A C210 PLT IS VECTORED TOO CLOSE BY THE N90 APCH CTLR TO AN APCHING MD80. BOTH ACFT LNDG AT ISLIP; NY.

Narrative

MY ACFT CESSNA CENTURION T210M WAS VFR TO LONG ISLAND'S MCARTHUR ARPT (ISP) UNDER NY TRACON APCH CTL. AFTER DEPARTING EAST HAMPTON; NY; (HTO) MY HEADING WAS 270 DEGS AND ALT OF 3000 FT. 10 MI FROM ISP I WAS ASSIGNED A HEADING OF 220 DEGS AND TOLD TO DSND TO 2000 FT AND WAS ADVISED I WOULD FOLLOW AN MD80 TO LAND RWY 33L. AT 7 MI I WAS TOLD TO FLY 270 DEGS AND MAINTAIN 2000 FT. AS I COMMENCED MY TURN I SAW THE MD80 TO MY 10 O'CLOCK POS 1/2 MI HORIZLY AWAY AND AT 2500 FT (CONFIRMED BY ATC AND MY TCASII). AS I BEGAN TO FEEL THE TURB OF HIS WINGTIP VORTICES AND TO MAINTAIN VISUAL CONTACT I TURNED PAST 270 DEGS. THE MD80 ADVISED HE HAD NO VISUAL CONTACT BUT HAD A TCASII READOUT. HAD I MAINTAINED 270 DEGS THERE WOULD HAVE BEEN A POSSIBLE COLLISION OR THE VORTICES WOULD HAVE THROWN ME INVERTED. ATC ADVISED ME TO CONTINUE MY R TURN INTO A 360 DEG TURN TO ALLOW THE MD80 TO DSND TO A LNDG ON RWY 33L (WIND 300 DEGS AT 15 KTS). ATC SHOULD HAVE MAINTAINED A 220 DEG HDG FOR ME UNTIL THE MD80 HAD PASSED PARALLEL TO ME. INSTEAD ATC TURNED ME TO 270 DEGS WHICH WAS PERPENDICULAR TO THE MD80 FLT PATH FORCING ME TO TAKE EVASIVE ACTION TO AVOID A COLLISION OR WAKE TURB UPSET.