I may have misused the term geographically - it's just the shortest, great circle route between 2 airports in the data. As the informed comments say though, the

I may have misused the term geographically - it's just the shortest, great circle route between 2 airports in the data. As the informed comments say though, there are flights that go over the poles - I think the longest commercial flight for a while was a Singapore Airlines NYC to SIN over the pole.