Narrative:

Single pilot, IFR, on vectors to ILS 27R. Intercepting localizer turned off autoplt, did not disengage. Trying to hand fly ILS, fighting autoplt, told approach was having autoplt problem. Could not find autoplt master switch. So I shut off aircraft master switch to disconnect autoplt. This worked, so I asked approach for a vector back to localizer. Localizer and GS indications were confusing, as I was flying a 290 degree heading to intercept. Approach then called and advised that I was south of course, heading sbound. I then realized that the directional gyroscope portion of the HSI had failed to erect after shutting off master. No light on second directional gyroscope, flashlight had fallen on floor, out of reach. Immediately asked for no-gyroscope vectors to localizer. During all this, several altitude excursions occurred (partial panel). The problem was twofold. Normally I fly a different aircraft with a different autoplt altogether, and had difficulty locating controls on this aircraft. Secondly, I had recently arranged an eye examination, but had not yet gotten it. Currently wearing bifocals, they focus either too close or too far away, so I missed the warning flag on the HSI. I did not realize until that very moment, how much my vision had deteriorated, and without the flashlight to add sufficient light to find the proper instruments and controls I nearly exceeded my capabilities. I currently hold a valid second class medical, passed the eye examination. I successfully completed single pilot part 135 IFR proficiency examination in oct, but the lack of complete familiarity with these aircraft certainly contributed. (As a safety feature if voltage is low, HSI will not erect. I have had this happen on the ground, but never in the air.)

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Original NASA ASRS Text

Title: SMA PLT REALIZES VISION DETERIORATION WHEN HE MISSES FLAG ON HSI. HAS TROUBLE WITH AUTOPLT DISCONNECT. FLASHLIGHT ON FLOOR, OUT OF REACH. ALTDEV.

Narrative: SINGLE PLT, IFR, ON VECTORS TO ILS 27R. INTERCEPTING LOC TURNED OFF AUTOPLT, DID NOT DISENGAGE. TRYING TO HAND FLY ILS, FIGHTING AUTOPLT, TOLD APCH WAS HAVING AUTOPLT PROBLEM. COULD NOT FIND AUTOPLT MASTER SWITCH. SO I SHUT OFF ACFT MASTER SWITCH TO DISCONNECT AUTOPLT. THIS WORKED, SO I ASKED APCH FOR A VECTOR BACK TO LOC. LOC AND GS INDICATIONS WERE CONFUSING, AS I WAS FLYING A 290 DEG HDG TO INTERCEPT. APCH THEN CALLED AND ADVISED THAT I WAS S OF COURSE, HDG SBOUND. I THEN REALIZED THAT THE DIRECTIONAL GYROSCOPE PORTION OF THE HSI HAD FAILED TO ERECT AFTER SHUTTING OFF MASTER. NO LIGHT ON SECOND DIRECTIONAL GYROSCOPE, FLASHLIGHT HAD FALLEN ON FLOOR, OUT OF REACH. IMMEDIATELY ASKED FOR NO-GYROSCOPE VECTORS TO LOC. DURING ALL THIS, SEVERAL ALT EXCURSIONS OCCURRED (PARTIAL PANEL). THE PROBLEM WAS TWOFOLD. NORMALLY I FLY A DIFFERENT ACFT WITH A DIFFERENT AUTOPLT ALTOGETHER, AND HAD DIFFICULTY LOCATING CTLS ON THIS ACFT. SECONDLY, I HAD RECENTLY ARRANGED AN EYE EXAMINATION, BUT HAD NOT YET GOTTEN IT. CURRENTLY WEARING BIFOCALS, THEY FOCUS EITHER TOO CLOSE OR TOO FAR AWAY, SO I MISSED THE WARNING FLAG ON THE HSI. I DID NOT REALIZE UNTIL THAT VERY MOMENT, HOW MUCH MY VISION HAD DETERIORATED, AND WITHOUT THE FLASHLIGHT TO ADD SUFFICIENT LIGHT TO FIND THE PROPER INSTS AND CTLS I NEARLY EXCEEDED MY CAPABILITIES. I CURRENTLY HOLD A VALID SECOND CLASS MEDICAL, PASSED THE EYE EXAMINATION. I SUCCESSFULLY COMPLETED SINGLE PLT PART 135 IFR PROFICIENCY EXAMINATION IN OCT, BUT THE LACK OF COMPLETE FAMILIARITY WITH THESE ACFT CERTAINLY CONTRIBUTED. (AS A SAFETY FEATURE IF VOLTAGE IS LOW, HSI WILL NOT ERECT. I HAVE HAD THIS HAPPEN ON THE GND, BUT NEVER IN THE AIR.)

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.