A CE-650 EFIS TYPE CITATION DSNDS BELOW THE GS DURING A VISUAL APCH TO RWY 28R AT CMH; OH.

Narrative

APCHING CMH ARPT AND IN VFR WX AND WITH THE ARPT IN SIGHT; WE WERE CLRED TO DSND FROM 4000 FT TO 3000 FT AND WERE ALSO CLRED BY ATC FOR THE VISUAL APCH TO RWY 28R AND TO CONTACT THE TWR. THE AUTOPLT WAS ON AND WE PROCEEDED TO CAPTURE THE LOC. HOWEVER; WHEN WE WERE CLRED FOR THE VISUAL APCH; THE FO PROCEEDED TO SELECT '0000' FT IN THE ALT WINDOW INSTEAD OF LEAVING '3000' FT IN ORDER TO DSND AND TO CAPTURE THE GS. (THE FO WOULD TELL ME LATER ON THAT HE HAD PICKED UP THIS HABIT IN HIS PREVIOUS JOB WHERE IT WAS CUSTOMARY TO SELECT '0000' ALT IN THE ALT WINDOW WHEN THE CREW WAS CLRED FOR A VISUAL APCH.) THE AIRPLANE PROCEEDED TO DSND UNTIL IT APPEARED TO ME; AND TO THE FO; TO BE UNUSUALLY LOW. AT THE SAME TIME WE HEARD AN AURAL 'GS' ANNUNCIATOR INFORMING US THAT WE WERE BELOW THE GS. I THEN PROCEEDED IMMEDIATELY TO DISCONNECT THE AUTOPLT AND TO IMMEDIATELY CLB TO GET BACK ON GS. BACK ON THE GS; WE WENT ON TO LAND. AFTER THE FLT; WE DISCUSSED THE SIT AND WE DECIDED THAT THIS WHOLE SIT COULD HAVE BEEN AVOIDED IF WE HAD USED OUR NORMAL SOP'S FORCING BOTH PLTS TO VERIFY AND CONFIRM THAT THE CORRECT ALT WAS SET IN THE ALT WINDOW.