A C310 PLT BECAME DISORIENTED DURING A LOC BACK COURSE APCH. THE PLT RPTS SEARCHING THE IAP LOC BACK COURSE APCH PLATE FOR AN INTXN AND INADVERTENTLY DISCONNECTING THE AUTOPLT IN THE PROCESS. AFTER THE PLT WAS VECTORED FOR ANOTHER APCH; HE MISTAKENLY CORRECTED TOWARD THE COURSE INDICATOR; AND HAD TO MISS THE APCH; AGAIN. AFTER A BRIEF DELAY AT 4000 FT; THE PLT WAS ABLE TO REALIZE HIS ERROR.

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FRI EVENING FLT AFTER A HECTIC WORK WK. NORMAL FULL WX BRIEF; HUT: IFR WITH 1200-1300 FT AGL CEILING AT HUT WITH TOPS AT 3500-4000 FT MSL; AND VISIBILITY 10 MI. UNEVENTFUL IFR FLT FROM HAYS IN VFR CONDITIONS ABOVE A SOLID OVCST AS FORECAST. ATIS AT HUT GAVE WX AS PER FORECAST; AND 'EXPECT LOC BACK COURSE RWY 31 CIRCLE TO LAND RWY 35.' HDOF FROM ZKC TO WICHITA APCH UNEVENTFUL. VECTORS AND ALT CHANGES TO INTERCEPT THE LOC BACK COURSE WERE FLOWN WITH THE AUTOPLT ON WITH HDG BUG SELECTED; AND ALT HOLD (DURING LEVEL SEGMENTS OF THE FLT AND APCH). EVERYTHING WAS AS EXPECTED UNTIL THE TURN ONTO THE LOC. WHILE COMPLETING THE TURN ONTO THE LOC AT 3000 FT MSL I DID PUSH THE ALT HOLD; BUT BEFORE I COULD LOOK TO SEE IF THE HOLD ALT CONFIRMATION LIGHT CAME ON I CHANGED TO TWR FREQ. WHEN I CHKED IN WITH THE TWR I WAS REQUESTED TO RPT XING STORG INTXN. ALTHOUGH I HAD ALREADY DIALED IN THE VOR AND RADIAL FOR STORG IN THE #2 RADIO; I DID NOT RECOGNIZE THE NAME AND LOOKED DOWN ONTO THE APCH PLATE TO CONFIRM THAT IT WAS NOT A POINT I HAD ALREADY PASSED OR WAS CURRENTLY OVER AS I HAD JUST INTERCEPTED THE LOC BACK COURSE FOR RWY 31. AS TWILIGHT WAS IN PROCESS AND THE ACFT WAS IN IMC CONDITIONS; LIGHTING AT LAP LEVEL WAS LESS THAN OPTIMUM. RATHER THAN TAKE THE TIME TO BRING UP THE CABIN LIGHTS I MADE THE MISTAKE OF SETTING THE SMALL METAL CLIPBOARD WITH THE APCH PLATES AGAINST THE TOP OF THE PLT CTL YOKE. AS I LOOKED UP TO CONFIRM THE VOR AND RADIAL SETTINGS I NOTED THAT I WAS XING OUT OF THE LOC BUT DID NOT YET COMPREHEND THAT I HAD TURNED OFF THE AUTOPLT. WITH THE FALSE ASSUMPTION THAT THE ALT HOLD WAS ENGAGED I LOOKED UP AT THE GPS DISPLAY THAT DID CONFIRM THE WORSENING POS ERROR. AS I REACHED OVER AND TURNED OFF THE AUTOPLT SWITCH ON THE FACE PLATE I SAW THAT I HAD DSNDED AND WAS OFF COURSE. STILL NOT COMPREHENDING HOW I HAD TURNED OFF THE AUTOPLT I ASSUMED THAT THERE WAS SOME OTHER PROB. I DID REAPPLY PWR; CLB; AND REQUEST MISSED APCH VECTORS AS I WAS NOT IN A POS TO REINTERCEPT THE LOC BACK COURSE. AS I WAS VECTORED FOR A SECOND APCH FOR THE LOC BACK COURSE RWY 31 I WAS NOT COMPLETELY SURE WHAT I HAD DONE OR DID NOT DO ON THE FIRST APCH THAT HAD RESULTED IN BOTH DIRECTIONAL AND ALT ERRORS. I HAD BOTH ANXIETY AND CONCERN ABOUT THE PREVIOUS APCH AND WAS DISTRACTED AS I STARTED THE SECOND INTERCEPT OF THE LOC BACK COURSE RWY 31. IN FACT I WAS DISTRACTED ENOUGH THAT I WAS TRYING TO FLY THE CORRECTIONS AS IF IT WAS A LOC RATHER THAN THE REVERSED CORRECTIONS REQUIRED FOR A LOC BACK COURSE. I REQUESTED VECTORS AND A CLB TO 4000 FT SO THAT I COULD ANALYZE THE SIT AS I NEITHER TRUSTED THE LOC BACK COURSE SIGNAL NOR MY RECEIVER. IN VFR CONDITIONS ABOVE THE CLOUD TOPS I FINALLY REALIZED WHAT I HAD DONE. I THEN REQUESTED THE VOR RWY 3 AND HAD AN UNEVENTFUL APCH AND LNDG. IN RETROSPECT IT HAS BEEN A LONG TIME SINCE I FLEW A LOC BACK COURSE OTHER THAN ON A SIMULATOR. IN ADDITION THERE IS A BUTTON ON THE ACFT AUTOPLT (LOC BACK COURSE) THAT ALLOWS THE NAV FUNCTION TO FLY REVERSED CORRECTIONS. SINCE I HAVE NOT USED THIS FUNCTION IN PRACTICE SITS I DID NOT TRUST IT TO WORK IN ACTUAL IFR CONDITIONS. THE UNEXPECTED DSCNT BELOW ALT CAUSED ENOUGH DISTRACTING ANXIETY THAT I SHOULD HAVE REFUSED THE SECOND APCH UNTIL I EITHER UNDERSTOOD THE FIRST PROB OR WAS CALMER. THE SECOND APCH ONLY ADDED TO THE STRESS. I DID NOT HAVE MY FULL ATTN ON THE SECOND APCH AS I FOUND MYSELF COMPARING IT TO THE FIRST RATHER THAN STARTING WITH A CLEAN SLATE. I HAVE NEVER RESTED THE APCH PLATES ON THE TOP OF THE PLT YOKE BEFORE AND WILL NEVER DO SO AGAIN. AS I HAVE NOT USED THE YOKE MOUNTED AUTOPLT RELEASE SWITCH I DID NOT REALIZE THAT I HAD A PROB UNTIL IT WAS WELL DEVELOPED.