Application of two-phase decomposition algorithm to practical airline crew rostering problem for fair working time

Abstract

IntroductionAutomating cost-efficient scheduling in the airlines is getting more and more significant in recent years. As new low cost carriers come to appear, it is highly required for traditional full service carriers to reduce the operational costs. In the airlines, there are many types of scheduling problems in order to operate their flights. These problems are commonly categorized into flight scheduling design, fleet assignment, aircraft maintenance routing and crew scheduling (Dawid et al., 2001). In these problems, crew scheduling problems are well-known as one of the most difficult problems in the airlines (Guo et al., 2006). There are commonly two phases in the airline crew scheduling problems: the crew pairing problems and the crew rostering problems. In the crew pairing problems, a crew pairing that is a sequence of flight duties is allocated. Pairings are generated such that all of the duties are covered by the least number of pairings. The pairing also originates and terminates at the crew base. In the crew rostering problems, each pairing, holidays and reserved duties are assigned to each crew member satisfying all hard constraints such as rest days, rules and regulations. The reserved duties are trainings, medical appointments and so on. In this paper, we study a static crew rostering problem when the set of crew pairings is given in advance. It is hard to solve the crew rostering problems due to a large number of hard constraints. However, it is still important to obtain a better schedule because the quality of the solution has a direct impact on the operational costs in the airline industry.The constraints of the airline crew rostering problems differ for each airline company or each case study. For instance, there are consecutive flight days constraints (Gamache et al., 1998), rest days constraints (Souai and Teghem, 2009), total working time constraints (Moudani et al., 2001;Souai and Teghem, 2009). The problem in this paper additionally considers the practical constraints on consecutive rest days after an international flight, prohibition of assignment of crew members with the same group to the same duty. Most of the conventional studies do not emphasize on these practical constraints. The objective function of the problem also differs for each case. For instance, minimizing the operational 1 Tsubasa DOI * and Tatsushi NISHI * * Graduate School of Engineering Science, Osaka University 1-3 Machikaneyama-cho, Toyonaka city 560-8531, Japan E-mail: nishi@sys.es.osaka-u.ac.jp Received 15 November 2015 AbstractWe propose an application of a two-phase decomposition algorithm for a practical airline crew rostering problem for fair working time. The problem is to find an optimal assignment of duties to individual crew members such that various hard constraints such as rest days, rules and regulations are satisfied. The objective is to minimize the total deviation of the average working time from the standard working time for crew members. A two-phase decomposition algorithm is successfully applied to ...

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