Airport stakeholders and policy makers involved in airport strategic planning, design, and operations have a vested interest in assessing how their decisions on alternative terminal layout concepts and operational policies affect overall airport terminal system performance. A considerable amount of research has been devoted to modeling airport terminal operations and performance evaluation. However, no aggregate model provides the capability of supporting strategic decision making while addressing the modeling requirements of a generic model that can capture the complexity of airport terminal processes and a flexible model that can be easily customized to reflect the configuration and operational characteristics of any airport terminal. The objective of this research was threefold: (a) to demonstrate the need for adopting a new approach for airport terminal modeling and performance analysis; (b) to present the overall methodological framework followed for the development of the proposed model, with discussion of the conceptual framework adopted, the airport terminal domain ontology developed, and the model architecture and design; and (c) to demonstrate the model capabilities through modeling and analyzing the Athens, Greece, International Airport terminal case under two alternative traffic demand scenarios.