Narrative:

Descending on SADDE6 arrival into lax (extremely congested airspace). Weather was clear with negligible winds aloft. We passed symon intersection at 12000 ft/280 knots and proceeded to sadde intersection. Checked in with socal approach and was cleared to descend to 10000 ft then slow to 250 knots. Socal advised we were following a B747 approximately 10 miles ahead. After 1 minute or so and passing approximately 11000 ft; socal directed us to turn direct to smo VORTAC. After entering the turn into the FMC; the aircraft began to bank left as expected. We then encountered either wake turbulence or jetwash; and the aircraft began a rapid; uncontrolled roll to the left. I disconnected the autopilot and initiated recovery procedures with full right aileron deflection. After rolling to what appeared to be 45-50 degrees of bank; the roll stopped and began to reverse toward wings level. Aircraft was recovered to wings level and I also reduced the descent rate to regain full aircraft control and situational awareness. During the recovery; we had rolled out of our turn; and this placed our path closer towards the lax departure corridor than normal. While initiating a turn back toward smo; we encountered a TCAS RA for traffic below us (probably on departure with a right turn-out from lax). We complied with the RA by stopping descent. Once clear of conflict; we continued turning towards smo and began descending. I immediately noticed we were passing 10200 ft with a greater than desired descent rate (due to the previous 2 distractions) and initiated a smooth leveloff. We momentarily passed through 10000 feet; and bottomed out at 9800 feet before reversing direction and climbing back to 10000 feet. At this time we received another TCAS RA for traffic above us (probably due to vertical closure rate on traffic in close proximity). We complied with the RA by stopping the climb. At this point; socal called and asked us if everything was ok. We replied that we just flew through some intense wake turbulence but everything was now under control. Socal replied that it was from the B747 in front of us. The captain then informed the passengers of what happened over the PA; and assured them everything was ok. He then called the flight attendants over the interphone and ascertained there were no injuries. Socal then directed us to descend to 7000 feet and we flew an uneventful approach and landing into lax. During the approach; we followed approximately 10 miles behind the same B747. Not to be bitten again by the same situation; I elected to fly approximately 1 DOT high on the glidepath but still felt the B747 turbulence all the way down to the runway due to the negligible winds on final approach. I have extensive experience flying dc-10 aircraft in close formation; and am very aware of wake turbulence hazards. In 20 years of flying; I have never experienced an aircraft upset of this magnitude. Contributing factors to be aware of: (1) following a large slow heavy aircraft and (2) negligible winds aloft. This allowed either the wake vortices or jetwash to remain in place longer than usual without dissipation in strength. Supplemental information from acn 698734: this maneuver caused our flight path to extend beyond sadde and toward the departure corridor. We immediately received an RA calling for us to reduce descent which was caused by the uncommanded roll. The conflict was apparently with a departing aircraft level at 9000 ft heading northbound. We got as low as 9800 ft before arresting the descent and climbing back up to 10000 ft and resuming our left turn to smo.

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Original NASA ASRS Text

Title: B737-700 FLT CREW ENCOUNTERS WAKE TURB AND HAS AN ACFT UPSET ALONG WITH A TCAS RA DURING THE SADDE6 ARR TO LAX.

