Safety Board (NTSB) has considered the prevention of runway incursions and of ground collisions of aircraft a high-priority safety issue (National Transportation Safety Board, 1995a, 1995b). In response to ground accidents at Atlanta (1990), Detroit (1990), Los Angeles (1991), and St. Louis (1994), the National Transportation Safety Board issued a series of recommendations for the prevention of ground collisions of aircraft. These recommendations include the reiteration of a 1991 recommendation that the FAA "expedite efforts to fund the development and implementation of an operational system analogous to the airborne conflict alert system to alert controllers to pending runway incursions" on the ground (National Transportation Safety Board, 1995b).
To address safety concerns in a manner that may also yield efficiency gains, the FAA is undertaking a broad set of activities that, taken together, are intended to provide controllers and pilots with automated warnings of potential and actual runway incursions and ground traffic conflicts, with automated means of communication, with positive identification of surface targets, and with the capability to maintain situation awareness in low-visibility conditions. These initiatives range from current implementation through near-term enhancement to long-term development programs.
The primary goal of the automation systems for the tower described below is to enhance the safety of airport operations. These systems provide to controllers and, in some cases, to pilots information that augments the current direct visual observations and verbal communications. In addition, these systems are based on surveillance technology that provides information under conditions of poor visibility (National Aeronautics and Space Administration, 1995). As with technologies that improve the availability and accuracy of in flight position, trajectory, and identification information, these systems may also permit improved efficiency by reducing delays otherwise dictated by less reliable information. Figure 5.2 presents the interrelationships among surveillance, processing, and tower and cockpit display systems.
Airport surface detection equipment (ASDE-3) includes an advanced digital radar that penetrates rain, snow, and fog and provides to controllers a display of superimposed radar images of airplanes and vehicles over a map of the airport surface. It permits controllers in the tower to view a continuous, real-time display of all movements on runways and taxiways in the terminal area. Airport surface detection equipment does not, however, provide identification of targets, so controllers cannot readily identify specific aircraft by looking at the radar display. The controller therefore has to rely on visual contact and voice communication to positively identify aircraft. In addition, the airport surface detection equipment has limitations that include blockage of certain terminal areas and some false returns. The equipment is currently installed in some airports and is targeted for wider implementation.
The airport movement area safety system (AMASS) augments the airport surface detection equipment with an automated alerting system. The airport