Abstract—A multiple-criteria decision support system is proposed for the best aircraft selection decision. Various strategic, economic, environmental, and risk-related factors can directly or indirectly influence this choice, and they should be taken into account in the decision-making process. The paper suggests a multiple-criteria analysis to aid in the airline management's decision-making process when choosing an appropriate aircraft. In terms of the suggested approach, an integrated entropic preference optimization programming (POP) for fleet modeling risk analysis is applied. The findings of the study of multiple criteria analysis indicate that the A321(neo) aircraft type is the best alternative in this particular optimization instance. The proposed methodology can be applied to other complex engineering problems involving multiple criteria analysis. Keywords—Aircraft selection, decision making, multiple criteria decision making, preference optimization programming, POP, entropic weight method, TOPSIS, WSM, WPM. I. INTRODUCTION or fleet planning and modeling, the proper aircraft must be chosen and made available for airline strategic, tactical, and operational requirements. Therefore, choosing the kind of aircraft that would please clients depends on their needs and demands in fleet modeling. Choosing an aircraft is a difficult procedure, therefore careful consideration is needed in the fleet modeling process. This choice has to do with how many aircraft to buy or lease for fleet planning. When an airline plans its fleet, some fleet types with similar capabilities are viewed as competitors, even though there are currently a wide variety of alternatives from which to choose for fleet planning. Additionally, because fleet planning involves a sizable capital investment with a long-term vision, it is a mid - and long-term strategic choice that affects the financial condition of airlines. The fleet planning process for the airline is a crucial multiple-criteria decision-making (MCDM) analysis process that considers a number of essential evaluation criteria [1]. In this situation, the right MCDM techniques should be applied to help airline management efficiently evaluate the many aircraft alternatives based on pertinent criteria. The weight of the selection criteria to select the best alternative is determined using the entropic weight method (EWM). As a strong and adaptable decision-support tool, it enables decision-makers to model complicated problems while taking both quantitative and qualitative factors into consideration. C. Ardil is with the National Aviation Academy, Baku, Azerbaijan. https://orcid.org/0000-0003-2457-7261 Numerous selection criteria can be successfully considered using the EWM methodology, and it also permits the objective consideration of criteria while allocating resources. The different options are also assessed using the preference optimization programming (POP) method. Decision-makers can choose solutions from a finite number of options using this MCDM approach to choose the best course of action. Combining these two techniques yields significant results when choosing the right aircraft type to meet the needs of the airline in the situation under consideration. Therefore, entropic preference optimization programming (POP), a relatively new MCDM technique, is applied to select the best possible aircraft alternatively based on different criteria [1]. In the chosen fleet planning scenario, the airline management recommends replacing the current aircrafts with new, modern, and sophisticated aircrafts that will improve capabilities and meet the most recent strategic, tactical, and operational needs with the least amount of maintenance and operating expense. In order to perform this study, a number of seasoned aviation industry participants with in-depth expertise in the subject evaluated the numerous aircraft types of options based on the predetermined criteria to prepare a shortlist of the potential alternatives. Determining the appropriate aircraft types based on the precise criteria established by experts, which should be chosen for the purpose of fleet optimization in a specific airline, using both the entropic weight method (EWM) and preference optimization programming (POP) is the MCDM research problem. The selection of aircraft for airlines is more prevalent challenge in the pertinent literature [1-26]. The principles of the aircraft selection problem are thoroughly reviewed in the literature on choosing different types of aircraft. The selection problems in these MCDM investigations use both traditional and fuzzy approaches. When there is incomplete knowledge of the multiple criteria decision problems, fuzzy methodologies are more practical and efficient to deal with uncertainty [28-54]. Since airlines have some unique characteristics that may affect the aircraft selection process, this research adds to the body of knowledge about the choice of aircraft by airlines. Additionally, the criteria for choosing an aircraft are related to the requirement to comprehend airline operations and structure. It is hoped that this research will be useful and aid in the decision-making process. Additionally, it will assist airline management who are involved in the selection of aircraft in reaching the best choice. Aircraft Selection Using Preference Optimization Programming (POP) C. Ardil F World Academy of Science, Engineering and Technology International Journal of Aerospace and Mechanical Engineering Vol:16, No:11, 2022 286 International Scholarly and Scientific Research & Innovation 16(11) 2022 ISNI:0000000091950263 Open Science Index, Aerospace and Mechanical Engineering Vol:16, No:11, 2022 publications.waset.org/10012772/pdf