POOR COCKPIT MGMNT AND COCKPIT RESOURCE MGMNT BY ACR FLC RESULTS IN ALT BUST AND GPWS BECAUSE OF TERRAIN CLOSURE.

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APCHING BOISE; ZLC KEPT US HIGH DUE TO TFC. THE FO WAS FLYING. HE IS NEW TO THE AIRLINE AND THE B727. THE FO IS AN EXPERIENCED PLT; HAVING FLOWN WITH 3 OTHER AIRLINES; THE LAST AS A CAPT. I BELIEVE HE HAS 100 HRS ON THE B727. THE FO GAVE ME THE PLANE AS HE BRIEFED THE APCH. WHILE HE WAS BRIEFING THE APCH WE WERE CLRED FROM 13000 FT TO 11000 FT. I ANSWERED THE ALT CHANGE BUT I DID NOT DSND. THIS PUT US FURTHER BEHIND. I DID NOT REALIZE UNTIL LATER THAT THE FO WAS USING HIS FLT DIRECTOR; WHICH WILL ONLY REVERSE SENSE. HE GOT OFF COURSE EARLY IN THE APCH; WHICH I CAUGHT RIGHT AWAY; AND VOICED A CORRECTION. HE WAS BEHIND THE AIRPLANE SO I WAS SUGGESTING FLAPS AND GEAR ACTIONS. SOON I NOTICED THAT WE WERE TO THE R OF COURSE; INSIDE THE 9.1 DME FIX AND AT 4700 FT. THE MINIMUM AT THIS POINT IS 4900 FT. I BELIEVE I TOOK THE PLANE JUST BEFORE OR JUST AFTER THE GPS WARNING WENT OFF. I ONLY REMEMBER ONE VOICE WARNING. I KNOW THAT I BANKED L; SAW THE GND BELOW OUT MY SIDE WINDOW; THEN SAW THE GND; ARPT AND RWY OUT IN FRONT. I WAS ON WHAT LOOKED LIKE A NORMAL VFR APCH; NORMAL RATE OF DSCNT; NORMAL SPD; AND NORMAL THRUST SETTING. I BELIEVE THAT ALL 3 OF US WERE BEHIND. ON REVIEWING MY ACTIONS I COULD HAVE ASKED CTR FOR DSCNT AT THE APPROPRIATE TIME; THIS WOULD HAVE GIVEN US THE TIME TO BRIEF EARLIER AND TALKED ABOUT THE PROPER INST SETUP. I THINK THAT I SENSED THAT THE FO WAS BEHIND AND I WAS TRYING TO DO EVERYTHING MYSELF. RUSHING OR BEING BEHIND HAS NO PLACE IN THE COCKPIT. THE PROPER ACTION WOULD HAVE BEEN TO ABANDON THE APCH; GO AROUND AND DO THE APCH SETUP PROPERLY.