AN ACR MD80 CREW NEARLY RAN INTO A PEAK NEAR ANC AFTER A WX FACTOR RECENT FRONTAL PASSAGE IN DESIGNATED MOUNTAINOUS TERRAIN. EMER NOT DECLARED; BUT CORRECT EMER RESPONSE TO THE GPWS WARNING.

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40 MI FROM ANC OVER MOUNTAINS CLRED TO 7000 FT MSL BY ATC; ALTIMETER 29.07. VECTORS TO ANC. SLOW DSCNT TO 7000 FT. AT 7000 FT; RADAR ALTIMETER SHOWED 2500 FT; THEN 1500 FT. AT 800 FT 'TERRAIN' GPWS; I CLBED TO 7300 FT. IN CLB; RADAR ALTIMETER BOTH SIDES SHOWED 400 FT AGL WITH TERRAIN WARN. ADVISED TWR FREQ AFTER SIT. HE SAID ANOTHER ACR HAD SAME EXPERIENCE A FEW WKS EARLIER. SAID SHOWED US AT 7000 FT; THEN 7300 FT WITH TERRAIN IN THAT AREA 5300 FT. I SUSPECT BIG ALTIMETER DIFFERENCE BTWN ANC AND OVER THE MOUNTAINS SEEMS TO BE MAJOR PROB. INFORMED NATIONAL PLT'S UNION WHO HAS COORDINATED WITH ANC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS CONVINCED THAT THIS WAS NOT A FALSE ALARM. HE DID NOT GO TO HIS ACR OR HIS COMPANY UNION; BUT WENT TO A LARGER UNION OF WHICH HE IS AN ACTIVE MEMBER. THEY IMMEDIATELY CONTACTED ATC IN ALASKA WHICH PULLED THE TAPES ON THIS INCIDENT AND CONFIRMED EVERYTHING THAT THE RPTR ALLEGED. SINCE THIS TIME; ATC IN ALASKA HAS RAISED THE FLOOR ON THIS DSCNT PROC TO 8000 FT AND HAS ASKED FOR A FLT CHK OF THE RTE. THE RPTR ASKED WHY THERE WAS NO REMOTE ALTIMETER ON THE TOP OF THE MOUNTAIN AND GOT NO SATISFACTORY REPLY. A FRONT HAD PASSED THROUGH SHORTLY BEFORE THIS INCIDENT CAUSING A LARGE ALTIMETER CHANGE AT ANC. ALASKA ATC RPTED THAT THIS WAS THE THIRD TIME THAT AN ACR HAD THIS PROB ON THE SAME RTE.