Date: 201807
Local time of day: 1801-2400
Location: LAX.Airport, CA
Light: Daylight
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B LAX
ATC / advisory: TRACON SCT
Second aircraft: B747 Undifferentiated or Other Model
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Anomaly: Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Regained Aircraft Control; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Procedure; Environment - Non Weather Related
Primary problem: Ambiguous

Narrative: As my First Officer (FO) and I approached LAX on the OLAAA1 RNAV arrival; we were given a crossing restriction of 8;000 and then descend and maintain 7;000. From previous wake turbulence encounters in LAX; I already had the TCAS in 'relative expanded' so I could start watching for potential threats. I also started listening to anything that involved 'heavy' or 'super' over the frequency several miles from the airport. As we approached; I/we heard a Cargo 'heavy'. Hmmm. So; we started scanning the TCAS data to try to decipher if he was ahead of us or behind us. We found what could potentially be a 'heavy' off in the distance and on TCAS. I just assumed that was him and started using caution. We were not behind him directly in the moment; but in the future could be. On we flew; and eventually began the descent of 8;000 at a crossing restriction and then maintain 7;000. At this point; the potential threat was approximately 7 miles ahead of us. As I started to level off at 7;000; I started to feel the 'tickle' of wake. I disconnected the autopilot and immediately got into the heavy's wake. Rolled around for what seemed like eternity; said a few colorful words; and attempted to climb above the wake. I got it under control...only ended up at 7;100 feet and my FO called SoCal to inform him of our wake encounter.We had just recently gotten handed off to this frequency. I recognized the Controller's voice; (one of my favorites; he does great) from previous flights and his voice was that of resignation. He said we got wake from a heavy that was ahead of us; and let's get you a new heading of 10 degrees right to get you out of his path. I turned immediately and then asked for the autopilot. I still guarded the controls. The Controller came back to us within about 60 seconds to ask how our new heading was. I gave my FO a thumbs up; but asked him to ask for 5 more degrees right for spacing. The Controller responded with a reduced airspeed to get the more spacing. Perfect for us. I flew the remainder of the arrival high and flew the ILS 25L a dot above glide slope. Right after the encounter; I also called the Flight Attendants to make sure everyone was safe and uninjured. All was well. Passengers were seated. One FA was seated. The other one was standing; but uninjured. I asked them to stay in their seats for the remainder of the flight. Once on final and on LAX tower frequency we were told to use caution wake turbulence; following a 747. Suggestions: This is not my first encounter with wake at LAX. Ask any of my FOs and I'm an ardent wake turbulence avoider. I sometimes ask miles out from LAX what we will be following in today; and sometimes I ask for reduced speeds to get more separation. The Controllers are always helpful. I just wish that the Controllers would provide the facts of what's ahead of us BEFORE we are on LAX tower frequency or before we fly into wake. I feel like some Controllers provide it; and some do not...unless asked.




Synopsis: EMB-175 Captain reported encountering wake turbulence on arrival into LAX in trail of a B747.