Narrative:

I was descending on the awson 1 arrival just inside of awson. There was a broken layer of cumulus clouds starting at about 7000 ft MSL. My descent was supposed to stop at 5000 ft MSL. As I entered the clouds, I began to enter an area of turbulence. With these clouds, you normally expect some turbulence. However, in january it usually doesn't amount to much. The autoplt was engaged to capture the altitude. As we reached the bases of the clouds the turbulence became more severe. I began to reduce the power to avoid overstressing the aircraft. I also clicked off the autoplt. We then experienced severe turbulence. As I began the leveloff at 5000 ft, the bottom just fell out and we ended up at 4500 ft. There was another aircraft somewhere below me on the arrival. ATC asked me what altitude I was descending to and warned of the traffic conflict. I immediately climbed and reported the turbulence. Nothing else was said and I never saw the other aircraft. I learned never to underestimate the power of WX. Just because it's not twring in july, this doesn't mean the clouds won't be turbulent in january. I should have slowed the aircraft and been in control in the clouds instead of using the autoplt.

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Original NASA ASRS Text

Title: BE90 PLT EXPERIENCES MOMENTARY LOSS OF CTL IN TURB ON APCH IN ZTL AIRSPACE.

Narrative: I WAS DSNDING ON THE AWSON 1 ARR JUST INSIDE OF AWSON. THERE WAS A BROKEN LAYER OF CUMULUS CLOUDS STARTING AT ABOUT 7000 FT MSL. MY DSCNT WAS SUPPOSED TO STOP AT 5000 FT MSL. AS I ENTERED THE CLOUDS, I BEGAN TO ENTER AN AREA OF TURB. WITH THESE CLOUDS, YOU NORMALLY EXPECT SOME TURB. HOWEVER, IN JANUARY IT USUALLY DOESN'T AMOUNT TO MUCH. THE AUTOPLT WAS ENGAGED TO CAPTURE THE ALT. AS WE REACHED THE BASES OF THE CLOUDS THE TURB BECAME MORE SEVERE. I BEGAN TO REDUCE THE PWR TO AVOID OVERSTRESSING THE ACFT. I ALSO CLICKED OFF THE AUTOPLT. WE THEN EXPERIENCED SEVERE TURB. AS I BEGAN THE LEVELOFF AT 5000 FT, THE BOTTOM JUST FELL OUT AND WE ENDED UP AT 4500 FT. THERE WAS ANOTHER ACFT SOMEWHERE BELOW ME ON THE ARR. ATC ASKED ME WHAT ALT I WAS DSNDING TO AND WARNED OF THE TFC CONFLICT. I IMMEDIATELY CLBED AND RPTED THE TURB. NOTHING ELSE WAS SAID AND I NEVER SAW THE OTHER ACFT. I LEARNED NEVER TO UNDERESTIMATE THE PWR OF WX. JUST BECAUSE IT'S NOT TWRING IN JULY, THIS DOESN'T MEAN THE CLOUDS WON'T BE TURBULENT IN JANUARY. I SHOULD HAVE SLOWED THE ACFT AND BEEN IN CTL IN THE CLOUDS INSTEAD OF USING THE AUTOPLT.

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.