Q: For routes between the west coast of the U.S. and the Far East, what determines whether the route goes over the Bering Strait or crosses the Pacific heading west?
A: Pacific routings are determined considering the prevailing winds and flying the shortest distance. Flights from the U.S. to northern Asia are shorter the more northerly you travel (Great Circle Routes). For flights from the U.S. east coast or Chicago into China we fly over the North Pole. Flights to Japan or from the U.S. west coast to Asia may fly across or just south of the Bering Strait, depending on winds. I have flown flights to Japan from Newark across the Bering Strait and then flown back the next day on a route south of Alaska because the winds that favor a westbound flight would not be advantageous to an eastbound flight. Going straight westerly is too far south for the Far East. The current Extended-range Twin-engine Operational Performance Standards regulations have allowed us to fly more directly in remote regions, such as over oceans and the Polar Region, which saves time and fuel.
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