ACR MLG ALT DEV EXCURSION FROM CLRNC ALT IN RESPONSE TO TCASII RA.

Narrative

WE WERE ON THE BUZZY 4 ARR; APCHING THE RDU ARPT; AT 8000 FT; 250 KTS; AND I WAS FLYING THE ACFT. RALEIGH APCH CTL ADVISED US TFC WAS AT 7500 FT; 10 O'CLOCK; AND 5 MI. WE SAW THE TFC APCHING US ON OUR TCASII DISPLAY SCREEN 500 FT BELOW US. BOTH THE CAPT AND I WERE TRYING TO VISUALLY IDENT THE APCHING TFC. I WAS HAND FLYING THE ACFT AT THE TIME. AS THE OTHER ACFT CAME CLOSER; THE TCAS GAVE US A TA BY ANNOUNCING 'TFC; TFC'. SHORTLY AFTER THAT; THE OTHER ACFT BEGAN CLBING AS HE APCHED US. THE TCASII THEN GAVE US AN RA BY ANNOUNCING 'MONITOR VERT SPD; MONITOR VERT SPD'. QUICKLY I CHKED THE RA/VERT SPD INDICATOR (RA/VSI); WHICH ADVISED US NOT TO DSND. I THEN GLANCED AT THE TCAS DISPLAY SCREEN AND; IN DISBELIEF; OBSERVED THAT THE OTHER ACFT WAS CLBING. WITHIN SECONDS THE TCASII ANNOUNCED; 'CLB; CLB; CLB'. I CHKED THE RA/VSI WHICH WAS INDICATING ABOUT A 4000-5000 FPM CLB. I SLAMMED BOTH THROTTLES TO THEIR STOPS AND RAPIDLY PULLED THE NOSE UP. WE CLBED TO 8400 FT THEN TCASII ANNOUNCED; 'CLR OF CONFLICT'. I IDLED BOTH ENGS AND DSNDED BACK TO 8000 FT WHILE THE CAPT ADVISED RALEIGH APCH OF OUR DEV. NEITHER THE CAPT NOR I EVER SAW THE OTHER ACFT. AS FAR AS VERT SEPARATION GOES; LAST TIME I LOOKED AT THE TCAS DISPLAY SCREEN; THE OTHER ACFT WAS 300 FT BELOW US AND STILL CLBING. I AM NOW A FIRM BELIEVER OF THE TCASII SYS. I HATE FLYING WITHOUT IT.