Narrative:

I was working a final approach sector for runway 8L at atl. I had accepted a handoff on medium large transport X and was in communication with medium large transport X. I then received a handoff on medium large transport Y and on initial contact instructed medium large transport Y to fly heading 185 degrees and reduce speed to 180 KTS. Medium large transport X read back this clearance. As the controller, I heard the heading and speed readback and continued to vector other aircraft for the approach sequence. I later observed medium large transport X heading southbound toward the final approach course. I advised medium large transport X he must have inadvertently taken another aircraft's turn and issued corrective instructions. Contributing factors: similar call signs, flight crews inattn, controller inattn in missing readback error. Workload and WX were not factors. Human beings were once again the big factor. Callback conversation with reporter revealed the following: reporter stated that he had 10 yrs experience as a radar and non radar fpl controller. A system error was declared and he was relieved from duty. The loss of sep occurred between an medium large transport and a widebody transport. The distance was 1.75 mi and 200'. The place was the atl 270 degree right 12 mi fix. He did not hear the readback because he was thinking about issuing WX that was changing rapidly.

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Original NASA ASRS Text

Title: APCH CTLR FAILED TO HEAR A CLRNC READBACK WHICH RESULTED IN LESS THAN STANDARD SEPARATION BETWEEN A WDB ON FINAL AND AN MLG THAT TOOK A CLRNC FOR ANOTHER ACFT.

Narrative: I WAS WORKING A FINAL APCH SECTOR FOR RWY 8L AT ATL. I HAD ACCEPTED A HDOF ON MLG X AND WAS IN COM WITH MLG X. I THEN RECEIVED A HDOF ON MLG Y AND ON INITIAL CONTACT INSTRUCTED MLG Y TO FLY HDG 185 DEGS AND REDUCE SPD TO 180 KTS. MLG X READ BACK THIS CLRNC. AS THE CTLR, I HEARD THE HDG AND SPD READBACK AND CONTINUED TO VECTOR OTHER ACFT FOR THE APCH SEQUENCE. I LATER OBSERVED MLG X HDG SBND TOWARD THE FINAL APCH COURSE. I ADVISED MLG X HE MUST HAVE INADVERTENTLY TAKEN ANOTHER ACFT'S TURN AND ISSUED CORRECTIVE INSTRUCTIONS. CONTRIBUTING FACTORS: SIMILAR CALL SIGNS, FLT CREWS INATTN, CTLR INATTN IN MISSING READBACK ERROR. WORKLOAD AND WX WERE NOT FACTORS. HUMAN BEINGS WERE ONCE AGAIN THE BIG FACTOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATED THAT HE HAD 10 YRS EXPERIENCE AS A RADAR AND NON RADAR FPL CTLR. A SYS ERROR WAS DECLARED AND HE WAS RELIEVED FROM DUTY. THE LOSS OF SEP OCCURRED BTWN AN MLG AND A WDB. THE DISTANCE WAS 1.75 MI AND 200'. THE PLACE WAS THE ATL 270 DEG R 12 MI FIX. HE DID NOT HEAR THE READBACK BECAUSE HE WAS THINKING ABOUT ISSUING WX THAT WAS CHANGING RAPIDLY.

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.