A Heuristic Method to Improve the Robustness of Flight Schedules: Estimating Optimal Slack and Re-Timing Flights

Abstract

An investigation was conducted concerning the problem of flight delays to propose a solution to enhance the robustness of airline flight schedules. The robustness of flight schedules depended on the ability to reduce the effects of flight delays on daily operations. The approach to achieve this objective was optimizing flight schedules by allocating the optimal amount of slack to scheduled connections. Identifying appropriate slack between two successive flights involved modeling primary delay distributions at departure airports, considering both time intervals and delay lengths. A threshold approach was subsequently devised to determine the optimal slack based on this distribution. The ideal allocation of slack to schedules was achieved by modifying flight departure times, a technique known as re-timing. Recognizing that the optimal allocation of slack could make schedules infeasible, an optimization model was established for adjusting flight departure times. The proposed model produced new schedules that optimized all slack. The practical application of this model to the schedules of Indonesian airlines demonstrated the method's efficiency in improving the robustness of flight schedules.