Volcanic eruptions become a danger to aviation because of the way ash clouds make it difficult for pilots to see. Volcanic ash, small pieces of volcanic rock, when it is sucked into jet engines can cause serious damage up to and including failure. Airplanes flying through ash released by volcanoes can also experience damage to control surfaces, sensors, and avionics.
In the aftermath of a volcanic eruption, the grounding of airline flights is often necessary because radar does not easily differentiate ash clouds from meteorological clouds, putting aircraft and passengers at high risk. Furthermore, ash clouds can travel great distances, making encounters with them unpredictable at best.
Problems with Volcanic Ash and Airplanes
Airplane manufacturers are adamant when advising that their planes should remain on the ground as long as the threat of volcanic ash exists. When flying, the speed of the airplane as it collides with the ash, magnifies the problem. Ash can even get into aircraft ventilation systems, causing distress inside the passenger cabin. The impact of the ash on hydraulic systems threatens the pilot’s ability to control and land the plane. Fuel nozzles in jet engines can become damaged or clogged, causing obvious operational risks.
Because volcanic ash has a relatively low melting point, ash that is sucked into a jet engine melts as it travels through it and then cools and sticks to engine parts. This obstructs air flow and put the turbine vanes off balance, creating additional stress on the power plant. The obstruction of air by the ash can easily result in stalled engines and the difficult scenarios that follow.
Volcanic Ash Countermeasures
The world has 9 centers that monitor the threat of volcanic ash. These Volcanic Ash Advisory Centers are run under international cooperative agreements that advice weather experts around the world about potential threats involving ash. These centers attempt to detect the location of ash clouds and then predict their movement in the atmosphere, although the science behind their efforts is often inexact.
Are You Sure Volcanic Ash Is Dangerous?
Skeptics point to the fact that no airplane to date has been downed as a result of volcanic ash in the sky. There are, however, records of airplanes that have flown through the ash and experienced damage as a result. Probably the worst of these events occurred after a volcano erupted in Indonesia in 1982. A British Airways plane affected by the ash lost power to all of the engines, although only one of the engines could not be restarted. Close calls like this one and others combine with the threat of costly damage to aircraft to make it customary to ground air travel in areas where volcanic ash is likely to become a factor.
