STUDENT PLT INBOUND TO GYR HAS NMAC WITH OPPOSITE DIRECTION UNKNOWN TYPE BUSINESS JET.

Narrative

DURING THE RETURN LEG OF A STUDENT PLT NAV SOLO; I WAS FLYING NW FROM THE TOWN OF SACATON TO VPGLX (GILA CROSSING) IN ORDER TO BEGIN AN APCH TO GOODYEAR ARPT. I WAS AT AN ALT OF 4500 FT MSL IN ORDER TO STAY BELOW THE PHX CLASS B SHELF AND WAS BEGINNING MY PRE-DSCNT CHKLIST; KEEPING A LOOKOUT IN BTWN ITEMS. AFTER REDUCING PWR AND RETUNING THE RADIO; I LOOKED OUT AGAIN AND CAUGHT SIGHT OF AN ACFT AT MY 11 O'CLOCK POS (FROM TOWARD THE ESTRELLA MOUNTAINS) APCHING AT SPD. WITHIN 3-4 SECONDS IT HAD PASSED DIRECTLY OVER ME; WITH ONLY APPROX 200 FT CLRNC VERTLY. DUE TO THE SPD OF THE ENCOUNTER AND THE FACT THAT I WAS ALREADY IN A DSCNT; I DID NOT DEVIATE FROM MY COURSE. THE ACFT WAS A LIGHT BIZJET THAT APPEARED TO BE CLBING OUT FROM GOODYEAR OR ANOTHER NEARBY ARPT TO THE N. DUE TO THE INTENSE STUDENT PLT ACTIVITY ACROSS THE AREA; AND THE PRESENCE OF SEVERAL TRAINING SCHOOLS IN THAT PART OF THE VALLEY; I FELT THAT IT WAS UNWISE FOR A JET TO PASS THROUGH THE AREA AT THAT ALT. I CANNOT MAKE ASSUMPTIONS ABOUT THE CTL STATUS OF THE JET BUT; HAD THE ACFT BEEN IN CONTACT WITH EITHER PHX APCH OR ANOTHER RADAR SVC; GREATER TFC SEPARATION COULD HAVE BEEN PROVIDED GIVEN THAT ALL OF THE TRAINING ACFT WE FLY OUT OF GOODYEAR ARE EQUIPPED (AND EQUIPPED) WITH MODE C XPONDERS. WHEN MANEUVERING IN THE AREA; WE ARE NOT TYPICALLY IN CONTACT WITH ANY ATC SVC; UNLESS FLT FOLLOWING IS REQUESTED FROM ZAB. THIS SVC IS OFTEN UNAVAILABLE.