B777 encountered severe clear air turbulence at FL330.

Attributes
ACN	715791
Time
Date	200611
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : rjaa.artcc
State Reference	FO
Altitude	msl single value : 33000
Environment
Weather Elements	Turbulence
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B767-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 100 flight time total : 21000 flight time type : 2000
ASRS Report	715791
Person 2
Function	flight crew : first officer
Events
Anomaly	inflight encounter : turbulence
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Weather
Primary Problem	Weather

Narrative:

Encountered severe turbulence at FL330. I had discussed the possibility of turbulence en route with the dispatcher prior to departure. I was advised that there was a good chance of moderate turbulence for the first 3 hours of the flight. I had briefed the flight attendants of this possibility. After leveloff; we had encountered light to moderate chop for 3 hours. The seatbelt sign was on; the flight attendants were seated with all carts stowed. After a brief period of somewhat smooth air; the turbulence rapidly increased in intensity up to severe for a period of 3-4 mins then began to smooth out again. It never did get that turbulent again. There were no injuries or apparent damage. Other aircraft in our vicinity at different altitudes did not receive turbulence as great as ours. We were on top and in the clear with no convective activity. The WX radar was on at the time. A message was sent and dispatch notified. I briefed the mechanic and in-flight supervisor that met the aircraft.

Original NASA ASRS Text

Title: B777 ENCOUNTERED SEVERE CLR AIR TURB AT FL330.

Narrative: ENCOUNTERED SEVERE TURB AT FL330. I HAD DISCUSSED THE POSSIBILITY OF TURB ENRTE WITH THE DISPATCHER PRIOR TO DEP. I WAS ADVISED THAT THERE WAS A GOOD CHANCE OF MODERATE TURB FOR THE FIRST 3 HRS OF THE FLT. I HAD BRIEFED THE FLT ATTENDANTS OF THIS POSSIBILITY. AFTER LEVELOFF; WE HAD ENCOUNTERED LIGHT TO MODERATE CHOP FOR 3 HRS. THE SEATBELT SIGN WAS ON; THE FLT ATTENDANTS WERE SEATED WITH ALL CARTS STOWED. AFTER A BRIEF PERIOD OF SOMEWHAT SMOOTH AIR; THE TURB RAPIDLY INCREASED IN INTENSITY UP TO SEVERE FOR A PERIOD OF 3-4 MINS THEN BEGAN TO SMOOTH OUT AGAIN. IT NEVER DID GET THAT TURBULENT AGAIN. THERE WERE NO INJURIES OR APPARENT DAMAGE. OTHER ACFT IN OUR VICINITY AT DIFFERENT ALTS DID NOT RECEIVE TURB AS GREAT AS OURS. WE WERE ON TOP AND IN THE CLR WITH NO CONVECTIVE ACTIVITY. THE WX RADAR WAS ON AT THE TIME. A MESSAGE WAS SENT AND DISPATCH NOTIFIED. I BRIEFED THE MECH AND INFLT SUPVR THAT MET THE ACFT.

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.