Narrative:

On final approach to ZZZ xxl ILS we received a TCAS RA. Normally we get that when an aircraft is on final to xxr. We could not find the other aircraft. We then received an RA to climb and did so. I looked straight below us out the right window and saw the intruder. He was directly below us appearing to also flying to xxl. We got to about 400 feet directly above him before we got the RA. We notified ATC and they responded that the aircraft was on the ILS to xxr. He obviously wasn't. We discontinued the approach and eventually landed on xyr. Fortunately we had not taken the advice on the 10-7 page and selected TA only. If we had; we would have had a midair.

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Original NASA ASRS Text

Title: A320 pilot crew reported receiving an RA on final approach and executing a missed approach. Crew reported RA was late; ATC did not issue traffic advisory and transponder was not in TA only mode as per company policy.

Narrative: On final approach to ZZZ XXL ILS we received a TCAS RA. Normally we get that when an aircraft is on final to XXR. We could not find the other aircraft. We then received an RA to climb and did so. I looked straight below us out the right window and saw the intruder. He was directly below us appearing to also flying to XXL. We got to about 400 feet directly above him before we got the RA. We notified ATC and they responded that the aircraft was on the ILS to XXR. He obviously wasn't. We discontinued the approach and eventually landed on XYR. Fortunately we had not taken the advice on the 10-7 page and selected TA only. If we had; we would have had a midair.

Data retrieved from NASA's ASRS site 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.