ACR X TCASII TA RA EVASIVE ACTION TAKEN STOPPED DSCNT FROM VFR Y.

Narrative

ACR X ON APCH TO EWR ESTABLISHED ON THE LOC RWY 4R APPROX 10 MI FROM THE RWY; WE RECEIVED A TA ON THE TCASII INDICATING AN INTRUDER AT 11:30 O'CLOCK AND 500 FT BELOW US. OUR ALT WAS 2000 FT MSL AND JUST STARTING TO BEGIN OUR DSCNT ON THE GS. THE FORWARD DISTANCE OF THE INTRUDER WAS APPROX 2 1/2 MI AND APCHING OUR 12 O'CLOCK AND MAINTAINING HIS ALT 500 FT BELOW US. THE FO REMAINED AT 2000 INSTEAD OF INTERCEPTING THE GS. THE TCASII THEN GAVE US A YELLOW TA FOLLOWED IMMEDIATELY BY A RED RA WITH A PREVENTIVE VOICE RESPONSE OF 'MONITOR VERT SPD.' NO EVASIVE ACTION HAD TO BE TAKEN EXCEPT FOR NOT DSNDING ON THE GS. THE INTRUDER PASSED DIRECTLY BELOW US AT 500 FT AS INDICATED ON THE TCASII. WE NEVER GOT A VISUAL CONTACT ON THE INTRUDER Y. I NOTIFIED EWR TWR OF THE TFC AND HIS ONLY REPLY WAS 'IT'S JUST A HELI.' I EMPHASIZED THAT THE TFC PASSED WITHIN 500 FT. I CALLED THE TWR CHIEF AFTER I ARRIVED AT THE TERMINAL AND EXPLAINED THE WHOLE SITUATION. HE TOOK ALL THE INFO AND SAID HE WOULD FILE A RPT AND TALK WITH THE TWR CTLR ON DUTY. EITHER THE APCH CTLR OR THE TWR CTLR OR BOTH SHOULD HAVE WARNED US OF THE HELI TFC IN OUR FLT PATH AND NOT HAVE GIVEN US CLRNC TO INTERCEPT THE GS UNTIL WELL CLR OF THE TFC; OR VECTOR THE TFC AWAY FROM OUR FLT PATH. TCASII DEFINITELY SAVED US FROM A VERY NEAR COLLISION.