GPWS WARNING ALERT WHILE ON RADAR VECTORS OVER DESIGNATED MOUNTAINOUS TERRAIN CAUSES ACR FLC TO EXECUTE A CLB CREATING AN ALTDEV ALT EXCURSION. RPT CITES GPWS AURAL INTERFERENCE AS DAMAGING TO INTER CREW COM AND ATC COM.

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WHILE WE WERE TRACKING IN ON THE SLC 34L LOC; THE SLC RVR WENT BELOW OUR CAT IIIA LNDG MINS. WE WERE INSTRUCTED TO CLB TO 8000 FT; AND TURN TO A HDG OF 180. AFTER WE WERE LEVEL AT 8000 FT; AND ON THE 180 HDG FOR SOME TIME; WE RECEIVED A CONTINUOUS TERRAIN WARNING FROM THE GPWS. THIS WAS OVER A COMPLETELY DARK AREA; AS OPPOSED TO AREAS TO THE E AND N OF US WHERE WE COULD SEE THE GLOW OF LIGHTS THROUGH THE FOG. I INITIATED A CLB AND THE FO ADVISED APCH CTL THAT WE WERE CLBING BECAUSE OF TERRAIN PROX WARNING; AND THAT WE NEEDED A HIGHER ALT IMMEDIATELY. THE APCH CTLR STATED THAT HE WAS PROVIDING TERRAIN CLRNC FOR US AND FOR US TO MAINTAIN 8000 FT. (THE APCH CTLR WAS ALSO VERY BUSY WITH SEVERAL OTHER ACFT IN THE AREA). HE GAVE US A TURN BACK TO THE NE TO INTERCEPT THE LOC. I TURNED TO THE DESIGNATED HDG AND DSNDED BACK TO 8000 FT FROM THE VICINITY OF THE 8400 FT THAT I HAD CLBED TO. THE FO SATED THAT HE HAD SEEN THE RADAR ALTIMETER INDICATING BTWN 1300-1400 FT AGL; AND THAT IT WAS DECREASING. WE WERE IN THE AREA JUST TO THE E OF THE OQUIRAH MOUNTAINS WITH NO OBSTRUCTION LIGHTS IN SIGHT AND WITH A KNOWN SPUR OF HIGH TERRAIN EXTENDING OUT TO THE E. PERHAPS A HIGHER VECTOR ALT WOULD BE APPROPRIATE IN THIS AREA. AT THIS POINT I WANT TO EMPHASIZE THAT THE GPWS WARNING WAS SO LOUD AS TO BE OVERPWRING. THIS MADE IT VERY DIFFICULT FOR US TO COMMUNICATE BOTH INSIDE AND OUTSIDE THE COCKPIT. WE HAD TO SHOUT TO EACH OTHER AND HAD GREAT DIFFICULTY UNDERSTANDING THE CTLR'S TFC AT 9000 FT. I COULD NOT UNDERSTAND IF HE WAS TALKING ABOUT TFC DIRECTLY ABOVE US; OR THE TFC THAT I COULD SEE IN THE DISTANCE AHEAD OF US. THE FO DID NOT CATCH THE TFC CALL AT ALL BECAUSE OF THE HIGH VOLUME OF THE TERRAIN WARNING. I HAVE ALWAYS THOUGHT THAT THE GPWS WARNINGS WERE TOO LOUD. OVERPWRING; AND TENACIOUS; AND THIS INSTANCE HAS CERTAINLY REINFORCED THAT FEELING. SUPPLEMENTAL INFO FROM ACN 201004: THE CTLR INSISTED THAT WE MAINTAIN 8000; BUT DID GIVE US A TURN TOWARD THE CTR OF THE VALLEY. WE TURNED; BUT IGNORED THE ALT INSTRUCTION AND CONTINUED THE CLB ENOUGH TO SILENCE THE GPWS WARNING. A CTLR'S EX POST FACTO STATEMENT THAT HE IS PROVIDING OBSTACLE CLRNC IS SMALL COMFORT WHEN 'WHOOP; WHOOP; PULL UP' IS RINGING IN ONE'S EAR. A CREW WITHOUT GPWS; UNFAMILIAR WITH THE COUNTRY; GIVEN NO LOST COM INSTRUCTION AND 'OVERLOOKED' FOR A FEW MI MIGHT HAVE PLOWED IN THE MOUNTAIN. REMEMBER FREIGHTER AT SLC SOME YRS AGO?