cloud hit my city a few hours ago (Sweden). Other than the airports closed (and I don't understand why), nothing out of ordinary is going on.
Here in England you wouldn't know anything was happening. The dust is passing over at high altitude, so its only the planes that are affected. I'm sure we'd have had a very nice sunset if it hadn't been cloudy...
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This is actually untrue. Actual sand is not a problem for a modern jet engine - if you ever bothered to watch the A380 ads, one of the tests on the engine was when they fed a constant thick stream of fine sand into the intake of a running engine, and it was going just fine. It will certainly stress the engine, but it will keep running just fine for a very long time before sand starts to really wear out the internal mechanics to cause serious damage and shutdown.
Problem is that hot ash is actually not sand (which would not be able to stay that high in the air), but actual hot ash. As a result, as it goes through the engine, it coats the fuel feeding system and as it's rapidly cooled by compressed cold air pre-ignition, it becomes a glass-like material that blocks the fuel from getting into combustion chamber. This is what is causing the engine flameout. The reason why keeping the engine shut, putting plane into descent and keeping on trying to restart the engine is current modus operandi is because the glass-like substance that ash forms on the inside of the engine becomes very brittle when engine is being cooled by fast air stream going through it. As a result, when temperature drops below certain threshold, the normal vibration caused by drag and turbulence shatters the brittle mass, clearing the nozzles and allowing for fuel feeding to work again.
This is what happened in the 747 that lost all 4 of it's engines to flameout when flying through volcanic ash in the past. The report should be available to the general public, at least I recall reading it somewhere (though in finnish). In general, ash doesn't really scratch as much as stick to surfaces and solidify into dark glassy mass (which does in fact block the windows as well, meaning pilots would most likely have to land in instruments-only conditions in addition to handling engine flameouts).
It's not nearly as complicated as it seems, "fjalla" means mountain and "jokull" glacier so a native would read it more like "the glacier of the mountain Eyja" or "Eyja Mountain Glacier". But like the Scandinavian and German language they build one long word out of it.
It is even simpler than that as Eyja means island (err, since Iceland is spelled Island in Icelandic maybe that isn't a simplification). It is a reference to the nearby Vestmann Islands, that lie just off the coast from where the glacier is.
So Eyjafjallajökull -> Islands Mountain Glacier.
> An automobile's air filter will plug within minutes of being introduced to
> volcanic ash.
Only when there is a great deal of it: enough to impede visibility. The levels we are talking about here might cut the life of your air filter in half. Jet engines are much more sensitive to this sort of dust than internal combustion engines are. They inhale much, much, much more air, it is impossible to filter it, and they run hot enough to melt the silica.
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There is another, larger, volcano nearby called Katla and ...
"Eyjafjallajokull has blown three times in the past thousand years," Dr McGarvie told The Times, "in 920AD, in 1612 and between 1821 and 1823. Each time it set off Katla." The likelihood of Katla blowing could become clear "in a few weeks or a few months", he said.
Given this, and given that the last eruption was on and off for 2 years, we could have travel interruptions for a while to come.
When this Iceland volcano erupts, nearby Katla always goes up soon after. A major eruption of Katla could give us another "Year without a summer" in the northern hemisphere.
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