Narrative:

Descending on downwind leg into lax through approximately 4;000 feet; 180 knots; flaps 10; irnmn 2 RNAV arrival; approximately gaddo intersection. ATC advised following a heavy 777 on the arrival. Winds were mostly calm; sometimes 7 knots on the tail; [and] sometimes 7 knots on the nose. Kept getting a few nibbles of wake; mostly just a bit of turbulence with mild; few degrees of roll. Approximately one minute later; got hit with an initial left roll of approximately 15 [degrees] left wing down. First officer (pilot flying) grabbed the controls; and autopilot remained engaged; returning aircraft to level flight. Almost immediately after; a hard roll of approximately 30 degrees left wing down was encountered (never heard 'bank angle' so believe we remained less than 35 degrees). Autopilot was disconnected; aircraft nose lowered; and a return to level flight accomplished. After approximately 30 seconds; captain (pilot monitoring) recycled autopilot cmd engage with no success. Cycled disconnect switch; flight directors; LNAV/flch; and eventually all functions of autopilot were returned. Reported a wake event to approach and requested additional separation on downwind leg to increase separation on final. Followed a 737 onto 24R. Remainder of descent; approach; and landing without incident.

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Original NASA ASRS Text

Title: B737NG Captain reported some autopilot system anomalies occurred following a wake turbulence encounter in trail of a B777 on arrival into LAX.

Narrative: Descending on downwind leg into LAX through approximately 4;000 feet; 180 knots; flaps 10; IRNMN 2 RNAV Arrival; approximately GADDO intersection. ATC advised following a heavy 777 on the arrival. Winds were mostly calm; sometimes 7 knots on the tail; [and] sometimes 7 knots on the nose. Kept getting a few nibbles of wake; mostly just a bit of turbulence with mild; few degrees of roll. Approximately one minute later; got hit with an initial left roll of approximately 15 [degrees] left wing down. First Officer (Pilot Flying) grabbed the controls; and autopilot remained engaged; returning aircraft to level flight. Almost immediately after; a hard roll of approximately 30 degrees left wing down was encountered (never heard 'bank angle' so believe we remained less than 35 degrees). Autopilot was disconnected; aircraft nose lowered; and a return to level flight accomplished. After approximately 30 seconds; Captain (Pilot Monitoring) recycled autopilot CMD engage with no success. Cycled disconnect switch; flight directors; LNAV/FLCH; and eventually all functions of autopilot were returned. Reported a wake event to approach and requested additional separation on downwind leg to increase separation on final. Followed a 737 onto 24R. Remainder of descent; approach; and landing without incident.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.