Narrative:

35 mins into flight, 'alternator fail' light illuminated. Placed back on buss successfully by cycling the battery switch (this situation had occurred frequently during the october-november time frame, but had been successfully repaired by reconditioned alternator and new battery switches, etc). No problem for at least 6 weeks. Previously, 30 mins into flight, had changed from l-hand to r-hand fuel tank. 1 hour 5 mins into flight, arrived abeam controller in charge. IMC, from bakersfield north in the valley, all the way to redding forecast had been 3000 ft scattered for controller in charge. 1 hour 15 mins into flight, 'alternator fail' light came on. Battery switch cycle successful. (Under vectors by ZOA to intercept localizer ILS runway 13L.) 1 hour 25 mins into flight, initiated missed approach procedures (had used autoplt navigation coupling procedures while intercepting localizer). It seemed to overreact during the 'capture' phase with excessive turn to center the localizer, then strong descent action to center glide path. I took over manually but was reluctant to continue descent with needles well off center. I had utilized the system to land earlier same day at cno in hazy, not IMC conditions. 1 hour 35 mins into flight, 'alternator fail' light came on. Battery switch cycle successful. (Under vectors by ZOA, now vector guidance went outbound more than 20 mi due to intercept spacing (4TH in pattern for ILS to controller in charge). Still IMC, I intercepted localizer while flying manually. Placed the gear down to start descent on centered GS needle. Soon became apparent that the GS indicator was not moving, but frozen in the center position. Elected to follow localizer, only to circling minimums (640 ft MSL). Reaction to following this decision resulted in breaking out of overcast at approximately 750 ft MSL, but already over runway threshold. Controller in charge tower called to say ZOA directed me to perform published missed approach procedure. 1 hour 52 mins into flight, advised controller in charge tower that I intended to maintain circling minimums, fly a modified visual pattern and land on that same ILS runway (runway 13L). Tower asked if I was declaring an emergency. I answered in the affirmative. Factors bearing on this decision included: 1) uncertainty about alternator power situation. Now dark with low ceilings. 2) concern about extended missed approach procedures taking up to 30 mins. This would require switching fuel back to l-hand tank (uncertain about fuel remaining, based upon time of usage only -- fuel gauges worthless). 3) assurance that I had the destination runway in visual conditions and could land safely, thus eliminating all the problems above.

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Original NASA ASRS Text

Title: A BE33 PLT DECLARED AN EMER, THEREBY DECLINING A GAR DIRECTION BY ZOA WHILE ON THE ILS RWY 13L TO CIC.

Narrative: 35 MINS INTO FLT, 'ALTERNATOR FAIL' LIGHT ILLUMINATED. PLACED BACK ON BUSS SUCCESSFULLY BY CYCLING THE BATTERY SWITCH (THIS SIT HAD OCCURRED FREQUENTLY DURING THE OCTOBER-NOVEMBER TIME FRAME, BUT HAD BEEN SUCCESSFULLY REPAIRED BY RECONDITIONED ALTERNATOR AND NEW BATTERY SWITCHES, ETC). NO PROB FOR AT LEAST 6 WKS. PREVIOUSLY, 30 MINS INTO FLT, HAD CHANGED FROM L-HAND TO R-HAND FUEL TANK. 1 HR 5 MINS INTO FLT, ARRIVED ABEAM CIC. IMC, FROM BAKERSFIELD N IN THE VALLEY, ALL THE WAY TO REDDING FORECAST HAD BEEN 3000 FT SCATTERED FOR CIC. 1 HR 15 MINS INTO FLT, 'ALTERNATOR FAIL' LIGHT CAME ON. BATTERY SWITCH CYCLE SUCCESSFUL. (UNDER VECTORS BY ZOA TO INTERCEPT LOC ILS RWY 13L.) 1 HR 25 MINS INTO FLT, INITIATED MISSED APCH PROCS (HAD USED AUTOPLT NAV COUPLING PROCS WHILE INTERCEPTING LOC). IT SEEMED TO OVERREACT DURING THE 'CAPTURE' PHASE WITH EXCESSIVE TURN TO CTR THE LOC, THEN STRONG DSCNT ACTION TO CTR GLIDE PATH. I TOOK OVER MANUALLY BUT WAS RELUCTANT TO CONTINUE DSCNT WITH NEEDLES WELL OFF CTR. I HAD UTILIZED THE SYS TO LAND EARLIER SAME DAY AT CNO IN HAZY, NOT IMC CONDITIONS. 1 HR 35 MINS INTO FLT, 'ALTERNATOR FAIL' LIGHT CAME ON. BATTERY SWITCH CYCLE SUCCESSFUL. (UNDER VECTORS BY ZOA, NOW VECTOR GUIDANCE WENT OUTBOUND MORE THAN 20 MI DUE TO INTERCEPT SPACING (4TH IN PATTERN FOR ILS TO CIC). STILL IMC, I INTERCEPTED LOC WHILE FLYING MANUALLY. PLACED THE GEAR DOWN TO START DSCNT ON CTRED GS NEEDLE. SOON BECAME APPARENT THAT THE GS INDICATOR WAS NOT MOVING, BUT FROZEN IN THE CTR POS. ELECTED TO FOLLOW LOC, ONLY TO CIRCLING MINIMUMS (640 FT MSL). REACTION TO FOLLOWING THIS DECISION RESULTED IN BREAKING OUT OF OVCST AT APPROX 750 FT MSL, BUT ALREADY OVER RWY THRESHOLD. CIC TWR CALLED TO SAY ZOA DIRECTED ME TO PERFORM PUBLISHED MISSED APCH PROC. 1 HR 52 MINS INTO FLT, ADVISED CIC TWR THAT I INTENDED TO MAINTAIN CIRCLING MINIMUMS, FLY A MODIFIED VISUAL PATTERN AND LAND ON THAT SAME ILS RWY (RWY 13L). TWR ASKED IF I WAS DECLARING AN EMER. I ANSWERED IN THE AFFIRMATIVE. FACTORS BEARING ON THIS DECISION INCLUDED: 1) UNCERTAINTY ABOUT ALTERNATOR PWR SIT. NOW DARK WITH LOW CEILINGS. 2) CONCERN ABOUT EXTENDED MISSED APCH PROCS TAKING UP TO 30 MINS. THIS WOULD REQUIRE SWITCHING FUEL BACK TO L-HAND TANK (UNCERTAIN ABOUT FUEL REMAINING, BASED UPON TIME OF USAGE ONLY -- FUEL GAUGES WORTHLESS). 3) ASSURANCE THAT I HAD THE DEST RWY IN VISUAL CONDITIONS AND COULD LAND SAFELY, THUS ELIMINATING ALL THE PROBS ABOVE.

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.