The Schedule Adjustment Problem

This chapter presents the current practice of the warm start approach. In this approach, most major airlines develop their schedules by tweaking and adjusting previous schedules to minimize schedule changes. The approach depends mainly on the fleet assignment formulation presented in this context. The chapter also summarizes several reasons for airlines to rely on the warm start approach. The schedule planning for airlines consists of four main steps: route planning; schedule development; frequency planning; and timetable development. Several adjustments to an existing schedule can be considered. These adjustments include flight deletion (removal), flight addition, and flight departure time adjustment. The formulation of the schedule adjustment problem is derived from the fleet assignment formulation presented in this context. The formulation ensures that all flights are covered, fleets are balanced at the different stations, and available resources are not exceeded.