The world's busy air traffic corridors pass over hundreds of volcanoes capable of sudden, explosive eruptions. In the United States alone, aircraft carry many thousands of passengers and millions of dollars of cargo over volcanoes each day.
Volcanic ash can be a serious hazard to aviation even thousands of miles from an eruption.
Airborne ash can diminish visibility, damage flight control systems, and cause jet engines to fail. USGS and other scientists with the Alaska Volcano Observatory are playing a leading role in the international effort to reduce the risk posed to aircraft by volcanic eruptions. The volcano had begun erupting 10 hours earlier on that morning of December 15, 1989. Partly in response to this near-fatal incident, the U.S. Geological Survey organized the first International Symposium on Volcanic Ash and Aviation Safety. This 1991 conference in Seattle, Washington, focused attention on ways to reduce the risk volcanic ash poses to the world's rapidly increasing air traffic.