Narrative:

On approach to sea, seattle approach asked if we had visual contact with air carrier X. Air carrier X B737 at 12 O'clock position. We were on base leg for south landing, 5000 ft, about 10 NM north of airport. First officer stated traffic in sight. ATC instructed us to follow air carrier X cleared visual approach runway 16R. First officer read back approach clearance. While descending on visual approach control asked if we had company B737 in sight 2-3 O'clock position. First officer stated affirmative. No response from ATC. While descending through approximately 3500 ft MSL over bfi airport, there was several aircraft on TCASII. Received TCASII TA alert for aircraft aft and below us, approximately 500 ft vertical separation, assumed it was pattern traffic at bfi. Frequency congestion prevented ATC query. At approximately 2500 ft MSL, descending on visual approach for runway 16R behind air carrier X, received TCASII RA to climb, we followed advisory, when warning ended, resumed descent to regain glide path. Received 2ND TCASII RA to climb, again followed advisory, notified ATC of RA climb, he said to contact sea tower. We leveled aircraft at approximately 2800 ft MSL switched to tower frequency. First officer contacted sea tower, advised we had TCASII RA climb on visual for runway 16R. Tower acknowledged us and stated now cleared to land on runway 16L. First officer confirmed that approach control had cleared us for visual approach runway 16R, now cleared to side-step to runway 16L, cleared to land. Tower acknowledged this, and confirmed cleared to land runway 16L. We landed uneventful on runway 16L, and saw company B737 on parallel approach runway 16R and lower, at 2-3 NM final. Traffic was within 300 ft vertical, and less than 1/2 NM horizontal. ATC congested frequency on approach prevented first advisory of RA climb. After landing on runway 16L, advised tower of poor handling by approach control and tower acknowledged that.

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Original NASA ASRS Text

Title: FLC OF A B737-300 DURING A VISUAL APCH CLBED IN RESPONSE TO A TCASII RA CAUSED BY A B737-500 ON A VISUAL APCH AHEAD AND 300 FT BELOW TO THE SAME RWY. THE FLC STOPPED DSNDING AND CLBED ON 2 SEPARATE OCCASIONS.

Narrative: ON APCH TO SEA, SEATTLE APCH ASKED IF WE HAD VISUAL CONTACT WITH ACR X. ACR X B737 AT 12 O'CLOCK POS. WE WERE ON BASE LEG FOR S LNDG, 5000 FT, ABOUT 10 NM N OF ARPT. FO STATED TFC IN SIGHT. ATC INSTRUCTED US TO FOLLOW ACR X CLRED VISUAL APCH RWY 16R. FO READ BACK APCH CLRNC. WHILE DSNDING ON VISUAL APCH CTL ASKED IF WE HAD COMPANY B737 IN SIGHT 2-3 O'CLOCK POS. FO STATED AFFIRMATIVE. NO RESPONSE FROM ATC. WHILE DSNDING THROUGH APPROX 3500 FT MSL OVER BFI ARPT, THERE WAS SEVERAL ACFT ON TCASII. RECEIVED TCASII TA ALERT FOR ACFT AFT AND BELOW US, APPROX 500 FT VERT SEPARATION, ASSUMED IT WAS PATTERN TFC AT BFI. FREQ CONGESTION PREVENTED ATC QUERY. AT APPROX 2500 FT MSL, DSNDING ON VISUAL APCH FOR RWY 16R BEHIND ACR X, RECEIVED TCASII RA TO CLB, WE FOLLOWED ADVISORY, WHEN WARNING ENDED, RESUMED DSCNT TO REGAIN GLIDE PATH. RECEIVED 2ND TCASII RA TO CLB, AGAIN FOLLOWED ADVISORY, NOTIFIED ATC OF RA CLB, HE SAID TO CONTACT SEA TWR. WE LEVELED ACFT AT APPROX 2800 FT MSL SWITCHED TO TWR FREQ. FO CONTACTED SEA TWR, ADVISED WE HAD TCASII RA CLB ON VISUAL FOR RWY 16R. TWR ACKNOWLEDGED US AND STATED NOW CLRED TO LAND ON RWY 16L. FO CONFIRMED THAT APCH CTL HAD CLRED US FOR VISUAL APCH RWY 16R, NOW CLRED TO SIDE-STEP TO RWY 16L, CLRED TO LAND. TWR ACKNOWLEDGED THIS, AND CONFIRMED CLRED TO LAND RWY 16L. WE LANDED UNEVENTFUL ON RWY 16L, AND SAW COMPANY B737 ON PARALLEL APCH RWY 16R AND LOWER, AT 2-3 NM FINAL. TFC WAS WITHIN 300 FT VERT, AND LESS THAN 1/2 NM HORIZ. ATC CONGESTED FREQ ON APCH PREVENTED FIRST ADVISORY OF RA CLB. AFTER LNDG ON RWY 16L, ADVISED TWR OF POOR HANDLING BY APCH CTL AND TWR ACKNOWLEDGED THAT.

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.