A C425 CPR PLT LOSES SITUATIONAL AWARENESS DURING AN ATTEMPTED GPS PROGRAMMED 15 DME ARC FOR A VOR A DME APCH INTO SAF; NM.

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ARRIVED IN SANTA FE AREA FROM W ON IFR FLT PLAN. AT ABOUT 17 DME W OF SAF VORTAC; I REMINDED CTLR THAT I STILL NEEDED AN APCH CLRNC. HE PROMPTLY CLRED ME FOR VOR-A APCH. I READ IT BACK; MENTIONING THAT I WOULD FLY THE 15 DME ARC FOR THE INITIAL APCH; WHICH HE APPROVED. I FELT FAMILIAR WITH THE APCH; AND COMMENCED TO SET IT UP ON THE GPS. THE GPS IS A KLN-90B; APCH CERTIFIED. I COMMENCED A L TURN TOWARDS THE NBOUND 15 DME ARC; AND STARTED SETTING UP THE SIT ON THE GPS. ALTHOUGH I HAVE DONE THIS APCH ABOUT 10 TIMES PREVIOUSLY; FOR SOME UNDETERMINED REASON; I HAD GREAT DIFFICULTY PROGRAMMING THE APCH IN; TO SHOW THE ARC ON SCREEN. I FIXATED ON THE PROB; WHILE THE AUTOPLT HELD THE WINGS LEVEL AND CTLED PITCH. I SHOULD HAVE ABANDONED THE GPS ASPECT OF THE NAV PROB; BUT INSTEAD OF REVERTING TO VOR/DME; I STUBBORNLY STAYED FOCUSED ON THE GPS; WHILE THE PLANE WANDERED INSIDE THE ARC. SOON; A SHARP COMMENT FROM THE CTR CTLR FOLLOWED; AND I RESPONDED BY DECLARING A MISSED APCH; REQUESTING CLRNC VIA DIRECT TO THE NORTHERN IAF FOR THE SAME APCH; WITHOUT ARC. THIS WAS GRANTED; WITH A CLB CLRNC TO 15000 FT. WHILE I WAS RECONFIGURING THE ACFT AND RESETTING THE NAV PROB FOR DIRECT TO POAKE INTXN; THE CTLR CLRED ME FOR AN APCH ON ARR AT POAKE. I ACKNOWLEDGED; AND KEPT CLBING FOR POAKE. A MIN LATER; HE ASKED WHERE I WAS GOING! MY WORKLOAD HAD BEEN EXTREMELY HIGH; AND I WAS 'ON EDGE.' THIS WAS NOT WHAT I WANTED TO HEAR! I REPLIED THAT I WAS GOING TO POAKE; STRAIGHT IN FRONT OF ME AT 6 (OR SO) MI AND STILL CLBING TO MY 15000 FT ALT ASSIGNMENT. THE CTLR THEN SAID THAT WE WERE EXPERIENCING A 'COMS GAP' OR WORDS TO THAT EFFECT; AND THAT HE HAD NOT EXPECTED ME TO GO THAT HIGH. PERHAPS HE EXPECTED ME TO NOT EXCEED THE PUBLISHED 'NO PT' ALT OF 8300 FT AT POAKE. HOWEVER; I WAS IN HIGH ANXIETY FROM THE 'BLOWN' APCH AND MISSED APCH; AND KNEW THAT THE TERRAIN IMMEDIATELY E OF POAKE VARIES FROM 12000-13000 FT MSL. 15000 FT SOUNDED OK! I ARRIVED AT POAKE AT AROUND 13500 FT; HAVING SLOWED MY CLB RATE; AND PERFORMED A SUCCESSFUL APCH TO A LNDG. PRIOR TO THIS INCIDENT; I CONSIDERED MYSELF WELL-VERSED IN THE PROGRAMMING OF THE KLN-90B GPS NAVIGATOR. I DID NOT MENTALLY PREPARE MYSELF FOR THE POSSIBILITY THAT IT WOULD NOT 'COOPERATE' WITH MY BUTTON-PUSHING. I STUBBORNLY STUCK WITH THE GPS LONG AFTER I SHOULD HAVE QUIT ON IT. I WILL FLY OVERLAY GPS APCHS IN A DUAL MODE HENCEFORTH; BY KEEPING THE NAV PROB SET UP AND DISPLAYED TO SHOW THE BASIC APCH. THE ANXIETY AND FRUSTRATION THAT DEVELOPED IN ME DURING THE INITIAL (ABORTED) ARC APCH DEGRADED MY PERFORMANCE FOR THE BAL OF THE FLT.