Why Volcanic Ash Is So Terrible for Airplanes

An ash plume from Iceland’s Eyjafjallajokull crater during it’s 2010 eruption, spewing tephra and ashes that drift toward continental Europe. Etienne De Malglaive/Getty Images

The Barðarbunga volcano in Iceland is showing signs of a potential eruption, sparking fears among airline executives that they could be facing another Eyjafjallajökull, whose 2010 eruption forced airlines to avoid huge swathes of airspace and lose billions of dollars. The risk posed to aircraft by airborne volcanic ash is as bad as ever, but airlines are better equipped to spot and avoid trouble—and save money—than they were four years ago.

The problem is that volcanic ash is simply terrible for airplanes. Made of up tiny glass particles and pulverized rock, it can be spewed tens of thousands of feet into the air, reaching jet cruising altitude. It’s abrasive enough to erode the blades of the compressor (which increases the pressure of the air that feeds the jet engine), reducing its efficiency. The ash that gets into the combustion chamber can melt, producing a substance like molten glass. That then solidifies on the turbine blades, blocking air flow, and potentially stalling the engine.

Beyond that already terrifying scenario, ash can mess with a plane’s airspeed sensors, block the pilots’ view out the windshield, and dirty up the cabin air, all of which make flying way more difficult. Less immediately dangerous effects include erosion of external components, contamination of ventilation and pressurization systems, and reduced cooling of electronic systems. The the International Civil Aviation Organization has records for 83 “encounters” between aircraft and volcanic ash between 1935 and 2008. Eight of those those led to temporary engine failure. The most famous case is from June 1982, when all four engines on a British Airways 747 failed after the plane flew through ash produced by the eruption of Mount Galunggung in Indonesia. The pilot managed to restart three of the engines and land safely.

Learning to Avoid Ash

The risks to air travel posed by volcanic activity have been well known for decades at least, but the eruption of Eyjafjallajökull spurred greater efforts to solve the problem, says Paul Moore, easyJet’s head of communications. In 2010, airlines didn’t have a good way to tell exactly where ash from Eyjafjallajökull had spread. Dependent on satellite imagery and local reports, they calculated how far it could possibly have gone, and avoided that whole area. It was a safe but costly move. The eruption shut down much of European airspace for a week, canceling roughly 100,000 flights and affecting 7 million passengers. Oxford Economics estimates it cost the aviation industry $2.6 billion.

That’s why easyJet—which itself lost $55 million—collaborated with Airbus and Nicarnica Aviation, a Norwegian company that works on infrared and ultraviolet technologies, to develop a better way to detect airborne ash. In November 2013, they successfully tested the Airborne Volcanic Object Imaging Detector (AVOID), which uses infrared cameras to spot ash up to 62 miles away. That allows pilots to change routes only when ash poses a real threat, staying safe and saving money.

Moore says easyJet will be the first airline to put the system into commercial use, sometime next year. But if the currently noisy Barðarbunga volcano does end up filling heavily trafficked airspace with ash in the coming days or weeks, Nicarnica will be ready. It has three ground-based infrared cameras in Iceland already, and it’s keeping the AVOID system on stand-by, ready to be fitted on the Airbus A340 plane that did the testing in November.

In the case of an eruption with repercussions for air travel—still a long shot but definitely possible—CEO Ove Bratsberg says, it could have the plane in the air, doing scouting flights and reporting ash sightings, within 36 hours. It’s not a perfect solution, but it’s better than keeping everyone on the ground.