Narrative:

Our aircraft experienced a wake turbulence upset from a preceding MD11. Momentary loss of aircraft control was experienced; however no aircraft damage was sustained. No aircraft parameters were exceeded during the event or the subsequent recovery. No injuries were reported by the crew or the passenger. We were inbound to our destination of sna proceeding direct to the psp VOR approximately 200 NM out. We had just passed northwest of the phoenix; az; area and were in contact with ZLA. WX conditions were VMC and the entire flight had been free of turbulence. We had started a descent from FL380 to FL340 per ZLA clearance. The autoplt was engaged with the LNAV and vs modes selected. Vs rate was selected at 1000 FPM. Mach was .82. Autothrottles were engaged. The descent checklist had been completed. Descending through approximately FL360; a nibble of light chop was encountered and my first thought was that we were beginning to enter an area of turbulence typically encountered in the socal area. However; the aircraft suddenly pitched down approximately 10 degrees. A small amount of negative 'G' was felt during the pitch down moment. As I grabbed the yoke; the aircraft violently rolled to the right. As the aircraft started to roll; I disengaged the autoplt and tried to counteract the roll with full left aileron. Rudder input was not used. My control inputs were ineffective until the aircraft reached approximately 60 degrees. Upon reaching the maximum roll; the aircraft felt like it had been released from a giant 'grip.' the aircraft then responded to my control inputs. I leveled the wings and then increased nose up pitch to regain a normal vs rate. I had positive control 800 ft above our assigned level off altitude; no ATC clearance limits were busted. After ascertaining that everyone onboard was ok; I queried center as to the type of aircraft that we were following. The controller stated that it was an MD11. I informed the controller that we had experienced a wake turbulence upset and that everything was ok. There was a bit of silence and then an offer of a different altitude. We declined the offer. The MD11 was observed on TCAS to be approximately 12 NM in front of and approximately 3 NM left of our course. We noted the upper wind components were 30 KTS on our nose with a 6 KT left crosswind. The MD11's vortices appear to have drifted into our flight path and based on our right hand roll; that we had encountered the left wing tip vortex. Having flown this particular arrival course countless times; there was nothing unusual in this routing or altitude. We were never advised by ATC that we were following a heavy aircraft. Had I known that the preceding aircraft was an MD11; I may have asked ATC for a course offset. This event also reinforces the need for all persons to remain seated with seat belts fastened unless there is a need to move about the cabin. The flight attendant had just sat down after leaving the cockpit when the upset occurred. Had she been standing; personal injury may have occurred. The wake turbulence models are realistic; the problem is that you know the upset is about to happen. Typically; we expect upsets to happen in the terminal area. The experience of the upset at such a high altitude was a complete surprise. At a previous company I had the opportunity to take part in an in-house upset training program in an experimental business jet aircraft. The unusual altitudes and recovery training in the real aircraft and world served me well during this actual upset event.

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Original NASA ASRS Text

Title: GLF4 ENCOUNTERS WAKE TURBULENCE FROM PRECEDING MD11 AT ALTITUDE WHICH RESULTS IN MOMENTARY LOSS OF CONTROL.

