Narrative:

ZTL on darc; midshift operation; light traffic. PA32/G climbed to jwn descended to mtv handed off from ZME/M41 (ZME also on darc) to me at ZTL/41. I enter code into bcn list and receive a 'duplicate flight identify' message. Target will not track; with a data block. However a 'free track' triangle appears. Airways facilities technicians summoned. Overriding the track (10K) results in the full data block appearing; however; there are now 2 tracked targets on top of each other for the same aircraft. This causes the conflict alert feature to activate continuously. Subsequent efforts to change the bcn code; remove the flight plan; reenter the flight plan; suppress the conflict alert are all unsuccessful. The aircraft displays 2 tracked symbols throughout ZTL airspace. There are no means to ascertain that there are no other aircraft involved; other than asking the pilot if he 'sees anybody else out there at his altitude.'

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Original NASA ASRS Text

Title: ZTL CTLR DESCRIBED DARC ANOMALY THAT RESULTED IN TWO DATA BLOCKS ON THE SAME ACFT CAUSING A CONTINUOS CONFLICT ALERT.

Narrative: ZTL ON DARC; MIDSHIFT OP; LIGHT TFC. PA32/G CLBED TO JWN DSNDED TO MTV HANDED OFF FROM ZME/M41 (ZME ALSO ON DARC) TO ME AT ZTL/41. I ENTER CODE INTO BCN LIST AND RECEIVE A 'DUPLICATE FLT IDENT' MESSAGE. TARGET WILL NOT TRACK; WITH A DATA BLOCK. HOWEVER A 'FREE TRACK' TRIANGLE APPEARS. AIRWAYS FACILITIES TECHNICIANS SUMMONED. OVERRIDING THE TRACK (10K) RESULTS IN THE FULL DATA BLOCK APPEARING; HOWEVER; THERE ARE NOW 2 TRACKED TARGETS ON TOP OF EACH OTHER FOR THE SAME ACFT. THIS CAUSES THE CONFLICT ALERT FEATURE TO ACTIVATE CONTINUOUSLY. SUBSEQUENT EFFORTS TO CHANGE THE BCN CODE; REMOVE THE FLT PLAN; REENTER THE FLT PLAN; SUPPRESS THE CONFLICT ALERT ARE ALL UNSUCCESSFUL. THE ACFT DISPLAYS 2 TRACKED SYMBOLS THROUGHOUT ZTL AIRSPACE. THERE ARE NO MEANS TO ASCERTAIN THAT THERE ARE NO OTHER ACFT INVOLVED; OTHER THAN ASKING THE PLT IF HE 'SEES ANYBODY ELSE OUT THERE AT HIS ALT.'

Data retrieved from NASA's ASRS site as of January 2009 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.