Citation Excel (C560XL)
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Loss Of Aircraft Control
Air Traffic Control Issued New Clearance; Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Environment - Non Weather Related; Procedure
While descending via the HLYWD 1 RNAV arrival into LAX at around 16;000 feet and 280 knots; we encountered severe turbulence. The nose dropped; our right wing dipped approximately 60 degrees and the autopilot shut off. I immediately grabbed the controls and pulled the power back then leveled off. I checked on our one passenger and she was shook up a little but not hurt and in good spirits. The cabin was a mess. You could see multiple seat cushions on the ground; chips and drinks were scattered about as well as the life raft and pillows that were moved. We reported to ATC that we encountered wake turbulence and that we would like to get off of our course. He told us that we were about 8 miles behind a Boeing 757 but to stay on our course. I repeated that we wanted to change course due to a wake encounter and he suggested that we could stay above him at 14;000 [feet]. We were happy with that as it would keep us clear of danger. Soon after we were cleared for the ILS 25L behind the 757. We notified approach and then Tower that we would need to land long. I hand flew the ILS one dot above the glideslope and landed uneventfully.Nothing on our end could have prevented our wake turbulence encounter. We were descending via an arrival as cleared by ATC and didn't even know about the 757 in front of us until we reported to ATC that we hit their wake. We had legal separation from the Boeing so it wasn't the fault of ATC either. One thing to note about the HLYWD 1 arrival is that the crossing restrictions are not exact altitudes. For example; AVATR is between FL240 and FL190; DAAAY is above 17;000 [feet]; WADUP is above 15;000 [feet]. If I descend steeper than the aircraft in front of me; I may have more potential to fly in their wake than if we cross each point at exactly the same altitude. Just a speculation.
Following a 757 on approach to [Runway] 25L. ATC warned us wake turbulence and assigned us 280 knots. Because on the FMS to activate VNAV for guidance; you have to change the at or above to hard altitudes. Not thinking; we put the bottom altitudes in the FMS causing us to possibly be under the wake of the 757. We were flying along as briefed when we felt the severe wake turbulence. Wing and nose dipped; a master warning went off and the auto pilot went off. Things went all over the cabin. Crew and passengers were fine because we all had our seatbelts on. I reported the wake to ATC and asked for a deviation while we regained our composure and addressed the passengers and the plane. They gave us some lip and had us keep on [the] assigned route but had us stay high by assigning our altitude. During this event; we lost altitude and slowed [below] our speed that was assigned. A minute or two later we were flying as normal and got another approach clearance and flew about a dot high. If I remember correctly; when we hit the wake; we were at 12;000 ft outside SEAVU.  Fly higher than normal approach and not worry about putting the altitudes in the box and just using vs to descend instead of VNAV.
C560XL flight crew reported encountering severe wake turbulence on the arrival into LAX in trail of a B757 that resulted in a 60 degree bank.