A Network Flow Approach to Crew Scheduling Based on an Analogy to an Aircraft/Train Maintenance Routing Problem

Abstract

Airlines’ and railways’ expensive resources, especially crews and aircraft or trains are to be optimally scheduled to cover flights or trips of timetables. Aircraft and trains require regular servicing. They are to be routed as to regularly pass through one of the few maintenance bases, e.g., every three to four operation days for inspection. Apart from complicating workrules, crews are to be scheduled so as to “pass through” their home bases weekly for a two-day rest. This analogy is utilized in order to recognize opportunities for integrating classical planning processes for crew scheduling, and to transfer solution methodologies. A mixed-integer flow model based on a state-expanded aggregated time-space network is developed. This mathematical model, used to solve large-scale maintenance routing problems for German Rail’s intercity trains, is extended to the airline crew scheduling problem where maintenance states are replaced by crew states. The resulting network flow approach to an integrated crew scheduling process involving multiple crew domiciles and various crew requests is tested with problems from a European airline. A decision support system and computational results are presented.