A320 flight crew encounters severe turbulence and loses altitude.

Attributes
ACN	727072
Time
Date	200702
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 36000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence Windshear Thunderstorm
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	727072
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : exited adverse environment
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Aircraft Weather Flight Crew Human Performance
Primary Problem	Weather

Narrative:

In cruise flight; 80 mi sse of ZZZ1; I am PF. We started to experience light chop and began to fly through high thin clouds. I turned on the seatbelt sign. I contacted ATC and asked about turbulence. The controller responded that we were going around the southern edge of a squall line and we should be clear of turbulence in about 40 mi. Our radar was clear. He had no pilot reports of turbulence in the area. I then slowed the aircraft to .76 mach and made a passenger announcement that we were flying over the top of an area of rain and should expect some turbulence and to assure they were seated with their seatbelt fastened. I then received a call from our 'a' flight attendant asking about turbulence and told her that it should last about 10 mins or so. At this point turbulence began to increase. We also entered cloud tops. I told her everyone should be seated. Shortly after that we entered the area of severe turbulence. We were not able to hold altitude and airspeed dropped quickly. The autoplt disconnected (on its own) and I began to hand fly the aircraft. I began to descend because we began to feel an impending stall. I tried to fly the flight director commands to the best of my ability. The captain called ZZZ and 'declared an emergency' since we were unable to hold altitude. We lost about 4000 ft in about 40 seconds and shortly thereafter we were in the clear. We then leveled off at FL320 and received clearance from ZZZ to remain at FL320 and turn left 20 degrees.

Original NASA ASRS Text

Title: A320 FLT CREW ENCOUNTERS SEVERE TURB AND LOSES ALT.

Narrative: IN CRUISE FLT; 80 MI SSE OF ZZZ1; I AM PF. WE STARTED TO EXPERIENCE LIGHT CHOP AND BEGAN TO FLY THROUGH HIGH THIN CLOUDS. I TURNED ON THE SEATBELT SIGN. I CONTACTED ATC AND ASKED ABOUT TURB. THE CTLR RESPONDED THAT WE WERE GOING AROUND THE SOUTHERN EDGE OF A SQUALL LINE AND WE SHOULD BE CLR OF TURB IN ABOUT 40 MI. OUR RADAR WAS CLR. HE HAD NO PLT RPTS OF TURB IN THE AREA. I THEN SLOWED THE ACFT TO .76 MACH AND MADE A PAX ANNOUNCEMENT THAT WE WERE FLYING OVER THE TOP OF AN AREA OF RAIN AND SHOULD EXPECT SOME TURB AND TO ASSURE THEY WERE SEATED WITH THEIR SEATBELT FASTENED. I THEN RECEIVED A CALL FROM OUR 'A' FLT ATTENDANT ASKING ABOUT TURB AND TOLD HER THAT IT SHOULD LAST ABOUT 10 MINS OR SO. AT THIS POINT TURB BEGAN TO INCREASE. WE ALSO ENTERED CLOUD TOPS. I TOLD HER EVERYONE SHOULD BE SEATED. SHORTLY AFTER THAT WE ENTERED THE AREA OF SEVERE TURB. WE WERE NOT ABLE TO HOLD ALT AND AIRSPD DROPPED QUICKLY. THE AUTOPLT DISCONNECTED (ON ITS OWN) AND I BEGAN TO HAND FLY THE ACFT. I BEGAN TO DSND BECAUSE WE BEGAN TO FEEL AN IMPENDING STALL. I TRIED TO FLY THE FLT DIRECTOR COMMANDS TO THE BEST OF MY ABILITY. THE CAPT CALLED ZZZ AND 'DECLARED AN EMER' SINCE WE WERE UNABLE TO HOLD ALT. WE LOST ABOUT 4000 FT IN ABOUT 40 SECONDS AND SHORTLY THEREAFTER WE WERE IN THE CLR. WE THEN LEVELED OFF AT FL320 AND RECEIVED CLRNC FROM ZZZ TO REMAIN AT FL320 AND TURN L 20 DEGS.

Data retrieved from NASA's ASRS site as of January 2009 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.