B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 223
Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance
Weather
At cruise we were cleared to ALICE waypoint direct VUZ. We were deviating left of course for buildups and navigating around the weather using the radar. We were IMC; while deviating; and we exited the IMC conditions and discovered a rapidly building cell was directly in front of us. We turned immediately to the right to avoid this new weather threat and we were caught in a very significant downdraft and heavy rain. Since we were in the turn; the downdraft caused us to exceed 30 degrees of bank; we got to approximately 45 degrees and we lost about 400 feet-500 feet from our assigned altitude of FL350. We quickly recovered the aircraft to level flight and exited the area of weather build ups. With the severity of the downdraft; I did not disconnect the automation for fear of exacerbating the condition we found ourselves in. We did not experience any turbulence during this event.
B737 Captain reported a 45 degree bank angle and 400-500 feet loss of altitude resulted when he encountered a thunderstorm cell at FL350.