Narrative:

TCASII RA on approach. On approach to runway 12R at stl, night, VFR. Cleared to 3500 ft and cleared for visual approach to runway 12R. Approximately 4000 ft got TA then RA on aircraft making visual to runway 12L. At time of RA conflict aircraft 300-400 ft above and nearly on top of us. Conflict aircraft never pointed out to us by ATC. Initial TCASII command to climb, crossing climb followed by descend, descend now. Performed as commanded by TCASII and notified ATC of same. ATC then informed us that traffic was at our 8 O'clock position and had us in sight. We first saw other aircraft after event was resolved. TCASII system did not inhibit in the terminal area with flaps extended as designed. Aircraft (air carrier X) was written up and TCASII system was placarded.

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Original NASA ASRS Text

Title: FLC OF AN LGT TOOK EVASIVE ACTION AND DSNDED IN RESPONSE TO A FALSE TCASII RA DURING A VISUAL APCH.

Narrative: TCASII RA ON APCH. ON APCH TO RWY 12R AT STL, NIGHT, VFR. CLRED TO 3500 FT AND CLRED FOR VISUAL APCH TO RWY 12R. APPROX 4000 FT GOT TA THEN RA ON ACFT MAKING VISUAL TO RWY 12L. AT TIME OF RA CONFLICT ACFT 300-400 FT ABOVE AND NEARLY ON TOP OF US. CONFLICT ACFT NEVER POINTED OUT TO US BY ATC. INITIAL TCASII COMMAND TO CLB, XING CLB FOLLOWED BY DSND, DSND NOW. PERFORMED AS COMMANDED BY TCASII AND NOTIFIED ATC OF SAME. ATC THEN INFORMED US THAT TFC WAS AT OUR 8 O'CLOCK POS AND HAD US IN SIGHT. WE FIRST SAW OTHER ACFT AFTER EVENT WAS RESOLVED. TCASII SYS DID NOT INHIBIT IN THE TERMINAL AREA WITH FLAPS EXTENDED AS DESIGNED. ACFT (ACR X) WAS WRITTEN UP AND TCASII SYS WAS PLACARDED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.