"Alaska airspace is extremely busy with long-range, wide-body aircraft as well as bush planes and smaller aircraft. The Anchorage International Airport handles more international air freight (in dollar value) than any other airport in the United States; the Fairbanks International airport, located in Alaska's interior, is ninth on the list and handles more and more freight each year. More than 60,000 aircraft and 10,000 people fly over or very near Alaska
volcanoes as they travel the north Pacific (NOPAC) and Russian far east (RFE) air routes. The reason for all the activity is Alaska's unique geographic location. All direct air routes between the United States (even Los Angeles and New York) and Asian cities such as Tokyo and Hong Kong pass along the NOPAC routes. Also, most of the aircraft carrying freight between Europe and Asia come through Anchorage for
refueling. A considerable percent of all air freight on earth passes near Alaska's many volcanoes.
North Pacific and Russian Far East air routes (gray lines) pass over or near more than a
hundred potentially active volcanoes (red triangles).
"Encounters between aircraft and volcanic ash are serious because the ash can cause severe damage to the engines as well as other parts of the airplane. Two processes damage jet engines, particularly long-range, wide-body airplanes such as DC-10s and Boeing 747s that are used for international transport. The first damaging process
is the mechanical abrasion of the moving parts in a jet engine, such as the compressor and turbine blades. This abrasion reduces the efficiency of the engine but does not typically cause engine failure. Another process with potentially more dangerous consequences is the introduction of ash into the hot parts of an aircraft's engines. Jet engines, particularly those on large airplanes used on international routes, operate near the melting temperature of volcanic ash. Ingestion of ash can clog fuel nozzles, combuster, and turbine parts causing surging, flame out, immediate loss of engine thrust, and engine failure.
"In the past 16 years more than 80 jet airplanes have been damaged by volcanic ash worldwide. Seven of those encounters actually resulted in engine failure, although all seven eventually managed to restart enough engines to land without loss of life. In Alaska, potentially lethal ash clouds put aircraft at risk an average of four days per year." For more information on aircraft and volcanic ash, see
Volcanic ash - danger to aircraft in the North Pacific
For detailed information on specific hazards at specific Alaska volcanoes, check out AVO's volcano-hazard reports.
From Nye, C. J., Queen, Katherine, and McCarthy, A. M., 1998, Volcanoes of Alaska: Alaska Division of Geological & Geophysical Surveys Information Circular IC 0038, unpaged, 1 sheet, scale 1:4,000,000: