Date: 201511
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Weather elements / visibility: Turbulence
Light: Night
Aircraft: B757 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Relief Pilot
Anomaly: Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Work Refused; General Physical Injury / Incapacitation
Contributing factors: Weather
Primary problem: Weather

Narrative: Approximately 10-15 mins after takeoff we encountered severe turbulence between 27;000-30;000 ft. Duration was approximately 5 mins. It was the worst turbulence I have encountered in my 30 plus years of flying. Location was close to the shoreline; as our routing on departure from ZZZ had us flying north for a bit; before being turned east; to cross the water. There had been no other aircraft on our frequencies mentioning severe turbulence. There was no convective activity in the area; although very high winds on the ground and aloft; associated with a cold front. The seat belt sign was turned on; passengers were all seated. The flight attendants in the back had just gotten their carts out to begin their service. Severe turbulence began without warning. The FB had just gone back to business class to begin his break. Both CA and FO had our hands full to maintain aircraft control. FO was pilot flying. We disconnected Auto Pilot and Auto Throttles; and attempted to climb out of the turbulence. It took us longer than expected; due to previously mentioned lack of complete aircraft control. Airspeed loss was approximately 60 knots; from 310 down to 250 before airspeed decay was arrested and a climb to smooth air was accomplished. Once we leveled at 310 and were out of the turbulence and building airspeed; I took over ATC communications and the CA handled the cabin. The Captain was informed of the cabin injuries and immediately [advised ATC] and directed a return to ZZZ. The FB remained in the cabin to help with the injured crew members. One woman had a head wound and the other; who was more seriously injured; had a flying full food service cart land on her. As soon as injured were as stable as possible; FB returned to cockpit to aid in our emergency return. We were all concerned that we might descend thru the turbulence area; so we flew south for 30 miles or so; before turning back west towards ZZZ. We were able to miss the turbulence on descent. We were going to be overweight by about 20;000 lbs; so we accomplished the Over Weight Landing checklist. We radioed ops and had ambulances waiting for us at gate. We asked for; and received; clearance to straight in ILS to Runway XXR. Weather was clear and wind was well within limits. Uneventful approach and landing on the long runway; with minimal brake usage; due to overweight condition. ZZZ ATC was outstanding through the entire event; enroute; approach and tower and ground at ZZZ.Arrived at gate; passengers remained seated to allow EMTs to get to rear of aircraft. Injured crew safely removed and passengers allowed to deplane. Many frightened; scared passengers. Cabin crew was injured; very emotionally upset; but still performed their duties admirably. The three of us pilots were very keyed-up and over-loaded on adrenaline after what we had been through; and after a brief; closed door conference; the three of us decided that we were not mentally or physically fit for duty to fly an 8 hour flight across the Atlantic into forecast heavy winds over in England; with possible missed approach and/or diversion. The Captain handled the communication with crew tracking and the chief pilot. We then went down to operations and spent the next 30-45 minutes winding down and reviewing our flight. The longer we talked the more convinced I was that we were making a wise decision in not continuing that evening.


Second narrative: We were about 30 minutes into our flight and I had just sat down in the cabin to start my break when we encountered severe turbulence. It lasted anywhere from 5-10 minutes. After the worst of it had passed I noticed our purser rushing through the cabin to the aft part of the aircraft. I curiously followed her and found [three] FA's injured in the back galley with a galley cart laying on its side and its content spilling out. I then returned to the flight deck to assist in coordinating our emergency arrival with ramp; dispatch and maintenance. After an uneventful landing; we were expedited to the gate. Next came firemen; paramedics; ambulances and police officers along with crying passengers and injured and upset FAs. At this point there was some discussion about getting a 767 and new FAs available to continue flight but nobody had a time frame set. The three of us then decided; per our Human Factors guidance; to discuss our ability to perform our duties safely going forward after an adrenaline producing event like the one we had just incurred and came to the conclusion that we were probably more affected than we cared to admit at that point. Looking at the weather both at ZZZ and the potential of similar weather at the destination according to the forecast; along with not knowing when an aircraft and crew would be ready; we decided after another 20-30 min. discussion that it wouldn't be in the best interest of safety for us to continue with [the] flight. We had all been under a great deal of stress and were all starting to feel a little overwhelmed. At that point; we returned to operations and spent the next 45 minutes discussing what had happened and decompressing. We didn't get any reports of severe turbulence and while we had heard reports of turbulence; none of them reached the point we experienced. Perhaps we could have kept the FAs seated a little longer but as mentioned there were no prior indications of turbulence of even close to this magnitude.


Synopsis: B757 flight crew reported encountering severe turbulence on climb out that resulted in injuries to several flight attendants.