Narrative:

On our descent into the atlanta area on the macey 1 arrival, just prior to logan intersection, we were leveling at 14000 ft and 320 KTS. We were then cleared to 12000 ft. As we passed through 14000 ft. We got a TCASII advisory, 'traffic, traffic.' we then got a TCASII RA 'monitor vertical speed, monitor vertical speed.' we slowed our descent and leveled at about 13600 ft. We saw the intruder on the radar TCASII showing a minus 01 with a solid red square. The RA then gave us 'climb, climb.' we climbed to approximately 14600 ft. The TCASII showed the traffic went directly below us at about minus 1100 indicated on the TCASII. The RA then annunciated 'clear of conflict.' we immediately descended to below 14000 ft, then began our normal descent. We told ZTL about the RA and the controller said that the traffic had just 'popped up' at 13500 ft. We never saw the traffic visually only on the TCASII. The remainder of the approach was uneventful. ATC had no further comment. No other conflict was indicated and no other was advised by ATC.

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Original NASA ASRS Text

Title: NMAC. AN ACR ON A STAR HAS AN NMAC WITH POPUP TFC.

Narrative: ON OUR DSCNT INTO THE ATLANTA AREA ON THE MACEY 1 ARR, JUST PRIOR TO LOGAN INTXN, WE WERE LEVELING AT 14000 FT AND 320 KTS. WE WERE THEN CLRED TO 12000 FT. AS WE PASSED THROUGH 14000 FT. WE GOT A TCASII ADVISORY, 'TFC, TFC.' WE THEN GOT A TCASII RA 'MONITOR VERT SPD, MONITOR VERT SPD.' WE SLOWED OUR DSCNT AND LEVELED AT ABOUT 13600 FT. WE SAW THE INTRUDER ON THE RADAR TCASII SHOWING A MINUS 01 WITH A SOLID RED SQUARE. THE RA THEN GAVE US 'CLB, CLB.' WE CLBED TO APPROX 14600 FT. THE TCASII SHOWED THE TFC WENT DIRECTLY BELOW US AT ABOUT MINUS 1100 INDICATED ON THE TCASII. THE RA THEN ANNUNCIATED 'CLR OF CONFLICT.' WE IMMEDIATELY DSNDED TO BELOW 14000 FT, THEN BEGAN OUR NORMAL DSCNT. WE TOLD ZTL ABOUT THE RA AND THE CTLR SAID THAT THE TFC HAD JUST 'POPPED UP' AT 13500 FT. WE NEVER SAW THE TFC VISUALLY ONLY ON THE TCASII. THE REMAINDER OF THE APCH WAS UNEVENTFUL. ATC HAD NO FURTHER COMMENT. NO OTHER CONFLICT WAS INDICATED AND NO OTHER WAS ADVISED BY ATC.

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.