Date: 201308
Local time of day: 1201-1800
Location: ATW.Airport, WI
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class D ATW
ATC / advisory: Tower ATW
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Conflict Airborne Conflict
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: TCAS RA on final approach: While descending to ATW and cleared down to 4;000 FT MSL; Green Bay Approach notified us of traffic southeast of the airport at 3;000 FT MSL. About 12 NM southeast from the airport; we were cleared the visual approach to Runway 30 and instructed to contact the Appleton Tower. I decided to continue my descent to 2;700 FT MSL at this time; which is the FAF altitude for the ILS 30 approach. When we switched radio frequencies; we heard the Tower instructing another aircraft to make a left 360 to make way for our arrival. At about 7 miles from the airport; on a left base for Runway 30; we received the initial TCAS TA for the conflicting traffic at about 10-11 o'clock and 3 miles; as observed on the TCAS display. After about 10 seconds; we received the TCAS RA 'CLIMB' command while passing through 3;500 FT MSL. At about this time; after reacting to the RA; we both visually acquired the aircraft at our 10 o'clock position; about 500 FT laterally and 200-300 FT below us. The act of slowing our descent with pitch and power was sufficient to clear the traffic; with no evasive maneuvering. However; this did put us out of position vertically for the final approach to Runway 30. Appleton Tower did offer us the option of entering a left downwind position for Runway 21; however I decided I could continue with the planned approach to Runway 30. This then required a higher than normal descent angle and descent rate for the approach. Despite this; the aircraft was in a stabilized state by 500 FT AGL and I made a normal landing.The primary threat in all terminal operations is the mid-air collision. We always accept that; but attempt to minimize it through the use of TCAS; ATC services; and visual scanning techniques. I made two errors during this event. First; I decided to make the descent to 2;700 FT MSL; while knowing of the conflicting traffic at 3;000 FT MSL. This placed us into multiple undesired states; first due to the proximity of the other aircraft; then subsequently having to react to the TCAS climb. I should have made the descent to 3;500 FT MSL; which should have kept us clear of the traffic; instead of the rote action of going down to the FAF altitude whenever cleared for a visual approach. Second; knowing I was out of position for the approach; I should have accepted the change in runway offer; which would have mitigated the descent angle and descent rate undesired state during the most critical phase of flight.




Synopsis: EMB-145 First Officer reported receiving an RA on approach to ATW.