B737 LNDG RWY 10 AT PDX EXPERIENCED TCASII RA WITH ATC ISSUED TFC.

Narrative

PDX WX 24 BROKEN; 35 OVCST 7-R 5 DEGS/4 DEGS 100-9 ILS RWYS 10L AND 10R IN USE. VISIBILITY LOWER TO THE W. APCH CTL: 'MAINTAIN 2000 FT TILL ESTABLISHED; CLRED FOR ILS RWY 10L. TFC 10 O'CLOCK POS; 6 MI; PROBABLY JUST OFF OF PEARSON AIRPARK.' TWR; 'CLRED TO LAND RWY 10L;' PLUS TFC RPT. US; 'IMC IN AND OUT OF THE BASES AND RAIN.' TCASII RA AT 800 FT AGL. TARGET SHOWED 600 FT ON TCASII. FO DISENGAGED AUTOPLT AND EXECUTED EVASIVE ACTION IN COMPLIANCE WITH RA TO 1200 FT AGL. AS WE PASSED CLR OF CONFLICT WE BROKE OUT OF THE CLOUDS AND MADE A NORMAL VISUAL APCH AND UNEVENTFUL LNDG. AFTER LNDG; #2 FLT ATTENDANT STATED THAT HE HEARD THE TCASII WARNING; FELT THE CLB; AND VISUALLY SAW THE SINGLE ENG ACFT PASS VERY NEAR AND SLIGHTLY BELOW US. TALKED TO TWR SUPVR AND HE STATED THAT THIS IS A FAIRLY COMMON OCCURRENCE WITH TFC AT PEARSON; AND THAT THE TFC WAS IN LEGAL AIRSPACE. HE STATED THE GA ACFT INTENTIONS WERE TO DEPART NW AND THAT HE THOUGHT THE PLT DECIDED VISIBILITY WAS TOO POOR SO STAYED IN THE PATTERN AND LANDED.