A B777 relief pilot at the controls and captain resting in the bunk reported a brief; severe; turbul...

Narrative:

Flying to the mainland; I was at the controls. We were on track east at 380. Two other company flights had gone before us at 350; and 370 with only some light chop. Our ride had been smooth for quite some time and it appeared to be clear. We were not in any SIGMET area. So with all that information; the seat belt sign was off. I noticed a sparse green radar return right at the tip of the airplane triangle on my navigation display (nd) which just popped up. When I reached over to tilt the radar lower; I felt the airplane nose being drawn down and the airspeed increasing. I immediately turned the seat belt on and put my hands back on the controls to help the airplane arrest the rapid increase in airspeed. The autopilot was on. It was at that moment that we experienced a jolt of med/sev turbulence. It lasted about a second and then dissipated quickly. I chose to leave the autopilot on and help it ride out the turbulence. While I was doing all that; the other first officer was trying to communicate to the flight attendants and the passengers to sit and be safe. We found out a bit later that the flight attendants had be thrown around; especially the ones in the back of the airplane. The passengers were all fine. We reported the incident to dispatch and suggested a severe turbulence inspection of the airplane was unwarranted. As we got close to the mainland; the flight attendants requested [a] supervisor meet the aircraft for as time went on they became more sore. [Our] flight attendants did an outstanding job. The rest of the flight was smooth and uneventful. As an aside; the radar pattern that popped up was something we normally see at or south of the equator; not between hawaii and the mainland. Don't know if the weather patterns are changing.

Original NASA ASRS Text

Title: A B777 Relief Pilot at the controls and Captain resting in the bunk reported a brief; severe; turbulence jolt which injured several flight attendants. The pilots were surprised by the lack of warning and mid north latitude at which the event occurred.

Narrative: Flying to the mainland; I was at the controls. We were on track E at 380. Two other company flights had gone before us at 350; and 370 with only some light chop. Our ride had been smooth for quite some time and it appeared to be clear. We were not in any SIGMET area. So with all that information; the seat belt sign was off. I noticed a sparse green radar return right at the tip of the airplane triangle on my Navigation Display (ND) which just popped up. When I reached over to tilt the radar lower; I felt the airplane nose being drawn down and the airspeed increasing. I immediately turned the seat belt on and put my hands back on the controls to help the airplane arrest the rapid increase in airspeed. The autopilot was on. It was at that moment that we experienced a jolt of MED/SEV turbulence. It lasted about a second and then dissipated quickly. I chose to leave the autopilot on and help it ride out the turbulence. While I was doing all that; the other First Officer was trying to communicate to the flight attendants and the passengers to sit and be safe. We found out a bit later that the flight attendants had be thrown around; especially the ones in the back of the airplane. The passengers were all fine. We reported the incident to Dispatch and suggested a severe turbulence inspection of the airplane was unwarranted. As we got close to the mainland; the Flight Attendants requested [a] Supervisor meet the aircraft for as time went on they became more sore. [Our] Flight Attendants did an outstanding job. The rest of the Flight was smooth and uneventful. As an aside; the radar pattern that popped up was something we normally see at or south of the equator; not between Hawaii and the mainland. Don't know if the weather patterns are changing.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1324874
Time
Date	201601
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Oceanic
Flight Plan	IFR
Person 1
Function	Pilot Flying First Officer
Experience	Flight Crew Last 90 Days 185.23 Flight Crew Total 10692.23 Flight Crew Type 4749.55
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 129 Flight Crew Total 11917 Flight Crew Type 2434
Events
Anomaly	Flight Deck / Cabin / Aircraft Event Illness Inflight Event / Encounter Weather / Turbulence

A B777 relief pilot at the controls and captain resting in the bunk reported a brief; severe; turbulence jolt which injured several flight attendants. The pilots were surprised by the lack of warning and mid north latitude at which the event occurred.