What are the busiest airline routes in the world?

The Korean island of Jeju doesn’t have the same international name recognition as popular tourist destinations such as Paris, Dubai, Miami, or Bali, at least outside of East Asia. However Jeju is in fact a hugely busy airline market mainly driven by domestic tourist traffic flying in from Seoul. As you can see from the rankings below, based on data from Diio by Cirium, the market between Jeju and Seoul’s Gimpo airport is the world’s busiest measured by number of flights and number of seats.

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Other leading markets by this measure are likewise domestic routes, in countries like Vietnam, Japan, Australia, Indonesia, India, and Saudi Arabia. The busiest US route by number of flights, in case you’re wondering, is New York LaGuardia-Chicago O’Hare.

The rankings change, however, when you factor in distance. On this list, using Available Seat Miles (ASMs) as a measure, London stands out, led by the Heathrow-New York JFK route.

Top City Pair Markets (both directions)
For 12 months ended Jan 2023 (distances In miles approximate)