B777 flight crew encounters moderate to severe turbulence while en route.

Attributes
ACN	717172
Time
Date	200609
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Night
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	B777 Undifferentiated or Other Model
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
ASRS Report	717172
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : anomaly accepted
Consequence	other
Supplementary
Problem Areas	Environmental Factor Weather
Primary Problem	Environmental Factor

Narrative:

While cruising at FL310 around 50W we started to encounter light turbulence; it quickly escalated to moderate to severe turbulence. Airspeed was easily +/-15 KTS and altitude +/-150 ft. This lasted 5-10 mins with turbulence and chop lasting another 30 mins as I recall. We went in and out of the unstable air for 30-40 mins. I had called the purser and told her that the flight attendants should be seated and I believe a PA followed. The flight attendants said the rear galley was trashed but no injuries were reported. I wrote it up in the logbook as severe turbulence to have the aircraft checked for damage. It was the worst turbulence myself and the copilot had experienced in a B777. I would probably rate it as heavy moderate turbulence.

Original NASA ASRS Text

Title: B777 FLT CREW ENCOUNTERS MODERATE TO SEVERE TURB WHILE ENRTE.

Narrative: WHILE CRUISING AT FL310 AROUND 50W WE STARTED TO ENCOUNTER LIGHT TURB; IT QUICKLY ESCALATED TO MODERATE TO SEVERE TURB. AIRSPD WAS EASILY +/-15 KTS AND ALT +/-150 FT. THIS LASTED 5-10 MINS WITH TURB AND CHOP LASTING ANOTHER 30 MINS AS I RECALL. WE WENT IN AND OUT OF THE UNSTABLE AIR FOR 30-40 MINS. I HAD CALLED THE PURSER AND TOLD HER THAT THE FLT ATTENDANTS SHOULD BE SEATED AND I BELIEVE A PA FOLLOWED. THE FLT ATTENDANTS SAID THE REAR GALLEY WAS TRASHED BUT NO INJURIES WERE RPTED. I WROTE IT UP IN THE LOGBOOK AS SEVERE TURB TO HAVE THE ACFT CHKED FOR DAMAGE. IT WAS THE WORST TURB MYSELF AND THE COPLT HAD EXPERIENCED IN A B777. I WOULD PROBABLY RATE IT AS HVY MODERATE TURB.

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.