Narrative:

While wbound at 12000 ft, ZNY provided a position report of an HS125 at my 3 O'clock and approximately 10 mi, descending from 13000 ft to 11000 ft. I picked up the HS125 visually and reported such to center. I was given a 'maintain visual separation' instruction by center and heard center clear the jet to 11000 ft while also providing a position report on myself. The jet pilot acknowledged the clearance, but did not report me in sight. I continued to track the jet and at about 4 mi separation determined that his descent might take him through my altitude at a very close range. Due to frequency congestion, I was unable to communicate this concern with center. As the jet was converging on me at a right angle, in a descent, I felt that neither a climb nor descent would be the safest action to take and initiated a sharp, right turn into the jet. This was initiated in order to maintain visual contact with the jet at all times. Having completed a 90 degree turn to the right, the jet passed slightly above my altitude (500 ft vertical separation, and about 400 ft horizontal separation) and off my left wing. The jet appeared to make no corrections or deviations in his descent to avoid me. I returned to original heading, contacted the center and informed them of my deviation. Later, I asked the controller how close our separation was on his screen. His reply was, 'very close.' conclusions: 1) should not have accepted a visual separation with a crossing traffic which would descend through my altitude. 2) might have asked controller to hold the jet at 13000 ft until he was closer, or had me in sight. 3) even on an IFR plan, visual separation is still the pilot's responsibility.

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Original NASA ASRS Text

Title: PLT OF AN SMT TWIN TOOK EVASIVE ACTION BY TURNING IN ORDER TO MAINTAIN SUFFICIENT SEPARATION. NMAC.

Narrative: WHILE WBOUND AT 12000 FT, ZNY PROVIDED A POS RPT OF AN HS125 AT MY 3 O'CLOCK AND APPROX 10 MI, DSNDING FROM 13000 FT TO 11000 FT. I PICKED UP THE HS125 VISUALLY AND RPTED SUCH TO CTR. I WAS GIVEN A 'MAINTAIN VISUAL SEPARATION' INSTRUCTION BY CTR AND HEARD CTR CLR THE JET TO 11000 FT WHILE ALSO PROVIDING A POS RPT ON MYSELF. THE JET PLT ACKNOWLEDGED THE CLRNC, BUT DID NOT RPT ME IN SIGHT. I CONTINUED TO TRACK THE JET AND AT ABOUT 4 MI SEPARATION DETERMINED THAT HIS DSCNT MIGHT TAKE HIM THROUGH MY ALT AT A VERY CLOSE RANGE. DUE TO FREQ CONGESTION, I WAS UNABLE TO COMMUNICATE THIS CONCERN WITH CTR. AS THE JET WAS CONVERGING ON ME AT A R ANGLE, IN A DSCNT, I FELT THAT NEITHER A CLB NOR DSCNT WOULD BE THE SAFEST ACTION TO TAKE AND INITIATED A SHARP, R TURN INTO THE JET. THIS WAS INITIATED IN ORDER TO MAINTAIN VISUAL CONTACT WITH THE JET AT ALL TIMES. HAVING COMPLETED A 90 DEG TURN TO THE R, THE JET PASSED SLIGHTLY ABOVE MY ALT (500 FT VERT SEPARATION, AND ABOUT 400 FT HORIZ SEPARATION) AND OFF MY L WING. THE JET APPEARED TO MAKE NO CORRECTIONS OR DEVS IN HIS DSCNT TO AVOID ME. I RETURNED TO ORIGINAL HDG, CONTACTED THE CTR AND INFORMED THEM OF MY DEV. LATER, I ASKED THE CTLR HOW CLOSE OUR SEPARATION WAS ON HIS SCREEN. HIS REPLY WAS, 'VERY CLOSE.' CONCLUSIONS: 1) SHOULD NOT HAVE ACCEPTED A VISUAL SEPARATION WITH A XING TFC WHICH WOULD DSND THROUGH MY ALT. 2) MIGHT HAVE ASKED CTLR TO HOLD THE JET AT 13000 FT UNTIL HE WAS CLOSER, OR HAD ME IN SIGHT. 3) EVEN ON AN IFR PLAN, VISUAL SEPARATION IS STILL THE PLT'S RESPONSIBILITY.

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.