A300-600 flight crew encounters severe turbulence while en route.

Attributes
ACN	572980
Time
Date	200301
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zdv.artcc
State Reference	CO
Altitude	msl bound lower : 29000 msl bound upper : 33000
Environment
Flight Conditions	Mixed
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp pilot : multi engine
Experience	flight time last 90 days : 60 flight time total : 8000 flight time type : 1500
ASRS Report	572980
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	aircraft equipment other aircraft equipment : airspeed indicator other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment flight crew : regained aircraft control flight crew : overrode automation
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Weather Aircraft
Primary Problem	Weather

Narrative:

Straight and level at FL330 at normal cruise mach .80, clear air, smooth ride, with no reports of turbulence. Airspeed began to slowly increase toward mmo (mach .82) as autothrottles slowly retarded, air still smooth. Disconnected autoplt and autothrottles as we entered severe turbulence and airspeed increased above mmo and altitude was 200 ft high and increasing. Even with throttles closed, speed increased 25 KTS above target (15 KTS above mmo of mach .82). Began a descent as airplane was marginally ctlable in order to have greater buffet margins. Notified ATC and with clearance, descended to FL290 in severe turbulence. Turbulence gradually subsided, continued to destination.

Original NASA ASRS Text

Title: A300-600 FLC ENCOUNTERS SEVERE TURB WHILE ENRTE.

Narrative: STRAIGHT AND LEVEL AT FL330 AT NORMAL CRUISE MACH .80, CLR AIR, SMOOTH RIDE, WITH NO RPTS OF TURB. AIRSPD BEGAN TO SLOWLY INCREASE TOWARD MMO (MACH .82) AS AUTOTHROTTLES SLOWLY RETARDED, AIR STILL SMOOTH. DISCONNECTED AUTOPLT AND AUTOTHROTTLES AS WE ENTERED SEVERE TURB AND AIRSPD INCREASED ABOVE MMO AND ALT WAS 200 FT HIGH AND INCREASING. EVEN WITH THROTTLES CLOSED, SPD INCREASED 25 KTS ABOVE TARGET (15 KTS ABOVE MMO OF MACH .82). BEGAN A DSCNT AS AIRPLANE WAS MARGINALLY CTLABLE IN ORDER TO HAVE GREATER BUFFET MARGINS. NOTIFIED ATC AND WITH CLRNC, DSNDED TO FL290 IN SEVERE TURB. TURB GRADUALLY SUBSIDED, CONTINUED TO DEST.

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.