America's busiest cargo airport is in Anchorage, Alaska, where international flights heading to and from the Far East make frequent stops.
The Alaska Volcano Observatory (AVO), celebrating its 25th anniversary this month, monitors volcanic eruptions that can wreak havoc on the busy air traffic.
For Alaska, a state that depends on air travel for moving people and goods to its far-flung and remote towns and villages, it's critical to know when and where to expect a volcanic plume.
"Since 1988, AVO has responded to over 70 eruptive events from Alaska's 52 historically active volcanoes," John Power, scientist-in-charge of AVO, said in a statement. "Many of these eruptions affected local and international air traffic, oil production, the fishing industry, municipalities, businesses and citizens."
The state's more than 50 active volcanoes have all erupted since 1760, and there are 29 more simmering on Russia's nearby Kamchatka Peninsula. All could belch ash plumes that clog airplane engines.
The Volcano Observatory was created in 1988, two years after the eruption of Augustine volcano, located 175 miles (280 km) southwest of Anchorage, affected the airport and the city of Homer.