Narrative:

After a go around due to windshear, we were being vectored back to intercept a visual approach runway 16L. Airport was called in sight and we were cleared for visual runway 16L. Traffic was also in sight and cleared for visual runway 16R (air carrier Y). Air carrier Y appeared to be lining up for runway 16L below us. We stayed well left of runway 16L and confirmed traffic was for runway 16R with approach. The first officer confirmed the traffic moving below us and we flew left of runway 16L, discontinued the approach, coordinated with ATC to break off the approach, declared minimum fuel. Subsequent approach to runway 16L was uneventful. We also confirmed proper visual alignment, navaids and courses, as well as proper visual clues. Continuing on the approach would have resulted in definite loss of separation. I called tower and approach after event for them to follow up on conflict. Supplemental information from acn 615941: I looked off the right side of the aircraft and about 2000 ft below us was an A319/320. He appeared to be on the final approach course for runway 16L. We asked approach to verify that the other aircraft was on the runway 16R approach course. We called the tower and they were not aware of any aircraft that landed on the wrong runway. We also called approach and asked the same question. They replied that they would review the tapes. I would bet money that we would have hit them had we continued our approach to runway 16L.

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Original NASA ASRS Text

Title: B737 LNDG DEN OBSERVED PARALLEL TFC LINING UP WITH WRONG RWY AND EXECUTES GAR.

Narrative: AFTER A GAR DUE TO WINDSHEAR, WE WERE BEING VECTORED BACK TO INTERCEPT A VISUAL APCH RWY 16L. ARPT WAS CALLED IN SIGHT AND WE WERE CLRED FOR VISUAL RWY 16L. TFC WAS ALSO IN SIGHT AND CLRED FOR VISUAL RWY 16R (ACR Y). ACR Y APPEARED TO BE LINING UP FOR RWY 16L BELOW US. WE STAYED WELL L OF RWY 16L AND CONFIRMED TFC WAS FOR RWY 16R WITH APCH. THE FO CONFIRMED THE TFC MOVING BELOW US AND WE FLEW L OF RWY 16L, DISCONTINUED THE APCH, COORDINATED WITH ATC TO BREAK OFF THE APCH, DECLARED MINIMUM FUEL. SUBSEQUENT APCH TO RWY 16L WAS UNEVENTFUL. WE ALSO CONFIRMED PROPER VISUAL ALIGNMENT, NAVAIDS AND COURSES, AS WELL AS PROPER VISUAL CLUES. CONTINUING ON THE APCH WOULD HAVE RESULTED IN DEFINITE LOSS OF SEPARATION. I CALLED TWR AND APCH AFTER EVENT FOR THEM TO FOLLOW UP ON CONFLICT. SUPPLEMENTAL INFO FROM ACN 615941: I LOOKED OFF THE R SIDE OF THE ACFT AND ABOUT 2000 FT BELOW US WAS AN A319/320. HE APPEARED TO BE ON THE FINAL APCH COURSE FOR RWY 16L. WE ASKED APCH TO VERIFY THAT THE OTHER ACFT WAS ON THE RWY 16R APCH COURSE. WE CALLED THE TWR AND THEY WERE NOT AWARE OF ANY ACFT THAT LANDED ON THE WRONG RWY. WE ALSO CALLED APCH AND ASKED THE SAME QUESTION. THEY REPLIED THAT THEY WOULD REVIEW THE TAPES. I WOULD BET MONEY THAT WE WOULD HAVE HIT THEM HAD WE CONTINUED OUR APCH TO RWY 16L.

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.