Narrative:

During night VMC to sll, we were being vectored on a downwind to runway 34L to follow an air carrier Y (a regional jet). Following an acknowledgement from us that we had the traffic in sight, we were cleared for a visual approach to runway 34L. We waited until the traffic we thought we were following made its base and turn to final before beginning our base turn from downwind. Passing through 7500 ft MSL during our turn to final, we received a TCASII RA to climb, followed shortly by ATC instructions to climb to 8000 ft MSL and fly 340 degrees. We were informed that we had turned inside the regional jet traffic and caused a conflict. The overriding cause was accepting a visual at night on an aircraft that could not be positively idented. We were not aware that the traffic we thought we were following was the wrong aircraft (an aircraft Z, MD80). All lights look the same at night and distance discrimination is not possible. Supplemental information from acn 449004: at night, during VMC, continue until on an intercept heading to final. Do not refer to the plane by aircraft type at night. The only thing that can be seen in some light. Aircraft lights do not identify an aircraft. Also, when issuing a visual clearance to follow another plane, give the position of that plane to help eliminate mistaken identities.

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Original NASA ASRS Text

Title: ACR ON NIGHT VISUAL TFC PATTERN FOLLOWS WRONG TFC AND HAS CONFLICT WITH ANOTHER ACFT.

Narrative: DURING NIGHT VMC TO SLL, WE WERE BEING VECTORED ON A DOWNWIND TO RWY 34L TO FOLLOW AN ACR Y (A REGIONAL JET). FOLLOWING AN ACKNOWLEDGEMENT FROM US THAT WE HAD THE TFC IN SIGHT, WE WERE CLRED FOR A VISUAL APCH TO RWY 34L. WE WAITED UNTIL THE TFC WE THOUGHT WE WERE FOLLOWING MADE ITS BASE AND TURN TO FINAL BEFORE BEGINNING OUR BASE TURN FROM DOWNWIND. PASSING THROUGH 7500 FT MSL DURING OUR TURN TO FINAL, WE RECEIVED A TCASII RA TO CLB, FOLLOWED SHORTLY BY ATC INSTRUCTIONS TO CLB TO 8000 FT MSL AND FLY 340 DEGS. WE WERE INFORMED THAT WE HAD TURNED INSIDE THE REGIONAL JET TFC AND CAUSED A CONFLICT. THE OVERRIDING CAUSE WAS ACCEPTING A VISUAL AT NIGHT ON AN ACFT THAT COULD NOT BE POSITIVELY IDENTED. WE WERE NOT AWARE THAT THE TFC WE THOUGHT WE WERE FOLLOWING WAS THE WRONG ACFT (AN ACFT Z, MD80). ALL LIGHTS LOOK THE SAME AT NIGHT AND DISTANCE DISCRIMINATION IS NOT POSSIBLE. SUPPLEMENTAL INFO FROM ACN 449004: AT NIGHT, DURING VMC, CONTINUE UNTIL ON AN INTERCEPT HDG TO FINAL. DO NOT REFER TO THE PLANE BY ACFT TYPE AT NIGHT. THE ONLY THING THAT CAN BE SEEN IN SOME LIGHT. ACFT LIGHTS DO NOT IDENT AN ACFT. ALSO, WHEN ISSUING A VISUAL CLRNC TO FOLLOW ANOTHER PLANE, GIVE THE POS OF THAT PLANE TO HELP ELIMINATE MISTAKEN IDENTITIES.

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.