A321 flight crew reported encountering wake turbulence on arrival into DFW; citing ATC procedures as contributing.
Synopsis
A321 flight crew reported encountering wake turbulence on arrival into DFW; citing ATC procedures as contributing.
Narrative
Experienced wake turbulence induced aircraft upset while joining the [Runway] 35R localizer outside Galop intersection. Autopilot disengaged in [an] approximately 15 degree nose high attitude. I cannot recall if we had leveled at 5000 [ft.] as cleared and then climbed or were still descending to 5000 [ft.] when this happened. I recovered by hand flying at approximately 5700 [ft.] MSL. Joined the localizer by hand. During the event ATC recleared us to 4000 ft. And I continued the descent. Re-engaged the automation. Cleared for approach and landed uneventfully. Unsure if we had an altitude deviation. The ATC Controller was extremely busy. We were task saturated with a late turn to join the localizer causing a 1 dot fly through and minor S turn joining the localizer. We experienced moderate wake turbulence in IMC and a surprise autopilot disconnect. The First Officer had a problem cleaning up the FMS waypoints and I looked over at his FMS at the exact time the autopilot disconnected. This led to an additional few seconds of startle factor. Our unusual attitude training kicked in automatically. More spacing from ATC. Smoother or less angled (90 degree turn) turn to final.
Second reporter narrative
We were given an intercept to intercept [Runway] 35R localizer. It was during the intercept that we encountered some turbulence and what might have been wake from a previous aircraft. Autopilot disconnected and gained approximately 4 to 500 feet. The Captain stabilized the aircraft and reengaged autopilot. We were cleared for the 35 right ILS approach and landing without incident.Intercept clearance appeared late; at the same time we were encountering turbulence and vortices. I am still not sure why we received an autopilot disconnect.
NASA callback
Reporter stated autopilot disconnect was probably related to the severity of the wake encounter.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.