Narrative:

I was climbing to an assigned altitude of 13000', en route from oak to rno. I entered the clouds at approximately 10000' MSL. I noticed a rapid accumulation of ice at approximately 11000' MSL. After repeated cycling of the boots, I realized that the ice was building so fast that I would not be able to climb any higher. I told ZOA, and they cleared me back to 11000'. In cruise flight, the airspeed dropped to 105 KIAS. After 5 mins of cruise the airspeed decayed to 90 KIAS, the airplane buffeted and the stall warning started to sound. I disengaged the autoplt at that point to descend further. The airplane started oscillating up and down, rolled approximately 30 degrees bank to the right, then back to the left approximately 45 degree bank in a nose down attitude. Total altitude loss was approximately 1300'. I climbed back to 10500' in VFR conditions and was still unable to maintain altitude. At that point I diverted to smf and landed west/O further incidence.

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Original NASA ASRS Text

Title: IN FLT ICING ENCOUNTER, EMERGENCY.

Narrative: I WAS CLBING TO AN ASSIGNED ALT OF 13000', ENRTE FROM OAK TO RNO. I ENTERED THE CLOUDS AT APPROX 10000' MSL. I NOTICED A RAPID ACCUMULATION OF ICE AT APPROX 11000' MSL. AFTER REPEATED CYCLING OF THE BOOTS, I REALIZED THAT THE ICE WAS BUILDING SO FAST THAT I WOULD NOT BE ABLE TO CLIMB ANY HIGHER. I TOLD ZOA, AND THEY CLRED ME BACK TO 11000'. IN CRUISE FLT, THE AIRSPD DROPPED TO 105 KIAS. AFTER 5 MINS OF CRUISE THE AIRSPD DECAYED TO 90 KIAS, THE AIRPLANE BUFFETED AND THE STALL WARNING STARTED TO SOUND. I DISENGAGED THE AUTOPLT AT THAT POINT TO DSND FURTHER. THE AIRPLANE STARTED OSCILLATING UP AND DOWN, ROLLED APPROX 30 DEGS BANK TO THE RIGHT, THEN BACK TO THE LEFT APPROX 45 DEG BANK IN A NOSE DOWN ATTITUDE. TOTAL ALT LOSS WAS APPROX 1300'. I CLBED BACK TO 10500' IN VFR CONDITIONS AND WAS STILL UNABLE TO MAINTAIN ALT. AT THAT POINT I DIVERTED TO SMF AND LANDED W/O FURTHER INCIDENCE.

Data retrieved from NASA's ASRS site as of August 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.