FLC OF MLG HAS CONFLICT WITH LTT ON VECTORS TO APCH.

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I WAS THE COPLT ON AN MLG ON THE SINCA 5 ARR. THE CAPT WAS FLYING. THE CTLR TURNED US FROM A 300 DEG HDG TO 360 DEGS TO GAIN SPACING BEHIND A COMPANY MLG ALSO ON RWY 27L. WE HAD BEEN TOLD TO DSND TO 2500 FT MSL. WE WERE DSNDING THROUGH 4000 FT TO 3500 FT WHEN VECTORED N. THERE WAS AN LTT BEING VECTORED ONTO FINAL FOR RWY 26R. HE WAS CTLED ON A DIFFERENT FREQ. HE WAS ALSO AT 3500 FT MSL AND TURNING BELLY UP TO OUR PLANE. OUR CTLR WAS LATE TURNING US BACK TO INTERCEPT THE RWY 27L LOC. CONSEQUENTLY; WE WERE NOW ON THE RWY 26R FINAL. THE TCASII IN OUR JET BEGAN DIRECTING US TO PULL UP TO MISS THE LTT. I WAS ALREADY EYES OUT TELLING THE CAPT ABOUT THE PROB. THE CTLR DID MAKE A CALL FOR US TO TURN BACK BUT IT WAS STEPPED ON BY SOMEONE ELSE ON SAME FREQ AND THE TCASII. WHEN WE FINALLY MADE OUR TURN BACK TO INTERCEPT RWY 27L LOC; WE WERE CO-ALT WITH THE LTT AND WE DELAYED OUR TURN BASED ON VISUAL ASSESSMENT THAT WE COULDN'T TURN BELLY UP TO LTT. WE PASSED LESS THAN 3000 FT. MY ASSESSMENT OF CONTRIBUTING FACTORS: 1) CTLR CUTTING SIT TOO CLOSE. 2) LOW-TIME CAPT; SLIGHTLY BEHIND JET; NOT ABLE TO BUILD THE ALT SEPARATION HE WOULD NORMALLY HAVE IF HE WERE AHEAD OF JET. 3) THE ALT SEPARATION SHOULD HAVE BEEN ESTABLISHED PRIOR TO TURNING US N. WE MAY HAVE BEEN LATE GETTING TO 2500 FT; BUT NO CRITERIA WAS ESTABLISHED WHEN TO BE THERE. SUPPLEMENTAL INFO FROM ACN 246821: AT THIS TIME TCASII CAME ON WITH AN ADVISORY OF 'TFC; TFC; MONITOR VERT SPD.' WITH THE ADVISORY GOING OFF NEITHER THE FO NOR I HEARD THE CTLR ISSUE A TURN TO 270 DEGS UNTIL THE CONFLICT OCCURRED.