Since they're high above any obstructions, you'd think a plane could just travel in a straight line to get to its destination. But it turns out that it's not quite so simple.
When flying to Europe from the United States, the route goes up into Northern Canada and then Greenland before skipping across the pond. Heading to Asia, they'll go over Alaska and Siberia.
Despite what you may have heard outside science class, the Earth is a spherical shape. So a straight line could actually be a much longer distance.
Add in the jet stream, which will push a plane using tailwinds above 200 miles per hour, and these factors can speed up your trip plus save fuel in the long run.