ENTERED ARSA WITHOUT CLRNC.

Narrative

ON A SCHEDULED FLT BTWN LOS ANGELES AND SAN LUIS OBISPO; CA; WE WERE UNEXPECTEDLY REQUIRED TO DIVERT TO SBA DUE TO FAILURE OF A NAV RECEIVER. IN MY CONCERN FOR COMMUNICATING THE CHANGE IN PLANS TO BOTH MY PAX AND MY COMPANY; I DIRECTED THE F/O TO FLY THE ACFT WHILE I MADE THE NECESSARY RADIO WORK. (THIS IS WHERE I MADE A CRITICAL ERROR IN NOT FLYING THE ACFT FIRST AND DELEGATING DUTIES TO THE F/O; IE; POOR COCKPIT RESOURCE MGMNT.) THE WORKLOAD WAS HEAVY IN OUR DSCNT TO SBA AND WE SOMEHOW LOST COM WITH ZLA. I DISCOVERED THE ERROR WHEN WE HAD NOT YET BEEN HANDED OFF TO SBA APCH. WHEN WE CONTACTED APCH WE HAD ALREADY ENTERED THEIR ARSA W/O ATC CLRNC. SBA APCH THEN NOTIFIED US OF THE ERROR AND ASSIGNED US 2000' ALT. SBA APCH AGAIN DISTRACTED US WITH QUESTIONS ABOUT ENTERING THE ARSA AND WE DSNDED THROUGH 2000' TO 1600 BEFORE NOTICING THE ERROR. (SBA APCH SHOULDN'T HAVE SAID ANYTHING ABOUT THEIR PROB UNTIL ON THE GND AND NOT IN THE CRITICAL PHASE OF FLT.) THE ONLY OTHER THING OTHER THAN BETTER COCKPIT RESOURCE MGMNT THAT WOULD HAVE PREVENTED ME FROM INADVERTENTLY DESELECTING ZLA WOULD BE A STANDARD COCKPIT LAYOUT FOR ALL OF MY COMPANY'S ACFT. WE HAD JUST SWAPPED INTO A NEW AIRPLANE IN WHICH THE COM AND NAV RADIOS WERE LOCATED IN DIFFERENT PLACES.