Narrative:

We were on approach vectors to a visual to runway 10R at boi. Approach cleared us from 11000 ft to 8000 ft. Just before level off at 8000 ft approach asked us if we preferred runway 10R or runway 10L and if we had the airport. The captain responded that either runway was ok. I looked down at the airport diagram to check the runways again, as I looked up the aircraft had descended to approximately 7800 ft. I returned to 8000 ft immediately. There was no ATC response and no other traffic in the area that I know of. Lesson: don't get distracted at level off.

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Original NASA ASRS Text

Title: THE RPTR ON A VISUAL FAILED TO MAINTAIN ASSIGNED 8000 FT AS HE WAS LEVELING OFF AND LOOKING AT THE ARPT DIAGRAM IN PREPARATION TO GETTING A VISUAL APCH.

Narrative: WE WERE ON APCH VECTORS TO A VISUAL TO RWY 10R AT BOI. APCH CLRED US FROM 11000 FT TO 8000 FT. JUST BEFORE LEVEL OFF AT 8000 FT APCH ASKED US IF WE PREFERRED RWY 10R OR RWY 10L AND IF WE HAD THE ARPT. THE CAPT RESPONDED THAT EITHER RWY WAS OK. I LOOKED DOWN AT THE ARPT DIAGRAM TO CHK THE RWYS AGAIN, AS I LOOKED UP THE ACFT HAD DSNDED TO APPROX 7800 FT. I RETURNED TO 8000 FT IMMEDIATELY. THERE WAS NO ATC RESPONSE AND NO OTHER TFC IN THE AREA THAT I KNOW OF. LESSON: DON'T GET DISTRACTED AT LEVEL OFF.

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.