Narrative:

Flight was being vectored to localizer 27 san and was assigned heading 250 degrees and descend to 4000 ft. As we were leveled off, TCASII alert RA came to climb. Traffic was visually contacted at 11:30 position about 3 mi. We complied with RA to climb and as the traffic passed under us and TCASII gave clear of conflict, I started descending to my altitude while keeping traffic in visual contact at about 4 O'clock position. We descended through our assigned altitude approximately 150 ft. Both of us were occupied doing our approach checklist and visual inspection of the traffic. San approach control called us about our assigned altitude which was immediately corrected and no safety was jeopardized. Lesson to learn was that during this type of situation, 1 person must pay attention to cockpit indications, although the other person keeps visual contact and performs visual maneuvers. We were asked to call san approach control. We talked to approach control reps about their concern. They wanted to assure that we did have the traffic in visual contact during all this maneuver, which we did.

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Original NASA ASRS Text

Title: AN ACR LTT CLBED IN RESPONSE TO A TCASII COMMAND, THEN OVERSHOT ITS ALT ON RETURN.

Narrative: FLT WAS BEING VECTORED TO LOC 27 SAN AND WAS ASSIGNED HDG 250 DEGS AND DSND TO 4000 FT. AS WE WERE LEVELED OFF, TCASII ALERT RA CAME TO CLB. TFC WAS VISUALLY CONTACTED AT 11:30 POS ABOUT 3 MI. WE COMPLIED WITH RA TO CLB AND AS THE TFC PASSED UNDER US AND TCASII GAVE CLR OF CONFLICT, I STARTED DSNDING TO MY ALT WHILE KEEPING TFC IN VISUAL CONTACT AT ABOUT 4 O'CLOCK POS. WE DSNDED THROUGH OUR ASSIGNED ALT APPROX 150 FT. BOTH OF US WERE OCCUPIED DOING OUR APCH CHKLIST AND VISUAL INSPECTION OF THE TFC. SAN APCH CTL CALLED US ABOUT OUR ASSIGNED ALT WHICH WAS IMMEDIATELY CORRECTED AND NO SAFETY WAS JEOPARDIZED. LESSON TO LEARN WAS THAT DURING THIS TYPE OF SIT, 1 PERSON MUST PAY ATTN TO COCKPIT INDICATIONS, ALTHOUGH THE OTHER PERSON KEEPS VISUAL CONTACT AND PERFORMS VISUAL MANEUVERS. WE WERE ASKED TO CALL SAN APCH CTL. WE TALKED TO APCH CTL REPS ABOUT THEIR CONCERN. THEY WANTED TO ASSURE THAT WE DID HAVE THE TFC IN VISUAL CONTACT DURING ALL THIS MANEUVER, WHICH WE DID.

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.