ACR X DSCNT BELOW MINIMUM VECTORING ALT RECEIVED GPWS WARNING CLB. SYS ERROR.

Narrative

DURING TERMINAL PHASE OF FLT PRIOR TO LNDG ON RWY 32 AT PIT TERRAIN WARNING ALERT TRIGGERED. ACR X BEING VECTORED FOR A VISUAL APCH TO RWY 32 AT PIT. THERE WERE RAINSHOWERS AND WX ACTIVITY TO THE E OF PIT AND ACFT WERE BEING VECTORED FOR VISUAL APCHS TO RWY 32. I WAS OUTSIDE OF WYLER TO THE E OF THE FINAL APCH COURSE. I WAS GIVEN A WESTERLY HDG WITH THE FIELD IN SIGHT AND CLRED TO DSND TO 2000 FT. I STARTED A DSCNT AND WHILE PASSING THROUGH 3000 THE TERRAIN WARNING ALERTED. I INITIATED A CLB WHICH SILENCED THE ALERT; THEN WAS CLRED FOR A VISUAL APCH. SUPPLEMENTAL INFO FROM ACN 244403: ACR X ARRIVED IN THE GREATER PIT AREA AND WAS RECEIVING RADAR VECTORS FROM PIT APCH CTL FOR AN ILS/VISUAL TO RWY 32. WE WERE CLRED TO 2000; IN WHICH WE READ BACK ACR X OUT OF 4000 FOR 2000. AT APPROX 2200 WE GOT A GPWS WARNING. I INSTRUCTED FO TO CLB. JUST AS WE BEGAN OUR CLB; WHAT I BELIEVE WAS A DIFFERENT CTLR SAID MAINTAIN 2500 CLRED FOR THE ILS 32. WE LANDED; TAXIED IN. NO COMMENTS WERE MADE NOR RECEIVED FROM ATC.