Narrative:

We were proceeding at 4000 ft MSL. We were told to expect runway 16L and to look for a widebody transport at 2-3 O'clock. We saw the widebody transport at the 2 O'clock position, much higher than we were, both of us about 10 mi from the airport. We called the airport and the widebody transport in sight and we were cleared for the visual runway 16L. We lined up on a 9 mi final for runway 16L and were on glide path with respect to the runway 16L VASI. We continued to watch the widebody transport above us descending rapidly. He was still on a southeast heading to intersect the runway 16R localizer. He flew through the runway 16R localizer and continued towards us. We were forced to deviate from a normal flight profile by turning 45 degrees to the left. The widebody transport, now known to us as air carrier number, still maintained his course and flew through the runway 16L centerline to a point of 1/4 mi on the east side of the runway 16L centerline. We continued to take evasive action as the widebody transport continued to a point almost directly over us at an altitude difference of 1000 ft or less. We prompted tower and asked what the widebody transport was doing. The tower gave the widebody transport instructions to turn right. The widebody transport crew was oblivious to our presence. The widebody transport crew was so high on final that they s-turned at a low altitude, less than 1000 ft AGL, to try and lose altitude. We lined our aircraft back onto the runway 16L final and made an uneventful, safe landing. We were forced to deviate from our flight profile because our safety was in jeopardy. A collision hazard existed and we experienced an near midair collision. Had we not deviated, the widebody transport would have caused us a considerable safety problem. The widebody transport crew seemed confused during the entire approach. We determined this through their radio xmissions with approach control and tower. They seemed to be 'behind the aircraft' throughout the approach.

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Original NASA ASRS Text

Title: WDB OVERSHOT TURN ONTO FINAL CAUSING CONFLICT WITH MLG ON FINAL FOR A PARALLEL RWY.

Narrative: WE WERE PROCEEDING AT 4000 FT MSL. WE WERE TOLD TO EXPECT RWY 16L AND TO LOOK FOR A WDB AT 2-3 O'CLOCK. WE SAW THE WDB AT THE 2 O'CLOCK POS, MUCH HIGHER THAN WE WERE, BOTH OF US ABOUT 10 MI FROM THE ARPT. WE CALLED THE ARPT AND THE WDB IN SIGHT AND WE WERE CLRED FOR THE VISUAL RWY 16L. WE LINED UP ON A 9 MI FINAL FOR RWY 16L AND WERE ON GLIDE PATH WITH RESPECT TO THE RWY 16L VASI. WE CONTINUED TO WATCH THE WDB ABOVE US DSNDING RAPIDLY. HE WAS STILL ON A SE HDG TO INTERSECT THE RWY 16R LOC. HE FLEW THROUGH THE RWY 16R LOC AND CONTINUED TOWARDS US. WE WERE FORCED TO DEVIATE FROM A NORMAL FLT PROFILE BY TURNING 45 DEGS TO THE L. THE WDB, NOW KNOWN TO US AS ACR NUMBER, STILL MAINTAINED HIS COURSE AND FLEW THROUGH THE RWY 16L CTRLINE TO A POINT OF 1/4 MI ON THE E SIDE OF THE RWY 16L CTRLINE. WE CONTINUED TO TAKE EVASIVE ACTION AS THE WDB CONTINUED TO A POINT ALMOST DIRECTLY OVER US AT AN ALT DIFFERENCE OF 1000 FT OR LESS. WE PROMPTED TWR AND ASKED WHAT THE WDB WAS DOING. THE TWR GAVE THE WDB INSTRUCTIONS TO TURN R. THE WDB CREW WAS OBLIVIOUS TO OUR PRESENCE. THE WDB CREW WAS SO HIGH ON FINAL THAT THEY S-TURNED AT A LOW ALT, LESS THAN 1000 FT AGL, TO TRY AND LOSE ALT. WE LINED OUR ACFT BACK ONTO THE RWY 16L FINAL AND MADE AN UNEVENTFUL, SAFE LNDG. WE WERE FORCED TO DEVIATE FROM OUR FLT PROFILE BECAUSE OUR SAFETY WAS IN JEOPARDY. A COLLISION HAZARD EXISTED AND WE EXPERIENCED AN NMAC. HAD WE NOT DEVIATED, THE WDB WOULD HAVE CAUSED US A CONSIDERABLE SAFETY PROB. THE WDB CREW SEEMED CONFUSED DURING THE ENTIRE APCH. WE DETERMINED THIS THROUGH THEIR RADIO XMISSIONS WITH APCH CTL AND TWR. THEY SEEMED TO BE 'BEHIND THE ACFT' THROUGHOUT THE APCH.

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.