Embraer Jet Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Aircraft; Environment - Non Weather Related; Human Factors; Procedure
The event began when we were cleared for the ILS 36L. We were following a heavy 777. Weather conditions were IMC with constant chop caused by light to moderate precipitation. The autopilot significantly undershot the localizer while attempting to capture from a normal 30 degree intercept. The aircraft began a series of sweeping turns to regain the course. The aircraft's reaction very well may have been caused by wake turbulence from the preceding heavy. The Pilot Flying disconnected the autopilot and set an appropriate heading to capture the localizer. While doing so; the aircraft's altitude climbed to approximately 3400 feet MSL. I noticed the aircraft in a climb and called out the altitude deviation. As Pilot Flying was correcting back to the original altitude of 3000 feet MSL; Approach Control monitor queried our altitude. As we corrected back to 3000 feet MSL; we had joined the glide slope. We continued the approach to a normal landing. The autopilot's poor performance; subsequent intervention; and potential wake encounter caused the aircraft to abruptly roll. This; I believe; caused both myself and pilot flying to fixate on correcting the roll attitude and focus on guiding the aircraft back to the localizer. By the time the altitude deviation was recognized; ATC had queried us regarding our altitude. I believe that myself and Pilot Flying were faced with a challenging situation that presented itself abruptly in poor weather conditions. I think we were correct in disengaging the autopilot and focusing instead on flying the aircraft; however; we should have maintained more vigilant on our scan. I believe the EMB's automation should be updated to allow for a more gradual and accurate localizer intercept. Additionally; I believe having smaller aircraft intercept the localizer at a point downwind of where a preceding heavy aircraft intercepted would lead to reduced wake encounters.
EMB Captain reported track and altitude deviations on approach to DFW; citing a wake turbulence encounter and poor aircraft autoflight performance as contributing.