Narrative: OUR ACFT EXPERIENCED A WAKE TURB UPSET FROM A PRECEDING MD11. MOMENTARY LOSS OF ACFT CTL WAS EXPERIENCED; HOWEVER NO ACFT DAMAGE WAS SUSTAINED. NO ACFT PARAMETERS WERE EXCEEDED DURING THE EVENT OR THE SUBSEQUENT RECOVERY. NO INJURIES WERE RPTED BY THE CREW OR THE PAX. WE WERE INBOUND TO OUR DEST OF SNA PROCEEDING DIRECT TO THE PSP VOR APPROX 200 NM OUT. WE HAD JUST PASSED NORTHWEST OF THE PHOENIX; AZ; AREA AND WERE IN CONTACT WITH ZLA. WX CONDITIONS WERE VMC AND THE ENTIRE FLT HAD BEEN FREE OF TURB. WE HAD STARTED A DESCENT FROM FL380 TO FL340 PER ZLA CLRNC. THE AUTOPLT WAS ENGAGED WITH THE LNAV AND VS MODES SELECTED. VS RATE WAS SELECTED AT 1000 FPM. MACH WAS .82. AUTOTHROTTLES WERE ENGAGED. THE DESCENT CHKLIST HAD BEEN COMPLETED. DESCENDING THROUGH APPROX FL360; A NIBBLE OF LIGHT CHOP WAS ENCOUNTERED AND MY FIRST THOUGHT WAS THAT WE WERE BEGINNING TO ENTER AN AREA OF TURB TYPICALLY ENCOUNTERED IN THE SOCAL AREA. HOWEVER; THE ACFT SUDDENLY PITCHED DOWN APPROX 10 DEGS. A SMALL AMOUNT OF NEGATIVE 'G' WAS FELT DURING THE PITCH DOWN MOMENT. AS I GRABBED THE YOKE; THE ACFT VIOLENTLY ROLLED TO THE RIGHT. AS THE ACFT STARTED TO ROLL; I DISENGAGED THE AUTOPLT AND TRIED TO COUNTERACT THE ROLL WITH FULL LEFT AILERON. RUDDER INPUT WAS NOT USED. MY CTL INPUTS WERE INEFFECTIVE UNTIL THE ACFT REACHED APPROX 60 DEGS. UPON REACHING THE MAX ROLL; THE ACFT FELT LIKE IT HAD BEEN RELEASED FROM A GIANT 'GRIP.' THE ACFT THEN RESPONDED TO MY CTL INPUTS. I LEVELED THE WINGS AND THEN INCREASED NOSE UP PITCH TO REGAIN A NORMAL VS RATE. I HAD POSITIVE CTL 800 FT ABOVE OUR ASSIGNED LEVEL OFF ALT; NO ATC CLRNC LIMITS WERE BUSTED. AFTER ASCERTAINING THAT EVERYONE ONBOARD WAS OK; I QUERIED CTR AS TO THE TYPE OF ACFT THAT WE WERE FOLLOWING. THE CTLR STATED THAT IT WAS AN MD11. I INFORMED THE CTLR THAT WE HAD EXPERIENCED A WAKE TURB UPSET AND THAT EVERYTHING WAS OK. THERE WAS A BIT OF SILENCE AND THEN AN OFFER OF A DIFFERENT ALT. WE DECLINED THE OFFER. THE MD11 WAS OBSERVED ON TCAS TO BE APPROX 12 NM IN FRONT OF AND APPROX 3 NM LEFT OF OUR COURSE. WE NOTED THE UPPER WIND COMPONENTS WERE 30 KTS ON OUR NOSE WITH A 6 KT LEFT CROSSWIND. THE MD11'S VORTICES APPEAR TO HAVE DRIFTED INTO OUR FLT PATH AND BASED ON OUR RIGHT HAND ROLL; THAT WE HAD ENCOUNTERED THE LEFT WING TIP VORTEX. HAVING FLOWN THIS PARTICULAR ARR COURSE COUNTLESS TIMES; THERE WAS NOTHING UNUSUAL IN THIS ROUTING OR ALT. WE WERE NEVER ADVISED BY ATC THAT WE WERE FOLLOWING A HVY ACFT. HAD I KNOWN THAT THE PRECEDING ACFT WAS AN MD11; I MAY HAVE ASKED ATC FOR A COURSE OFFSET. THIS EVENT ALSO REINFORCES THE NEED FOR ALL PERSONS TO REMAIN SEATED WITH SEAT BELTS FASTENED UNLESS THERE IS A NEED TO MOVE ABOUT THE CABIN. THE FLT ATTENDANT HAD JUST SAT DOWN AFTER LEAVING THE COCKPIT WHEN THE UPSET OCCURRED. HAD SHE BEEN STANDING; PERSONAL INJURY MAY HAVE OCCURRED. THE WAKE TURB MODELS ARE REALISTIC; THE PROB IS THAT YOU KNOW THE UPSET IS ABOUT TO HAPPEN. TYPICALLY; WE EXPECT UPSETS TO HAPPEN IN THE TERMINAL AREA. THE EXPERIENCE OF THE UPSET AT SUCH A HIGH ALT WAS A COMPLETE SURPRISE. AT A PREVIOUS COMPANY I HAD THE OPPORTUNITY TO TAKE PART IN AN IN-HOUSE UPSET TRAINING PROGRAM IN AN EXPERIMENTAL BUSINESS JET ACFT. THE UNUSUAL ALTS AND RECOVERY TRAINING IN THE REAL ACFT AND WORLD SERVED ME WELL DURING THIS ACTUAL UPSET EVENT.

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.