Places where hot gas, ash, and lava come out of the earth and create hazards for aircraft.

Volcanoes are places on the Earth where geologic activity causes the (often violent) release of hot gasses, chunks of rock, ash, steam, and lava (molten rock). Erupting volcanoes are very dangerous to aviation, primarily due to the large ash clouds many eruptions generate, which can severely damage s on aircraft that fly through the ash cloud, sometimes causing the complete failure of all of a aircraft's engines; for instance, when one volcano in Iceland erupted in 2010, the ash cloud it generated temporarily forced an almost total halt to air travel in much of Europe. Volcanoes are to aircraft in other ways as well, such as the violent an eruption can create and the corrosive gasses emitted from most volcanoes.