Flight crew in a B26B on IFR departure from vny airport encounters strong up- and downdrafts.

Attributes
ACN	462910
Time
Date	200002
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : vny.airport
State Reference	CA
Altitude	msl bound lower : 4000 msl bound upper : 4700
Environment
Flight Conditions	IMC
Weather Elements	Thunderstorm Windshear
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon tower : lgb.tower
Operator	general aviation : personal
Operating Under FAR Part	Part 91
Route In Use	departure sid : glendale 8
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Experience	flight time last 90 days : 6.8 flight time total : 1500 flight time type : 488
ASRS Report	462910
Person 2
Affiliation	other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : cfi pilot : multi engine pilot : flight engineer
Experience	flight time last 90 days : 50 flight time total : 14000 flight time type : 50
ASRS Report	463017
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter : turbulence
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Weather
Primary Problem	Weather

Narrative:

On the morning of feb/xa/00 at XA30, I departed vny for a flight to trm. The WX was IFR as a series of WX fronts were moving through southern california. I had filed an IFR flight plan and was in continuous contact with socal departure. I penetrated the cloud bottoms at approximately 2500-3500 ft MSL in the climb out using the glendale 8 departure SID. I then experienced a series of significant updrafts and turbulence. I reduced power and implemented a series of downward pitch changes to the maximum extent possible without exceeding the prescribed safety limits for the aircraft. Despite my best efforts the aircraft continued to climb to 4600-4700 ft. The updrafts and turbulence lasted 20-25 seconds after which time I descended to my assigned altitude of 4000 ft. I acknowledged to the socal controller that I knew my altitude was too high and that I was correcting it. I do not believe this problem would have occurred had I advised the controller of the updrafts instead of stating I was 'correcting my altitude.' upon landing, I contacted socal TRACON and advised the supervisor of the incident including the turbulence and updrafts.

Original NASA ASRS Text

Title: FLC IN A B26B ON IFR DEP FROM VNY ARPT ENCOUNTERS STRONG UP- AND DOWNDRAFTS.

Narrative: ON THE MORNING OF FEB/XA/00 AT XA30, I DEPARTED VNY FOR A FLT TO TRM. THE WX WAS IFR AS A SERIES OF WX FRONTS WERE MOVING THROUGH SOUTHERN CALIFORNIA. I HAD FILED AN IFR FLT PLAN AND WAS IN CONTINUOUS CONTACT WITH SOCAL DEP. I PENETRATED THE CLOUD BOTTOMS AT APPROX 2500-3500 FT MSL IN THE CLBOUT USING THE GLENDALE 8 DEP SID. I THEN EXPERIENCED A SERIES OF SIGNIFICANT UPDRAFTS AND TURB. I REDUCED PWR AND IMPLEMENTED A SERIES OF DOWNWARD PITCH CHANGES TO THE MAX EXTENT POSSIBLE WITHOUT EXCEEDING THE PRESCRIBED SAFETY LIMITS FOR THE ACFT. DESPITE MY BEST EFFORTS THE ACFT CONTINUED TO CLB TO 4600-4700 FT. THE UPDRAFTS AND TURB LASTED 20-25 SECONDS AFTER WHICH TIME I DSNDED TO MY ASSIGNED ALT OF 4000 FT. I ACKNOWLEDGED TO THE SOCAL CTLR THAT I KNEW MY ALT WAS TOO HIGH AND THAT I WAS CORRECTING IT. I DO NOT BELIEVE THIS PROB WOULD HAVE OCCURRED HAD I ADVISED THE CTLR OF THE UPDRAFTS INSTEAD OF STATING I WAS 'CORRECTING MY ALT.' UPON LNDG, I CONTACTED SOCAL TRACON AND ADVISED THE SUPVR OF THE INCIDENT INCLUDING THE TURB AND UPDRAFTS.

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.