Air traffic management moves into the 21st century.

Learn about the major changes in concepts and technology that will soon make flying safer and more economical.

By the year 2005, the number of commercial passengers flying in the U.S. will increase by almost 45% - from about 625 to some 900 million annually. To meet that increased demand, as well as to modernize equipment that often dates back to the 1960s and, in some cases, even the 1950s, the Federal Aviation Administration (FAA) will be making major changes in the Air Traffic Management system.

The Air Traffic Management (ATM) system is designed to ensure the safe and efficient flight of aircraft flying under instrument flight rules (IFR). It is responsible for the aircrafts safety from takeoff to landing. That responsibility is divided into three controlled airspaces - airport, terminal, and en route [ILLUSTRATION FOR FIGURE 1 OMITTED]. At the busiest airports, the airport airspace as well as the airport's surface traffic is supervised by the control tower. Beyond the airport airspace, while flying in terminal airspace, aircraft are supervised by Terminal Radar Approach Control (TRACON). The en route airspace, where aircraft spend most of their flying time, is supervised by an Air Route Traffic Control Center (ARTCC). ATM modernization will affect all aspects of the IFR flight - communications, navigation, surveillance and ATM automation.

Communications. Currently, air-ground communications uses mostly voice on the VHF and HF bands, and is pretty much limited to flight-plan changes, aircraft separation and sequence instructions, weather, and advisories on other aircraft flying under visual flight rules (VFR) in the area. Communications between adjacent air-traffic service locations is by land-line (telephone) using voice and a limited amount of data transmission.

One example of modernization already underway is the Voice Switching and Control System (VSCS) to replace 1950s electromechanical and vacuum-tube technology with fiber-optics, touch screens, and digital electronics. By the end of this year, a total of 21 VSCSs will be installed at ATC (air-traffic control) centers around the country. VSCS virtually eliminates delays and allows controllers to adjust their communications …