MD-82
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness
Conflict Airborne Conflict
Flight Crew Took Evasive Action
Human Factors; Airport; Airspace Structure
We were descending on a visual approach to Runway 26 when we noted traffic on our TCAS ahead about 5 miles and below us. To avoid a TCAS RA I stopped the descent. As the aircraft captured approximately 7;000 the TCAS commanded; 'Monitor vertical speed.' At that point we had 500 FT vertical and between 500 FT to 1;000 FT lateral separation. A moment later the TCAS commanded; 'end of conflict' as the aircraft passed behind us. Shortly after I resumed our descent TCAS commanded; 'Monitor vertical speed; climb; climb.' I disconnected the autopilot and began a climb as indicated. The traffic was behind us; but no longer diverging away but remained just slightly behind us with 300 FT vertical separation as we began to climb. We again received an; 'end of conflict' message from the TCAS. By that time we were too high to continue a strait in approach and the aircraft was too close to start another descent. This aircraft may have started practicing steep turns or other maneuvers as we flew over it because it did not appear to be diverging away from us as we typically see. To get well clear of this traffic we flew level for about a minute before executing a left 360 to lose altitude and enter a stable final approach to landing on Runway 26. We had made traffic announcements on CTAF starting from at least 20 miles out indicating we were an MD80 on a strait in to Runway 26. A small aircraft which I assume was the aircraft involved in this event responded. We notified him we would remain north of the highway. He acknowledged. We assumed he would not fly north of the highway after acknowledging our communication when in fact; he seemed to loiter directly in the approach path to Runway 26 while maneuvering.
MD82 Captain describes a TCAS RA event during a visual approach to an uncontrolled airport. After maneuvering for the RA a 360 degree turn is required to get back on the approach path.