A PLT FLYING A LOC DME BACK COURSE APCH WITH A VOR DME ARC LEAD-IN; APPARENTLY WITH MINIMUM NAV EQUIP; FAILED TO PROPERLY TUNE AND IDENT HIS RADIOS; RESULTING IN A MISSED APCH.

Narrative

I FAILED TO INTERCEPT THE LOC WHILE ON THE 11 DME ARC OF THE LOC DME (BACK COURSE) RWY 21 APCH TO PAHO. THE DME ARC IS BASED ON THE VOR AND INTERCEPTING THE BACK COURSE LOC REQUIRES SWITCHING A KING 'FLIP-TYPE STANDBY FREQ' RADIO FROM THE VOR FREQ TO THE 'STANDBY' LOC FREQ AFTER XING THE 034 DEG LEAD RADIAL. PROPER FREQS WERE ENTERED IN ALL RADIOS AND I MADE THE SWITCH TO THE LOC 'STANDBY' FREQ. IT'S USUALLY A SLOW LOC CAPTURE FROM THE LEAD RADIAL AND I EVIDENTLY FIXATED ON THE HSI WAITING FOR THE CDI TO COME ALIVE. I DIDN'T REALIZE THE RADIO NEVER ACTUALLY SWITCHED TO THE LOC FREQ AND I WAS STILL ON THE VOR FREQ. I FINALLY REALIZED THAT SOMETHING WAS WRONG AS IT WAS TAKING AN INORDINATE AMOUNT OF TIME FOR THE CDI TO COME ALIVE. I DISCOVERED THE ERROR AND ENDED UP PASSING THROUGH THE LOC BY 2 MI (ACCORDING TO AN ATC RELAY THROUGH THE LCL FSS). I DISCOVERED THE ERROR IMMEDIATELY BEFORE THE FSS RADIO CALL AND HAD ALREADY BEGUN THE TURN BACK TO FLY THE MISSED APCH PROC. FATIGUE WAS A DEFINITE FACTOR. MY RESPONSIBILITIES ARE NUMEROUS OUTSIDE OF JUST FLYING. NORMALLY MY CHKLIST DISCIPLINE IS VERY GOOD AND MY INST SCAN WOULD HAVE INCLUDED VERIFICATION OF THE PROPER FREQ BY A VISUAL CHK OF THE 'ACTIVE' RADIO FREQ NUMBERS ON THE RADIO AND BY IDENTING THE FREQ'S AUDIBLE MORSE CODE IDENTIFIER. THE 'FLIP-TYPE STANDBY FREQ' PUSH BUTTON SWITCHES ON THE KING RADIOS FOR THIS AIRPLANE ARE TOUCHY. THEY CAN SOMETIMES REQUIRE SEVERAL (4-6) ATTEMPTS TO SWITCH TO THE STANDBY FREQ BEFORE THE RADIO WILL FINALLY ACCEPT THE NEW FREQ. THIS PROB HAS BEEN BROUGHT TO THE ATTN OF MAINT. AS FAR AS THE FUTURE IS CONCERNED; INCREASED DILIGENCE DURING ALL APCHS; ESPECIALLY WHERE STANDBY FREQ SWITCHES ARE CONCERNED IS IN ORDER. ALSO; NON-FLYING RESPONSIBILITIES WILL HAVE TO BE REALLOCATED AND MANAGED BETTER SO AS TO PROVIDE ADEQUATE REST BEFORE FLYING.