While over 150,000 flights per day land at their intended destination, some divert due to weather, mechanical, or medical reasons. When a flight diverts, we’re often asked why the aircraft didn’t land at the nearest airport. While there are instances when landing as soon as possible is the best course of action—such as the recent Southwest flight 1380 or Air France flight 66 in 2017—most of the time the best outcome involves a more complicated calculation about where to divert a flight.