Computational & Numerical Investigation of Heuristics for Maximizing Fleet Availability subject to Flight & Maintenance Requirements

Flight and Maintenance Planning (FMP) addresses the question of which available aircraft should fly and for how long, and which grounded aircraft should perform maintenance operations, in a group of aircraft that comprise a unit. The objective is to achieve maximum availability of the unit over the planning horizon. The availability of a unit is expressed in terms of the total number of aircraft that are available to fly and of the total residual flight time (remaining flight time until next maintenance) of all available aircraft. Computational experience with optimization models that have been developed for the FMP problem shows that their computational effort increases rapidly with problem size. As a result, the applicability of these models on large problems is quite limited. To this end, we study two heuristic solution procedures for the FMP problem in this work and we present results which illustrate their computational performance and evaluate the quality of the solutions that they produce. A very important outcome of the analysis of these results is that, besides maximizing the fleet availability level, it is also very crucial to ensure that this level remains relatively constant throughout the entire planning horizon. A novel multiobjective formulation that addresses this issue is proposed, along with some important properties which point to several interesting directions for future research.