Air carrier flight crew reported temporary loss of aircraft control due to severe turbulence during initial descent.
Synopsis
Air carrier flight crew reported temporary loss of aircraft control due to severe turbulence during initial descent.
Narrative
The flight attendants and passengers had been seated for approximatly 20 minutes. I had used the Flight [attendants]; take your jumpsuit command. We were originally on the ZZZZZ1 arrival; that closed off due to thunderstorms. Hey had been slowed by ATC; we told ATC our minimus speed at FL320 was .74 due to weight. The next assigned STAR was the ZZZZZ 2 arrival. Via CPDLC we were cleared over ZZZZZ1 and onto the ZZZZZ 2 arrival. Prior to reaching ZZZZZ1; heading approximately west; we were descended to Fl300. Onboard radar showed us above weather; but we were IMC. I believe we were just south of ZZZ1 airport when airspeed began to increase rapidly in moderate turbulence. The turbulence intensified; I disconnected the auto thrust first and ask the PM for an immediate climb and turn. that autopilot was disengaged; I began a turn to the South and a climb to exit severe turbulence. The auto pilot would not engage. I believe we descended approximate 300 feet and climbed about 500 feet without receiving clearance due to radio congestion. the turbulence event lasted approximately 3-5 minutes before light turbulence prevailed. Autopilot and Auto-thrust were restored. PM reported the incident; and I consulted with the Purser on the status of the back of the aircraft. No injuries reported.
Second reporter narrative
The flight itself had progressed as planned. We expected some weather and began to build contingency plans once we heard that other aircraft were holding awaiting arrival into ZZZ. Our alternate was originally ZZZ2 but ZZZ3 was added a third into the flight.The weather became more of an issue once were taken off of our original route and taken South along the water. This is where the aircraft radar on the NEO came in handy. The radar did a great job depicting what weather was a threat. We were able to assess the threat(s) as ZZZ Center worked us toward ZZZ.This is when the workload for the controllers seemed to become busy. The weather was continuing to get worse. The convective activity that was originally not a threat now was. The frontal passage was fueling a large group of storms that ranged along our path in size and shape. Most of the storms looked to be to our sides.ZZZ center began to bring us closer to ZZZ yet again and this is where we began to encounter light to moderate chop. The captain already had the passengers down and had previously instructed the flight attendants to be in their jumpsuits.We began to notice a number of cells ahead that were becoming stronger but the radar was depicting them below us. The radar gave these storms a lighter shade of color and the hatching to depict them below us. We agreed that they looked to be a threat and asked for vectors. ZZZ Center assisted but they eventually placed us into an area with a large amount of turbulence.From the controllers standpoint; they most likely saw an area with no convection; and even our radar was not depicting anything where we were. This is where; as we progressed into the IMC conditions at FL 320; things began to degrade further in terms of ride.The ride began to deteriorate as we encountered some rather persistent and bright St Elmoes fire. Not shortly after; ZZZ Center instructed us to descend to FL 300. We complied but were cautious. Once there the ride was constant chop and a good amount of moderate turbulence. The radar was depicting more cells around us but nothing directly below. After about three to five more minutes of this ride; the radar began to depict several areas of weather ahead and below. We asked for vectors but were not heard.Here we began to encounter severe turbulence. We were given left of course but that ended up not being enough. As the Captain came left; the airspeed began to increase. We initially saw a ten knot increase; but probably more. It seemed that we had entered the edge of a vertical sheer zone at FL 300; because shortly after we encountered turbulence so bad that the autopilot turned off.The Captain took control of the aircraft and did his best to manage the best attitude for safety. However; the area in the clouds that we had found was very active. The turbulence was so bad that focusing on the instruments was near impossible at times and at best you could make out trends with brief clear shots of speed and altitude. The Captain asked for a climb and I requested that from ZZZ Center. The call was not heard clearly; and after several failed attempts we declared we were climbing to escape severe turbulence.We were promptly given a clearance to FL 320. As the Captain intimated the climb; the aircraft was still struggling. Note; a descent was not an option considering the surrounding weather. As we approached FL 306 the airspeed became very erratic and approached vls. The Captain was about to initiate an Upset" recovery when thankfully the turbulence subsided enough that the aircraft came back into a more controlled state. As we passed FL 313; the turbulence began to subside to light and occasional moderate. Within about ten minutes after that we found an area of light IMC and then eventually a gap between the storms with smooth air.A check in was made with the flight attendants. They were okay and no injuries reported."
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.