The behavior of the National Airspace System is the result of the real-time decisions of individual pilots and air traffic controllers. Successes or failures of the system are often due to how they react to the rapidly changing situation and information load that confronts them. A Virtual National Airspace System is proposed that utilizes live pilots and controllers. To maintain their instrument flight skills, pilots routinely use Personal Computer Aviation Training Devices (PCATD?s) that are owned and operated by flight schools, Fixed-Base Operators (FBO?s), and other private parties. Each pilot represents a potential participant in NASA air traffic simulation studies. The proposed Virtual National Airspace System incorporates the state vectors of multiple aircraft and the problems of shared frequency radio communication. Key architectural concerns for the simulation include: state vector and protocol design, simulation server and network operating in real-time with pilots and controllers, and multi-frequency voice communication. A user / pilot database can track pilots for various ratings and, thereby, provide air traffic studies with pilots screened for particular purposes, including maintaining the overall quality of the simulation. POTENTIAL COMMERCIAL APPLICATIONS PCATD's operated by flight schools and FBO?s can have more realistic simulation since the system simulates surrounding traffic and the shared frequency radio communication with air traffic controllers and other pilots. Large flight simulation facilities other than those used by NASA can benefit by ?purchasing? the miscellaneous traffic and air traffic controller services. The FAA and its contractors can use the system to train air traffic controllers in an environment with rated pilots. The simulation server can be commercially operated in a fashion similar to an Internet Service Provider.
