Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Total 9700
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Returned To Clearance
Environment - Non Weather Related; Procedure
While in cruise flight at FL290 in smooth air; we encountered wake turbulence. The First Officer was the Pilot Flying with the autopilot on. I noticed the aircraft roll abruptly left followed by a roll to the right. The First Officer took immediate action by simultaneously disconnecting the autopilot and providing positive control inputs. An Autopilot Fail EICAS message appeared as well. While he did that; I put the fasten seatbelt sign on; then noticed the aircraft climbing above assigned altitude and brought this to the Pilot Flying's attention. He was clearly attempting to arrest the climb. We continued a slow climb and I mentioned it again to him. He verbally responded that he was pushing forward. At this point I also pushed forward on the yoke until a descent began. The climbed stopped at FL295. I advised ATC that we had encountered wake turbulence and were descending back to FL290 which ATC acknowledged. Next; I called the Flight Attendant to find out the status of the cabin and passengers. She stated everyone was fine but that some were looking at her (presumably for information). I told her I would make a PA which I did. The First Officer and I discussed re-engaging the autopilot. The Autopilot Fail EICAS message had extinguished almost immediately after it appeared. We agreed to engage the autopilot again and did so with no issues. The rest of the flight continued without any other issues. I sent the appropriate ACARS message to Maintenance as per our SOP; made the AML entry; and called [Maintenance Director] after landing. [Maintenance Director] stated that the EICAS message was expected during a wake turbulence event.Wake turbulence during cruise causing autopilot disconnect. In my opinion; the Pilot Flying acted appropriately and we worked together as a team to make sure the aircraft; passengers; and crew were all OK. I cannot think of anything to be done differently. We were not given any traffic advisories from ATC that may have alerted us to the potential for wake turbulence. I've experienced several wake encounters prior to this one and it was the least severe of all of my experiences.
EMB-140 Captain reported encountering wake turbulence at FL290 that led to an altitude excursion.