ALTDEV FROM PUBLISHED ILS APCH.

Narrative

APCHING SAT WE RECEIVED THE ATIS AND THE WX WAS STATED AS VFR. WE CONCLUDED OUR PRELIMINARY LNDG CHKLIST WITH A VFR APCH BRIEFING. WHEN ZHU TURNED US OVER TO SAT APCH; APCH UPDATED THE WX AS 800 BROKEN; 3 MI VISIBILITY. I WAITED FOR THE PF TO UPDATE THE APCH BRIEF TO AN ILS APCH. WHEN IT WAS OBVIOUS HE WAS NOT GOING TO DO AN UPDATE; I BRIEFED THE APCH. SOON AFTER THE BRIEF; APCH GAVE US A 150 DEG HDG AND TOLD US TO MAINTAIN 3000 FT UNTIL ESTABLISHED AND CLRED FOR THE APCH AND TO CONTACT THE TWR. I CONFIRMED THE PF WAS IN APCH MODE AND LOOKED AT MY AUDIO PANEL TO CONFIRM THE ILS IDENT. WHEN I LOOKED BACK UP THE ALT WINDOW WAS SET AT 2000 FT AND WE WERE DSNDING. AT THE SAME TIME SAT TWR AND GPWS STARTED TO WARN US OF OUR ALT. AFTER SOME DIRECTION; THE PF INITIATED A PULL UP. HE ESTABLISHED OURSELVES ON THE GS AND CONTINUED THE APCH. I FEEL THE INCIDENT COULD HAVE BEEN AVOIDED IF THE PF HAD FOLLOWED ESTABLISHED PROCS. THE ALT AWARENESS PROGRAM AT OUR AIRLINE SAYS ANY TIME A NEW ALT IS ASSIGNED; THE ALT WINDOW WILL BE SET AND BOTH PLTS AGREE BEFORE AN ALT CHANGE IS MADE. THE PF TOOK IT UPON HIMSELF TO CHANGE THE ALT WINDOW TO 2000 FT AND START DOWN WITHOUT INCLUDING ME IN THE LOOP. THE PF WAS UNDER THE IMPRESSION THE APCH CTLR SAID TO MAINTAIN 2000 FT UNTIL ESTABLISHED. THE PF AGAIN SHOULD HAVE GIVEN A PROPER ILS BRIEF ONCE HE KNEW IT WAS IMC. EVEN THOUGH I GAVE THE BRIEF; HE WAS NOT PAYING ATTN AND DID NOT REALIZE THE IAF ALT WAS 3000 FT. THIS WAS A LINE CHK/TRAINING FLT. THE PF WILL BE BACK FOR MORE TRAINING BEFORE BEING RELEASED TO THE LINE.