In this paper, we present the structural modeling approach, an application framework and development process for the construction of flight simulators. Structural modeling was developed to address functional, nonfunctional, and process requirements for flight simulators. It has been successfully used in the development of large scale (one million lines of ADA code) flight simulators for the United States Air Force. A structural model promotes a simple and coherent software architecture with a small number of specialized structural elements obeying a few systemwide coordination strategies. It is this simplicity coherence of the software architecture that enables analysis to demonstrate the quality of the system.