DEV FROM CLRNC RTE. PLT TRACKS INBOUND ON THE WRONG APCH RADIAL AND STARTS HIS DSCNT. THE ALERT CTLR CORRECTS HIM.

Narrative

I WAS FLYING MY CESSNA FROM PDX TO LGD ON IFR FLT PLAN. AT APPROX 20 MI FROM LGD NDB; I NOTED INABILITY TO RECEIVE LGD NDB SUITABLE FOR NAV. 2 OTHER ACFT ON FREQ ALSO NOTED NO LGD SIGNAL. I WAS #1 FOR LGD NDB-A APCH WITH ANOTHER ACFT CONVERGING BEHIND ME WHO WAS HAVING INITIAL DIFFICULTY RECEIVING LGD. AT ABOUT 10 MI OUT; I ADVISED THE CTLR BKE WOULD BE MY ALTERNATE IF I WAS UNABLE TO RECEIVE LGD NDB. AT APPROX 6 MI FROM LGD NDB; I WAS STILL UNABLE TO RECEIVE LGD NDB SO I ASKED TO BE CLRED TO INITIAL FOR VOR DME RWY 12 BKE APCH. CTLR CLRED ME DIRECT TO BKE VOR 325 DEG RADIAL; 20 DME FIX; FOR THE DME ARC TO FINAL. I CORRECTLY SET IN 325 DEG RADIAL (145 DEGS TO) BUT AS MY NEEDLE CTRED JUST OUTSIDE THE ARC; I MENTALLY TRANSPOSED HAVING SET IN THE DME ARC RADIAL WITH THE INBOUND COURSE RADIAL (297 DEGS; 117 DEGS INBOUND) AND MISTAKENLY THOUGHT THAT I WAS INTERCEPTING THE INBOUND COURSE. I ASKED THE CTLR IF I WAS BEING VECTORED TO THE INBOUND COURSE DIRECTLY OR THE 325 DEG 20 ARC FIX; AND SHE REPLIED THE LATTER. I CONTINUED TO INSIST THAT I WAS ON THE INBOUND COURSE ALREADY AND WOULD PROCEED AS CLRED. SHE OBVIOUSLY DID NOT KNOW THAT I HAD MISREAD MY COURSE SETTING; SO SHE CONTINUED TO TELL ME TO PROCEED TO THE ARC FIX (325 DEGS; 20 ARC FIX). WHEN I CROSSED THE ARC AND FAILED TO TURN R TO FOLLOW THE ARC WBOUND TO THE 297 DEG RADIAL; BUT INSTEAD BEGAN LETTING DOWN ON THE 325 DEG RADIAL; SHE AGAIN TOLD ME TO FOLLOW THE ARC. AT THIS POINT I REALIZED MY ERROR HAVING PROCEEDED TO THE 16.7 DME FIX AND LET DOWN TO ABOUT 7700 FT MSL. SHE VECTORED ME 290 DEGS TO THE ARC/FINAL APCH FIX AND TOLD ME TO CLB WHICH I DID. UPON REACHING THE ARC/FINAL APCH FIX I COMPLETED THE APCH WITHOUT FURTHER DIFFICULTY. FACTORS AFFECTING THE SIT: 1) CURRENCY. I AM 'LEGALLY' CURRENT IN ALL REQUIRED FLT OPS; BUT MY ACFT HAD JUST EMERGED FROM 2 MONTHS OF SCHEDULED AND UNSCHEDULED MAINT. THIS DECREASED MY USUAL 2-3 INST APCHS PER MONTH. 2) FRUSTRATION. THE LA GRANDE (LGD) NDB HAS A HISTORY OF FULL OR PARTIAL OUTAGES; ESPECIALLY DURING WET (IE; INST) WX. I ACTUALLY BEGAN RECEIVING THE NDB AS I WAS BEING VECTORED TO THE 325 DEG RADIAL; 20 ARC FIX; BUT THE CTLR HAD THEN CLRED THE TFC BEHIND ME FOR THE APCH. SO; I KNEW THAT IF I ASKED TO RETURN FOR THE NDB-A APCH IN LA GRANDE I WOULD HAVE A LENGTHY HOLD AT LGD NDB AND STILL NOT BE ASSURED OF GETTING INTO LA GRANDE. THIS FRUSTRATION TENDED TO DISTRACT MY CONCENTRATION ON THE APCH PLATE FOR MY ALTERNATE.