Narrative:

During a vectored approach to the ILS runway 16R at seatac, we informed sea approach control we had both traffic and the airport in sight. We were told to expect a visual approach to runway 16R following B757 traffic. After receiving an assigned heading and altitude of 3000 ft we were informed we would now be cleared for a visual approach to runway 16L. The air carrier B757 was then cleared for the visual approach to runway 16R. Our flight was approaching from the west, B757 flight approaching from the east. We accepted the visual approach. In order to line up for final it was necessary for both planes to cross over one another's paths and land on opposite runways. We were instructed to follow the B757. The diverging and eventually crossing flight path would have crossed me directly under the B757's flight path at a too dangerous distance. To avoid imminent wake turbulence, I initiated a climb. To avoid the wake, this climb took me as high as 4300 ft before I felt it was safe to begin a descent for my runway. We failed to inform sea approach of our intentions, and was never queried about them. We switched to seatac tower and completed the approach. The problem was not with the B757, rather an air carrier MD80 on a vectored approach for runway 16R, 3 mi in trail at 4000 ft. MD80 asked sea approach if we were climbing. Sea approach responded, 'apparently so, the beechcraft traffic is 3 mi ahead at 1 O'clock.' once MD80 verified he had us in sight, they were cleared for the visual approach to runway 16R. Our failure to notify ATC of our intentions, to climb and avoid the wake turbulence, caused a brief traffic separation problem until it was confirmed MD80 had us in sight the entire time.

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Original NASA ASRS Text

Title: COMMUTER BE02 ON A VECTOR FOR VISUAL TO RWY 16R ADVISED HAD TFC AND ARPT IN SIGHT. CLRED VISUAL TO RWY 16L AND B757 CLRED VISUAL RWY 16R. B757 APCHING FROM THE E AND BE02 FROM THE W. BE02 AT 3000 FT ELECTED TO CLB TO CLR JET WASH OF THE B757, BUT FAILED TO ADVISE CTLR. MD80 FOLLOWING BE02 QUERIED CTLR AS TO THE CLB THROUGH HIS ALT 4000 FT. SINCE TFC IN SIGHT OK TO CONTINUE THE VISUAL TO RWY 16L. NO COMMENT FROM CTLR TO BE02.

Narrative: DURING A VECTORED APCH TO THE ILS RWY 16R AT SEATAC, WE INFORMED SEA APCH CTL WE HAD BOTH TFC AND THE ARPT IN SIGHT. WE WERE TOLD TO EXPECT A VISUAL APCH TO RWY 16R FOLLOWING B757 TFC. AFTER RECEIVING AN ASSIGNED HDG AND ALT OF 3000 FT WE WERE INFORMED WE WOULD NOW BE CLRED FOR A VISUAL APCH TO RWY 16L. THE ACR B757 WAS THEN CLRED FOR THE VISUAL APCH TO RWY 16R. OUR FLT WAS APCHING FROM THE W, B757 FLT APCHING FROM THE E. WE ACCEPTED THE VISUAL APCH. IN ORDER TO LINE UP FOR FINAL IT WAS NECESSARY FOR BOTH PLANES TO CROSS OVER ONE ANOTHER'S PATHS AND LAND ON OPPOSITE RWYS. WE WERE INSTRUCTED TO FOLLOW THE B757. THE DIVERGING AND EVENTUALLY XING FLT PATH WOULD HAVE CROSSED ME DIRECTLY UNDER THE B757'S FLT PATH AT A TOO DANGEROUS DISTANCE. TO AVOID IMMINENT WAKE TURB, I INITIATED A CLB. TO AVOID THE WAKE, THIS CLB TOOK ME AS HIGH AS 4300 FT BEFORE I FELT IT WAS SAFE TO BEGIN A DSCNT FOR MY RWY. WE FAILED TO INFORM SEA APCH OF OUR INTENTIONS, AND WAS NEVER QUERIED ABOUT THEM. WE SWITCHED TO SEATAC TWR AND COMPLETED THE APCH. THE PROB WAS NOT WITH THE B757, RATHER AN ACR MD80 ON A VECTORED APCH FOR RWY 16R, 3 MI IN TRAIL AT 4000 FT. MD80 ASKED SEA APCH IF WE WERE CLBING. SEA APCH RESPONDED, 'APPARENTLY SO, THE BEECHCRAFT TFC IS 3 MI AHEAD AT 1 O'CLOCK.' ONCE MD80 VERIFIED HE HAD US IN SIGHT, THEY WERE CLRED FOR THE VISUAL APCH TO RWY 16R. OUR FAILURE TO NOTIFY ATC OF OUR INTENTIONS, TO CLB AND AVOID THE WAKE TURB, CAUSED A BRIEF TFC SEPARATION PROB UNTIL IT WAS CONFIRMED MD80 HAD US IN SIGHT THE ENTIRE TIME.

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.