Mutual influence across routes using a common airport: The case of the domestic market in Japan

•The interaction of traffic across routes serving the same airport is investigated.•Regression analysis uses the data on Japan's domestic air transport market.•Results show the positive mutual influence of traffic across routes.•Results are similar for the subsample of routes with rare transit usage.

This paper empirically investigates the mutual influence of traffic volumes across routes serving the same airport. Regression analysis using the data on Japan's domestic air transport market reveals that an increase in passengers on a given route has a positive effect on the number of passengers on other routes that share an endpoint airport with the given route. This result implies that a change in policy for an airport is likely to influence routes that do not serve that airport as well as the routes that do.