Eli5: why is volcanic ash dangerous to aircraft, and yet they can fly through forest fire smoke?

Question

Thank you!

In: 32

Answer 1

Volcanic ash usually contains more than just the ash. There are corrosive gases, such as h2s and so2 that are likely to corrode engine internals. Also, if a volcano is emitting smoke, it’s pretty likely that the activity is considered too dangerous for a fly-over. Imagine flying over it with a couple tons of earth and magma are thrown you.