Narrative:

We were given a holding clearance at teddy intersection. There was a line of thunderstorms to the south of the holding fix. We were to hold at teddy with right turns which meant we would be turning toward the storms. The WX radar showed we had ample room to complete this holding pattern and other aircraft in the hold already had not complained about turbulence. As we began our first outbound we discovered with the illumination created by nearby lightning that we were going to penetrate some cumulus clouds. Once inside this cloud we experienced very strong, but still regarded it as moderate, turbulence. The turbulence was mostly strong updrafts. As the aircraft climbed the autoplt attempted to maintain altitude, which it could not. At this time the aircraft rolled further right to about 45 degree bank. I disconnected the autoplt and regained control but the aircraft had already climbed 500-600 ft from our assigned altitude. We descended back to our altitude, reported the conditions and promptly diverted to our alternate airport. I don't believe there was a conflict between other aircraft but I would hope ATC might increase altitude separation during those types of conditions.

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Original NASA ASRS Text

Title: CORPORATE LTT HAS ALTDEV DURING HOLDING WHEN TURB CAUSES TEMPORARY LOSS OF ACFT CTL AND AUTOPLT IS UNABLE TO MAINTAIN ALT.

Narrative: WE WERE GIVEN A HOLDING CLRNC AT TEDDY INTXN. THERE WAS A LINE OF TSTMS TO THE S OF THE HOLDING FIX. WE WERE TO HOLD AT TEDDY WITH R TURNS WHICH MEANT WE WOULD BE TURNING TOWARD THE STORMS. THE WX RADAR SHOWED WE HAD AMPLE ROOM TO COMPLETE THIS HOLDING PATTERN AND OTHER ACFT IN THE HOLD ALREADY HAD NOT COMPLAINED ABOUT TURB. AS WE BEGAN OUR FIRST OUTBOUND WE DISCOVERED WITH THE ILLUMINATION CREATED BY NEARBY LIGHTNING THAT WE WERE GOING TO PENETRATE SOME CUMULUS CLOUDS. ONCE INSIDE THIS CLOUD WE EXPERIENCED VERY STRONG, BUT STILL REGARDED IT AS MODERATE, TURB. THE TURB WAS MOSTLY STRONG UPDRAFTS. AS THE ACFT CLBED THE AUTOPLT ATTEMPTED TO MAINTAIN ALT, WHICH IT COULD NOT. AT THIS TIME THE ACFT ROLLED FURTHER R TO ABOUT 45 DEG BANK. I DISCONNECTED THE AUTOPLT AND REGAINED CTL BUT THE ACFT HAD ALREADY CLBED 500-600 FT FROM OUR ASSIGNED ALT. WE DSNDED BACK TO OUR ALT, RPTED THE CONDITIONS AND PROMPTLY DIVERTED TO OUR ALTERNATE ARPT. I DON'T BELIEVE THERE WAS A CONFLICT BTWN OTHER ACFT BUT I WOULD HOPE ATC MIGHT INCREASE ALT SEPARATION DURING THOSE TYPES OF CONDITIONS.

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.