Robust integrated maintenance aircraft routing and crew pairing

Given a daily flight schedule and a set of aircraft fleets, the integrated aircraft routing and crew scheduling problem requires finding a maintenance feasible set of aircraft routes and crew pairings such that each individual flight is covered by exactly one aircraft route and one crew pairing. Although these problems are interdependent, they have been traditionally solved sequentially, where the aircraft routing problem, which is solved first, defines a set of periodic aircraft rotations that impose some restrictions on short connections that are subsequently accommodated by the crew pairing problem. A major drawback of this sequential approach is that it ignores most of the interdependencies between the two problems. In particular, it fails to build robust solutions that are resilient to unpredictable disruptions (like adverse weather, aircraft breakdowns, etc.) that translate into delayed and canceled flights. In this paper, we propose an integrated robust model that incorporates the aircraft routing and crew pairing problems within a single framework that aims at generating aircraft routes that are both robust and cost-effective while accommodating technical constraints. A peculiar feature of the proposed model is that it includes a polynomial number of variables and constraints. We solve the resulting integrated model by using a general-purpose solver. Computational results obtained by using data from major airlines demonstrate the benefits of the proposed robust model.