CRJ550 flight crew reported an inflight upset that resulted from a wake turbulence encounter on approach to ORD in trail of an Airbus.
Synopsis
CRJ550 flight crew reported an inflight upset that resulted from a wake turbulence encounter on approach to ORD in trail of an Airbus.
Narrative
While on approach to the ILS 28C into ORD we experienced severe wake turbulence between the fixes Koenn & Memaw on the ILS 28C. We were following an Airbus 320/321 by 5 miles and in front of them was a 777. The aircraft had a slight roll to the left (5-10 degrees); followed by an uncommanded snap roll to the right. The roll was estimated to be between 35-45 degrees. The Captain (PF) and myself (PM) both said; 'Upset' which the CPT (Captain) performed incredibly well. The aircraft initially did not roll to the left; in fact I still remember hearing the CPT slam the flight controls against the stop to the left as he tried to correct the a/c and the a/c did not respond. After recovery the CPT checked on the flight attendant and passengers and we continued with the approach. I notified ATC multiple times which until I informed them about how far we rolled (approx 35-45 degrees) and our actions to get back on the approach; they seemed to not understand the severity of the situation. Once clear of the runway the CPT made an announcement to the passengers for some reassurance. We continued to the gate without further issue.Cause is unknown.Contributing factors have to be the spacing of the 777 then the Airbus 320/321 a/c (Aircraft); however we did note that there was 5 mile spacing between the aircraft as shown on our map rings.Suggestions: Unsure; unless they would like to provide more spacing for regional jets following heavy a/c or 320/321 a/c on approach.
Second reporter narrative
After joining the ILS 28C approach course; we were made aware by ATC that there was a heavy Boeing 777 two spots in front of us; approximately 10nm ahead. Around 5 miles ahead of us was an Airbus 319/20. I think they both joined the final approach course around KOENN at 7;000 ft; making a right base-to-final turn from the North. We joined the approach from a Southeast arrival ( I believe it was the WATSN 4); so we joined a 30 nm straight in for the approach. It had been an uneventful flight; and good weather conditions with a small layer over the field but we were in VMC. The spacing seemed normal; so both me and my first officer weren't thinking wake turbulence would be an issue; however; around KOENN we got hit with significant wake turbulence. at first; the aircraft banked left about 10-20 degrees slowly; which we acknowledged as wake and the autopilot corrected promptly. As it was correcting back to straight-and-level; the aircraft sharply banked right between 40-50 degrees uncommanded . Both me and my first officer called 'Upset' simultaneously; and I hand flew the upset recovery procedure. I believe we lost around 400 feet of altitude in the recovery before I was able to get the wings level and the aircraft stabilized. My airspeed increased to around 220 knots before I slowed back to our assigned speed. While I was recovering; my First Officer made a call to ATC to let them know we were deviating and recovering; but stepped on someone else's transmission so ATC was unaware for about 2-3 minutes until we found space to talk to them and inform them of our situation. I returned to normal flight at 7000 ft. and once I had the autopilot back on I asked my first officer to reach out to the flight attendant to verify that everyone in the back was okay. My flight attendant said everyone was fine and no injuries; but that people were pretty nervous. We reported no injuries to ATC when they asked. Since I was around 15 miles away from landing I decided to continue approach to land; which was uneventful. After clearing the runway; I set the parking brake and made a passenger announcement to apologize for the bumpy ride; and explained to them that it was due to wake turbulence from an aircraft in front of us. We then went to the gate; deplaned; and I called the Manager and filled out a report. Then we continued our flight day.Wake turbulence induced the undesired aircraft state. Busy radios made communicating with ATC during the upset recovery messy.Suggestions: I think this was an unavoidable event. Spacing and altitude seemed good to me; and we did a textbook upset recovery procedure prescribed by Standard Operating Procedures.
NASA callback
Reporter stated he was very concerned at the apparent lack of understanding from ATC as to the severity of the encounter. Controller seemed very unconcerned when they were advised of the sharp roll and inflight upset.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.