The impact of hubbing concentration on flight delays within airline networks: An empirical analysis of the US domestic market

•We compute time- and carrier-specific hubbing concentration indices for US airlines.•We quantify the impact of changing hubbing concentration on three delay indicators.•Increasing hubbing concentration contributes to longer excess travel times.•We find no influence of changing hubbing concentration on delays against schedule.•Our results indicate that airlines use buffers to mitigate passenger-perceived delays. This paper explores the relationship between hubbing activities and flight delays in the United States from an airline-specific network perspective. Airline hubbing is measured with the Hubbing Concentration Index. We estimate the impact of hubbing behavior on delays, using three measures of delay, two based on delay against schedule, and the third based on buffer-corrected excess travel times. A significant (and positive) influence of hubbing concentration can only be found for the latter delay indicator. We conclude that airlines use buffer times to mitigate passenger-perceived delays against schedule that would, without buffers, arise from more complex network operations.