Near midair collision. An air carrier on a STAR has an near midair collision with popup traffic.

Attributes
ACN	307580
Time
Date	199506
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 13600 msl bound upper : 14000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15200 flight time type : 1550
ASRS Report	307580
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance

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.

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.