Narrative:

On aug/thu/99, I was scheduled to make a flight from fort lauderdale executive airport to tampa bay international airport in a piper aztec, registration number 123. I started the aircraft at about XA35 hours and taxied the aircraft to the runway and did a normal run-up. The aircraft ammeter showed that the electrical system was charging adequately. I departed ft lauderdale executive airport at about XA50 hours. The flight proceeded normally until about the time I reached bridge intersection southeast of tampa bay. As I approached bridge intersection I noticed that the interior lights were becoming dimmer and the display on my ADF was beginning to blink. I suspected that I had electrical problems and I checked the ammeter. The battery was showing a slight discharge and the ammeters were reading zero. I turned off all unnecessary electrical equipment and I advised the approach controller that I was having electrical problems and that it was possible that I might lose radio communication. The controller asked if I needed assistance. I told him that I did not need assistance at the time and I expected my battery power to last until I reached my destination. The ctrl gave me a direct vector to tampa international to save time. Shortly thereafter, both of my CDI's displayed navigation flags and I turned them off. On my last contact with ATC, the controller told me to switch to tower control frequency. I switched frequency and called the tower but could not understand the reply. Several mins later the radios went out completely. Having received no light gun signal from the control tower, and because I was in VFR conditions, I decided to discontinue my approach to tampa international. I instead decided to land at nearby vandenburg airport, an uncontrolled field. I landed without incident and advised flight service of my situation. Because of the electrical failure, I was forced to deviate from my IFR clearance.

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Original NASA ASRS Text

Title: A COMMERCIAL PLT FLYING A PIPER AZTEC TO TPA, WHO WAS EXPERIENCING ELECTRICAL PROBS, TURNED DOWN ASSISTANCE OFFERED FROM ATC AND ACTUALLY BELIEVED THAT HIS BATTERY WOULD LAST THE ADVERTISED 30 MINS. HE WENT LOST COM AFTER BEING TURNED OVER TO TPA TWR. THE RPTR BROKE OFF HIS APCH, AND LANDED AT X16, A NEARBY UNCTLED FIELD.

Narrative: ON AUG/THU/99, I WAS SCHEDULED TO MAKE A FLT FROM FORT LAUDERDALE EXECUTIVE ARPT TO TAMPA BAY INTL ARPT IN A PIPER AZTEC, REGISTRATION NUMBER 123. I STARTED THE ACFT AT ABOUT XA35 HRS AND TAXIED THE ACFT TO THE RWY AND DID A NORMAL RUN-UP. THE ACFT AMMETER SHOWED THAT THE ELECTRICAL SYS WAS CHARGING ADEQUATELY. I DEPARTED FT LAUDERDALE EXECUTIVE ARPT AT ABOUT XA50 HRS. THE FLT PROCEEDED NORMALLY UNTIL ABOUT THE TIME I REACHED BRIDGE INTXN SE OF TAMPA BAY. AS I APCHED BRIDGE INTXN I NOTICED THAT THE INTERIOR LIGHTS WERE BECOMING DIMMER AND THE DISPLAY ON MY ADF WAS BEGINNING TO BLINK. I SUSPECTED THAT I HAD ELECTRICAL PROBS AND I CHKED THE AMMETER. THE BATTERY WAS SHOWING A SLIGHT DISCHARGE AND THE AMMETERS WERE READING ZERO. I TURNED OFF ALL UNNECESSARY ELECTRICAL EQUIP AND I ADVISED THE APCH CTLR THAT I WAS HAVING ELECTRICAL PROBS AND THAT IT WAS POSSIBLE THAT I MIGHT LOSE RADIO COM. THE CTLR ASKED IF I NEEDED ASSISTANCE. I TOLD HIM THAT I DID NOT NEED ASSISTANCE AT THE TIME AND I EXPECTED MY BATTERY PWR TO LAST UNTIL I REACHED MY DEST. THE CTRL GAVE ME A DIRECT VECTOR TO TAMPA INTL TO SAVE TIME. SHORTLY THEREAFTER, BOTH OF MY CDI'S DISPLAYED NAV FLAGS AND I TURNED THEM OFF. ON MY LAST CONTACT WITH ATC, THE CTLR TOLD ME TO SWITCH TO TWR CTL FREQ. I SWITCHED FREQ AND CALLED THE TWR BUT COULD NOT UNDERSTAND THE REPLY. SEVERAL MINS LATER THE RADIOS WENT OUT COMPLETELY. HAVING RECEIVED NO LIGHT GUN SIGNAL FROM THE CTL TWR, AND BECAUSE I WAS IN VFR CONDITIONS, I DECIDED TO DISCONTINUE MY APCH TO TAMPA INTL. I INSTEAD DECIDED TO LAND AT NEARBY VANDENBURG ARPT, AN UNCTLED FIELD. I LANDED WITHOUT INCIDENT AND ADVISED FLT SVC OF MY SIT. BECAUSE OF THE ELECTRICAL FAILURE, I WAS FORCED TO DEVIATE FROM MY IFR CLRNC.

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.