Over north atlantic; B777-200 attempts to climb out of turbulence and is unable to reach cleared altitude or maintain airspeed. Descends off course until able to regain aircraft control and receive new clearance.

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Attributes
ACN	694487
Time
Date	200604
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : czqx.artcc
State Reference	FO
Altitude	msl single value : 36000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : czqx.artcc
Operator	common carrier : air carrier
Make Model Name	B777-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute : other oceanic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : relief pilot
Experience	flight time last 90 days : 200 flight time total : 11500 flight time type : 1500
ASRS Report	694487
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence non adherence : clearance other anomaly other anomaly other spatial deviation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : declared emergency flight crew : took precautionary avoidance action flight crew : regained aircraft control
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance Weather
Primary Problem	Ambiguous

Narrative:

I was the relief pilot but in front seat as flying first officer was on break. FL360 approaching east coast of greenland. Started to get chop so we sat the passenger. Got worse so we sat the flight attendants. Getting moderate to severe turbulence we received climb clearance to FL370 from gander via cpdlc. Close to FL370 aircraft could not maintain airspeed or altitude. Got severe turbulence. Captain called for 5 mi right offset and to set FL340 in MCP (we were going to be descending whether we wanted to or not). I called gander and reported severe turbulence; that we were offsetting and descending. Gander came back and stated traffic below us at FL340; could we maintain FL350. We said we would try. Gander cleared us to FL350 and since we had clearance we turned back to on course. We never got further than about 2.5 mi right of course. Shortly before leveling at FL350 the turbulence stopped. ( I don't think we descended through it; I think we flew out the back side of it).

Original NASA ASRS Text

Title: OVER NORTH ATLANTIC; B777-200 ATTEMPTS TO CLB OUT OF TURB AND IS UNABLE TO REACH CLRED ALT OR MAINTAIN AIRSPD. DSNDS OFF COURSE UNTIL ABLE TO REGAIN ACFT CTL AND RECEIVE NEW CLRNC.

Narrative: I WAS THE RELIEF PLT BUT IN FRONT SEAT AS FLYING FO WAS ON BREAK. FL360 APCHING EAST COAST OF GREENLAND. STARTED TO GET CHOP SO WE SAT THE PAX. GOT WORSE SO WE SAT THE FLT ATTENDANTS. GETTING MODERATE TO SEVERE TURB WE RECEIVED CLB CLRNC TO FL370 FROM GANDER VIA CPDLC. CLOSE TO FL370 ACFT COULD NOT MAINTAIN AIRSPD OR ALT. GOT SEVERE TURB. CAPT CALLED FOR 5 MI R OFFSET AND TO SET FL340 IN MCP (WE WERE GOING TO BE DSNDING WHETHER WE WANTED TO OR NOT). I CALLED GANDER AND RPTED SEVERE TURB; THAT WE WERE OFFSETTING AND DSNDING. GANDER CAME BACK AND STATED TFC BELOW US AT FL340; COULD WE MAINTAIN FL350. WE SAID WE WOULD TRY. GANDER CLRED US TO FL350 AND SINCE WE HAD CLRNC WE TURNED BACK TO ON COURSE. WE NEVER GOT FURTHER THAN ABOUT 2.5 MI R OF COURSE. SHORTLY BEFORE LEVELING AT FL350 THE TURB STOPPED. ( I DON'T THINK WE DSNDED THROUGH IT; I THINK WE FLEW OUT THE BACK SIDE OF IT).

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.