AN HS125 FLC GETS CAUGHT IN ROTOR CLOUD TURB AT 4000 FT WHILE ON A DEP VECTOR FROM SCT DEP CTLR NE OF VNY; CA.

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DEP OCCURRED AT ABOUT XA45 FROM VNY. IMMEDIATELY NOTICED SEVERE TURB IN CLBOUT DUE TO NORTHERLY WIND; WITH SANTA ANA TYPE CONDITIONS AND MOISTURE. WE WERE ASKED TO CIRCLE L AND S TO GO TO VNY VOR AND TRACK OUTBOUND ON 095 DEG RADIAL. WAS PLACED ON A VECTOR INTO MOUNTAINS EVEN THOUGH VOR NEEDLE SHOWED CTRED ON AIRWAY. AS WE CROSSED CLOSER INTO THE MOUNTAINS; WE ENCOUNTERED SEVERE ROTOR TURB WITH AN IMMEDIATE ALT LOSS OF 200 FT. WE THEN FLEW INTO THE DOWNWIND SIDE OF THE ROTOR AND ENCOUNTERED A HVY SINK RATE IN EXCESS OF 4000 FPM. RECOVERY OCCURRED AT APPROX 300-360 FT DOWN FROM ASSIGNED ALT. PWR AND PITCH UP BARELY STOPPED THE DSCNT RATE. A FULL RECOVERY WAS MADE. THE TREMENDOUS SINK RATE AND SUDDEN TURB WAS COMPOUNDED WHEN THE AUTOPLT UNCOUPLED AT THE SAME TIME DUE TO THE SUDDEN TURB AND HIGH SINK RATE. THE CTLR WAS AWARE OF THE NORTHERLY WINDS SINCE HE MENTIONED OTHER ACFT DRIFTING DUE TO THE STRONG WINDS. I DO NOT UNDERSTAND WHY A CTLR WOULD VECTOR ACFT INTO A ROTOR CONDITION. I FIND THIS FORM OF VECTORING UNSAFE WHEN METEOROLOGICAL CONDITIONS ARE NOT TAKEN INTO CONSIDERATION. 2 FAA AVIATION SAFETY COUNSELORS WERE ON BOARD THE ACFT AT THE TIME OF THE EVENT. THE WRITER IS A VETERAN OF MOUNTAIN WAVE SOARING. SINCE ATC WAS VERY BUSY; WE DID NOT RESPOND ON TAPE. ONLY LATER ON; DOWN BY SAN DIEGO; WERE WE ASKED TO MAKE A CALL TO THE CTLR.