Volcanic ash vs. airplanes

As I write this post, planes across the Europe take off, after being grounded for several days due to volcanic ash from Iceland. Eyjafjallajökull, volcano located at the south of Iceland, is ‘responsible’ for chaos in air transport in Europe. About 95.000 flights were canceled last week, and airlines lost billions of Euros.

So, there is a question – Why is the volcanic ash so harmful to airplanes?

Volcanic ash consists of very small particles, from several microns to 1-2 millimeters in diameter. Being so small and light, they are very easy carried by wind, and can ‘travel’ thousands of kilometers from the volcano and reach very high altitudes. The ash mostly affects aircraft engines. The silica, the material ash particles are mostly made of, melts at about 1100°C. Modern jet engines operate at 1400ºC. So, when such particles enter the engine, they melt and fuse on the turbine blades and other hot engine parts. Therefore, rotating parts can be destabilised and severely damaged, or fuel nozzles blocked, which results in decreased thrust, or complete engine failure.

Since volcanic ash is highly abrasive, it also affects all surfaces of the aircraft. The most affected are windscreen, fuselage, leading edges of wings, control surfaces (ailerons, elevators, flaps, etc.). Damaged pilot windscreen or light covers can make visual landing very hard or impossible. Ash accumulated on a runway can cause problems during take-off or landings, when it is easily thrown in the air, and can be sucked by a jet engine and cause enormous damage to the rotating parts. The ash can also lead to landing gear failure.

Being able to cause severe damage on the aircraft, volcanic ash is a big threat to the safety of passengers and crew. What is more, large amount of money is needed to fully repair aircraft which encountered volcanic ash. Several airplanes almost crashed after their engines went silent because of ash damage. All in all, more than 50 airplanes were written off of due to damage from volcanic ash.

So, recent blockade in air traffic was a reasonable precaution, taking in account possible consequences.