Narrative:

We arrived on the sadde 6 arrival at the derbb waypoint. After filmore VOR ATC placed us on a series of headings to descend down to 10000 ft. After we were put back on the arrival the airplane required a sharp left turn to intercept the course after sadde (not a flyover point). This sharp turn resulted in not to reaching sadde intersection so as to intercept the arrival course properly to bayst waypoint. Apparently this sharp turn placed our airplane a couple miles behind an airliner (we believe it was a 757). ATC had us slow immediately to 180 KTS. As soon as we slowed to 180 KTS; the aircrafts right wing abruptly dropped (aircraft was at flaps 15). Pilot flying added full power to recover. ATC gave us a descent to 6000 ft (I believe); and again told us to slow to 180 KTS. Again at exactly 180 KTS our right wing dropped and flying pilot recovered with full power. We immediately informed approach that the slowest we could give them was 190 KTS; we were encountering wake turbulence. At both times when the wing dropped the aoa indicator did not reflect any movement and there was no stick shaker. I assumed the problem was the 757 only a couple miles ahead and TCAS showing 300 ft below us. During the recovery procedures; the flying pilot clicked off the autopilot. After getting the airplane stabilized back at 10;200 ft we kept the airspeed at 190 KTS and started again with our descent down to 6000 ft. Then another approach controller took over; and changed our runway from 24R to 25L and gave us a series of heading and altitude changes and 5 miles behind a md-80; which was more manageable. This scenario was frustrating in that we could not make the airplane do what we wanted it to because it would stop flying. At those moments we were too busy flying the airplane to talk with approach to tell them what we were fighting. The frequency was so busy that we probably could not tell them if we wanted. Also this entire descent and approach was not in normal aircraft profile that we fly everyday; which is normally no big deal until you start throwing in aircraft upset scenarios.

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Original NASA ASRS Text

Title: A CE-680 on the LAX SADDE 6 encountered several wake vortex upsets behind a B757. Unable to contact ATC due to flying duties and radio traffic; the crew had difficulty taking action to avoid the wake while following ATC instructions.

Narrative: We arrived on the SADDE 6 Arrival at the DERBB waypoint. After Filmore VOR ATC placed us on a series of headings to descend down to 10000 FT. After we were put back on the arrival the airplane required a sharp left turn to intercept the course after SADDE (Not a flyover point). This sharp turn resulted in not to reaching SADDE intersection so as to intercept the arrival course properly to BAYST waypoint. Apparently this sharp turn placed our airplane a couple miles behind an airliner (we believe it was a 757). ATC had us slow immediately to 180 KTS. As soon as we slowed to 180 KTS; the aircrafts right wing abruptly dropped (aircraft was at flaps 15). Pilot flying added full power to recover. ATC gave us a descent to 6000 FT (I believe); and again told us to slow to 180 KTS. Again at exactly 180 KTS our right wing dropped and flying pilot recovered with full power. We immediately informed approach that the slowest we could give them was 190 KTS; we were encountering wake turbulence. At both times when the wing dropped the AOA indicator did not reflect any movement and there was no stick shaker. I assumed the problem was the 757 only a couple miles ahead and TCAS showing 300 FT below us. During the recovery procedures; the flying pilot clicked off the autopilot. After getting the airplane stabilized back at 10;200 FT we kept the airspeed at 190 KTS and started again with our descent down to 6000 FT. Then another approach controller took over; and changed our runway from 24R to 25L and gave us a series of heading and altitude changes and 5 miles behind a MD-80; which was more manageable. This scenario was frustrating in that we could not make the airplane do what we wanted it to because it would stop flying. At those moments we were too busy flying the airplane to talk with approach to tell them what we were fighting. The frequency was so busy that we probably could not tell them if we wanted. Also this entire descent and approach was not in normal aircraft profile that we fly everyday; which is normally no big deal until you start throwing in aircraft upset scenarios.

Data retrieved from NASA's ASRS site as of April 2012 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.