A C206 pilot reported icing 10 NM northeast of sgf, which forced him to descend inadvertently.

Attributes
ACN	572805
Time
Date	200302
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : sgf.vortac
State Reference	MO
Altitude	msl bound lower : 2600 msl bound upper : 4000
Environment
Flight Conditions	IMC
Weather Elements	Fog Ice Rain Turbulence Windshear other
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Cessna Stationair/Turbo Stationair 6
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 35 flight time total : 800 flight time type : 350
ASRS Report	572805
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather inflight encounter other non adherence : far non adherence : clearance other anomaly other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Weather
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was on top of an overcast layer at 7000 ft. Icing was not forecast. F2 level was forecast at 10000 ft. Pilots were picking up moderate mixed ice ahead of me descending into sgf. I was cleared to descend, at pilot's discretion, to 3000 ft. At 3000 ft, it was very turbulent with windshear. Turbulence forced me, inadvertently, to 3600 ft. At that altitude, I entered VMC. I climbed back to 4000 ft and requested a contact approach, which I executed without incident. No traffic conflict occurred. Factors were ice, windshear and turbulence. I picked up 1/2 - 3/4 inches mixed to rime ice.

Original NASA ASRS Text

Title: A C206 PLT RPTED ICING 10 NM NE OF SGF, WHICH FORCED HIM TO DSND INADVERTENTLY.

Narrative: I WAS ON TOP OF AN OVCST LAYER AT 7000 FT. ICING WAS NOT FORECAST. F2 LEVEL WAS FORECAST AT 10000 FT. PLTS WERE PICKING UP MODERATE MIXED ICE AHEAD OF ME DSNDING INTO SGF. I WAS CLRED TO DSND, AT PLT'S DISCRETION, TO 3000 FT. AT 3000 FT, IT WAS VERY TURBULENT WITH WINDSHEAR. TURB FORCED ME, INADVERTENTLY, TO 3600 FT. AT THAT ALT, I ENTERED VMC. I CLBED BACK TO 4000 FT AND REQUESTED A CONTACT APCH, WHICH I EXECUTED WITHOUT INCIDENT. NO TFC CONFLICT OCCURRED. FACTORS WERE ICE, WINDSHEAR AND TURB. I PICKED UP 1/2 - 3/4 INCHES MIXED TO RIME ICE.

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.