Narrative:

On civet arrival, was cleared for visual approach to runway 25R, and advised would have traffic from south for runway 25L. At approximately 13 NM, air carrier B727 hooked in from south for runway 25L, and had solid visual contact with traffic. While tracking the runway 25R localizer, kept B727 in sight from above and just aft on right side of B727. From my position, it looked as if air carrier was not exactly tracking the centerline of runway 25L. After check-in with tower on 120.95, at approximately 5 NM, the B727 started to drift slightly right and alter his glide path to what might have been a go around maneuver. This drift caused me to disconnect autoplt and come right to increase diminishing lateral separation. B727 asked tower if they were cleared to land as if they were confused. Tower again reconfirmed that he was cleared for runway 25L and we were cleared for runway 25R. I then had to come back to the left to re-establish the centerline for runway 25R and subsequent uneventful landing was made. I strongly recommend that socal approach not use this procedure if there is any doubt as to what is happening. This could have gotten very ugly.

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Original NASA ASRS Text

Title: AN ACR MD80S ON VISUAL APCH AND ADVISED OF TFC TO THE L WHO IS LNDG ON PARALLEL RWY. OTHER ACFT OVERSHOT CTRLINE WHICH REQUIRED RPTR TO TAKE EVASIVE ACTION. RPTR CAPT SAYS SIDE-BY-SIDE APCHS WHEN ONE ACFT IS TURNING IN ON FINAL IS A SETUP FOR CONFLICT.

Narrative: ON CIVET ARR, WAS CLRED FOR VISUAL APCH TO RWY 25R, AND ADVISED WOULD HAVE TFC FROM S FOR RWY 25L. AT APPROX 13 NM, ACR B727 HOOKED IN FROM S FOR RWY 25L, AND HAD SOLID VISUAL CONTACT WITH TFC. WHILE TRACKING THE RWY 25R LOC, KEPT B727 IN SIGHT FROM ABOVE AND JUST AFT ON R SIDE OF B727. FROM MY POS, IT LOOKED AS IF ACR WAS NOT EXACTLY TRACKING THE CTRLINE OF RWY 25L. AFTER CHK-IN WITH TWR ON 120.95, AT APPROX 5 NM, THE B727 STARTED TO DRIFT SLIGHTLY R AND ALTER HIS GLIDE PATH TO WHAT MIGHT HAVE BEEN A GAR MANEUVER. THIS DRIFT CAUSED ME TO DISCONNECT AUTOPLT AND COME R TO INCREASE DIMINISHING LATERAL SEPARATION. B727 ASKED TWR IF THEY WERE CLRED TO LAND AS IF THEY WERE CONFUSED. TWR AGAIN RECONFIRMED THAT HE WAS CLRED FOR RWY 25L AND WE WERE CLRED FOR RWY 25R. I THEN HAD TO COME BACK TO THE L TO RE-ESTABLISH THE CTRLINE FOR RWY 25R AND SUBSEQUENT UNEVENTFUL LNDG WAS MADE. I STRONGLY RECOMMEND THAT SOCAL APCH NOT USE THIS PROC IF THERE IS ANY DOUBT AS TO WHAT IS HAPPENING. THIS COULD HAVE GOTTEN VERY UGLY.

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.