Ash

Apart from possibly affecting climate, volcanic clouds from explosive eruptions also pose a hazard to aviation safety.[3] For example, during the 1982 eruption of Galunggung in Java; British Airways Flight 9 flew into the ash cloud, suffering temporary engine failure and structural damage. During the past two decades, more than 60 airplanes, mostly commercial jetliners, have been damaged by in-flight encounters with volcanic ash. Some of these encounters have resulted in the power loss of all engines, necessitating emergency landings. Luckily, to date no crashes have happened because of jet aircraft flying into volcanic ash.[3] Ashfall is a threat to health when inhaled, and is also a threat to property with high enough accumulation. Greater than 30 cm (12 in) of accumulation is sufficient to collapse most buildings.