TCASII. VFR TFC IN BUSY CLB AREA.

Narrative

DEPARTING RWY 13; LGA (WHITESTONE CLB); DEP TURNED US W AND CLRED US TO 15000 FT. AS WE SWITCHED TO 120.4; WE WERE TOLD TO CLB TO 13000 FT AND ADVISED OF VFR TFC AT 10 O'CLOCK CIRCLING. AS WE APCHED 11600 FT ATC ASKED IF LEAR TFC WAS DSNDING. WE IMMEDIATELY GOT A TCASII RA; AND WERE TOLD BY TCASII TO DSND AT 2000 FPM DOWN. IMMEDIATE ACTION BY US WAS NEEDED TO AVOID A MAJOR CONFLICT AS THIS VFR LEAR JET DSNDED THROUGH OUR ALT. WE WERE NOT TOLD OF VFR TFC TYPE OR ALT. WAS THE LEAR ASSIGNED A HARD ALT? WE WERE ONLY ON 120.4 A FEW SECONDS BEFORE ALL THIS HAPPENED. WE NEVER GOT ALL THE INFO FROM ATC TO AVOID A CLOSE CONFLICT. HATS OFF TO TCASII. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: WHILE ON THE WHITESTONE CLB FROM LGA JUST AFTER A FREQ CHANGE; ATC ADVISED FLC OF VFR TFC AT 10 O'CLOCK. THEN; IN AN EXCITED VOICE ASKED RPTR IF THE LEAR WAS DSNDING. SIMULTANEOUSLY RPTR ACFT RECEIVED TCASII RA WITH A DSND COMMAND. RPTR SAYS THAT TCASII SAVED THEM AND TO INSURE THE WORD IS PASSED WHAT A GREAT SYS TCASII IS. RPTR WAS ALSO VERY SURPRISED THAT THERE WOULD BE VFR TFC IN THE VERY BUSY CLB CORRIDOR FROM NY.