AERO COMMANDER 560E, N3827C (27C), WAS RETURNING FROM BLAIRSTOWN WHERE IT HAD BEEN FLOWN FOR MINOR MAINT. THE PLT WAS ON AN IFR FLT PLAN, CLEARED BY NEW YORK TRACON TO PROCEED AT 2000 FT MSL ON A RADAR VECTOR OF 170 DEG FOR AN ILS APCH TO THE TETERBORO ARPT. THE ACFT WAS EQUIPPED WITH AN ALT ENCODING TRANSPONDER THAT WAS BEING USED. THE PLT WAS ADVISED OF NUMEROUS TARGETS AT HIS 12 O'CLOCK POSITION. AT APRX THE SAME TIME, CESSNA 182Q, N96402 (402), WAS ON A FLT FROM THE KUPPER ARPT TO RAMAPO ARPT. A DIRECT ROUTE BETWEEN THESE ARPTS WOULD HAVE INTERSECTED THE NW EDGE OF THE NEW YORK TCA WHERE POSITIVE CONTROL BEGAN BETWEEN 1800 & 7000 FT MSL. THE PLT WAS PROCEEDING VFR WITH NO FLT PLAN & WAS NOT IN RADIO COMM WITH ANY ATC FACILITY. 402 WAS EQUIPPED WITH A TRANSPONDER THAT WAS OPERATING, BUT HAD NO ALT ENCODING CAPABILITY. AS THE ACFT CONVERGED, 402 WAS ON A NORTHEASTERLY HEADING. THE PLANES COLLIDED ABOUT 1 MI INSIDE THE TCA. THEN IMPACTED THE GROUND APRX 1500 FT APART. A MAP WAS FOUND IN 402 WITH A LINE DRAWN BETWEEN THE ARPTS & INTERSECTING THE TCA.