Exploring airlines scheduled buffer time adjustment strategies: an analytical approach

Airlines add buffer times in schedules to absorb the impacts of stochastic disruptions and improve on-time performance. However, it remains unclear whether and how their buffer-setting strategies effectively mitigate delays or, in some cases, worsen on-time performance. To this end, we develop an analytical approach to quantitatively capture the trade-off between buffer time and delay in the schedule adjustment process. We also define 12 buffer adjustment scenarios, enabling the analysis of effectiveness. Using an open-source dataset, the proposed methods were applied to empirical studies on five U.S. airlines. Results suggest that buffer adjustments for around 31%-38% of the flights are ineffective in these airlines from a retrospective view. Alternatively, it highlights the potential improvements that could be made if airlines consider future delay variations in schedule adjustments. Also, we find that airlines tend to make minor adjustments in buffer, which limits their adaptability to system changes. We employ the Multinomial Logit Model to identify contributing factors of ineffective buffer adjustments. Empirical evidence suggests that tailored adjustment strategies are needed for flights with low frequency, small true delay variation, and long flight time to enhance effectiveness. This research offers theoretical insights and practical tools to enhance airlines’ schedule adjustment strategies.