Volcanic ash vs jet engines: Why flying into a cloud of volcanic ash is bad, and the nerves of steel it takes to recover
Wednesday, August 20, 2014, 7:04 PM - With earthquakes and magma movement possibly heralding an eruption of Icelandic volcano Bárðarbunga, authorities are very concerned about the effects this would have on air traffic, not just in the region of Iceland, but potentially around the world.
Although it's happened several times in the past, the 2010 eruption of the Eyjafjallajökull volcano (click here for pronunciation) was the most recent and dramatic example of the disruptions to air traffic that can happen due to an erupting volcano. The tons of ash thrown into the sky during roughly two months of eruptions spread across the North Atlantic into eastern Canada, south over most of Europe and east across much of western Russia. For nearly a week, from April 14 to 23, flights all across northern Europe were cancelled, stranding travellers and costing the airline industry an estimated $1.7 billion.
DID YOU KNOW?: How to pronounce Bárðarbunga
So, what is it about volcanic ash that makes it so dangerous to fly through?
First off, if you grab a sample of volcanic ash out of the sky, you're going to find a chaotic assortment, not only in the size of the particles, but in the shapes and also what they're made of. Larger, rounder particles can only make it so far away from the volcano before they fall to the ground, but smaller and more 'flake'-like particles can stay aloft for thousands of kilometres. They can even circle the entire globe before they finally settle to the ground. So, the ash is capable of travelling for large distances on the winds, delivering - depending on the size of the eruption - far-reaching effects.
As for the effects on jet airliners, it's what the ash is made of that matters most.
In the case of Eyjafjallajökull, when it erupted, it blasted straight through a thick layer of glacial ice in the process. This simultaneously melted the glacier and rapidly cooled the ash as it exited the volcano, causing it to crystallize into shards of glass. As this video from BBC's Bang Goes The Theory shows, shards of glass flying into a jet engine is very bad, due to the temperatures jet engines work at (~1,500 degrees C) compared to the temperature at which glass melts (~1,000 degrees C):
So, for the unfortunate airliner that does fly into a volcanic ash cloud, their only recourse, it seems, is to either let the engines shut down on their own or shut them down manually. Then, steeling themselves for what's to come, ride the winds to take the plane down through a layer of cold air. This will cause the glass to cool rapidly and actually pop off of the rotor blades, so the engines can be restarted. If it looks too much like the host's stream of compressed air is actually blasting the glass from the rotor blade, check out the video below, from New Scientist.
Once the researchers in the video coated the rotor blade with glass from volcanic ash, they simply allowed the blade to cool on a tabletop. The glass still pops right off the surface of the metal.
According to the researchers, cooling the rotor blade to just 720 degrees C was enough for the glass to transition to a crystalline structure that wasn't able to stick to the metal.
It's still possible that Bárðarbunga won't erupt. While there have been around 1,000 small earthquakes clustered to the east of the volcano just on Tuesday, scientists monitoring the volcano are reporting that there is still no indication that magma is headed for the surface. There are many eyes on this volcano, though, and many brains assessing whether or not an eruption will happen and what its effects will be if it does.
If you'd like to add your eyes to the effort, there are life-feed cameras watching the volcano 24-7 (click here). Currently, the view is pretty, but not all that exciting, but that could change in the days to come.
(Teaser image courtesy Sixty Symbols)