In-flight encounter with severe turbulence, temporary loss of aircraft control.

Attributes
ACN	283888
Time
Date	199409
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : roa
State Reference	VA
Altitude	msl bound lower : 38000 msl bound upper : 39000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : rsw
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other descent other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time total : 8900
ASRS Report	283888
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

In cruise at FL390, IMC, intermittent to continuous left chop, thunderstorm radar returns 40 mi east and 65 mi west of our position. Flew into unrpted severe turbulence. Airspeed plus and minus 25 KTS altitude plus and minus 500 ft autoplt disengaged itself. Requested immediate descent to lower altitude and was told to standby. Aircraft was very near a stalled condition so I declared an emergency and the first officer initiated a descent -- we were then cleared to FL370 and shortly thereafter to FL350. Descended into VMC between layers at FL365 and the severe turbulence ceased.

Original NASA ASRS Text

Title: INFLT ENCOUNTER WITH SEVERE TURB, TEMPORARY LOSS OF ACFT CTL.

Narrative: IN CRUISE AT FL390, IMC, INTERMITTENT TO CONTINUOUS L CHOP, TSTM RADAR RETURNS 40 MI E AND 65 MI W OF OUR POS. FLEW INTO UNRPTED SEVERE TURB. AIRSPD PLUS AND MINUS 25 KTS ALT PLUS AND MINUS 500 FT AUTOPLT DISENGAGED ITSELF. REQUESTED IMMEDIATE DSCNT TO LOWER ALT AND WAS TOLD TO STANDBY. ACFT WAS VERY NEAR A STALLED CONDITION SO I DECLARED AN EMER AND THE FO INITIATED A DSCNT -- WE WERE THEN CLRED TO FL370 AND SHORTLY THEREAFTER TO FL350. DSNDED INTO VMC BTWN LAYERS AT FL365 AND THE SEVERE TURB CEASED.

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.