B787 flight crew reported temporary loss of control due to turbulence.
Synopsis
B787 flight crew reported temporary loss of control due to turbulence.
Narrative
Approaching the ZZZZZ fix in cruise at FL370; we received a PIREP from Airbus at FL350 of Severe Turbulence in the area. We were approximately 10 min from that area. Captain called the purser to let her know that there would be an area of possible turbulence and to inform the rest of the crew members. We turned the seatbelt sign on. As we approached the area; the airspeed started to increase; indicating a mountain wave. The thrust levers were restarted to idle and the speed brake were deployed to arrest the increasing airspeed. With both action accomplished; the speed continued to increase into the 'barber pole'. The speed was approximately 10 KTS above the barber pole for about 5 to 7 seconds. We had a climb of 500 feet from FL370 to FL375. As the altitude leveled; at FL375; it began to descent at FL367. Shortly afterwards; the aircraft stabilized at FL370. We requested lower altitude to ZZZ ATC and we were given a block altitude of FL370 to FL330. We leveled at FL350.We made a PA for Flight Attendants to 'Check In' and the Purser called to say that no passengers or Flight Attendants were injured. We sent a PIREP and informed Dispatch of the event. We later called Maintenance Control to inform them of the event as well as submitting a maintenance write up. We proceeded to ZZZ without further incident. We called the Chief Pilot on arrival to ZZZ to verbally report the incident.
Second reporter narrative
Approaching the ZZZZZ fix in cruise at FL370; we received a PIREP from an Airbus at FL350 of Severe turbulence. We were approximately 10 minutes from that area. I called the Purser and asked if they were finished with their service. She said they almost were finished and I informed her that within 5-7 minutes; there would be an area of possible turbulence and to pass the information to the others (Flight Attendants). We turned the seatbelt sign on. As we approached area; the airspeed started increasing; indicating mountain wave. The thrust levers were retarded to idle and speed brakes were fully deployed to arrest the increasing speed. With both actions accomplished; the speed continued to increase into the 'barber pole'. The speed was approximately 10 KTS above the barber pole for only 5 to 7 seconds. In addition to the speed; the altitude climbed to 500' above assigned altitude of FL370. As the altitude leveled at FL375; it began a descent to FL367. Shortly afterwards; the aircraft stabilized at FL370. We asked ZZZ Center for lower and were given a block altitude of FL370 to FL330. We leveled at FL350.We made a PA for Flight Attendants to 'Check In' and the Purser called to say that no passengers or Flight Attendants were injured. We sent a PIREP and informed Dispatch of what occurred. We later called Maintenance Control to inform them of the situation as well as submitting a maintenance write up. We proceeded to ZZZ without further incident. We call the Chief Pilot on arrival to ZZZ to verbally report the incident.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.