Narrative:

On ILS runway 16R at ksea we were at target speed and still gaining on turboprop twin in front of us. I saw 16L and requested visual approach to it. A dense morning fog was burning off and still very patchy around airport. Although WX was reported good by WX observer near terminal, we lost sight of preceding aircraft to 16R as it descended into fog bank. At approximately 200 ft AGL I realized we were lined up on bravo taxiway, runway 16L was obscured by fog and a bright reflective sun from the south. I executed a go around and was vectored back around for an ILS 16R. In the rapidly changing conditions, the visibility at the runway was much improved on this next approach. Fortunately there were no aircraft on or in the vicinity of bravo taxiway and no conflict occurred. My decision to request a visual approach was affected by a desire to make up time after a late departure and realizing that we might have to go around due to preceding traffic. Even though official WX was good, I should not have tried a visual approach in such rapidly changing conditions.

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Original NASA ASRS Text

Title: ACR MLG PIC INADVERTENTLY MAKES APCH TO TXWY DURING MANEUVER ON A VISUAL APCH IN PATCHY FOG CONDITIONS.

Narrative: ON ILS RWY 16R AT KSEA WE WERE AT TARGET SPD AND STILL GAINING ON TURBOPROP TWIN IN FRONT OF US. I SAW 16L AND REQUESTED VISUAL APCH TO IT. A DENSE MORNING FOG WAS BURNING OFF AND STILL VERY PATCHY AROUND ARPT. ALTHOUGH WX WAS RPTED GOOD BY WX OBSERVER NEAR TERMINAL, WE LOST SIGHT OF PRECEDING ACFT TO 16R AS IT DSNDED INTO FOG BANK. AT APPROX 200 FT AGL I REALIZED WE WERE LINED UP ON BRAVO TXWY, RWY 16L WAS OBSCURED BY FOG AND A BRIGHT REFLECTIVE SUN FROM THE S. I EXECUTED A GAR AND WAS VECTORED BACK AROUND FOR AN ILS 16R. IN THE RAPIDLY CHANGING CONDITIONS, THE VISIBILITY AT THE RWY WAS MUCH IMPROVED ON THIS NEXT APCH. FORTUNATELY THERE WERE NO ACFT ON OR IN THE VICINITY OF BRAVO TXWY AND NO CONFLICT OCCURRED. MY DECISION TO REQUEST A VISUAL APCH WAS AFFECTED BY A DESIRE TO MAKE UP TIME AFTER A LATE DEP AND REALIZING THAT WE MIGHT HAVE TO GAR DUE TO PRECEDING TFC. EVEN THOUGH OFFICIAL WX WAS GOOD, I SHOULD NOT HAVE TRIED A VISUAL APCH IN SUCH RAPIDLY CHANGING CONDITIONS.

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.