Volcanic Ash and Aviation: When Eruptions Ground the Skies
In 2010, a relatively modest eruption in Iceland brought European air travel to a standstill, stranding millions of passengers. The culprit was volcanic ash, an invisible but serious hazard to aircraft that can damage planes and stall their engines in mid-flight. As global air travel has grown, so has the challenge of keeping aircraft safe from the ash that volcanoes can inject high into the busy skies.
Why ash threatens aircraft
Volcanic ash is not soft like fire ash but made of tiny, hard, abrasive fragments of rock and glass. When an aircraft flies through an ash cloud, this material sandblasts windscreens and surfaces, clogs sensors, and, most dangerously, can melt inside hot jet engines. The molten ash coats engine components and can cause the engines to lose power or stop entirely, a potentially catastrophic failure.
The British Airways incident
The danger was dramatically demonstrated in 1982, when a British Airways jumbo jet flew into an ash cloud from an Indonesian volcano at night. All four engines failed, and the aircraft glided in silence for several minutes before the crew managed to restart the engines and land safely. This terrifying incident, and a similar one over Alaska, alerted the world to the threat of ash to aviation.
The 2010 Eyjafjallajokull eruption
The most famous ash-and-aviation event was the 2010 eruption of Eyjafjallajokull in Iceland. Though modest in volcanic terms, it sent ash drifting across Europe at the busiest air-travel altitudes. With the danger of engine failure in mind, authorities closed much of European airspace for days, cancelling over a hundred thousand flights and stranding millions of travellers, the largest air-travel disruption since the Second World War.
Ash clouds and the jet stream
Volcanic ash can travel enormous distances on high-altitude winds, spreading far from the erupting volcano. The jet stream and other winds can carry ash across continents and oceans, meaning an eruption in one region can threaten air routes thousands of kilometres away. This is why monitoring and forecasting the movement of ash clouds is a global concern.
Volcanic Ash Advisory Centres
To manage this hazard, a global network of Volcanic Ash Advisory Centres tracks ash clouds and issues warnings to aviation authorities and airlines. Using satellite data, ground observations, and computer models of wind and ash dispersal, these centres predict where ash will travel, allowing aircraft to be rerouted around the danger.
Lessons of 2010
The 2010 disruption prompted a rethink of how aviation responds to ash. Rather than simply closing all airspace, authorities and airlines worked to define safe thresholds of ash concentration through which aircraft could fly, balancing safety with the enormous economic cost of grounding flights. Improved monitoring and forecasting have since made the response more flexible and targeted.
A continuing challenge
As long as volcanoes erupt beneath busy air routes, ash will remain a challenge for aviation. Volcanoes from Iceland to Indonesia, Kamchatka to the Andes can all threaten the skies. Continued investment in monitoring, forecasting, and international cooperation is essential to keep the world's aircraft safe from this invisible volcanic hazard.
Explore on the map
From Iceland to the volcanoes of the Pacific Ring of Fire, eruptions beneath busy air routes pose an ongoing challenge to aviation. Explore these volcanoes on the interactive map — filter by region to see where the ash of the Earth's volcanoes reaches into the skies that aircraft cross.