Narrative:

I was the captain flying the airplane. Went to level off at 13000 ft went to 13400 ft. Immediately back down to 13000 ft. Avoiding a thunderstorm at the time.

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Original NASA ASRS Text

Title: F100-30 NE ORD CLBING TO 13000 FT. DEVIATING TSTMS GOT TO 13400 FT. CORRECTED IMMEDIATELY.

Narrative: I WAS THE CAPT FLYING THE AIRPLANE. WENT TO LEVEL OFF AT 13000 FT WENT TO 13400 FT. IMMEDIATELY BACK DOWN TO 13000 FT. AVOIDING A TSTM AT THE TIME.

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.