EXCURSION FROM ASSIGNED ALT AND HDG DUE TO A POTENTIAL TFC CONFLICT DURING APCH.

Narrative

ON DSCNT FOR LNDG INTO WILL ROGERS ARPT AT OKLAHOMA CITY ON A VECTOR TURN FROM APCH CTL TO INTERCEPT THE FINAL APCH COURSE FOR THE 35R ILS. APCH CTL CALLED OUT VFR TFC AT OUR 10 O'CLOCK POS AT 5500 FT. WE WERE AT 6000 FT. TFC WAS DISPLAYED ON OUR (MLG) TCASII AT 500 FT BELOW US. THE (SMA) CALLED THAT HE HAD US IN SIGHT AND AS TOLD TO SEE AND AVOID US AT THAT POINT. I THEN GOT A WARNING FROM TCASII FOR TFC AND SAW HE WAS STILL 500 FT BELOW US - BUT THEN NOTICED HE CAME UP TO 400 FT; THEN 300 FT. I THEN LOOKED TO CONFIRM THIS VISUALLY AND DETERMINED THERE COULD BE A CONFLICT AND CHOSE TO TURN AWAY AND DSND TO THE R AND DOWN. TCASII WARNING US TO AVOID AT EXACTLY THE SAME MOMENT. APCH CTL WAS ADVISED OF OUR DEV. I TURNED 30 DEG TO THE R AND DSNDED 400-500 FT. THE TCASII CALLED CLR OF CONFLICT AND WE THEN CONTINUED WITH APCH CTL TO VECTORS FOR OUR FINAL APCH AND LNDG. I CALLED THE APCH CTL SUPVR UPON LNDG AND VOICED MY CONCERN. I DISCUSSED THE SITUATION WITH MR. (TRACON AC); HE UNDERSTOOD MY CONCERN AND RECORDED OUR CONVERSATION. HE SAID HE KNEW OF THE SMA AND THAT THEY OPERATE IN THAT AREA OFTEN DROPPING PARACHUTISTS.