BE40 crew had strong up- and downdrafts and turbulence in D21 class east airspace.

Attributes
ACN	476608
Time
Date	200006
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : lyntn
State Reference	MI
Altitude	msl bound lower : 9000 msl bound upper : 10000
Environment
Flight Conditions	IMC
Weather Elements	Turbulence other
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Beechjet 400
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 90 flight time total : 9800 flight time type : 1800
ASRS Report	476608
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather inflight encounter other non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Weather
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

We were assigned 10000 ft and upon reaching 10000 ft we entered the clouds and all of a sudden the plane started to climb and just in a split second the plane descended to approximately 9000 ft. I called approach and advised that we could not maintain altitude. He said 'roger, maintain 10000 ft,' and a short time after that we flew out of the cloud sand regained the altitude. This all happened so fast we could not hold altitude.

Original NASA ASRS Text

Title: BE40 CREW HAD STRONG UP- AND DOWNDRAFTS AND TURB IN D21 CLASS E AIRSPACE.

Narrative: WE WERE ASSIGNED 10000 FT AND UPON REACHING 10000 FT WE ENTERED THE CLOUDS AND ALL OF A SUDDEN THE PLANE STARTED TO CLB AND JUST IN A SPLIT SECOND THE PLANE DSNDED TO APPROX 9000 FT. I CALLED APCH AND ADVISED THAT WE COULD NOT MAINTAIN ALT. HE SAID 'ROGER, MAINTAIN 10000 FT,' AND A SHORT TIME AFTER THAT WE FLEW OUT OF THE CLOUD SAND REGAINED THE ALT. THIS ALL HAPPENED SO FAST WE COULD NOT HOLD ALT.

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.