Date: 201811
Local time of day: 1801-2400
Location: PCT.TRACON, VA
Weather elements / visibility: Turbulence
Light: Night
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B PCT
ATC / advisory: TRACON PCT
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Contributing factors: Weather
Primary problem: Weather

Narrative: During our flight to IAD we encountered severe turbulence during the descent phase of our flight just prior to the approach. We were holding at the RIC VOR when we were given a clearance to IAD via vectors. After our initial heading leaving the hold; we saw an area of weather between us and the airport. We asked for a deviation left of course to go west of the weather. The Controller indicated that east was better and sighed into the microphone. We agreed to go right (east) of the weather. After going around that band of weather we turned towards the airport and were in a descent to 3;000 feet initially; and then 2;000 feet. During this stage of the descent approximately 25-30 miles from the airport (est) we encountered severe turbulence. This was noted by the momentary loss of control; the inability to maintain altitude (in what I suspect was a downdraft); significant and abrupt changes in attitude causing blurry vision of the instruments; increase in airspeed from 250 up to 280-290 within just a few seconds without any change in power or pitch; uncommanded loss of the autopilot along with multiple caution messages which included all of but not limited to the following: stab and mach trim disconnect; right or left wing down ( I don't remember which); autopilot pitch trim; and I think I remember seeing an AOA caution as well. During the portion of the event where we were unable to maintain our altitude; we temporarily descended to 1;800 feet. ATC noted that we were below the minimum vectoring altitude and to make an immediate climb to 3;000 feet. Initially I was unable to climb; but then was able to and the aircraft began climbing. We reach approximately 2;600 feet when we were given the descent by ATC back down to 2;000 feet. Once we were out of the severe turbulence and were in smoother air; we were vectored to final approach of 1R and concluded the flight uneventfully.A few things to note:-We did notify ATC of our inability to maintain altitude and that we were experiencing severe turbulence. -We were unable to see the weather that was near the airport until after we deviated around the initial band of weather; so we did not know until we were in a position where we could not turn around that it was there until it was too late.Our gut told us to divert to ZZZ while we were in the hold for almost an hour. We should have done that. We had about 25 minutes of hold fuel left so we decided to hold off. There is nothing that says we need to wait until the last drop of fuel is expended. So when we began to get the itch to get on the ground and wait for the weather to pass we should've. -We should have been made aware long before we were in that position that there was moderate to severe precipitation along final approach and between us and the airport. Our radar was not painting what was behind the initial band that we encountered; so our request to fly west of the weather should not have been met with hesitation from ATC.




Synopsis: CRJ-200 Captain reported an encounter with severe turbulence resulted in momentary loss of control on arrival into IAD.