Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Environment - Non Weather Related; Procedure
Inbound on a visual approach to [Runway] 8R into IAH over the JELLI fix. Airspeed was 180 KIAS slowing to 170 KIAS per ATC instructions. Captain and First Officer called the airport so ATC Approach Control told us to cross the fix EELPO at 3;000 feet and cleared for visual approach to [Runway] 8R. ATC identified preceding aircraft 4 miles ahead. Upon intercepting the glideslope near the fix REIGN; the aircraft unexpectedly encountered moderate wake turbulence from the preceding aircraft. Aircraft started rolling in both directions at approximately 30-35 degree bank angles. Pilot Flying immediately hand flew the aircraft to regain control as the Autopilot Fail warning message appeared on the EICAS. Aircraft was leveled off and pilot flying stayed slightly right of the localizer and above the glide path to avoid any more wake. Pilot Monitoring immediately reported the wake to ATC and to identify the preceding aircraft. Aircraft was a 737-900. Pilot Monitoring told ATC of our new flight path to avoid any further wake. Captain checked with Flight Attendant to ensure no one was injured - none reported by her. Approach Control handed aircraft over to IAH Tower who asked if we needed assistance - Captain reported none needed. Aircraft back on proper visual path to Runway 8R before Final Approach Fix MATON. Final approach and landing normal. Normal exit and taxi to the arrival gate.Threat was the unanticipated encounter with wake turbulence during the approach. Spacing from ATC was normal for typical operations in IAH. [Loss of control] was the sudden roll of the aircraft with the Autopilot Fail warning message on the EICAS with Pilot Flying needing a quick recovery to maintain altitude and heading.Spacing minimums should be reviewed and revised with ATC given the amount of wake turbulence the 737-900 series put out in our flight path. There wasn't enough separation allowed given the event.
EMB-145 First Officer reported encountering wake turbulence on approach to IAH 4 miles in trail of a B737-900.