FLC OF AN EMBRAER 120 OVERSHOT DSCNT ALT DURING TRANSITION FOR A VISUAL APCH TO A NON TWR ARPT RESULTING IN DSNDING BELOW RADAR COVERAGE AND ALERTING ARTCC CTLR.

Narrative

WHILE ON DSCNT OUT OF 8000 FT FOR 4000 FT; ATL DEP HANDED ACR X OVER TO ZTL. CLRNC DOWN TO 4000 FT WAS REVERIFIED. FO (PNF) ADVISED ZTL OF LEAVING 7000 FT FOR 4000 FT. ACFT WAS ON AUTOPLT DURING DSCNT. FO ADVISED CAPT (PF) THAT I (THE FO) WOULD BE ON RADIO #2 TO CALL COMPANY OPS AND RPT IN RANGE. WHILE PROCEEDING THROUGH DSCNT AND APCH CHKLIST; CTR ASKED FOR VERIFICATION OF ALT. I NOTICED CURRENT ALT WAS 3000 FT. CAPT RPTED CURRENT ALT. I ADVISED ATC WE WERE CORRECTING BACK TO 4000 FT. ATC ADVISED THAT 3000 FT WOULD BE OUR NEW CLRNC ALT. ALT CAPTURE MODE HAD DISENGAGED DURING DSCNT WITHOUT PLT INPUT. SINCE I WAS BUSY WITH RADIOS AND DSCNT CHKLIST; THE CAPT WAS LOOKING OUTSIDE TO RPT 'ARPT IN SIGHT' AS REQUESTED BY ATC. BOTH CAPT AND I WERE UNFAMILIAR WITH ARPT LOCATION. I PERSONALLY HAVE NEVER FLOWN INTO COLUMBUS; GA; AT NIGHT AND ONLY ONCE DURING THE DAY. TEMP AND DEWPOINT WERE RPTED AS 7 DEGS C/7 DEGS C RESPECTIVELY; AND LOW PATCHY CLOUDS AND FOG WITH LIGHT RAIN WERE PRESENT. ONCE THE ARPT WAS IN SIGHT; WE WERE CLRED FOR THE VISUAL AND MADE CTAF RADIO CALLS ACCORDINGLY. ALL ELSE IN THE FLT PROCEEDED NORMALLY AND WE CANCELED WITH ZTL ONCE ON THE GND. IN HINDSIGHT; A REQUEST FOR VECTORS FOR AN ILS WOULD HAVE HELPED PREVENT THIS; THEREBY ALLOWING THE PF TO NOT BE 'OUTSIDE' FOR VISUAL CUES WHILE IN A DSCNT. THERE WAS NO LCL TFC RPTED IN THE AREA AND NO TERRAIN OBSTRUCTIONS.