Narrative:

We had received numerous traffic callouts from the tower while on final to runway 30L. At about 1200 ft I was monitoring a light aircraft at our 10 O'clock, who had turned onto left base for runway 29. He was in a low, close pattern for that runway, which is typical, but my distraction to assure myself of his time base-to-final turn contributed to my forgetting to deactivate the RA function of our TCASII by 1000 ft, which is our (company) procedure. I was unable to determine with confidence that the TCASII climb command, which occurred a couple of seconds later, was triggered by that aircraft, his possible turn overshot (the runway centerline are about 750 ft apart), or another aircraft. I initiated a go around, and we were turned onto a right downwind and landed about 8 mins later. Had TCASII been turned to a 'TA only' prior to 1000 ft, the go around probably would not have appeared advisable. Our additional exposure time in a high density traffic pattern certainly wasn't desirable. My forgetfulness notwithstanding, a procedural change to turn off the RA function earlier than at 1000 ft might better distribute cockpit workload at a peak time.

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Original NASA ASRS Text

Title: ACR PIC OF MLG PERFORMS GAR PROC ON THE STRENGTH OF A TCASII RA ON SHORT FINAL WITH OTHER ARR TFC IN SIGHT.

Narrative: WE HAD RECEIVED NUMEROUS TFC CALLOUTS FROM THE TWR WHILE ON FINAL TO RWY 30L. AT ABOUT 1200 FT I WAS MONITORING A LIGHT ACFT AT OUR 10 O'CLOCK, WHO HAD TURNED ONTO L BASE FOR RWY 29. HE WAS IN A LOW, CLOSE PATTERN FOR THAT RWY, WHICH IS TYPICAL, BUT MY DISTR TO ASSURE MYSELF OF HIS TIME BASE-TO-FINAL TURN CONTRIBUTED TO MY FORGETTING TO DEACTIVATE THE RA FUNCTION OF OUR TCASII BY 1000 FT, WHICH IS OUR (COMPANY) PROC. I WAS UNABLE TO DETERMINE WITH CONFIDENCE THAT THE TCASII CLB COMMAND, WHICH OCCURRED A COUPLE OF SECONDS LATER, WAS TRIGGERED BY THAT ACFT, HIS POSSIBLE TURN OVERSHOT (THE RWY CTRLINE ARE ABOUT 750 FT APART), OR ANOTHER ACFT. I INITIATED A GAR, AND WE WERE TURNED ONTO A R DOWNWIND AND LANDED ABOUT 8 MINS LATER. HAD TCASII BEEN TURNED TO A 'TA ONLY' PRIOR TO 1000 FT, THE GAR PROBABLY WOULD NOT HAVE APPEARED ADVISABLE. OUR ADDITIONAL EXPOSURE TIME IN A HIGH DENSITY TFC PATTERN CERTAINLY WASN'T DESIRABLE. MY FORGETFULNESS NOTWITHSTANDING, A PROCEDURAL CHANGE TO TURN OFF THE RA FUNCTION EARLIER THAN AT 1000 FT MIGHT BETTER DISTRIBUTE COCKPIT WORKLOAD AT A PEAK TIME.

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.