ACR X HAD NMAC WITH SMT Y IN TFC PATTERN. SEE AND AVOID CONCEPT. TCASII RA EVASIVE ACTION TAKEN.

Narrative

ACR X WAS AT THE ABEAM DOWNWIND POS FOR RWY 36L WHEN TWR ADVISED SOMETHING LIKE 'ACR X YOU HAVE TFC AT 1 O'CLOCK A MI AND A HALF AN SMT Y WHO WILL BE LNDG ON 36R; HE HAS THE ARPT IN SIGHT AND WILL NOT BE A FACTOR; CLRED TO TURN BASE YOUR DISCRETION.' SHORTLY THEREAFTER; THE SO AND I (NOW STRAPPED IN TO THE JUMP SEAT) SAW THE TFC. SOMETIME AFTER OUR SIGHTING; THE CAPT IN THE SEAT AND FO STUDENT RPTED THE TFC IN SIGHT AS WELL. WE BEGAN OUR BASE TURN WHEN IT APPEARED THAT SMT Y WAS TURNING SLIGHTLY TOWARD US STILL A LITTLE HIGH APPEARING TO BE IN A DSCNT. WE ROLLED OUT ON BASE HDG 090; STILL HAVING SMT Y IN SIGHT. SMT Y RAPIDLY TURNED TOWARD US I OBSERVED THE COLLISION COURSE DYNAMIC. HE APPEARED TO BE HEADED TOWARD US IN COURSE AND DSCNT. AT THAT MOMENT; TCASII SAID 'STOP CLB; STOP CLB!!' AND THE THREE COLORED RADIALS APPEARED ON BOTH VSI'S. THE COMMAND WAS TO LEVEL OR DSND. I LOUDLY SAID 'LOWER THE NOSE' AND THE CAPT IN THE SEAT IMMEDIATELY TOOK THE ACFT AND ABRUPTLY LOWERED THE NOSE; AS I RECALL; TCASII THEN SAID 'DSND; DSND' AND COMMANDED AT LEAST A 1000 FPM DSCNT. SMT Y PASSED OVERHEAD. I BELIEVE LATERAL SEPARATION MAY HAVE BEEN NIL AND VERT SEPARATION LESS THAN 300 FT. SMT Y THEN RPTED THAT HE HAD MISTAKEN ANOTHER LANDMARK FOR THE ARPT AND REQUESTED VECTORS FOR ANOTHER APCH. I RECALL THE TWR ASKING SMT Y IF HE HAD THE LGT IN SIGHT AND HE SAID NO. THE TWR CTLR THEN QUICKLY CALLED US USING HIS 'MAY-DAY' VOICE ASKING IF WE HAD SEEN SMT Y AND TELLING THAT 'TFC IS NO LONGER A FACTOR'. TCASII PROVED ITS VALUE AND RELIABILITY. HUMAN FACTORS PARTICULARLY RELEVANT WERE OUTSIDE VIGILANCE AND TEAM WORK. WHEN NECESSARY; AT COCKPIT. ALSO; ALL COCKPIT CREW MEMBERS CLEARLY PERFORMED AS IF TFC VIGILANCE AND AWARENESS WERE HIS OWN PERSONAL RESPONSIBILITIES.