B737 Next Generation Undifferentiated
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 124.18; Flight Crew Type 3160.02
Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action
Environment - Non Weather Related; Procedure
We were at FL340 on the ANJLL4 arrival to LAX. Approaching SHTNR we encountered wake turbulence from a preceding aircraft. The aircraft rolled approximately 30 degrees to the left. About 5 seconds later; we were rolled approximately 40 degrees to the right. Aircraft AP disengaged. We recovered and turned 20 degrees right to avoid additional turbulence. We lost approximately 500 feet of altitude.  LA Center then cleared us to offset 3 nm and to descend to FL320. We were assigned .76 Mach at the time of event. Later we were told to descend via ANJLL 4 except maintain 260 on the arrival. Later ATC asked what our airspeed was; we were doing .76 until the descent. We now think ATC wanted us to slow earlier and then descend at 260 Kts.
[Report narrative contains no additional information.]
B737NG flight crew reported encountering wake turbulence at FL340 on arrival into LAX that resulted in 30-40 degree bank left and right and a 500 feet loss of altitude.