Narrative:

While being radar vectored for a visual approach to parallel runways, we were asked if we had opposing traffic (being vectored to other parallel runway) in sight. We replied we did not, but we had the runway in sight. The controller then cleared us for the visual approach with the remark, 'the other aircraft has you in sight and will maintain visual separation.' halfway through the turn from base to final I spotted the traffic and told the controller, 'we see the traffic, but will lose sight of him as we continue the turn.' (we were 'belly up' to traffic as we continued the turn.) at this point it should be noted, that we were well above GS descending and the opposing traffic was below GS flying into the GS. 5-6 mi from the runway, the TCASII gave the verbal advisory, 'traffic.' a few seconds later, an RA, 'climb' was given. Shortly thereafter a 'descend' advisory was given. During the 'advisory period' we were approximately 200-300 ft right off centerline, giving the other aircraft extra room for the turn-on. After the first RA, I spotted the other aircraft off the left side, very close to us. My best guess 300 ft. It was apparent he was tracking to the right off centerline for his runway and directly abeam us. At this point he started to slow, and fall behind us the rest of the approach. It's readily apparent either he lost sight of us (and didn't report it to ATC), or overshot final and accepted tracking right of course or both. Those occurrences happen. This entire situation could have been avoided if: ATC had applied a 'stagger' to our spacing on final, or if the rules were changed whereby both aircraft must have each other in sight throughout the entire procedure. There's too much risked depending on only 1 aircraft's ability to maintain visual separation (each others) (to reach the GS), also, having to 'cross' altitude, when abeam spacing is used wrong. Period. Supplemental information from acn 489631: started getting numerous RA's while trying to get down to GS. Chose to ignore because felt close proximity to other aircraft required to keep him in sight, turned slightly east to line up east of runway 34R runway edge. Remained offset until we pulled clear. Called ATC upon block in. Asked to file midair. Slam dunk, head to head turn by ATC exasperated an already hazardous condition (closely spaced parallel approach) into a near fatal one. ATC will blame aircraft Y, but ATC should bear the majority of the burden. Safety took a back seat to capacity.

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Original NASA ASRS Text

Title: TFC CONFLICT ON FINAL APCH TO RWY 34R/L AT SEATTLE, WA.

Narrative: WHILE BEING RADAR VECTORED FOR A VISUAL APCH TO PARALLEL RWYS, WE WERE ASKED IF WE HAD OPPOSING TFC (BEING VECTORED TO OTHER PARALLEL RWY) IN SIGHT. WE REPLIED WE DID NOT, BUT WE HAD THE RWY IN SIGHT. THE CTLR THEN CLRED US FOR THE VISUAL APCH WITH THE REMARK, 'THE OTHER ACFT HAS YOU IN SIGHT AND WILL MAINTAIN VISUAL SEPARATION.' HALFWAY THROUGH THE TURN FROM BASE TO FINAL I SPOTTED THE TFC AND TOLD THE CTLR, 'WE SEE THE TFC, BUT WILL LOSE SIGHT OF HIM AS WE CONTINUE THE TURN.' (WE WERE 'BELLY UP' TO TFC AS WE CONTINUED THE TURN.) AT THIS POINT IT SHOULD BE NOTED, THAT WE WERE WELL ABOVE GS DSNDING AND THE OPPOSING TFC WAS BELOW GS FLYING INTO THE GS. 5-6 MI FROM THE RWY, THE TCASII GAVE THE VERBAL ADVISORY, 'TFC.' A FEW SECONDS LATER, AN RA, 'CLB' WAS GIVEN. SHORTLY THEREAFTER A 'DSND' ADVISORY WAS GIVEN. DURING THE 'ADVISORY PERIOD' WE WERE APPROX 200-300 FT R OFF CTRLINE, GIVING THE OTHER ACFT EXTRA ROOM FOR THE TURN-ON. AFTER THE FIRST RA, I SPOTTED THE OTHER ACFT OFF THE L SIDE, VERY CLOSE TO US. MY BEST GUESS 300 FT. IT WAS APPARENT HE WAS TRACKING TO THE R OFF CTRLINE FOR HIS RWY AND DIRECTLY ABEAM US. AT THIS POINT HE STARTED TO SLOW, AND FALL BEHIND US THE REST OF THE APCH. IT'S READILY APPARENT EITHER HE LOST SIGHT OF US (AND DIDN'T RPT IT TO ATC), OR OVERSHOT FINAL AND ACCEPTED TRACKING R OF COURSE OR BOTH. THOSE OCCURRENCES HAPPEN. THIS ENTIRE SIT COULD HAVE BEEN AVOIDED IF: ATC HAD APPLIED A 'STAGGER' TO OUR SPACING ON FINAL, OR IF THE RULES WERE CHANGED WHEREBY BOTH ACFT MUST HAVE EACH OTHER IN SIGHT THROUGHOUT THE ENTIRE PROC. THERE'S TOO MUCH RISKED DEPENDING ON ONLY 1 ACFT'S ABILITY TO MAINTAIN VISUAL SEPARATION (EACH OTHERS) (TO REACH THE GS), ALSO, HAVING TO 'CROSS' ALT, WHEN ABEAM SPACING IS USED WRONG. PERIOD. SUPPLEMENTAL INFO FROM ACN 489631: STARTED GETTING NUMEROUS RA'S WHILE TRYING TO GET DOWN TO GS. CHOSE TO IGNORE BECAUSE FELT CLOSE PROX TO OTHER ACFT REQUIRED TO KEEP HIM IN SIGHT, TURNED SLIGHTLY E TO LINE UP E OF RWY 34R RWY EDGE. REMAINED OFFSET UNTIL WE PULLED CLR. CALLED ATC UPON BLOCK IN. ASKED TO FILE MIDAIR. SLAM DUNK, HEAD TO HEAD TURN BY ATC EXASPERATED AN ALREADY HAZARDOUS CONDITION (CLOSELY SPACED PARALLEL APCH) INTO A NEAR FATAL ONE. ATC WILL BLAME ACFT Y, BUT ATC SHOULD BEAR THE MAJORITY OF THE BURDEN. SAFETY TOOK A BACK SEAT TO CAPACITY.

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.