Narrative: DESCENDING ON SADDE6 ARRIVAL INTO LAX (EXTREMELY CONGESTED AIRSPACE). WEATHER WAS CLEAR WITH NEGLIGIBLE WINDS ALOFT. WE PASSED SYMON INTERSECTION AT 12000 FT/280 KNOTS AND PROCEEDED TO SADDE INTERSECTION. CHECKED IN WITH SOCAL APPROACH AND WAS CLEARED TO DESCEND TO 10000 FT THEN SLOW TO 250 KNOTS. SOCAL ADVISED WE WERE FOLLOWING A B747 APPROXIMATELY 10 MILES AHEAD. AFTER 1 MINUTE OR SO AND PASSING APPROXIMATELY 11000 FT; SOCAL DIRECTED US TO TURN DIRECT TO SMO VORTAC. AFTER ENTERING THE TURN INTO THE FMC; THE AIRCRAFT BEGAN TO BANK LEFT AS EXPECTED. WE THEN ENCOUNTERED EITHER WAKE TURBULENCE OR JETWASH; AND THE AIRCRAFT BEGAN A RAPID; UNCONTROLLED ROLL TO THE LEFT. I DISCONNECTED THE AUTOPILOT AND INITIATED RECOVERY PROCEDURES WITH FULL RIGHT AILERON DEFLECTION. AFTER ROLLING TO WHAT APPEARED TO BE 45-50 DEGREES OF BANK; THE ROLL STOPPED AND BEGAN TO REVERSE TOWARD WINGS LEVEL. AIRCRAFT WAS RECOVERED TO WINGS LEVEL AND I ALSO REDUCED THE DESCENT RATE TO REGAIN FULL AIRCRAFT CONTROL AND SITUATIONAL AWARENESS. DURING THE RECOVERY; WE HAD ROLLED OUT OF OUR TURN; AND THIS PLACED OUR PATH CLOSER TOWARDS THE LAX DEPARTURE CORRIDOR THAN NORMAL. WHILE INITIATING A TURN BACK TOWARD SMO; WE ENCOUNTERED A TCAS RA FOR TRAFFIC BELOW US (PROBABLY ON DEPARTURE WITH A RIGHT TURN-OUT FROM LAX). WE COMPLIED WITH THE RA BY STOPPING DESCENT. ONCE CLEAR OF CONFLICT; WE CONTINUED TURNING TOWARDS SMO AND BEGAN DESCENDING. I IMMEDIATELY NOTICED WE WERE PASSING 10200 FT WITH A GREATER THAN DESIRED DESCENT RATE (DUE TO THE PREVIOUS 2 DISTRACTIONS) AND INITIATED A SMOOTH LEVELOFF. WE MOMENTARILY PASSED THROUGH 10000 FEET; AND BOTTOMED OUT AT 9800 FEET BEFORE REVERSING DIRECTION AND CLIMBING BACK TO 10000 FEET. AT THIS TIME WE RECEIVED ANOTHER TCAS RA FOR TRAFFIC ABOVE US (PROBABLY DUE TO VERTICAL CLOSURE RATE ON TRAFFIC IN CLOSE PROXIMITY). WE COMPLIED WITH THE RA BY STOPPING THE CLIMB. AT THIS POINT; SOCAL CALLED AND ASKED US IF EVERYTHING WAS OK. WE REPLIED THAT WE JUST FLEW THROUGH SOME INTENSE WAKE TURBULENCE BUT EVERYTHING WAS NOW UNDER CONTROL. SOCAL REPLIED THAT IT WAS FROM THE B747 IN FRONT OF US. THE CAPTAIN THEN INFORMED THE PASSENGERS OF WHAT HAPPENED OVER THE PA; AND ASSURED THEM EVERYTHING WAS OK. HE THEN CALLED THE FLIGHT ATTENDANTS OVER THE INTERPHONE AND ASCERTAINED THERE WERE NO INJURIES. SOCAL THEN DIRECTED US TO DESCEND TO 7000 FEET AND WE FLEW AN UNEVENTFUL APPROACH AND LANDING INTO LAX. DURING THE APPROACH; WE FOLLOWED APPROXIMATELY 10 MILES BEHIND THE SAME B747. NOT TO BE BITTEN AGAIN BY THE SAME SITUATION; I ELECTED TO FLY APPROXIMATELY 1 DOT HIGH ON THE GLIDEPATH BUT STILL FELT THE B747 TURBULENCE ALL THE WAY DOWN TO THE RUNWAY DUE TO THE NEGLIGIBLE WINDS ON FINAL APPROACH. I HAVE EXTENSIVE EXPERIENCE FLYING DC-10 AIRCRAFT IN CLOSE FORMATION; AND AM VERY AWARE OF WAKE TURBULENCE HAZARDS. IN 20 YEARS OF FLYING; I HAVE NEVER EXPERIENCED AN AIRCRAFT UPSET OF THIS MAGNITUDE. CONTRIBUTING FACTORS TO BE AWARE OF: (1) FOLLOWING A LARGE SLOW HEAVY AIRCRAFT AND (2) NEGLIGIBLE WINDS ALOFT. THIS ALLOWED EITHER THE WAKE VORTICES OR JETWASH TO REMAIN IN PLACE LONGER THAN USUAL WITHOUT DISSIPATION IN STRENGTH. SUPPLEMENTAL INFO FROM ACN 698734: THIS MANEUVER CAUSED OUR FLIGHT PATH TO EXTEND BEYOND SADDE AND TOWARD THE DEPARTURE CORRIDOR. WE IMMEDIATELY RECEIVED AN RA CALLING FOR US TO REDUCE DESCENT WHICH WAS CAUSED BY THE UNCOMMANDED ROLL. THE CONFLICT WAS APPARENTLY WITH A DEPARTING ACFT LEVEL AT 9000 FT HEADING NORTHBOUND. WE GOT AS LOW AS 9800 FT BEFORE ARRESTING THE DESCENT AND CLIMBING BACK UP TO 10000 FT AND RESUMING OUR LEFT TURN TO SMO.

Data retrieved from NASA's ASRS site as of January 2009 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.