Narrative:

We were flying the sjc ILS/visual approach to runway 30L in good VFR WX with visibility 10 mi plus. Several TCASII targets to each side as we transitioned from gilro to klyde, 17 DME, captain was hand flying. There was a B757 behind us and we were asked to keep the speed up, so I held 170 KTS until just before ironn, the FAF. Approaching ironn, we received a TCASII TA and observed a yellow target slightly below and about 1/2 mi behind the right wing. I increased airspeed slightly thinking to put the target behind us while the first officer queried ATC. I am not sure, but believe we had already been handed off to tower by then. ATC advised no traffic in that area. I held airspeed figuring that any jets would be known to them. The bandit was probably a light plane and would drop behind us at 170 KTS. The target changed to a white, no threat. Approaching LMM, as I finished configuring and slowing, the target returned, first as a TA then as an RA. Monitor vertical speed was replaced by a climb command. The target was about 400 ft below us and to the right, within a half mi. I began a slow climb while first officer looked visually and told tower we were beginning a climb and might go missed approach. No traffic in sight or on radar. Then the target totally disappeared. I made an s-turn to the left to put distance between us and the target, and to lose altitude as I reinitiated the visual approach. As we angled back from the left towards centerline, the first officer had a good view behind and saw nothing. We landed without further incident.

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Original NASA ASRS Text

Title: ACR FLIES A TCASII RA IN THE SJC CLASS C WITH NO RPTED OR SIGHTED TFC.

Narrative: WE WERE FLYING THE SJC ILS/VISUAL APCH TO RWY 30L IN GOOD VFR WX WITH VISIBILITY 10 MI PLUS. SEVERAL TCASII TARGETS TO EACH SIDE AS WE TRANSITIONED FROM GILRO TO KLYDE, 17 DME, CAPT WAS HAND FLYING. THERE WAS A B757 BEHIND US AND WE WERE ASKED TO KEEP THE SPD UP, SO I HELD 170 KTS UNTIL JUST BEFORE IRONN, THE FAF. APCHING IRONN, WE RECEIVED A TCASII TA AND OBSERVED A YELLOW TARGET SLIGHTLY BELOW AND ABOUT 1/2 MI BEHIND THE R WING. I INCREASED AIRSPD SLIGHTLY THINKING TO PUT THE TARGET BEHIND US WHILE THE FO QUERIED ATC. I AM NOT SURE, BUT BELIEVE WE HAD ALREADY BEEN HANDED OFF TO TWR BY THEN. ATC ADVISED NO TFC IN THAT AREA. I HELD AIRSPD FIGURING THAT ANY JETS WOULD BE KNOWN TO THEM. THE BANDIT WAS PROBABLY A LIGHT PLANE AND WOULD DROP BEHIND US AT 170 KTS. THE TARGET CHANGED TO A WHITE, NO THREAT. APCHING LMM, AS I FINISHED CONFIGURING AND SLOWING, THE TARGET RETURNED, FIRST AS A TA THEN AS AN RA. MONITOR VERT SPD WAS REPLACED BY A CLB COMMAND. THE TARGET WAS ABOUT 400 FT BELOW US AND TO THE R, WITHIN A HALF MI. I BEGAN A SLOW CLB WHILE FO LOOKED VISUALLY AND TOLD TWR WE WERE BEGINNING A CLB AND MIGHT GO MISSED APCH. NO TFC IN SIGHT OR ON RADAR. THEN THE TARGET TOTALLY DISAPPEARED. I MADE AN S-TURN TO THE L TO PUT DISTANCE BTWN US AND THE TARGET, AND TO LOSE ALT AS I REINITIATED THE VISUAL APCH. AS WE ANGLED BACK FROM THE L TOWARDS CTRLINE, THE FO HAD A GOOD VIEW BEHIND AND SAW NOTHING. WE LANDED WITHOUT FURTHER INCIDENT.

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.