RPTR'S ACFT GPWS ACTIVATED IN AN AREA OF KNOWN HIGH TERRAIN.

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COMING FROM THE W FOR ILS RWY 34R AT SLC; SOUNDED LIKE IT COULD HAVE BEEN A CTLR IN TRAINING. ALMOST DIRECTLY OVER FFU VOR; HEADED FOR 'PLAGE' FIX ON ILS RWY 34R; I WAS CLRED TO 9000 FT MSL. CAPT REMARKED HOW HE'D NEVER BEEN SO LOW 30 DME OUT. SHORTLY AFTER DSCNT INITIATED; GOT 'TERRAIN; TERRAIN' WARNING; FOLLOWED IMMEDIATELY BY 'PULL UP! PULL UP!' FROM GPWS. I HIT TOGA PWR AND CLBED TO ABOUT 10300 FT. CAPT NOTIFIED ATC AND THEY HAD US LEVEL AT 10000 FT. CLRED FOR ILS RWY 34R WITH UNEVENTFUL LNDG. I'M NOT SURE OF THE LOGIC DSNDING US SO EARLY. APCH PLATE SAYS 10500 FT OVER FFU AND 10500 FT (9000 FT WHEN AUTH BY ATC) AT PLAGE. I CAN'T TELL YOU HOW UNCOMFORTABLE IT IS TO HEAR 'PULL UP' IN CLOUDS WITH MOUNTAINS IN PROX. I RECOMMEND NOT DSNDING ACFT BELOW 10500 FT UNTIL PLAGE INTXN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: TALKING TO SLC TRACON REVEALED THAT THEY HAVE RECEIVED MANY COMPLAINTS ABOUT ACFT GPWS BEING ACTIVATED IN THE SAME GENERAL AREA WHILE BEING VECTORED TO THE SLC FINAL RWY 34R. BTWN THE FFU VOR AND PLAGE; CTLRS HAVE THE OPTION TO USE 9000 FT. THIS IS DEPICTED ON THE CHARTS. ZLC HAS HAD THE TERRAIN CLRNC ALTS CHKED MANY TIMES AS A RESULT OF THESE COMPLAINTS; AND HAVE FOUND NOTHING WRONG. THE MVA IN THIS AREA VARIES BTWN 8000-9000 FT. THE MAX HT OF THE TERRAIN ON EITHER SIDE OF THE FINAL APCH COURSE IN THE VICINITY OF PLAGE IS 6682 FT ON THE E SIDE AND 6824 FT ON THE W SIDE. ONE REASON FOR SO MANY GPWS ACTIVATIONS IS THE RIDGE LINE JUST INSIDE OF PLAGE. IN THIS AREA; WE HAVE A RAPIDLY RAISING TERRAIN TO A POINT 2000 FT ABOVE THE FLOOR OF THE VALLEY. CALLBACK TO RPTR REVEALED THAT HIS ACFT WAS EQUIPPED WITH THE OLDER GPWS. HE BELIEVES THAT HIS GPWS WAS ACTIVATED BY RAPIDLY RAISING TERRAIN AND A HIGH RATE OF DSCNT. RPTR STATED THE SCARY PART OF THIS WAS THEY WERE IN THE CLOUDS WHEN THEIR GPWS WENT OFF.