Date: 201811
Weather elements / visibility: Turbulence
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Autopilot
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Physiological - Other
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Regained Aircraft Control
Contributing factors: Weather
Primary problem: Weather

Narrative: We were climbing towards our cruising altitude with roughly one hour left to go in the flight. Between 27;000 and 28;000 feet we began encountering what I would classify as moderate turbulence which was soon followed by a brief pocket of stronger turbulence causing the aircraft to enter a sharp and abrupt roll to the left. At this point in the flight the auto pilot was engaged. Due to the large change in bank angle; I reached for the autopilot disengage button to regain control of the aircraft as soon as possible. As I reached up for the control wheel and pressed the disengage switch we received an AUTOPILOT FAIL warning message. I was quickly able to regain control of the aircraft and after a few moments of more moderate turbulence; the flight conditions improved. It was at this point that I asked the First Officer to run the appropriate checklist for the warning message. We informed ATC that we had encountered a pocket of moderate to severe turbulence; had lost our autopilot; and needed to remain in non-RVSM airspace. We were cleared up to 28;000 feet. I called the flight attendant to ensure that she was unharmed and that the passengers were alright as well. She explained that she was doing her service near the exit row and hit her head on the side of one of the overhead bins. She assured me that she was ok; did not hit her head hard; and was not feeling any discomfort. She told me that she was willing and able to continue the flight. I explained that if she; at any point during the flight; began to feel any discomfort or felt that she was unable to perform her duties to let me know. She also explained to me that all the passengers were seated with their seat belts fastened; as we had not turned off the fasten belt sign. No one was injured or uncomfortable; and that she had only received a few comments of concern primarily for her to make sure she was ok after seeing her hit her head. She again assured me that she was ok to continue. We messaged Dispatch informing them of the turbulence; the autopilot failure; and let them know we would be cruising at 28;000 feet; which we had the appropriate data for. Besides the autopilot failure; myself and the first officer noticed nothing else wrong with the aircraft or the flight controls and decided that we could safely continue to [destination] without the autopilot. We landed and concluded the flight with no other issues. I made sure once again that the flight attendant was ok; and that no passengers had complained about any discomfort during any point in the flight. I feel I should mention that I decided to classify the moment of turbulence as severe because; although brief; it seemed worse than any moderate turbulence I had encountered in the past. Although I'm not sure of the exact bank angle at the time of the incident; it caused a sharp uncommanded roll to the left which was dramatic and severe enough that I would classify it as a momentary loss of control; which also seemingly failed our autopilot. Myself and the First Officer were in agreement that we should classify it as moderate to severe.




Synopsis: E145 Captain reported encountering severe turbulence which caused the auto pilot to fail.