Emb-175 captain reported severe turbulence encounter resulting in momentary loss of control.

Narrative:

At FL200 in cruise to ZZZ; we were experiencing continuous moderate turbulence for the majority of the flight. The seat belt sign was on and the fas (flight attendants) were seated when we suddenly experienced severe/extreme turbulence 50 miles northeast of ZZZ1. The event lasted approximately 20 seconds and we encountered airspeed deviations of +/- 20 knots and altitude deviations of +/- 200 feet. The aircraft was briefly uncontrollable. We were maintaining 270 knots when we experienced this encounter. We did not experience any indications of an over-speed. During this encounter we immediately made a report with ATC and were cleared to descend to 17;000 MSL. We then confirmed the safety of our fas and passengers and then sent a message to dispatch via ACARS.we then continued in moderate turbulence and began a descent into ZZZ. At 13;000 feet over ZZZ2 we experienced approximately 10-15 seconds of severe/extreme turbulence again; made the notification to ATC and again confirmed everyone was stilled seated. We received reports from the preceeding aircraft on the approach into ZZZ; which indicated occasional moderate turbulence and a ceiling of approximately 1;000 feet. We continued the approach and landing at ZZZ with no further incident and immediately contacted dispatch and maintenance control at the gate.

Original NASA ASRS Text

Title: EMB-175 Captain reported severe turbulence encounter resulting in momentary loss of control.

Narrative: At FL200 in cruise to ZZZ; we were experiencing continuous moderate turbulence for the majority of the flight. The seat belt sign was on and the FAs (Flight Attendants) were seated when we suddenly experienced severe/extreme turbulence 50 miles NE of ZZZ1. The event lasted approximately 20 seconds and we encountered airspeed deviations of +/- 20 knots and altitude deviations of +/- 200 feet. The aircraft was briefly uncontrollable. We were maintaining 270 knots when we experienced this encounter. We did not experience any indications of an over-speed. During this encounter we immediately made a report with ATC and were cleared to descend to 17;000 MSL. We then confirmed the safety of our FAs and passengers and then sent a message to Dispatch via ACARS.We then continued in moderate turbulence and began a descent into ZZZ. At 13;000 feet over ZZZ2 we experienced approximately 10-15 seconds of severe/extreme turbulence again; made the notification to ATC and again confirmed everyone was stilled seated. We received reports from the preceeding aircraft on the approach into ZZZ; which indicated occasional moderate turbulence and a ceiling of approximately 1;000 feet. We continued the approach and landing at ZZZ with no further incident and immediately contacted Dispatch and Maintenance Control at the gate.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1618441
Time
Date	201902
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 170/175 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Cruise Descent
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Total 12064 Flight Crew Type 3415
Events
Anomaly	Inflight Event / Encounter Loss Of Aircraft Control Inflight Event / Encounter Weather / Turbulence