CTLED FLT TOWARDS TERRAIN AFTER A HDG TRACK DEV DURING A MAP.

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THIS EVENT OCCURRED JUST AFTER RELEASE FROM HOLDING AT FL210 OVER FFU VOR. ATC INSTRUCTED US TO DSND TO 11000 FT; TO MAINTAIN 250 KTS OR LESS; AND TO CONTACT SLC APCH CTL. APCH CTL CLRED US TO INTERCEPT RWY 34 LOC AND TO CROSS LUFCO INTXN AT 9000 FT. AS WE WERE ABOUT TO LEVEL AT 9000 FT APCH POINTED OUT A 727 AT 8000 FT AT OUR 12 O'CLOCK POS; AND 1 1/2 MI. WE DID NOT SEE THIS TFC VISUALLY DUE TO THE MASSIVE AMOUNT OF GND LIGHTS OVER WHICH IT WAS SUPERIMPOSED. THE TCASII DISPLAY SHOWED NUMEROUS TARGETS INCLUDING WHAT WE BELIEVED TO BE THIS TFC BELOW AND SLIGHTLY TO THE FRONT OF US. APCH INDICATED THAT THIS 727 WAS BEING CLRED BELOW US TO RWY 35 AND AT THIS TIME CLRED US TO 8500 FT AND THEN TO 7000 FT. WE WERE STILL AT 250 KTS AND WERE COVERING GND RAPIDLY DUE TO A STRONG TAILWIND. AT ABOUT THIS TIME WE WERE NEARING THE FINAL APCH FIX (OM) STILL HIGH AND FAST AND APCH CTL; REALIZING THIS; VECTORED US OFF THE LOC ON A 310 DEG HDG. WE WERE STILL ON A 310 DEG HDG AND ABOUT 240 KTS AND STILL DSNDING TO 7000 FT WHEN THE CTLR ASKED US TO VISUALLY ACQUIRE A SBOUND 757 AT OUR 11 O'CLOCK AND 3 MI. MY COPLT SAID THAT HE SAW ANOTHER ACFT AT OUR 11-12 O'CLOCK SLIGHTLY BELOW US AND PROBABLY 5 OR 6 MI AWAY. I DID NOT SEE THIS PARTICULAR TFC AT THAT TIME AS I WAS MANUALLY FLYING THE AIRPLANE. THE RADIO WAS REALLY BUSY AT THIS TIME AND WHEN HE GOT A CHANCE MY COPLT RPTED TO THE CTLR THAT WE SAW 2 ACFT TO OUR L AND THE CTLR REPLIED THAT WE WOULD FOLLOW THE ONE AT 11-12 O'CLOCK. HE THEN GAVE US A TURN TO 260 DEGS AND CLRED US TO 6000 FT AND MY COPLT REPEATED THIS BACK TO HIM. THE CTLR ASKED 'DO YOU STILL HAVE THE 757 TFC IN SIGHT?' MY COPLT REPLIED 'NO' AND THEN THE CTLR ASKED IF WE WERE ON A 160 DEG HDG AND MY COPLT RESPONDED 'NO; YOU TOLD US 260 DEGS' AND THE CTLR THEN SAID 'NO -- I GAVE YOU 160 DEGS -- WE CAN TALK ABOUT THIS LATER -- TURN TO 160 DEGS.' HE THEN ASKED US IF WE HAD THE TERRAIN IN SIGHT. MY COPLT RESPONDED 'NO; IT'S DARK!' THE CTLR THEN SAID TURN TO 160 DEGS AND CLB TO 7000 FT AND WE TURNED TO 160 DEGS. AGAIN THE CTLR ASKED US IF WE SEE THE TERRAIN; AT WHICH TIME HE SEEMED TO GET QUITE EXCITED. HE SAID 'TURN QUICKLY;' AND ADDED 'TURN IMMEDIATELY TO 090 AND CLB TO 12000 FT.' AFTER WE LEVELED AT 12000 FT HE VECTORED US TO 160 DEGS AND AGAIN CLRED US TO 7000 FT. THEN HE VECTORED US 090 TO INTERCEPT 34 LOC THEN 'A TIGHT TURN' TO 340 TO INTERCEPT. A STRONG TAILWIND AT THIS ALT PUSHED US THROUGH THE LOC BUT WE CORRECTED BACK VISUALLY AND FROM THAT POINT OF THE LNDG WAS NORMAL.SUPPLEMENTAL INFO FROM ACN 284331: ATC RPTED 727 TFC AT 8000 FT; 12 O'CLOCK; 1.5 MI; WHICH WE NEVER SAW VISUALLY; BUT HAD ON TCASII.