Narrative:

We were assigned a cruise altitude of 9000 ft however, inadvertently 10000 ft was put into the autoplt. I guess after seeing the new altitude, I assumed it was right. When we reached 10000 ft, ATC questioned our altitude and reassigned us 7000 ft. It was a stupid mistake and could have been avoided.

Google
 

Original NASA ASRS Text

Title: ATR 42 FLC SETS WRONG ALT INTO THE AUTOPLT.

Narrative: WE WERE ASSIGNED A CRUISE ALT OF 9000 FT HOWEVER, INADVERTENTLY 10000 FT WAS PUT INTO THE AUTOPLT. I GUESS AFTER SEEING THE NEW ALT, I ASSUMED IT WAS RIGHT. WHEN WE REACHED 10000 FT, ATC QUESTIONED OUR ALT AND REASSIGNED US 7000 FT. IT WAS A STUPID MISTAKE AND COULD HAVE BEEN AVOIDED.

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.