Narrative:

I was en route from ZZZ1 to ZZZ2 when an unexpected alternator failure forced me to abort my flight. The ammeter did not register any drain on the battery and the garmin 430 was the first to lose power; shortly followed by the communication radios; transponder; then all other electrical equipment. Shortly after the garmin 430 failure; I squawked emergency 7700 as I had lost radio communication. The WX was mixed VMC and IMC as I found a break in the clouds and descended below the cloud layer. It was getting darker and I decided to look for a nearby airport by looking for the familiar green/white beacon. Using my sectional; I recognized some landmark features and decided that an airport was to the south and headed in that direction and ultimately landed safely at ZZZ3.

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Original NASA ASRS Text

Title: C172 PLT ON IFR FLT SUFFERS AN ALTERNATOR FAILURE AND LOSS OF ALL ELECTRICAL EQUIPMENT INCLUDING COM AND NAV CAPABILITY. INTERMITTENT VMC CONDITIONS ALLOW SAFE DIVERSION TO A NEARBY ARPT.

Narrative: I WAS ENRTE FROM ZZZ1 TO ZZZ2 WHEN AN UNEXPECTED ALTERNATOR FAILURE FORCED ME TO ABORT MY FLT. THE AMMETER DID NOT REGISTER ANY DRAIN ON THE BATTERY AND THE GARMIN 430 WAS THE FIRST TO LOSE PWR; SHORTLY FOLLOWED BY THE COM RADIOS; XPONDER; THEN ALL OTHER ELECTRICAL EQUIP. SHORTLY AFTER THE GARMIN 430 FAILURE; I SQUAWKED EMER 7700 AS I HAD LOST RADIO COM. THE WX WAS MIXED VMC AND IMC AS I FOUND A BREAK IN THE CLOUDS AND DSNDED BELOW THE CLOUD LAYER. IT WAS GETTING DARKER AND I DECIDED TO LOOK FOR A NEARBY ARPT BY LOOKING FOR THE FAMILIAR GREEN/WHITE BEACON. USING MY SECTIONAL; I RECOGNIZED SOME LANDMARK FEATURES AND DECIDED THAT AN ARPT WAS TO THE S AND HEADED IN THAT DIRECTION AND ULTIMATELY LANDED SAFELY AT ZZZ3.

Data retrieved from NASA's ASRS site as of May 2009 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.