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In recent events we have seen an unprecedented grounding of air traffic due to a volcanic eruption in Iceland. For those of you who may be surprised about this particular issue, and maybe you’re even stranded because of it, here are several very critical reasons why airplanes and volcanic ash just don’t mix.
Sandblasting
Plane Sensors
Electromagnetic Wave Insulation
Combustion Power Failure
Sandblasting
One of the first things that comes to mind for me when I see an ash cloud is “why can’t I just fly through that? I’d be IFR, but I could do it”. Bad idea. The makeup of ash is basically lightweight glass pieces that have been blasted into the air.
That means that as you cut through this “floating rock” the aircraft windshield can become damaged and fogged, the aircraft fuselage can be severely damaged, and it can add weight to the aircraft and change the weight and balance.
This is dangerous for ANY kind of aircraft.
Interesting Pictures of Sand Blasting
Plane Sensors
Because ash is very thick, it can clog your pitot instruments and then you will lose all ‘air data’ like altitude, airspeed and vertical speed. This is NOT good. Especially if there is some IFR weather in the area, you are in big trouble.
Electromagnetic Wave Insulation
As an aircraft cuts through volcanic ash it creates a lot of electromagnetic disturbance which can severally affect radio communication. It is known to make major interruptions in to communications that would otherwise be normal.
Combustion Power Failure
This is the most dangerous of all of the reasons volcanic ash hurts aircraft. In this instance, the glass particles we talked about earlier are enjested into the engine (which pulls in a LOT of air). These particles, up in the atmosphere where jets fly, will melt in the engines at about 1100*, because typical engine temperature at that altitude is around 1400*.
So as this ash starts to melt in the engine, it bonds to the blades and to the inner workings that allow the engine to operate correctly. You are also guaranteed to have your engines shut down if you fly through ash in an airliner. The only way out of this is to fly at a lower altitude (where the ash isn’t) or a lower engine power to lower the temperature at the engine (thus reducing the chance of melting) although this is no guarantee there won’t be damage.
There is a particular instance that is very scary where a 747-200, British Airways Flight 9 had complete failure of ALL engines and became a glider from about 36000 feet to 12,500 feet. This particular flight had flown through this ash cloud and they were as good as dead.
Like any great professional flight crew, these experienced english gentlemen at the helm were able to finally start lighting up the engines when they glided down to a lower altitude and with much persistence.
Conclusion
So if you were in Europe in April 2010 and stuck on the ground due to volcanic ash, just think that you could have become a glider during your flight if the pilots would have gone. To me, that would not be a comforting feel.
What do you think about Volcanic Ash? Is there too much hype? Should airlines push the envelope more?
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