Narrative:

On approach at pit on 28L ILS with no GS at 3000 ft about 10 DME. Approach called out traffic at 2500 ft. Shortly after, the TCASII warning sounded and then said 'descend, descend, crossing descend.' the captain started a descent and about that time we realized that the traffic was below us and the captain started a climb. The descent had only gone to 3800 and climb to 3200. The cause for this deviation was that the TCASII gave us faulty commands.

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Original NASA ASRS Text

Title: AN MLG CREW RESPONDED TO A TCASII DSND COMMAND. THE ONLY PROBLEM -- THE INTRUDER TFC WAS BELOW THE RPTING ACR ACFT.

Narrative: ON APCH AT PIT ON 28L ILS WITH NO GS AT 3000 FT ABOUT 10 DME. APCH CALLED OUT TFC AT 2500 FT. SHORTLY AFTER, THE TCASII WARNING SOUNDED AND THEN SAID 'DSND, DSND, XING DSND.' THE CAPT STARTED A DSCNT AND ABOUT THAT TIME WE REALIZED THAT THE TFC WAS BELOW US AND THE CAPT STARTED A CLB. THE DSCNT HAD ONLY GONE TO 3800 AND CLB TO 3200. THE CAUSE FOR THIS DEV WAS THAT THE TCASII GAVE US FAULTY COMMANDS.

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.