I am using airline data to construct a network of competition in the airline industry. As part of this, I am listing the routes that are the most competitive – not necessarily the ones that have the most flights, but the ones that have the most competitors.
And here they are
HKG-ICN Hong Kong – Incheon, Seoul (South Korea)
TPE-NRT Taipei (Taiwan) – Narita, Tokyo (Japan)
SIN-CGK Singapore – Jakarta (Indonesia)
SIN-DPS Singapore – Denpasar, Bali (Indonesia)
Please note that these data are a few years old, are preliminary and not completely accurate, and airlines come and go on such competitive routes.