Narrative:

We were cleared for a visual approach to runway 26R at ontario; ca. We were configured and descending on the glide slope. At about 5 miles from the runway tower called traffic at 11 o'clock. They stated they were not in contact with them and intentions were unknown. We began looking to see the traffic and saw it on TCAS. It was about 3 miles away. The terrain and buildings on the ground made it impossible for us to visually acquire the traffic. Then the TCAS target went to a TA. We were still trying to find the traffic and then the TCAS RA occurred. I started a shallow climb to comply with the vertical guidance. The traffic passed 450 ft below us; and we were never able to see the other aircraft. After clear of conflict received; we reported the TCAS climb to the tower. Then I started to descend again and recaptured the glide path. Then we made a normal landing.

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Original NASA ASRS Text

Title: An A320 crew on approach to ONT Runway 26R took evasive action to a TCAS RA as an aircraft passed about 450 FT beneath their aircraft.

Narrative: We were cleared for a visual approach to Runway 26R at Ontario; CA. We were configured and descending on the glide slope. At about 5 miles from the runway Tower called traffic at 11 o'clock. They stated they were not in contact with them and intentions were unknown. We began looking to see the traffic and saw it on TCAS. It was about 3 miles away. The terrain and buildings on the ground made it impossible for us to visually acquire the traffic. Then the TCAS target went to a TA. We were still trying to find the traffic and then the TCAS RA occurred. I started a shallow climb to comply with the vertical guidance. The traffic passed 450 FT below us; and we were never able to see the other aircraft. After clear of conflict received; we reported the TCAS climb to the Tower. Then I started to descend again and recaptured the glide path. Then we made a normal landing.

Data retrieved from NASA's ASRS site as of July 2013 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.