Consequently, although the reported position of the aircraft will be wrong, their positions relative to each other will be fairly accurate. This allows the controller to maintain separation safely. In an ADS system, if an aircraft is reporting an incorrect position to the system, its reported position relative to other aircraft will also be in error. This could lead to a situation in which a controller believes the aircraft is properly separated, when in fact it is not. Therefore, when used together, the two types of system must complement each other.

If a radar is jammed or fails, only a small area of airspace is affected. If a system link satellite is jammed or fails, a much larger region would be without surveillance capability (Bartkiewicz and Berkowitz, 1993). Also, there is a problem with equipping aircraft with GPS-based automatic dependent surveillance broadcasters and receivers. Not only would this be a large expense, but also aircraft without or with nonfunctioning equipment would not be detectable in a pure automatic dependent surveillance system.

Because these two types of systems are so different in principle, they naturally complement each other. Integrating the automatic dependent surveillance system with the current system may increase air traffic control operational cost and complexity, but it potentially could also increase the integrity, reliability, and overall safety of the entire system. The cost of actually implementing an automatic dependent surveillance system would potentially be less if it were to complement instead of replace independent surveillance. A detailed study of fault tolerances is needed in order to compare the overall reliability of an automatic dependent surveillance system to current independent surveillance. Also, the reliability of a combined system should be examined.

If some kind of automatic dependent surveillance system is implemented, decisions need to be made about mandates on system equipment. This is also true in the case of accepting GPS-based navigation as a standard. Will certain airspace require aircraft to be GPS or automatic dependent surveillance equipped? What about the multitude of general aviation aircraft that exist now with no navigation equipment?

The key challenges in the arena of weather data are to provide additional useful weather information, integrate information from multiple sensors, predict weather more effectively, and disseminate information more efficiently. The aviation weather distribution system includes subsystems that collect, process, display, and disseminate weather data that can affect the safety and efficiency of the national airspace system. The FAA considers the highest-priority weather functions to be those that detect phenomena posing a potential hazard to aviation and disseminate this information to controllers, traffic managers, flight service specialists, and pilots (Federal Aviation Administration, 1996a). The current weather distribution system for air traffic control relies on a variety of information

Front Matter (R1-R14)

Summary (1-8)

Part I: Automation Issues and Emerging Technologies (9-10)

1 Automation Issues in Air Traffic Management (11-47)

2 Emerging Technological Resources (48-62)

Part II: Current and Envisioned Automation of Air Traffic Control Tasks (63-84)

3 Surveillance and Communication (85-110)

4 Flight Information (111-126)

5 Immediate Conflict Avoidance (127-155)

6 Strategic Long-Range Planning (156-183)

7 Support Functions (184-200)

Part III: Integration (201-202)

8 Integration of Research and Development (203-224)

9 Airspace System Integration: The Concept of Free Flight (225-242)

10 Conclusions and Recommendations (243-261)

References (262-286)

Appendixes (287-288)

Appendix A (289-293)

Appendix B (294-295)

Appendix C (296-304)

Index (305-319)

Color Plates (320-327)