The [Kasatochi volcano] eruption was handled very differently in the U.S. compared with Europe's reaction to the Iceland volcano. In Europe, government authorities decide whether the skies are safe or not.
In contrast, in the U.S., data about ash clouds are given to the airlines, and it's mostly up to them to decide whether it's safe to fly or not. During the Alaska eruptions, the Federal Aviation Administration closed only small patches of airspace, immediately around the volcanoes.
Still, points out a United Airlines dispatcher, the North American geography helped. More airspace and more dispersed airports left airlines a lot of room to detour around ash clouds.
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