Narrative:

On descent into den, IFR in VMC night, cleared to 13000 ft captain flying, I called out passing 14000 ft to 13000 ft, according to SOP and continued outside vigilance due to numerous aircraft approaching to multiple runways. Somewhere near 13000 ft, I looked down to advise flight attendants on PA to 'prepare for landing' when I heard the altitude alert go off indicating descent through 12700 ft. The captain arrested the descent and, while returning to 13000 ft, was cleared by ATC to descend and maintain 9000 ft. Probably cause of altitude deviation was over concern with outside vigilance due to night VMC and numerous aircraft lights in view, while approaching den with parallel runway operations and the necessity in 2 man aircraft of second pilot distraction with other duties.

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Original NASA ASRS Text

Title: CAPT OF AN MLG OVERSHOT DSCNT ASSIGNED ALT.

Narrative: ON DSCNT INTO DEN, IFR IN VMC NIGHT, CLRED TO 13000 FT CAPT FLYING, I CALLED OUT PASSING 14000 FT TO 13000 FT, ACCORDING TO SOP AND CONTINUED OUTSIDE VIGILANCE DUE TO NUMEROUS ACFT APCHING TO MULTIPLE RWYS. SOMEWHERE NEAR 13000 FT, I LOOKED DOWN TO ADVISE FLT ATTENDANTS ON PA TO 'PREPARE FOR LNDG' WHEN I HEARD THE ALT ALERT GO OFF INDICATING DSCNT THROUGH 12700 FT. THE CAPT ARRESTED THE DSCNT AND, WHILE RETURNING TO 13000 FT, WAS CLRED BY ATC TO DSND AND MAINTAIN 9000 FT. PROBABLY CAUSE OF ALTDEV WAS OVER CONCERN WITH OUTSIDE VIGILANCE DUE TO NIGHT VMC AND NUMEROUS ACFT LIGHTS IN VIEW, WHILE APCHING DEN WITH PARALLEL RWY OPS AND THE NECESSITY IN 2 MAN ACFT OF SECOND PLT DISTR WITH OTHER DUTIES.

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.