A C340 PLT DID NOT EXECUTE THE DME ARC PROPERLY AT MTJ.

Narrative

THE WX WAS 500 FT OVCST; WITH TOPS AT APPROX 9000 FT MSL. THIS WAS AN ILS APCH INTO A MOUNTAIN ARPT; ELEVATION 5700 FT MSL. I WAS ASSIGNED THE ILS DME 17 APCH TO MTJ; VIA THE 14.8 DME ARC. I ENTERED THE ARC FROM V-26; AS DEPICTED; BEGAN FLYING THE ARC; AND DSNDED TO 9500 FT MSL; THE CORRECT ALT FOR THAT SEGMENT. I TUNED NAV #1 TO THE ILS FREQ AND VERIFIED THE IDENT. AFTER SEVERAL MINS ON THE ARC; THE CDI HAD NOT COME IN. UPON CHKING NAV #2; I REALIZED THAT I HAD GONE THROUGH THE LOC BY PERHAPS 1 MI. FORTUNATELY; WE WERE ABOVE THE CLOUD DECK AND COULD SEE ALL SURROUNDING TERRAIN. THUS; WE WERE SIMPLY ABLE TO REJOIN THE PROPER COURSE AND FLY AN UNEVENTFUL ILS. HOWEVER; HAD WE BEEN IN IMC ON THE ARC; WE COULD HAVE BEEN IN SERIOUS DANGER; GIVEN THE TERRAIN IN THE AREA. THE REASON THAT THE CDI DID NOT COME IN; WAS THAT IT WAS SET TO RECEIVE ITS SIGNAL FROM MY LORAN; AS OPPOSED TO NAV #1. ON ONE LEVEL; THIS PROB COULD HAVE BEEN AVOIDED SIMPLY BY SWITCHING MY CDI TO RECEIVE NAV #1; INSTEAD OF MY LORAN. HOWEVER; IN A MORE IMPORTANT SENSE; I SEE THIS PROB AS ONE OF PROC. WHAT I NEED TO DO IS DEVELOP A PROC TO ENSURE THE PROPER CDI SETTING ON EVERY APCH. THERE ARE 2 WAYS I CAN (AND INTENT) TO DO THIS IN THE FUTURE. FIRST; I WILL ADD 'CDI INPUT -- SET' TO MY APCH CHKLIST. SECOND; I WILL ADD TO MY MENTAL CHKLIST TO SWITCH MY CDI ANY TIME I TUNE IN AN APCH FREQ. (I CAN DOUBLECHK THIS BY ROTATING MY OBS TO ENSURE THAT THE CDI CHANGES AS I DO; WHICH IT DOES NOT WHEN TUNED TO MY LORAN.) ANOTHER THING I CAN TO DO AVOID A PROB LIKE THIS ON A DME ARC IN THE FUTURE -- OR AT LEAST DETECT IT MORE QUICKLY -- IS TO FOLLOW MY PROGRESS ALONG THE ARC MORE CLOSELY ON NAV #2. THIS APCH HAS A TURN-IN RADIAL OF 341 DEGS; ANTICIPATING AN APCH ALONG THE 348 DEG RADIAL FROM MTJ. I HAD TUNED MY NAV #2 TO CTR ON THIS RADIAL; BUT DID NOT LOOK AT THIS UNTIL I HAD PASSED THE TURN IN. SO WHEN NAV #2 DID NOT CTR; I SIMPLY EXPECTED IT TO CTR -- WITHOUT REALIZING FOR SOME TIME THAT IT WAS NOT GOING TO CTR. I REALIZED MY MISTAKE ONLY WHEN I CTRED THE CDI ON MY NAV #2 AND REALIZED I WAS PAST THE TURN-IN TO THE LOC. HAD I BEEN CTRING AND RE-CTRING MY NAV #2 CDI CONSTANTLY AS I FLEW ALONG THE DME ARC; I WOULD HAVE REALIZED WHERE I WAS ALONG THE ARC AT ALL TIMES. INSTEAD OF ONLY AT THE TURN IN POINT; AND WOULD NOT NEED TO RELY AS MUCH ON THE LOC TO LET ME KNOW WHEN TO TURN IN. THIS IS BASIC INST PROC.