As some of you may probably know, a volcano erupted in the Canary island of La Palma, causing its airport to be closed and many planes and routes to be redirected as the ashes reach the atmosphere. But why is it dangerous?
For this article, I will be analyzing from lower hazard to higher.
First, as you know, ash clouds are made of volcanic particles in suspension, which means that your plane will go through “little flying stones” and if you have ever gone in a car and a little pebble stroked into the windscreen it probably scratched it, well, same happens in planes, even reaching to points where the windscreen turns completely opaque.
Secondly, the ash clouds could interfere with navigation and electronic systems, blinding the meteorological radar or messing up communications and examples. Ash could even enter inside the cabin and turn off the fire alarm system.
More dangerously ash could get inside instruments like the Pitot tube and repercuss in bad lectures of the IAS: Indicated Air Speed, which could mean fatal problems.
And finally, the most dangerous hazard: engines.
Imagine the turbofan engine of a plane as a compacted furnace: air gets sucked by it, compressed, then gets combusted and decompressed. The same happens to everything that gets inside, even birds, so happens with the ash, but the ash erodes the compressor’s blades, blocks the fuel nozzles, filters, etc and melts inside, an accumulation of problems that will eventually turn off (or even destroy) the engine.
To finalize I will mention the incident of the British Airways Flight 9, which happened in Jakarta in 1982, this Boeing 747 went through an ash cloud coming from the eruption of Mount Galunggung causing the malfunction and eventual death of its four engines due to the volcanic ash. Fortunately, once they got out of the ash cloud the melted ash inside the engines solidified and broke apart, allowing the crew to restart the engines.
You can learn more about the Jakarta incident by clicking here.