The figure is a block diagram of a proposed system of portable illuminated signs, electronic monitoring equipment, and radio-communication equipment for preventing (or taking corrective action in response to) improper entry of aircraft, pedestrians, or ground vehicles onto active airport runways. Such an entry, denoted a runway incursion, poses a risk of collision with an aircraft properly moving on the affected runway. The major causes of runway incursions are mistakes by pilots, ground-vehicle drivers, and control-tower personnel. Heretofore, there have been no automated, systematic, reliable means of monitoring and regulating airport ground traffic to prevent or correct for runway incursions. The main overall functions of the proposed system would be to automatically monitor aircraft ground traffic on or approaching runways and to generate visible and/or audible warnings to affected pilots, ground-vehicle drivers, and control-tower personnel when runway incursions take place.
The system would include one or more portable units, denoted runway intersection display and monitor (RIDAM) units, that could be placed near taxiways. Each RIDAM unit would include an illuminated sign [and, optionally, a red (“stop”) and a green (“go”) traffic light mounted on top] that would be remotely controlled by means of encrypted signals transmitted from the control tower via a free-space or carrier-current radio-frequency (RF) link. The sign, lights, and associated communication and monitoring equipment could utilize solar power with battery backup. Alternatively or in addition, at night, power for operation and battery charging could be drawn from the power connection for pre-existing blue night taxiway lights. The system could readily be enhanced through addition of lights, signs, and other equipment at various taxiway and runway locations; this portability and enhanceability could be of great value during emergencies and airport modifications.
The illuminated sign could display stop/go signals or other short alphanumeric text messages to pilots of aircraft awaiting further clearance. The RIDAM unit would include one or more proximity sensors in the form of short-range radar, lidar, or video units that would generate movement-confirmation signals: that is, they would monitor positions of aircraft and ground vehicles and send information on those positions to the control tower. The RIDAM unit could include a transceiver that would interact with transponders on aircraft to identify or to confirm the identities of the aircraft. The RIDAM unit would periodically transmit, to the control tower, a “watchdog” signal, which would contain information on the statuses of the lights, sign, proximity sensor(s), and other components. A command processor in the RIDAM unit would automatically generate audible warnings to potential clearance violators and would both (1) broadcast the warnings locally via a short-range radio transmitter operating in a pre-existing aviation ground communication frequency band and (2) transmit the warnings to the control tower via the aforementioned free-space or carrier-current RF link.
This work was done by Richard Dabney and Susan Elrod of Marshall Space Flight Center.