AIR TAXI HAS NMAC AT CRUISE ABOVE TCA CEILING.

Narrative

ON A FLT FROM TRENTON; NJ (TTN) TO BEDFORD; MA (BED); WHILE OVER THE NEW YORK TCA; I HAD A NEAR MISS WITH AN ACR TWINJET. I HAD THE TFC IN SIGHT FOR SEVERAL SECONDS BEFORE WE CAME INTO CLOSE PROX AND WAS AWARE OF IT AS A THREAT; BUT EXPECTED IT TO EITHER LEVEL OFF OR MAKE A SLIGHT R TURN; ON ADVICE OF EITHER ATC OR TCASII. I BEGAN A L TURN BUT COULDN'T DSND MUCH AS I WAS AT 7500 FT MSL; ONLY 500 FT ABOVE THE CEILING OF THE TCA. I MAINTAINED SIGHT OF THE ACR AIRPLANE AND WAS CERTAIN IT WOULD MISS; BUT WE GOT CLOSER THAN I WOULD HAVE LIKED. CONTRIBUTING TO THIS OCCURRENCE WAS THE LOAD OF TFC WHICH PRECLUDED NEW YORK APCH FROM ISSUING THE VFR ADVISORIES I REQUESTED. I'M NOT SURE IF I SHOWED UP ON THE TCASII. I SUSPECT NOT; OTHERWISE ACR WOULD HAVE CHANGED HDG OR STOPPED THE CLB. XPONDER WAS ON AND REPLY LIGHT WAS FLASHING; THOUGH PERHAPS A BIT IRREGULARLY. ANOTHER FACTOR WAS MY PROX TO THE CEILING OF THE TCA WHICH LIMITED MY VERT AVOIDANCE OPTIONS. THE BIGGEST LESSON I LEARNED WAS TO KEEP EYES OUTSIDE THE COCKPIT WHEN VFR; ESPECIALLY IN CROWDED AIRSPACE AS MOST OF THE NE CORRIDOR IS; AND KEEP LIGHTS ON TO BE AS VISIBLE AS POSSIBLE.