CLOSE PROX ACR-MLG GA-SMA IN TRAFFIC AT AUS.

Narrative

ON A NIGHT VISUAL APCH; TWR CLRED OUR FLT TO LAND ON RWY 13R; BUT CAUTIONED THAT A LIGHT ACFT WOULD LAND ON INTERSECTING RWY 17 JUST AHEAD OF US. WHEN I FINALLY SAW THE TFC (HIS LIGHTS WERE MASKED IN THE CITY LIGHTS BELOW); I REALIZED IMMEDIATELY THAT WE WERE ON A COLLISION COURSE WITH THIS ACFT. I TOLD THE TWR THAT THIS WAS NOT GOING TO WORK OUT AND THAT WE WOULD HAVE TO GO AROUND. THEY SEEMED SURPRISED AND IMMEDIATELY ASKED THE LIGHT ACFT IF HE COULD STILL LAND ON THE PARALLEL RWY (13L). AFTER INITIALLY HESITATING; THE OTHER ACFT AGREED THAT HE COULD MAKE RWY 13L AND BOTH ACFT LANDED UNEVENTFULLY. I AM CONVINCED THAT HAD I NOT SEEN THE OTHER ACFT WHEN I DID; THAT WE WOULD HAVE HIT HIM AT THE INTXN OF THE RWYS--WE WERE DEFINITELY ON A COLLISION COURSE--UNDETECTED BY THE TWR. WHEN QUESTIONED; THE TWR SUPVR WAS UNAWARE OF THE SITUATION! IT WAS DISCONCERTING THAT ATC WOULD SPACE ACFT SUCH THAT A SITUATION LIKE THIS COULD OCCUR IN A RADAR ENVIRONMENT! WE WERE 1/4-1/2 MI OUT WHEN WE SAW THE ACFT AND WERE 500-1000' FROM IT HORIZ.