Abstract:

The fractional aircraft market is the fastest growing segment of the business aircraft industry. A fractional aircraft operation is complex – essentially an unscheduled airline in a constantly changing environment. Bombardier Flexjet implemented a comprehensive three-module optimization system to simultaneously maximize its use of aircraft, crews, and facilities. AD OPT Technologies designed the modules, using the GENCOL optimizer developed at GERAD, which employs a column generation approach to decompose large-scale mixed-integer nonlinear programming problems. Since inception, the project has generated savings in excess of $54M with projected additional savings of $27M annually, primarily by substantially lowering crew levels (20 percent), aircraft inventory (40 percent), and supplemental charter aircraft usage (5 percent) while increasing aircraft utilization (10 percent). The quality of customer service has remained consistently high, with significant reduction in supply.

Download the PDF to learn more

Abstract:

Given the sets of flights and aircraft of an airline carrier, the fleet assignment problem consists of assigning the most profitable aircraft type to each flight. In this paper we propose a model for the periodic fleet assignment problem with time windows in which departure times are also determined. Anticipated profits depend on the schedule and the selection of aircraft types. In addition, short spacings between consecutive flights which serve the same origin-destination pair of airports are penalized. We propose a non-linear integer multi-commodity network flow formulation. We develop new branch-and-bound strategies which are embedded in our branch-and-price solution strategy. Finally, we present computational results for periodic daily schedules on three real-world data sets.

Key Words: Integer programming; Dantzig-Wolfe decomposition; Column generation; Routing; Scheduling; Airline fleet assignment.

Download the PDF to learn more