Narrative:

While on descent out of 8000 ft for 4000 ft, atl departure handed air carrier X over to ZTL. Clearance down to 4000 ft was reverified. First officer (PNF) advised ZTL of leaving 7000 ft for 4000 ft. Aircraft was on autoplt during descent. First officer advised captain (PF) that I (the first officer) would be on radio #2 to call company operations and report in range. While proceeding through descent and approach checklist, center asked for verification of altitude. I noticed current altitude was 3000 ft. Captain reported current altitude. I advised ATC we were correcting back to 4000 ft. ATC advised that 3000 ft would be our new clearance altitude. Altitude capture mode had disengaged during descent without pilot input. Since I was busy with radios and descent checklist, the captain was looking outside to report 'airport in sight' as requested by ATC. Both captain and I were unfamiliar with airport location. I personally have never flown into columbus, GA, at night and only once during the day. Temperature and dewpoint were reported as 7 degrees C/7 degrees C respectively, and low patchy clouds and fog with light rain were present. Once the airport was in sight, we were cleared for the visual and made CTAF radio calls accordingly. All else in the flight proceeded normally and we canceled with ZTL once on the ground. 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 descent. There was no local traffic reported in the area and no terrain obstructions.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.