HILLS E OF RWY 25 CAUSE GPWS ALARM RESULTING IN PULL-UP.

Narrative

ON VISUAL APCH TO RWY 25 GEG; GOT 'TERRAIN; TERRAIN' ALERT. PULLED UP TO SILENCE ALERT. ON 070 DEG RADIAL INBOUND GEG AT 7000 FT; WITHIN 10 MI; DSNDED FROM 7000 FT TO 4100 FT. AT ALT CAPTURE GOT PULL-UP. GND AND RWY IN SIGHT. SHOULD HAVE PASSED 1000 FT ABOVE TWR AT 3100 FT AND PASSED ABOUT 1 MI N OF TWRS AT 4500 FT ON FINAL APCH TO RWY 25. VERY DIFFICULT TO FLY TRANSPORT CATEGORY ACFT ON NORMAL APCH FOR STRAIGHT IN RWY 25 GET. SEA APCH SHOULD ADVISE ACFT BEING VECTORED FOR VISUAL STRAIGHT IN RWY 25 GEG OF HIGH OBSTRUCTIONS. ACFT WITHOUT PROPER CHARTS COULD HIT TWRS IF UNAWARE OF THESE. THE TWRS ARE ONLY NOTED ON ILS 21 CHART. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THEY WERE CLRED TO 7000 FT ON THE GEG 070 DEG RADIAL TO RPT THE FIELD IN SIGHT. UPON SIGHTING THE ARPT THEY WERE CLRED FOR A VISUAL APCH. AT THAT TIME THEY TURNED S OF THE RADIAL AND DSNDED TO 4100 FT. UNABLE TO FIND OUT WHY 4100 FT. THE GPWS CAUSED A MANDATORY PULL-UP EVEN THOUGH THEY HAD THE OBSTRUCTION IN SIGHT. RWY 21 WAS CLOSED.