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

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Anonymous 0 Comments

Volcanic ash is tiny fragments of actual rock that is hard and abrasive, causing rapid wear in airplane engines. Smoke particles are mostly carbon and not nearly as dangerous.

Anonymous 0 Comments

The smoke is burned particles of whatever is burning. So a forest fire produces smoke in the form of sot. This may have some effect on aircraft engines as the carbon can build up in a few places. However nothing major. Volcanic ash however is quite different as it is made up of tiny pieces of rock that have been molten and cooled down to glass. And where sot from forest fires will burn when heated the glass from a volcano will just melt and clump together in large pieces of rock inside the engine.

Anonymous 0 Comments

The smoke is burned particles of whatever is burning. So a forest fire produces smoke in the form of sot. This may have some effect on aircraft engines as the carbon can build up in a few places. However nothing major. Volcanic ash however is quite different as it is made up of tiny pieces of rock that have been molten and cooled down to glass. And where sot from forest fires will burn when heated the glass from a volcano will just melt and clump together in large pieces of rock inside the engine.

Anonymous 0 Comments

Volcanic ash is tiny fragments of actual rock that is hard and abrasive, causing rapid wear in airplane engines. Smoke particles are mostly carbon and not nearly as dangerous.

Anonymous 0 Comments

It’s like sitting next to a camp fire and smelling the woodsmoke vs grabbing a handful of ash out of the embers and snorting it.

Edit because my comment got mod removed…

The smoke causes no damage to an engine whereas the intake of larger particles can cause friction and abrasion. The sheer volume of this that they pass through over a volcano means an engine could be ingesting several kilos per second which will cause immediate catastrophic failure. This is not good.

Anonymous 0 Comments

Engines are millions of dollars each, and flying through volcanic Ash ruins them completely. The others have mentioned how. Not only do the engines themselves cost money to replace even if the plane lands safely, the plane won’t be allowed to fly passengers with completely new engines without a long procedure of test flights to recertify the aircraft as safe. That’s a ton of profit lost on top of the risk to human life.

The volcanic Ash will cause all engines to fail with enough time. And depending on what else happens, the plane very well could crash just from that. There’s a chance that the engines can be restarted if the rock formed inside can be broken or remelted. But you can’t know that in the moment. The volcanic ash also sandblasts the windscreen and the pilots can no longer see out of their windows. Doesn’t sound like a big deal but when there’s no engine power there may not be electrical power to the autopilot or systems that guide the plane to land.

Anonymous 0 Comments

This person s favorite of mine and does an excellent job explaining aircraft incidents. To answer your question here is british airways flight 9

Here is him doing a more in depth for the specific hazards of volcanic ash

Anonymous 0 Comments

Volcanic ash is not the same as wood ash. Volcanic eruptions spit out a ton of microscopic rocks and glass particles that are the same hardness as steel. If those particles got into an engine, it would act like sand paper and grind down the precision surfaces.

Anonymous 0 Comments

It’s like sitting next to a camp fire and smelling the woodsmoke vs grabbing a handful of ash out of the embers and snorting it.

Edit because my comment got mod removed…

The smoke causes no damage to an engine whereas the intake of larger particles can cause friction and abrasion. The sheer volume of this that they pass through over a volcano means an engine could be ingesting several kilos per second which will cause immediate catastrophic failure. This is not good.

Anonymous 0 Comments

Engines are millions of dollars each, and flying through volcanic Ash ruins them completely. The others have mentioned how. Not only do the engines themselves cost money to replace even if the plane lands safely, the plane won’t be allowed to fly passengers with completely new engines without a long procedure of test flights to recertify the aircraft as safe. That’s a ton of profit lost on top of the risk to human life.

The volcanic Ash will cause all engines to fail with enough time. And depending on what else happens, the plane very well could crash just from that. There’s a chance that the engines can be restarted if the rock formed inside can be broken or remelted. But you can’t know that in the moment. The volcanic ash also sandblasts the windscreen and the pilots can no longer see out of their windows. Doesn’t sound like a big deal but when there’s no engine power there may not be electrical power to the autopilot or systems that guide the plane to land.