Narrative:

I was working 3 final positions combined in the early morning on a large arrival bank. I was distracted by another aircraft that checked in and caused me to be late on my visual approach clearance to aircraft X. I did not ensure proper altitude separation from opposite bases and was betting that I would clear the opposing base traffic for the visual approach before separation was lost. Aircraft Y directly under flew aircraft X while descending to 3;000 and aircraft X responded to an RA by climbing. I resolved the situation by breaking aircraft X out to the east and re sequencing the aircraft. Both airplanes had the airport in sight but I never cleared either. I would recommend I follow procedures and/or not allow all finals to be combined while working 14-15 aircraft on final.

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Original NASA ASRS Text

Title: TRACON Controller working combined positions with heavy traffic reported a TCAS RA event when failing to insure separation.

Narrative: I was working 3 final positions combined in the early morning on a large arrival bank. I was distracted by another aircraft that checked in and caused me to be late on my Visual Approach clearance to Aircraft X. I did not ensure proper altitude separation from opposite bases and was betting that I would clear the opposing base traffic for the visual approach before separation was lost. Aircraft Y directly under flew Aircraft X while descending to 3;000 and Aircraft X responded to an RA by climbing. I resolved the situation by breaking Aircraft X out to the east and re sequencing the aircraft. Both airplanes had the airport in sight but I never cleared either. I would recommend I follow procedures and/or not allow all finals to be combined while working 14-15 aircraft on final.

Data retrieved from NASA's ASRS site as of April 2012 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.