Date: 202003
Local time of day: 0601-1200
Location: ORD.Tower, IL
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ORD
ATC / advisory: Tower ORD
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness; Distraction; Workload
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Wake Vortex Encounter
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors; Environment - Non Weather Related; Procedure
Primary problem: Human Factors

Narrative: While on approach to Runway 27L at ORD; at approximately a 10 to 15 mile final; we encountered wake turbulence. We were on glide slope and slowing to 170 kts. until the final approach fix as instructed by ATC. The wake turbulence resulted in an uncommanded roll to the right between 30 and 40 degrees. Upon the encounter the Captain who was Pilot Flying disengaged the autopilot and leveled the wings and began to return to the desired flight path. Four EICAS caution messages were displayed: AT FAIL; WINDSHEAR FAIL; STALL PROT FAIL; and AOA LIMIT FAIL. We waited a brief period to see if the messages would clear. They did not. At the Captain's direction; I began to run the QRH for the displayed messages. While running the QRH checklist for STALL PROT FAIL which included entering new approach speeds; the Captain realized that we were below 1;000 ft. AGL and not configured. We executed a go around. Initially we were told to level at 2;500 ft.; then instructed to turn toward the north and climb 5;000 ft. and expect ILS Runway 27R. During this time; QRH items were completed and we returned for an uneventful landing Runway 27R. ATC stated the largest aircraft ahead of us was an E175. Given the nature of the wake turbulence; we believe it is possible that we may have encountered a wake from heavier traffic to a parallel runway although we do not know for sure.As a recommendation; it may be prudent to execute a go around earlier in these circumstances. We allowed the aircraft to get below 1;000 ft. prior to realizing that we were unstable while I was running the QRH. Given the added tasks created by the QRH checklist; it was easy to get behind the aircraft.


Second narrative: While on the localizer for ILS Runway 27L in ORD; we were descending in PTH mode coincident with the glideslope. Around 4;000 ft.; we began to experience wake turbulence with a slight roll to the left the autopilot compensated and returned to level flight then we got a hard roll to the right which resulted in a bank angle between 30 and 40 degrees. I took over the controls and recovered from the roll as well as initiated a slight climb to get above the wake. During the event; multiple EICAS messages were presented. These included AT FAIL; WINDSHEAR FAIL; STALL PROT FAIL; and AOA LIMIT FAIL. After recovering the aircraft and returning it to the desired flight path; I queried ATC as to what aircraft we were following. They said it was an E170. When I said we got pretty rough wake he said he wasn't sure what from since the aircraft in front of that E170 was an E145. We continued the approach while the First Officer ran the checklist. With the distraction of the wake event leading to multiple unusual checklists; I got behind the airplane and noticed the approach was not going to be stable. At that point I commanded a go around. We executed the go around; completed the checklists and landed on Runway 27R. Once on the ground the EICAS caution messages disappeared and were replaced by ADS PROBE 3 FAIL and ADS PROBE 1 FAIL messages.During the event ATC did not mention what traffic was on ILS for 28C; but I did notice on TCAS there was one approximately 2 to 3 miles ahead on that approach. I did not ask what type it was and being in IMC I didn't get a visual; however I suspect the turbulence may have been from that aircraft since the winds were coming from the southwest.In the future; I think it would be a good idea to go around earlier. We were hoping to get the checklists done but due to the number of them it wasn't possible and lead to a go around at a lower altitude than was necessary. Also; although my primary attention was still flying the aircraft; I allowed myself to get distracted watching the Pilot Monitoring make the changes associated with the abnormal checklists and this is how I got behind the airplane. In the future I'll do a better job as pilot flying to ensure the aircraft does not enter the undesired aircraft state.


Synopsis: E170 flight crew reported that a possible wake turbulence encounter resulted in an unstabilized approach and a go around.