B737-700 FLT CREW TAKES EVASIVE ACTION; OBSERVING A SMA ACFT AT THE PHX CLASS B BOUNDARY AS PSO ISSUES A TCASII CONFLICT ALERT.

Narrative

WHILE DSNDING INTO PHX ON THE COYOT 1 STAR; WE HAD A TCASII RA AND NEAR MISS WITH A LIGHT ACFT. WE WERE 10 MI S OF MAHEM/20 MI N OF PXR; DSNDING TO 8000 FT. AT 8200 FT; WE GOT A TCASII TA SHOWING THE OTHER ACFT 700 FT BELOW US AND APPROX 4-5 MI IN FRONT OF US AT 12 O'CLOCK. MY FIRST THOUGHT WAS HE WAS A VFR ACFT AT 7500 FT. I LEVELED WHILE LOOKING OUT THE WINDOW FOR HIM. WHEN I LOOKED BACK AT THE TCASII DISPLAY TO CHK HIS POS; I SAW THAT HE WAS CLBING AND NOW ONLY 200 FT BELOW US AT ABOUT 2 MI ON THE NOSE. NOW I WAS MUCH MORE CONCERNED. NEXT; THE CTLR STARTED GIVING US A TA CALL AND; SIMULTANEOUSLY; THE CAPT AND I STARTED TALKING ABOUT A R TURN TO AVOID HIM. AFTER BEGINNING THE TURN; WE GOT A TCASII RA; 'MONITOR VERT SPD.' IT DIRECTED LEVEL TO DSCNT (IE; NO CLB). THE TCASII DISPLAY NOW SHOWED THE OTHER ACFT 100 FT ABOVE US. BY THIS TIME; THE CAPT HAD A VISUAL ON HIM; A SINGLE ENG; LOW-WING AIRPLANE. CAPT STATED HE PASSED 200 FT ABOVE AND 1/4-1/2 MI HORIZ. I NEVER GAINED A VISUAL ON THE ACFT DUE TO FOLLOWING TCASII RA. CAPT ALSO STATED THE OTHER ACFT WAS IN A HARD TURN AWAY FROM US WHEN HE SAW HIM. WE DEVIATED SLIGHTLY W OF COURSE FOR THE RA; THEN RESUMED THE ARR. I WAS SURPRISED AT JUST HOW LATE THE TCASII RA CAME.