Narrative:

Departed sli VOR 320 degrees heading at 7000' MSL. Slowed to 180 KTS and turned to 020 degree heading by ATC. Further airspeed reduction to 170 KTS. Asked by approach if we had traffic at 11 O'clock in sight. We had one at 8-9 O'clock and one at 12 O'clock. Reported 12 O'clock traffic in sight. We were then cleared for a visual approach behind that traffic for runway 25R. I asked the first officer to verify which aircraft we were to follow. First officer couldn't get into ATC due to frequency congestion. Continued on 020 degree heading to follow the 12 O'clock traffic, but still weren't sure if it was correct traffic to follow. Finally got approach to verify and he advised us that we should have turned sooner (to follow traffic that had originally been at our 8-9 O'clock position). Started turn to 260 degrees and descent per ATC. At about 6600' MSL in descent controller changed instructions to turn to 210 degree heading and maintain 7000' for resequence. We complied and were vectored around for another visual approach. Problems were: inability to positively identify aircraft we were to follow, frequency congestion prevented verification sooner and ATC workload extremely high. Corrections: both controller and crew should be positively sure of traffic before visual approach is issued and, altitude of aircraft to be followed, in descent or level flight, should always be given. The traffic at our 8-9 O'clock was considerably lower than the traffic at 12 O'clock and this would have alerted us sooner and prevented or helped to prevent looking at the wrong aircraft.

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Original NASA ASRS Text

Title: ACR MLG SIGHTED WRONG ACFT INSTRUCTED TO FOLLOW ON VISUAL APCH.

Narrative: DEPARTED SLI VOR 320 DEGS HDG AT 7000' MSL. SLOWED TO 180 KTS AND TURNED TO 020 DEG HDG BY ATC. FURTHER AIRSPD REDUCTION TO 170 KTS. ASKED BY APCH IF WE HAD TFC AT 11 O'CLOCK IN SIGHT. WE HAD ONE AT 8-9 O'CLOCK AND ONE AT 12 O'CLOCK. RPTED 12 O'CLOCK TFC IN SIGHT. WE WERE THEN CLRED FOR A VISUAL APCH BEHIND THAT TFC FOR RWY 25R. I ASKED THE F/O TO VERIFY WHICH ACFT WE WERE TO FOLLOW. F/O COULDN'T GET INTO ATC DUE TO FREQ CONGESTION. CONTINUED ON 020 DEG HDG TO FOLLOW THE 12 O'CLOCK TFC, BUT STILL WEREN'T SURE IF IT WAS CORRECT TFC TO FOLLOW. FINALLY GOT APCH TO VERIFY AND HE ADVISED US THAT WE SHOULD HAVE TURNED SOONER (TO FOLLOW TFC THAT HAD ORIGINALLY BEEN AT OUR 8-9 O'CLOCK POS). STARTED TURN TO 260 DEGS AND DSCNT PER ATC. AT ABOUT 6600' MSL IN DSCNT CTLR CHANGED INSTRUCTIONS TO TURN TO 210 DEG HDG AND MAINTAIN 7000' FOR RESEQUENCE. WE COMPLIED AND WERE VECTORED AROUND FOR ANOTHER VISUAL APCH. PROBS WERE: INABILITY TO POSITIVELY IDENT ACFT WE WERE TO FOLLOW, FREQ CONGESTION PREVENTED VERIFICATION SOONER AND ATC WORKLOAD EXTREMELY HIGH. CORRECTIONS: BOTH CTLR AND CREW SHOULD BE POSITIVELY SURE OF TFC BEFORE VISUAL APCH IS ISSUED AND, ALT OF ACFT TO BE FOLLOWED, IN DSCNT OR LEVEL FLT, SHOULD ALWAYS BE GIVEN. THE TFC AT OUR 8-9 O'CLOCK WAS CONSIDERABLY LOWER THAN THE TFC AT 12 O'CLOCK AND THIS WOULD HAVE ALERTED US SOONER AND PREVENTED OR HELPED TO PREVENT LOOKING AT THE WRONG ACFT.

Data retrieved from NASA's ASRS site as of August 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.