Date: 201903
Local time of day: 1201-1800
Location: ZFW.ARTCC, TX
Flight conditions: VMC
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZFW
ATC / advisory: Center ZFW
Second aircraft: B777 Undifferentiated or Other Model
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Wake Vortex Encounter
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Procedure; Environment - Non Weather Related
Primary problem: Procedure

Narrative: While in level flight at FL250 with autopilot and autothrottles ON; seat belt sign ON; in the vicinity of SAYLR on the SEEVR4 RNAV Arrival; we felt some light chop/turbulence and then the aircraft suddenly rolled left approximately 35 degrees angle of bank (we got the 'Bank Angle' aural warning). As pilot flying I disconnected the autopilot and rolled back to wings level and corrected back to FL250 and on course to SEEVR. We lost approximately 150 feet in altitude during the event; and notified ATC of the event and deviation. We asked ATC what type aircraft was in front of us; and were told that it was a '777.' Flight attendants reported no passengers were up at the time of the event; no passenger or flight attendant injuries; and no complaints from the passengers. Continued on and landed uneventfully at DFW.I am not sure of how/why this event occurred. It may have been that we descended to FL250 faster than the B777 in front of us; which could have put us in their wake vortices in level flight. Possibly consider wake turbulence separation in flight by not only distance and airspeed; but also by vertical speeds/rate of descent/climb. Continue simulator training in upset/unusual attitude recovery.


Second narrative: Enroute to DFW nearing the arrival; level at FL250; the aircraft rolled hard left; the bank angle alerted. Pilot flying disconnected autopilot; rolled wings level and returned to assigned altitude. Approximately 200 foot altitude loss; bank angle near 35 degrees. Advised ATC of the event; they responded nothing was noticed by them of our action. Asked what we were following. They advised it was a 777. The pilot flying then passed pilot flying duties to me. He then contacted the cabin crew of the event to inquire if anything happened within the cabin. No effects reported. No more further event took place.The aircraft ahead of us was about 12 miles ahead descending. Wind direction was left to right; slightly off our course. [I] can only speculate the 777 was above our path; descending; and his wake descended into our path.Continue good situational awareness to hope to notice aircraft while autopilot on when wake turbulence occurring. Very grateful for our continued training of unusual attitude training in recurrent training.


Synopsis: B737-800 flight crew reported encountering wake turbulence from preceding B777 approaching DFW.