Two-Stage Metaheuristic Framework Based on Irregular Contours Matching for Outsourced Aircraft Maintenance Parking Stand Allocation Problem

Abstract

With the increase in aircraft maintenance orders and heterogeneity of aircraft irregular shapes, outsourced aircraft maintenance companies urgently need a more efficient and tailored intelligent aircraft parking allocation method. However, existing methods could be improved in lightweight handling of non-overlapping constraints and effective use of problem-specific heuristics. To tackle these challenges and achieve a more rational allocation of parking stands, a bi-objective optimization model involving rotation angles is firstly constructed to maximize hangar utilization and safety margin, and is decomposed into two single-objective optimization problems via a lexicographic method. To efficiently solve this model, problem characteristics of “irregular contours matching” are analyzed. Furthermore, a series of mechanisms that fully utilize the problem characteristics are designed, thus integrating a two-stage metaheuristic framework based on irregular contours matching. These mechanisms include an aircraft parking strategy based on geometric fit for rationally locating aircraft parking positions and mitigating the dimensional explosion problem, a metaheuristic optimizer with similar insertion neighborhood operation for enhancing the hangar utilization, and a fast safety margin optimization algorithm based on binary searching iterator. Experimental studies conducted on 18 real-world instances show that the proposed framework outperforms several state-of-the-art algorithms, as well as the dynamic search algorithm automatically selected by the CPLEX optimizer. Note to Practitioners—This paper investigates an aircraft parking stand allocation problem that originated in outsourced aircraft maintenance companies. The goal of the problem is to maximize the hangar utilization and safety margin. Existing aircraft parking stand allocation methods ignore the lightweight handling of non-overlapping constraints, optimal configuration of rotation angles and safety margins, and effective utilization of problem-specific heuristics. Thus the allocation efficiency could be further improved when coping with large-scale order requirements. This paper constructs a mathematical optimization model with limited rotation angles, and introduces a concise geometric tool to address aircraft collision problem. Furthermore, a two-stage metaheuristic framework based on problem characteristics is proposed to solve the model efficiently. The superiority of the present method was verified on 18 real-instances with various hangar sizes and maintained aircraft. It is believed that this method effectively improves maintenance resource utilization, reducing labor and maintenance costs of outsourced aircraft maintenance companies.