AN ACR L1011 CREW EXPERIENCED UNUSUALLY RAPID CLBS AND DIVES IN TURB. THIS TURB OVERPOWERED THE AUTOPLT. WX FACTORS VERT WINDSHEARS OF UNUSUALLY STRONG BUT SMOOTH NATURE THAT CAUSED SEVERAL ALTDEVS.

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WHILE CRUISING AT FL330 WITH THE AUTOPLT ENGAGED IN FMS; THE VERT SPD INDICATOR BEGAN OSCILLATING RAPIDLY BTWN 2000 FPM RATES OF CLB AND DSCNT. WITHIN A SECOND OR TWO THE ACFT RAPIDLY DSNDED 400 FT; THEN CLBED 800 FT BEFORE DSNDING ANOTHER 1800 FT. DURING THIS ENCOUNTER; WHICH ONLY LASTED BTWN 10-20 SECONDS; THE AUTOPLT LIMIT FLAG FLICKERED ON AND OFF BEFORE THE AUTOPLT DISENGAGED. AS THE ACFT BOTTOMED OUT AT FL316 WITH THE FO FLYING; I NOTIFIED ZME THAT WE HAD ENCOUNTERED SEVERE TURB AND LOST 1400 FT IN ALT. MEMPHIS ADVISED US TO DSND TO FL290. AT THAT POINT THE ACFT BEGAN CLBING RAPIDLY IN MODERATE CHOP. WHEN I COULD TALK; I ADVISED MEMPHIS THAT WE WERE 'TRYING.' THE FO MANAGED TO LEVEL THE ACFT AT FL322 AND BEGAN A DSCNT TO FL290. LIGHT TO MODERATE TURB CONTINUED AT FL290 UNTIL WE BROKE OUT OF THE CLOUDS ABOUT 2 MINS LATER. DURING THE ENTIRE BRIEF ENCOUNTER; THE ACFT PITCH; ROLL AND AIRSPD DID NOT CHANGE ABRUPTLY. THE RIDE WAS MORE LIKE BEING ON AN EXPRESS ELEVATOR IN A TALL BUILDING. THE CLBS AND DSCNTS WERE FLAT IN PITCH EXCEPT THAT THERE WAS A SIGNIFICANT AMOUNT OF CHOP WHICH MADE IT DIFFICULT TO COMMUNICATE WITH ATC OR THE OTHER CREW MEMBERS. FORTUITOUSLY; KNOWLEDGE AND TECHNOLOGICAL ADVANCEMENTS MADE OVER THE LAST 20 YRS BY ATC AND THE AIRLINE PAID OFF. I HAD REVIEWED THE RADAR SUMMARY ON THE COMPUTER BEFORE PREFLT. THEN I BRIEFED THE CUSTOMER SVC COORDINATOR THAT THE LAST HR OF THE 2 HR 50 MIN FLT MIGHT BE A LITTLE ROUGH AND I WANTED HER TO CONDUCT THE CABIN SVC AS QUICKLY AS POSSIBLE SO THAT SHE COULD GET THE SERVING CARTS STOWED AND THE FLT ATTENDANTS SEATED FOR THE LAST HR. AS WE ENTERED THE CLOUDS W OF MEMPHIS; I TURNED THE SEAT BELT LIGHT ON AND ASKED THE SO TO MAKE SURE THE FLT ATTENDANTS WERE SEATED. THEY WERE. THE RADAR WAS ON AND I SCANNED THE 180 MI RANGE -- THERE WERE NO RETURNS. I THEN SELECTED THE 80 NM RANGE AND LOWERED THE ANTENNA TO PAINT GND RETURN BTWN 70-80 NM -- STILL NO WX RETURNS -- BEFORE OR AFTER THE EVENT. SHORTLY AFTER STABILIZING AT FL290; I ASKED THE SO TO MAKE SURE EVERYBODY WAS OK. THERE WERE NO INJURIES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTING CAPT IS NOT SURE IF THE FO DISENGAGED THE AUTOPLT OR IF IT DISENGAGED ITSELF. THE AUTOPLT LIMIT FLAG WAS FLASHING ON/OFF AS FAST AS IT COULD AND THE VSI WAS GOING BTWN 2000 FPM UP TO 2000 FPM DOWN AS FAST AS IT COULD GO. THE ACR'S FLT MANUAL CALLS FOR THE AUTOPLT TO BE TURNED OFF AND THE ACFT HAND FLOWN IN VERT WINDSHEARS SUCH AS THIS TO PREVENT THE AUTOPLT TRIM FROM GETTING OUT OF PHASE WITH THE WINDSHEARS. THE ONLY WARNING OF THIS SIT THAT THE CREW HAD WAS FROM THE PREFLT WX BRIEFING. THE RPTR HAS CONFIDENCE THAT THE WX RADAR WAS WORKING PROPERLY AS IT TESTED PROPERLY ON THE GND AND PAINTED SHOWERS LATER IN THE FLT.