Time-Indexed Formulations for the Runway Scheduling Problem

The problem of sequencing and scheduling airplanes landing and taking off on a runway is a major challenge for air traffic management. This difficult real-time task is still carried out by human controllers, with little help from automatic tools. Several methods have been proposed in the literature, including mixed-integer programming (MIP)-based approaches. However, there is an opinion that MIP is unattractive for realtime applications, since computation times are likely to grow too large. In this paper, we reverse this claim, by developing a MIP approach able to solve to optimality real-life instances from congested airports in the stringent times allowed by the application. To achieve this, it was mandatory to identify new classes of strong valid inequalities, along with developing effective fixing and lifting procedures.