CARGO ACFT ON APCH TO BTV RECEIVES A GPWS WHILE IMC.

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FLT FROM ABE TO BTV HAD BEEN CLRED DOWN TO 2000 FT AND CLRED TO HDG 330 DEGS TO INTERCEPT THE 216 DEG RADIAL. WE HAD THEN BEEN CLRED FOR THE VOR OR GPS RWY 1 APCH CIRCLE TO LAND RWY 33 AT BTV. WE WERE IMC AT THE TIME WITH LIGHT TO MODERATE RIME ICE. WE INTERCEPTED THE RADIAL INBOUND AND AT 9 DME FROM BTV I SET UP ABOUT A 300-500 FPM DSCNT DOWN TO 1700 FT. AS SOON AS I PUSHED THE NOSE GEAR OVER THE GPWS ALERTED; 'TOO LOW; TERRAIN; WHOOP WHOOP; PULL UP!' WE THEN PROCEEDED TO EXECUTE THE MISSED APCH. I BELIEVE THERE IS A 'HILL' VERY CLOSE TO THAT POS ON THE APCH AND EVEN THOUGH THE CAPT IOE STUDENT (SITTING IN THE L SEAT); NOR I EVER SAW LESS THAN 1000 FT ON THE RADAR ALTIMETER; I BELIEVE THAT IS WHAT SET OFF THE WARNING. I BELIEVE THE BEST CORRECTIVE ACTION WOULD BE FOR THE CTLR TO NOT GIVE QUITE SO LOW AN INITIAL ALT TO START THE APCH. THE APCH CHART CALLS FOR 2700 FT UNTIL 10 MI FROM THE VOR; THEN DOWN TO 1700 FT. MAYBE AN ALT CLOSER TO PUBLISHED WOULD BE IN ORDER SO THAT YOU AREN'T QUITE SO CLOSE TO THE HILL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE PIC DID TALK WITH THE APCH CTLR REGARDING THIS GPWS ACTIVATION. ALTHOUGH THE CTLR DID MENTION THAT ANOTHER ACR HAD A SIMILAR EXPERIENCE A WK BEFORE; HE DID NOT ACT AS THOUGH THERE WAS ANY PROB WITH THE APCH OR ALT CLRNC. RPTR DID NOT PRESS ON HIM FOR A RESOLUTION TO THIS INCIDENT. HE HAS NOT HAD THIS HAPPEN TO HIM ON ANY PREVIOUS APCHS INTO BTV. HIS ACR WAS NOTIFIED OF THE EVENT. RPTR IS A CHK PLT AND HAD A STUDENT CAPT IN TRAINING IN THIS B727-100F. THE STUDENT CAPT'S RESPONSE TO THE GPWS WAS AN INSTANT PULL UP; GAR MANEUVER.