Narrative:

We approached sea-tac from the east to land on runway 34. On right base, approach cleared us for a visual to 34R to follow air carrier flight which was pointed out to us and we verified. On final, approximately 2700 ft TCASII showed TA ahead and below air carrier and unknown approximately 8 O'clock higher. I had just tuned tower frequency when we got an RA and so called out 'he's right behind us 400 ft -- it's showing 200 ft descent.' first officer pushed forward out of 2000 ft/min range (red), as I looked for aircraft. My first sight of the large transport was a few hundred ft above us, very near our course, a bit behind, passing rapidly. As aircraft cleared, first officer leveled off and re-intercepted GS. The large transport aircraft pulled ahead approximately 3/4 mi then put his gear down and slowed to his approach speed which was less than ours. We were now overtaking him. Meanwhile, back on 34R, the traffic we were following was very slow to exit the runway and tower told us to be ready for a go around. As we went around from approximately 100 ft, the aircraft that passed us was just touching down. When we went to approach control frequency, they asked if we went around because of large transport overtaking. There was some conversation and they apologized for not telling us about large transport aircraft for the left runway. During phone conversation with tower and approach, I was told that air carrier Y was given a clearance to maintain visual contact with us during his turn to final. Only he knows how close he was to our aircraft. It was too close for me and a great distraction on our approach. How can anyone maintain visual separation after passing the other?

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Original NASA ASRS Text

Title: ACR WDB ACFT OVERTAKEN DURING FINAL ON A VISUAL APCH BY ANOTHER ACR LGT ACFT ON APCH TO THE PARALLEL RWY RESULTING IN A NMAC.

Narrative: WE APCHED SEA-TAC FROM THE E TO LAND ON RWY 34. ON R BASE, APCH CLRED US FOR A VISUAL TO 34R TO FOLLOW ACR FLT WHICH WAS POINTED OUT TO US AND WE VERIFIED. ON FINAL, APPROX 2700 FT TCASII SHOWED TA AHEAD AND BELOW ACR AND UNKNOWN APPROX 8 O'CLOCK HIGHER. I HAD JUST TUNED TWR FREQ WHEN WE GOT AN RA AND SO CALLED OUT 'HE'S R BEHIND US 400 FT -- IT'S SHOWING 200 FT DSCNT.' FO PUSHED FORWARD OUT OF 2000 FT/MIN RANGE (RED), AS I LOOKED FOR ACFT. MY FIRST SIGHT OF THE LGT WAS A FEW HUNDRED FT ABOVE US, VERY NEAR OUR COURSE, A BIT BEHIND, PASSING RAPIDLY. AS ACFT CLRED, FO LEVELED OFF AND RE-INTERCEPTED GS. THE LGT ACFT PULLED AHEAD APPROX 3/4 MI THEN PUT HIS GEAR DOWN AND SLOWED TO HIS APCH SPD WHICH WAS LESS THAN OURS. WE WERE NOW OVERTAKING HIM. MEANWHILE, BACK ON 34R, THE TFC WE WERE FOLLOWING WAS VERY SLOW TO EXIT THE RWY AND TWR TOLD US TO BE READY FOR A GAR. AS WE WENT AROUND FROM APPROX 100 FT, THE ACFT THAT PASSED US WAS JUST TOUCHING DOWN. WHEN WE WENT TO APCH CTL FREQ, THEY ASKED IF WE WENT AROUND BECAUSE OF LGT OVERTAKING. THERE WAS SOME CONVERSATION AND THEY APOLOGIZED FOR NOT TELLING US ABOUT LGT ACFT FOR THE L RWY. DURING PHONE CONVERSATION WITH TWR AND APCH, I WAS TOLD THAT ACR Y WAS GIVEN A CLRNC TO MAINTAIN VISUAL CONTACT WITH US DURING HIS TURN TO FINAL. ONLY HE KNOWS HOW CLOSE HE WAS TO OUR ACFT. IT WAS TOO CLOSE FOR ME AND A GREAT DISTR ON OUR APCH. HOW CAN ANYONE MAINTAIN VISUAL SEPARATION AFTER PASSING THE OTHER?

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.