Airlines’ fleet assignment heavily affects the economic and ecological performance of the global air transportation system (ATS). Consequently, it is inevitable to include potential changes of the fleet assignment when modeling and assessing future global ATS scenarios. Therefore, this arti- cle presents a novel explanatory approach to modeling the fleet assignment in the global ATS. The presented approach is based on the formulation and solving of an optimization problem, which describes the fleet assignment in the ATS through a suitable combination of objective function and constraints. While the objective function combines both the airline and the pas- senger perspective on the fleet assignment, the constraints include additional operational and technological aspects. The advantages of the presented approach in comparison to the available models in the literature lie in the overall scenario capability and the consideration of explicit aircraft types instead of simplifying seat categories. The model results are compared with fleet assignments in historic flight schedule data. The calibration and validation results underline the strengths and weaknesses of the presented approach and indicate potential for future improvement.
