Commuter encounters downdraft in proximity of thunderstorm. Altitude deviation.

Attributes
ACN	188944
Time
Date	199109
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pmd
State Reference	CA
Altitude	msl bound lower : 13700 msl bound upper : 17000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Light Transport
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute airway : zla
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 255 flight time total : 4982 flight time type : 2750
ASRS Report	188944
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

Clearance: direct pmd 17000 (VMC). Visually saw buildups over pmd and north along ridge. We painted cells over pmd and asked and received clearance to deviate 20 degree left (north). Asked and received another 15 degree left at cells. ATC was hesitating on the deviation because of the edwards restr area. We skirted the north edge of the cell by 1 1/2 to 2 mi. At all times had contact with the ground. Picked up some rime ice, and then heavy rain. We then ascended 300 ft, autoplt on, and then started down with negative G's. Floated in seat for about 15 seconds. At the same time got an aural engine oil warning twice. Leveled off at 13700, called ATC, reassigned to 14000. Uneventful to psp. Checked with flight attendant after level off and everything ok.

Original NASA ASRS Text

Title: COMMUTER ENCOUNTERS DOWNDRAFT IN PROX OF TSTM. ALT DEV.

Narrative: CLRNC: DIRECT PMD 17000 (VMC). VISUALLY SAW BUILDUPS OVER PMD AND N ALONG RIDGE. WE PAINTED CELLS OVER PMD AND ASKED AND RECEIVED CLRNC TO DEVIATE 20 DEG L (N). ASKED AND RECEIVED ANOTHER 15 DEG L AT CELLS. ATC WAS HESITATING ON THE DEV BECAUSE OF THE EDWARDS RESTR AREA. WE SKIRTED THE N EDGE OF THE CELL BY 1 1/2 TO 2 MI. AT ALL TIMES HAD CONTACT WITH THE GND. PICKED UP SOME RIME ICE, AND THEN HVY RAIN. WE THEN ASCENDED 300 FT, AUTOPLT ON, AND THEN STARTED DOWN WITH NEGATIVE G'S. FLOATED IN SEAT FOR ABOUT 15 SECONDS. AT THE SAME TIME GOT AN AURAL ENG OIL WARNING TWICE. LEVELED OFF AT 13700, CALLED ATC, REASSIGNED TO 14000. UNEVENTFUL TO PSP. CHKED WITH FLT ATTENDANT AFTER LEVEL OFF AND EVERYTHING OK.

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.