Narrative:

We were being vectored to an ILS approach when we got good visual contact with boeing field (our destination). We requested and were granted a visual approach and were directed to proceed to the space needle to intercept final. No traffic was called out by seattle approach. Shortly after turning as directed, and descending from our last assigned at 2200 ft, we noticed traffic sbound below us. Then we noticed traffic head on at our altitude of 1800 ft. It started a right turn to avoid and so did we. Then suddenly the traffic turned sharply left into us (EST 60 degree bank turn) on a collision course. The copilot who was the PF evidently missed this turn. I grabbed the controls and pushed down strongly to give us the best chance to miss, since we were already in a descent. I estimate we missed by less than 20 ft vertically and less than 75 ft horizontally. The other aircraft was a C172 and was a traffic spotter. Boeing tower subsequently talked to the pilot who admitted he saw us and still turned into us when he should have avoided to the right as per right of way rules. I would really like to talk with that pilot. This has been reported to our FAA inspector via my director of operations. Supplemental information from acn 371870: I ran the lifeguard underneath the sea final again with a pointout when C500 said he had the airport and was requesting a visual. WX was ok, but not good enough to vector for the visual runway 13R at boeing field. I quick checked the WX at bfi and cleared C500 for the visual approach to runway 13R at bfi. I was also responsible for feeding the sea final controller as our 4 corner post system dictated. I needed to turn a B757 to the downwind for sea. After doing that I went right back to the lifeguard and observed a VFR discrete code (traffic watch C172) under the maze of data blocks. I attempted to issue the traffic but wasn't timely enough. We aren't required to quick look these targets as they are usually never a factor to us as we are always above them. Lifeguard said after I issued the traffic that he had just dodged that one. I had asked him to turn final north of the space needle to space himself behind an AC50. He descended rapidly from 2200 ft to 1500 ft. The traffic watch cessna was at 1600 ft. I asked C500 if he was in VFR conditions, he replied affirmative. Although I pride myself on timely/pertinent traffic calls, this one got by me. Workload prevented me from seeing the cessna in a timely manner. The lifeguard's quick descent from 2200 ft didn't help. I'm sure he was trying to keep bfi in sight clear of clouds.

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Original NASA ASRS Text

Title: A C500 ON VISUAL APCH TO BFI OBSERVES A TFC WATCH C172 IN CLOSE PROX OPPOSITE DIRECTION. BOTH ACFT TAKE EVASIVE ACTION TO MISS EACH OTHER.

Narrative: WE WERE BEING VECTORED TO AN ILS APCH WHEN WE GOT GOOD VISUAL CONTACT WITH BOEING FIELD (OUR DEST). WE REQUESTED AND WERE GRANTED A VISUAL APCH AND WERE DIRECTED TO PROCEED TO THE SPACE NEEDLE TO INTERCEPT FINAL. NO TFC WAS CALLED OUT BY SEATTLE APCH. SHORTLY AFTER TURNING AS DIRECTED, AND DSNDING FROM OUR LAST ASSIGNED AT 2200 FT, WE NOTICED TFC SBOUND BELOW US. THEN WE NOTICED TFC HEAD ON AT OUR ALTITUDE OF 1800 FT. IT STARTED A R TURN TO AVOID AND SO DID WE. THEN SUDDENLY THE TFC TURNED SHARPLY L INTO US (EST 60 DEG BANK TURN) ON A COLLISION COURSE. THE COPLT WHO WAS THE PF EVIDENTLY MISSED THIS TURN. I GRABBED THE CTLS AND PUSHED DOWN STRONGLY TO GIVE US THE BEST CHANCE TO MISS, SINCE WE WERE ALREADY IN A DSCNT. I ESTIMATE WE MISSED BY LESS THAN 20 FT VERTLY AND LESS THAN 75 FT HORIZLY. THE OTHER ACFT WAS A C172 AND WAS A TFC SPOTTER. BOEING TWR SUBSEQUENTLY TALKED TO THE PLT WHO ADMITTED HE SAW US AND STILL TURNED INTO US WHEN HE SHOULD HAVE AVOIDED TO THE R AS PER RIGHT OF WAY RULES. I WOULD REALLY LIKE TO TALK WITH THAT PLT. THIS HAS BEEN RPTED TO OUR FAA INSPECTOR VIA MY DIRECTOR OF OPS. SUPPLEMENTAL INFO FROM ACN 371870: I RAN THE LIFEGUARD UNDERNEATH THE SEA FINAL AGAIN WITH A POINTOUT WHEN C500 SAID HE HAD THE ARPT AND WAS REQUESTING A VISUAL. WX WAS OK, BUT NOT GOOD ENOUGH TO VECTOR FOR THE VISUAL RWY 13R AT BOEING FIELD. I QUICK CHKED THE WX AT BFI AND CLRED C500 FOR THE VISUAL APCH TO RWY 13R AT BFI. I WAS ALSO RESPONSIBLE FOR FEEDING THE SEA FINAL CTLR AS OUR 4 CORNER POST SYS DICTATED. I NEEDED TO TURN A B757 TO THE DOWNWIND FOR SEA. AFTER DOING THAT I WENT RIGHT BACK TO THE LIFEGUARD AND OBSERVED A VFR DISCRETE CODE (TFC WATCH C172) UNDER THE MAZE OF DATA BLOCKS. I ATTEMPTED TO ISSUE THE TFC BUT WASN'T TIMELY ENOUGH. WE AREN'T REQUIRED TO QUICK LOOK THESE TARGETS AS THEY ARE USUALLY NEVER A FACTOR TO US AS WE ARE ALWAYS ABOVE THEM. LIFEGUARD SAID AFTER I ISSUED THE TFC THAT HE HAD JUST DODGED THAT ONE. I HAD ASKED HIM TO TURN FINAL N OF THE SPACE NEEDLE TO SPACE HIMSELF BEHIND AN AC50. HE DSNDED RAPIDLY FROM 2200 FT TO 1500 FT. THE TFC WATCH CESSNA WAS AT 1600 FT. I ASKED C500 IF HE WAS IN VFR CONDITIONS, HE REPLIED AFFIRMATIVE. ALTHOUGH I PRIDE MYSELF ON TIMELY/PERTINENT TFC CALLS, THIS ONE GOT BY ME. WORKLOAD PREVENTED ME FROM SEEING THE CESSNA IN A TIMELY MANNER. THE LIFEGUARD'S QUICK DSCNT FROM 2200 FT DIDN'T HELP. I'M SURE HE WAS TRYING TO KEEP BFI IN SIGHT CLR OF CLOUDS.

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.