Small aircraft encounters embedded thunderstorm with turbulence and icing. Altitude deviation.

Attributes
ACN	256998
Time
Date	199311
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fmn
State Reference	NM
Altitude	msl bound lower : 12000 msl bound upper : 13000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : zab
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 120 flight time total : 7000 flight time type : 200
ASRS Report	256998
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter other non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

While at cruise in an small aircraft, I inadvertently flew into an imbedded thunderstorm at 13000 ft. I picked up moderate to severe icing and encountered moderate to severe turbulence. I reported this to the controller. By the time I came out of the severe turbulence I was at 12500. I was very shaken and the airplane had so much ice on it I could barely make it back to 13000. After making it back to 13000 the airplane was hanging on the propeller and performing very poorly. The MEA was 12000 on V-210. I was worried about picking up more ice and not being able to even hold 12000. I asked for and got 12000. The airplane seemed to fly very well at 12000. I encountered more turbulence and ended up at 12500. I let the airplane stay there for a little while because I wanted to see how it was performing at the higher altitude. The controller asked my altitude and I promptly descended back to 12000 with no further incident.

Original NASA ASRS Text

Title: SMA ENCOUNTERS EMBEDDED TSTM WITH TURB AND ICING. ALTDEV.

Narrative: WHILE AT CRUISE IN AN SMA, I INADVERTENTLY FLEW INTO AN IMBEDDED TSTM AT 13000 FT. I PICKED UP MODERATE TO SEVERE ICING AND ENCOUNTERED MODERATE TO SEVERE TURB. I RPTED THIS TO THE CTLR. BY THE TIME I CAME OUT OF THE SEVERE TURB I WAS AT 12500. I WAS VERY SHAKEN AND THE AIRPLANE HAD SO MUCH ICE ON IT I COULD BARELY MAKE IT BACK TO 13000. AFTER MAKING IT BACK TO 13000 THE AIRPLANE WAS HANGING ON THE PROP AND PERFORMING VERY POORLY. THE MEA WAS 12000 ON V-210. I WAS WORRIED ABOUT PICKING UP MORE ICE AND NOT BEING ABLE TO EVEN HOLD 12000. I ASKED FOR AND GOT 12000. THE AIRPLANE SEEMED TO FLY VERY WELL AT 12000. I ENCOUNTERED MORE TURB AND ENDED UP AT 12500. I LET THE AIRPLANE STAY THERE FOR A LITTLE WHILE BECAUSE I WANTED TO SEE HOW IT WAS PERFORMING AT THE HIGHER ALT. THE CTLR ASKED MY ALT AND I PROMPTLY DSNDED BACK TO 12000 WITH NO FURTHER INCIDENT.

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.