Narrative:

During descent on approach to stl we were cleared down as a flight attendant knocked on the cockpit door. We were approximately 6500 ft when approach control said clearance limit was 7000 ft. We climbed back from 6500 ft to 7000 ft. They asked what altitude we were cleared to. I responded with the altitude set in our altitude alert of 6000 ft. Later the first officer said he had made a mistake and set 6000 ft instead of 7000 ft. Approach control said no problem. But I think the sterile cockpit below 10000 ft was not observed and this distraction contributed to our altitude excursion.

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Original NASA ASRS Text

Title: ALT DEV. ACFT DSNDED BELOW CLRED ALT AND HAD WRONG ALT SET IN ALERT WINDOW. ATC INTERVENED.

Narrative: DURING DSCNT ON APCH TO STL WE WERE CLRED DOWN AS A FLT ATTENDANT KNOCKED ON THE COCKPIT DOOR. WE WERE APPROX 6500 FT WHEN APCH CTL SAID CLRNC LIMIT WAS 7000 FT. WE CLBED BACK FROM 6500 FT TO 7000 FT. THEY ASKED WHAT ALT WE WERE CLRED TO. I RESPONDED WITH THE ALT SET IN OUR ALT ALERT OF 6000 FT. LATER THE FO SAID HE HAD MADE A MISTAKE AND SET 6000 FT INSTEAD OF 7000 FT. APCH CTL SAID NO PROB. BUT I THINK THE STERILE COCKPIT BELOW 10000 FT WAS NOT OBSERVED AND THIS DISTR CONTRIBUTED TO OUR ALT EXCURSION.

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.