CJ ON ILS INTERCEPT VECTOR DEPARTS CLEARED ALT PRIOR TO GS CAPTURE. LOW ALT ALERT RESULTS FOLLOWED BY A TRACK DEVIATION REQUIRING ATC INTERVENTION.

Narrative

I WAS SIC AND PNF DURING THIS LEG. WE WERE VECTORED IN IMC FOR OUR DSCNT INTO SAC. WE WERE GIVEN A TURN THROUGH FINAL AND THEN THE CTLR ASKED IF WE NEEDED ANOTHER TURN BACK TO FINAL. I TOLD HIM YES AND HE GAVE US THE HDG TO INTERCEPT FINAL; AN ALT OF 1500 FT UNTIL ESTABLISHED AND 'CLRED FOR THE ILS RWY 2 APCH SAC.' WE WERE CONTINUING ON THE APCH WHEN THE PIC ANNOUNCED THAT WE WERE NOT INTERCEPTING GS. I DOUBLECHKED THAT WE WERE INDEED BELOW GS WHERE WE WANTED TO BE SO THAT WE COULD INTERCEPT GS; WHICH WE WERE SO I FIGURED THAT WE WOULD PICK IT UP. IN REFING THE CHART; WE DISCUSSED THAT WE SHOULD HAVE INTERCEPTED GS AT 1347 FT AND WE WERE STILL AT 1500 FT WITH AN INDICATION ON OUR PFD THAT WE WERE UNDER THE GS STILL WHILE WE WERE IN IMC WITH RAIN; AND POOR VISIBILITY. COURSE AND FREQS WERE VERIFIED. THE PF/PIC BEGAN TO DSND EVEN THOUGH WE DID NOT HAVE GS INTERCEPT AND HAD NO INDICATION THAT WE WERE ON THE PROPER GS FOR THE ILS WHICH MADE ME NERVOUS. I DIDN'T REALLY REALIZE THAT HE WAS DOING SO AS I WAS FOCUSED 'OUTSIDE' LOOKING FOR THE RWY LIGHTING UNTIL I SAW GND CONTACT OUT OF MY SIDE WINDOW AND WE WERE MUCH CLOSER TO THE GND THAN I WAS COMFORTABLE WITH NOT HAVING PROPER INDICATIONS THAT WE WERE INDEED ON THE GS. I REALIZED THAT THE PIC HAD LEFT OUR DECISION ALT WITHOUT GS CAPTURE ABOUT THE SAME TIME TWR NOTED A 'LOW ALT ALERT' AND WE WERE INSTRUCTED TO CHK OUR ALT IMMEDIATELY. I TOLD PIC TO 'GO MISSED; GO MISSED -- WE DON'T KNOW WHERE WE ARE ON THE APCH' WHERE HE AGREED TO GO MISSED. WE WERE PROBABLY AROUND 300 FT AGL AT THAT POINT. TWR INSTRUCTED US TO CONTINUE RWY HDG ON THE APCH AND CLB TO 2000 FT. I'M UNSURE OF THE NEXT HDG INSTRUCTION NOW IN HINDSIGHT AS I WAS PRETTY UNCOMFORTABLE AT THIS POINT AND WAS TRYING TO MONITOR WHAT THE PIC WAS DOING BUT THE TWR WASN'T HAPPY WITH THE HDG THE PIC WAS ACTUALLY FLYING AT THIS POINT AND CORRECTED US BACK TO YET ANOTHER HDG OF WHICH NOW I AM UNABLE TO REMEMBER. WE WERE PASSED BACK TO NORCAL APCH CTL WHO VECTORED US AROUND FOR THE APCH AGAIN. WE WERE TOLD THAT THEY HAD A GREEN LIGHT ON THE GS INDICATOR AND THAT IT APPEARED TO BE FUNCTIONING PROPERLY AND NO ONE ELSE HAD HAD ANY PROBS WITH IT. WE WERE VECTORED AROUND SUCCESSFULLY FOR THE APCH AND WE MADE A SUCCESSFUL LNDG ON RWY 2 AT SAC.