Reporter contends that the excursion from his assigned altitude was caused by an updraft.

Attributes
ACN	465250
Time
Date	200003
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sna.airport
State Reference	CA
Altitude	msl bound lower : 6000 msl bound upper : 6400
Environment
Weather Elements	Rain Turbulence
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	465250
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Environmental Factor
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On departure from sna, we were assigned 6000 ft altitude. There were numerous twring cumulus nimbus and heavy rain in the area. Aircraft was being vectored to intercept the 061 degree radial off santa catalina, per the departure. Chop was moderate to heavy in the clouds when we experienced a gust that pushed us up 350-400 ft above assigned altitude. I was hand flying at the time and immediately took corrective action to return to assigned altitude. In retrospect, I feel if I had the autoplt engaged it may have been more effective in reacting to the gust.

Original NASA ASRS Text

Title: RPTR CONTENDS THAT THE EXCURSION FROM HIS ASSIGNED ALT WAS CAUSED BY AN UPDRAFT.

Narrative: ON DEP FROM SNA, WE WERE ASSIGNED 6000 FT ALT. THERE WERE NUMEROUS TWRING CUMULUS NIMBUS AND HVY RAIN IN THE AREA. ACFT WAS BEING VECTORED TO INTERCEPT THE 061 DEG RADIAL OFF SANTA CATALINA, PER THE DEP. CHOP WAS MODERATE TO HVY IN THE CLOUDS WHEN WE EXPERIENCED A GUST THAT PUSHED US UP 350-400 FT ABOVE ASSIGNED ALT. I WAS HAND FLYING AT THE TIME AND IMMEDIATELY TOOK CORRECTIVE ACTION TO RETURN TO ASSIGNED ALT. IN RETROSPECT, I FEEL IF I HAD THE AUTOPLT ENGAGED IT MAY HAVE BEEN MORE EFFECTIVE IN REACTING TO THE GUST.

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.