A BE35 PLT ATTRIBUTED AN EARLY DESCENT ON AN ILS APPROACH TO A LACK OF TRAINING IN THE USE OF A PANEL MOUNTED GPS UNIT WITH COMPLEX FUNCTIONALITY.

Narrative

WHILE BEING VECTORED TO THE ILS RWY 25R APCH INTO LVK; I SET UP THE 'VECTORS TO FINAL' FUNCTION IN MY GARMIN GPS 530. RATHER THAN MANUALLY SELECTING THE NAV FREQ FOR THE LOCALIZER; I RELIED UPON THE 530 TO AUTO SWITCH TO THE FREQ; WHICH IT FAILED TO DO. I SWITCHED FROM 'GPS' MODE TO 'VLOC' MODE AS I INTERCEPTED THE LOCALIZER; AND FAILED TO NOTICE THE 'FAIL' FLAGS ON THE CDI. ACCORDINGLY; I BEGAN MY DSCNT PREMATURELY; VIOLATING THE ATC INSTRUCTION TO MAINTAIN 3300 FT UNTIL FOOTO. A CONTRIBUTING FACTOR WAS MY FAILURE TO POSITIVELY IDENTIFY FOOTO BEFORE DSNDING THROUGH 3300 FT. THIS RESULTED; IN PART; FROM THE FACT THAT THE GPS 530 DROPS MOST INTXNS OTHER THAN THE FAF WHEN YOU ARE ON ACTIVE VTF (VECTORS TO FINAL) MODE.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE RECEIVED ZERO TRAINING WITH HIS SYSTEM PRIOR TO FLYING WITH IT. HE WOULD RECOMMEND AS A MINIMUM; A CHK OUT WITH A CFI WHO WOULD PRESUMABLY RUN A PLT THROUGH THE EQUIP'S PACES. HE COMMUTES TO A LARGE METROPOLITAN ARPT AND USES HIS ACFT'S DUAL GPS SYSTEMS TO REDUCE THE WORKLOAD TREMENDOUSLY. DURING THIS PARTICULAR INCIDENT; HE WAS VMC AND WHEN HE STARTED HIS DSCNT; APCH CTL CALLED IMMEDIATELY WANTING TO KNOW WHAT HE WAS DOING. THERE WAS NO FURTHER DISCUSSION AFTER HE CLBED BACK TO 3300 FT.