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Wildfire and Volcanic Ashes

Updated: Jun 8, 2021

Find here some Q&A about the effects of wildfire and volcanic ashes over a flight:

Photo by Ben Kuo on Unsplash

1. What happens when planes fly through smoke? How are the engines affected?

It depends on the type of smoke…

Smoke from wildfire contains different compounds such as carbon monoxide, volatile organic compounds (VOCs), carbon dioxide, hydrocarbons and nitrogen oxides, which are far from the hazard of volcanic ashes, for instance: volcanic ashes, though, are made up of tiny fragments of rock, minerals and volcanic glass, which are hard and abrasive.

Experience has shown that flying through a volcanic ash cloud can cause damage to aircraft surfaces, windshields and powerplants. Aircraft ventilation, hydraulic, electronic and air data systems, can also be contaminated.

Partial or total engine power loss events in extreme cases (such as volcanic ash ingestion), while not frequent, are major safety concerns: simultaneous power loss in all engines has occurred, where the crew succeeded in restarting the engines, after application of operational procedures.

Wildfire smoke is unlikely to cause as much damage, as it is not that abrasive.

2. At what point must a plane avoid flying through smoke?

Flying through a volcanic ash cloud should be avoided by all means due to the extreme hazard for the aircraft as mentioned above.

In terms of wildfire smoke, though, most commercial flights are only likely to come close to it on approach to landing (due to flight altitude and the smoke reach).

When overflying an area of wildfire, the aircraft may experience some turbulence and loss of lift, while on approach flight crews are likely to experience strong wind shear and reduced visibility. Depending on the proximity to the airport, visibility may even drop to near zero and close its operations.

In case of wildfires along the route, it’s unlikely for smoke to reach cruise level (differently from volcanoes eruptions), but depending on the fire intensity, it may form a so-called firestorm, with a pyrocumulonimbus cloud, which as other cumulonimbus (thunderstorm) shall be avoided.

3. Will smoke ever enter the cabin through the fresh-air intake, or will filtration systems prevent this?

Filtration systems will certainly prevent most of it, but it all depends on the amount of smoke and particles concentration and granulation. HEPA filters installed in modern aircraft can remove 99.97% of airborne particles of 0.3 microns in diameter. With wildfire smoke, and air pollution generally, the most concerning are the microscopic particles that are about 2.5 microns in size. Volcanic ash, though, is made of very fine particles that can go down to 1 micron.

We have contributed to an article on this subject, which can be found here.



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