LGT DEPARTING PHX HAS NMAC WITH SMT WITHIN THE ARSA.

Narrative

THE CAPT WAS FLYING THE DEP (PAYSO 3). AFTER XING THE NDB WE WERE ABOUT TO INTERCEPT THE 030 DEG R OF SRP. THE CAPT BEGAN A 30 DEG LEFT BANK TURN FROM APPROX 080 DEGS TO INTERCEPT THE 030 DEG R OUTBND. PASSING THROUGH ABOUT 060 DEGS THE F/E POINTED TO OUR RIGHT AND I OBSERVED A LIGHT TWIN ENG PROP (LIGHT BROWN; OR TAN) HEADED DIRECTLY AT US AT OUR ALT. BEFORE WE COULD TAKE ANY EVASIVE ACTION THE TWIN PROP BEGAN A LEFT CLBING TURN AND PASSED OVER AND BEHIND OUR ACFT AT APPROX 400'. WE HAD RECEIVED NO TFC CALLOUT FROM DEP. I FEEL THE MAJOR CONTRIBUTING FACTORS WERE THE FOLLOWING: ALLOWING VFR TFC TO FLY UNCONTROLLED IN BUSY DEP CORRIDOR OF A MAJOR ARPT. ADDITIONALLY WE HAD PREVIOUSLY BEEN GIVEN OUR TKOF CLRNC BASED ON OUR MAINTAINING VISUAL SEP WITH A PREVIOUSLY DEPARTED MLG. WE HAD TO KEEP HIM IN SIGHT WHILE FLYING AN INSTRUMENT DEP WHICH SOMEWHAT DETRACTED FROM OUR ABILITY TO OBSERVE OTHER VFR TFC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: CONFIRMED THAT THE NMAC HAPPENED JUST INSIDE THE E BOUNDARY OF THE ARSA. ATC ADVISED REPORTERS THAT THEY WERE NOT WORKING THE SMT AND WERE UNAWARE OF HIS PRESENCE.