ACR HAS SMA CROSS IN FRONT ON CROSS RWY AS THEY ARE ROLLING OUT AFTER LNDG.

Narrative

7 MI N OF BUF; WE RPTED THE RWY IN SIGHT AND WERE CLRED FOR A VISUAL APCH TO RWY 23. WE WERE ADVISED BY APCH CTL TO SLOW TO 180 KTS AND CONTACT TWR. THE FO WAS FLYING. I CONTACTED TWR AND WAS CLRED TO LAND. WE CONFIGURED THE ACFT AND THE ILS APCH WAS OPTIMAL WHILE I AND THE FLT ENGINEER CLRED THE AREA FOR OTHER ACFT. AT APPROX 800 FT WE RECEIVED A TCASII WARNING AND I VISUALLY ACQUIRED A HELI AT OUR 11 O'CLOCK POS APPROX 2 MI AWAY. THE TWR CTLR RPTED THE HELI AND I ELECTED TO CONTINUE THE APCH. WE LANDED NORMALLY ON RWY 23. I DEPLOYED THE SPD BRAKE BUT BEFORE THE FO COULD SELECT REVERSE THRUST; WE OBSERVED AN SMA LNDG IN FRONT OF US ON RWY 32. I SLAMMED ON THE BRAKES WHICH HAD LITTLE EFFECT AND THE SMA PASSED LESS THAN 500 FT IN FRONT OF OUR LNDG ROLL. I ASKED TWR WHAT HAD HAPPENED AND SHE SAID; 'THAT WAS A LITTLE CLOSER THAN I THOUGHT IT WOULD BE.' OUR TCASII NEVER WARNED US OF THE IMPENDING (REAL) CONFLICT. I LATER LEARNED FROM THE TWR SUPVR THAT THE SMA WAS VFR AND WAS CLRED TO LAND. HE ALSO SAID THAT THE TWR CTLR HAD ERRED AND WAS BEING REMOVED FROM DUTY PENDING ADDITIONAL TRAINING. IF THE SMA HAD A TRANSPONDER; OUR TCASII MAY HAVE ALERTED US AND THE NEAR MISS BEEN AVOIDED; DESPITE THE TWR CTLR'S MISJUDGMENT!