Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Deviation - Altitude Excursion From Assigned Altitude; Ground Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Became Reoriented; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action
Weather
While enroute from ZZZZ to ZZZZ1; we encountered an area of convective activity near the ZZZZ VOR that continued beyond the ZZZZ VOR. After analyzing the information provided by our radar and HUD systems; we decided to deviate approximately 80 miles east-north east from our filed routing. We made the appropriate request with ATC and the request was approved. As we made our deviation around the area of embedded thunderstorms; we encountered continuous light and occasional moderate turbulence; as we expected we would. As we were emerging from the weather; we received a couple of moderate jolts followed by a brief period of severe turbulence. The autopilot (AP2) kicked off and we began to descend at a rapid rate. As Pilot Flying; I assumed manual control of the aircraft; and gently arrested the descent; being cautious not to over stress the aircraft. Once the aircraft was back in control; (approximately 500 feet below) I began to climb back up to our assigned altitude (10400 M). During this event; ATC queried us about or reason for descending. The Captain; pilot monitoring; responded to the ATC inquiry; explaining that we had encountered severe downdrafts that had forced us off our assigned altitude. As we proceeded away from the weather; ATC handed us off to another frequency. The controller on the next frequency; who spoke better English; continued to inquire about our event and also asked for more details about our aircraft; departure point and destination. This controller also stated that there had been traffic directly below us. We had been closely monitoring our flight path and radar displays and we never saw any TCAS returns from another aircraft. Upon arrival in ZZZZ1; we conducted a thorough debrief about the event. The Captain contacted Maintenance; Operations; and the Dispatch Office to complete all of the requisite tasks.It's difficult to say how this could have been avoided; as we followed the appropriate TS avoidance procedures. We were using all of the tools at our disposal to the best of our abilities and we still ran into severe turbulence. Our radar was displaying light-moderate returns and showed us clearing the heavy returns by more than 40 miles. Perhaps we could have chosen a different path of deviation that would have taken us several hundred miles to the south and west of this weather system. A path further to the E-NE would have put us near Country X airspace. Having real time Radar pictures from a WiFi connection would have been extremely helpful. It would be nice to see a larger picture of the weather system to help us make a better informed decision.
Flight Crew reported turbulence caused a loss of aircraft control; requiring evasive action to regain aircraft control.