Beacon Collision Avoidance System (BCAS) - Active Mode.
Interim rept. Mar 75-Jul 76,
NATIONAL AVIATION FACILITIES EXPERIMENTAL CENTER ATLANTIC CITY NJ
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This document describes the FAAMITRE Active Mode of the Beacon Collision Avoidance System BCAS through its initial phase. The hardware, its procurement and modification are described the theory of operation is presented and the system performance and accuracy during the feasibility flight tests in the NAFEC and Washington, D.C. airspace were discussed. This is a ground-independent, air-to-air system activated by airborne omnidirectional ATCRBS mode C interrogations occurring at a rate of 2 per second. Range and altitude are obtained for each aircraft replying within a 32-nmi radius. Range and altitude rates are computed, and approaching aircraft are tracked. The cockpit CAS display warns the pilot of aircraft crossing with adequate altitude separation and gives a command to climb or dive if the intruding aircraft is at or near the same altitude. Warnings andor commands are provided 30 seconds before range minimum. System performance was evaluated during test encounters with 400 ft altitude separation. Performance and accuracy analysis is derived from BCAS and ARTS III magnetic tape, and from the tracking phototheodolites over the NAFEC measurement range. Data analysis was performed by the MITRE Corporation. The system in its initial form was not expected to function in high-density areas however, the system met the initial design goals. Design ideas to distribute the reply population by using multilevel power interrogations have been incorporated in the system for the next phase. This will, hopefully, allow the system to function in the higher density areas. In a later phase, the compatibility of BCAS with DABS will be evaluated. Author
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