Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Conflict Airborne Conflict
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Airspace Structure; Human Factors
While in the descent Approach had cleared us from 5;000 FT to 4;000 FT. As we left 5;000 FT the Controller informed us of GA traffic in our area. We saw the aircraft in question visually as well as on TCAS and it would have been fairly close but not an issue. Passing approximately 4;500 FT the GA aircraft suddenly turned directly into our flight path which triggered a TCAS RA climb. We climbed approximately 300 FT until TCAS advised clear of traffic; then informed ATC what we had done and continued our descent back to 4;000 FT with no further issues.GA aircraft are a common annoyance and threat in this area. The GA pilots need to be more alert of their surroundings and action should be taken against them when they cause issues such as this with other aircraft; particularly commercial aviation.
An EMB-145 flight crew experienced a close encounter with a light aircraft and complied with a TCAS RA while descending in contact with Approach Control.