Narrative:

Just prior to coast-in, flight encountered tops of cumulonimbus on track, unable to avoid. About time of radar contact with ZDC, experienced turbulence which disconnected autoplt. Aircraft climbed 300 ft above assigned altitude before the excursion was corrected.

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Original NASA ASRS Text

Title: AN ACR WDB CREW CLBED ABOVE ITS ASSIGNED ALT. ALTDEV. WX FACTORS CUMULONIMBUS THAT COULD NOT BE AVOIDED THAT PRODUCED TURB. ACFT EQUIP PROB AUTOPLT COULD NOT HANDLE TURB AND DISCONNECTED.

Narrative: JUST PRIOR TO COAST-IN, FLT ENCOUNTERED TOPS OF CUMULONIMBUS ON TRACK, UNABLE TO AVOID. ABOUT TIME OF RADAR CONTACT WITH ZDC, EXPERIENCED TURB WHICH DISCONNECTED AUTOPLT. ACFT CLBED 300 FT ABOVE ASSIGNED ALT BEFORE THE EXCURSION WAS CORRECTED.

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.