Institute of Transportation, MOTC

      Schedule padding, a method which is often used by airlines, could reduce flight delays and improve on-time performance, however, it also makes passengers take more time to finish their travel. Because buffer time which is included in a flight schedule could directly influence flight delay, more and more researchers are interested in the topic of schedule padding and trying to figure out the factors that affect buffer time. Because of the relationship between schedule padding and flight delay, the factors which influence flight delay might potentially change the amount of buffer time, even so, most of the studies have not discussed the relationship between airline networks (which is considered as a key factor of fight delay) and buffer time. For this reason, this study aims to build up a relationship model to investigate the effects of airline networks on schedule padding in the United States. The U.S. domestic market on-time performance data between 2010 and 2019 were used in this study. Airline networks could be easily divided into two types: the Hub-and-Spoke network and the Point-to-Point network. The features of Hub-and-Spoke network structure are different from Point-to-Point network, it has more connecting passengers, larger hub airports, and operates several connecting banks in a day. In view of these features, this study developed three measurements to represent the characteristics of airline networks. In addition, the 5th to 20th percentiles of actual block time were used to estimate buffer time. The major finding suggested that airline network was significantly affects schedule padding. To avoid passengers disconnecting their connecting flights, airlines were willing to increase the buffer time of fights of the first segment. On top of that, the flight flied to a large hub airport which had lots of connecting passengers had a longer buffer time. Last but not least, the fight which was operated with banking method had more buffer time. In conclusion, the airline whose network is similar to Hub-and-Spoke network might actively pad their flight schedule, because these airlines have more connecting passengers, larger hub airports, and banking their flights.