Equity and efficiency trade-off in allocating airport and airspace capacity in a multiple airport system

The objective of airport slot allocation is to distribute slots to airlines following specific procedures and regulations. With the rapid growth of air traffic and increasing congestion at major airports, optimizing slot allocation has become a critical issue to enhance operational efficiency and mitigate delays. While extensive research has been conducted on slot allocation at individual airports, less attention has been given to the complexities of slot allocation in a Multiple Airport System (MAS), where airlines must compete for both airport and airspace resources. In a single airport slot allocation, the only resource that airlines compete for is airport capacity; in an MAS, there are several resources that must be taken into account, such as airport capacity and fix (i.e., route point) capacity. In this article, a model is presented that considers the capacity of the airport and airspace, as well as the efficiency and fairness among airlines operating in the MAS. The goal of the model is to minimize total slot displacements of the MAS, while satisfying airport capacity and fix capacity constraints, operational constraints, and fairness constraints. To measure fairness, comprehensive fairness metrics for airlines are developed. The trade-off between efficiency and equity in an MAS slot allocation problem is investigated, with the Price of Fairness(POF) taken into account. The proposed model is tested using MAS slot request data from an MAS in China. The results demonstrate that the model can achieve a better Gini-based fairness by sacrificing a certain amount of slot displacements. These findings have significant implications for slot regulators in improving the efficiency of managing airport slot resources within an MAS.