Narrative:

We were being vectored from metropolitan intersection to the VOR B approach at teb. We were cleared to descend from 8000' to 3000'. Descending through 5000' we were given 'stop descent at 4500' turn left heading 300 degree for traffic.' my copilot reset the altitude sel to 4500', I verified altitude arm/capture and rolled the heading bug to 300 degree. As the aircraft leveled at 4500' I added power and looked inside to verify north, when I looked up again small aircraft Y was virtually motionless in my windshield at our altitude. As my aircraft was starting to roll out of the turn I rolled back into a 035 degree to 040 degree left bank and turned 15 to 20 degrees by the assigned heading. Aircraft Y passed off our right side with not more than 100' lateral sep. As I recall the controller issued 'traffic in your turn at 12 O'clock' at the same time I saw aircraft Y. I wish the traffic would have been issued before the turn. Had I seen the traffic earlier I could have been part of the decision process rather than just reacting to a controller created situation. Any solution, other than turning at the target, would have been safer. Callback conversation with reporter revealed following information. There was no review with ATC after landing, and reporter flight crew did not file near midair collision report with FAA. Says aircraft Y was still outside of TCA and controller was following target to see if TCA was penetrated. Aircraft Y was unknown VFR traffic. Aircraft X northbound and Y was nebnd. X passed slightly behind Y after evasive maneuver.

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Original NASA ASRS Text

Title: NMAC BETWEEN CORP JET AND UNKNOWN SMALL ACFT.

Narrative: WE WERE BEING VECTORED FROM METRO INTXN TO THE VOR B APCH AT TEB. WE WERE CLRED TO DSND FROM 8000' TO 3000'. DSNDING THROUGH 5000' WE WERE GIVEN 'STOP DSCNT AT 4500' TURN L HDG 300 DEG FOR TFC.' MY COPLT RESET THE ALT SEL TO 4500', I VERIFIED ALT ARM/CAPTURE AND ROLLED THE HDG BUG TO 300 DEG. AS THE ACFT LEVELED AT 4500' I ADDED PWR AND LOOKED INSIDE TO VERIFY N, WHEN I LOOKED UP AGAIN SMALL ACFT Y WAS VIRTUALLY MOTIONLESS IN MY WINDSHIELD AT OUR ALT. AS MY ACFT WAS STARTING TO ROLL OUT OF THE TURN I ROLLED BACK INTO A 035 DEG TO 040 DEG L BANK AND TURNED 15 TO 20 DEGS BY THE ASSIGNED HDG. ACFT Y PASSED OFF OUR R SIDE WITH NOT MORE THAN 100' LATERAL SEP. AS I RECALL THE CTLR ISSUED 'TFC IN YOUR TURN AT 12 O'CLOCK' AT THE SAME TIME I SAW ACFT Y. I WISH THE TFC WOULD HAVE BEEN ISSUED BEFORE THE TURN. HAD I SEEN THE TFC EARLIER I COULD HAVE BEEN PART OF THE DECISION PROCESS RATHER THAN JUST REACTING TO A CTLR CREATED SITUATION. ANY SOLUTION, OTHER THAN TURNING AT THE TARGET, WOULD HAVE BEEN SAFER. CALLBACK CONVERSATION WITH RPTR REVEALED FOLLOWING INFO. THERE WAS NO REVIEW WITH ATC AFTER LNDG, AND RPTR FLT CREW DID NOT FILE NMAC RPT WITH FAA. SAYS ACFT Y WAS STILL OUTSIDE OF TCA AND CTLR WAS FOLLOWING TARGET TO SEE IF TCA WAS PENETRATED. ACFT Y WAS UNKNOWN VFR TFC. ACFT X NBOUND AND Y WAS NEBND. X PASSED SLIGHTLY BEHIND Y AFTER EVASIVE MANEUVER.

Data retrieved from NASA's ASRS site as of August 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.