Traffic watch aircraft has electrical problem. Lost communication.

Attributes
ACN	252500
Time
Date	199309
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : oak
State Reference	CA
Altitude	msl bound lower : 2000 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	other
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : cfi pilot : commercial
Experience	flight time last 90 days : 34 flight time total : 400 flight time type : 30
ASRS Report	252500
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

When I was on a traffic watch flight circling above toll plaza bay bridge at 2000 ft MSL, I lost my electrical power. The last thing I heard was the ATC announcing that he lost my transponder. When I tried to respond the radio totally died. At this point, I looked at the ammeter and saw that the needle was just a little bit off to the negative side. I touched the low voltage and it illuminates. During this time I decided to leave the class C airspace to the northeast because of lost radio communications with the ATC. While leaving the class C airspace I started to trouble-shoot. I turned off all electrical equipment and recycled the master switch. The ammeter showed a strong positive load and the low voltage light goes off. To be on the safe side I decided to fly back to hayward airport and land. I turned on the radios just outside the class D airspace and picked up the ATIS and talked with the tower and landed. What I missed on my runup was to recycle the alternator switch and to check the ammeter properly. So by following the checklist and not letting any private problems interfere with the flying, a problem like this should not occur again.

Original NASA ASRS Text

Title: TFC WATCH ACFT HAS ELECTRICAL PROB. LOST COM.

Narrative: WHEN I WAS ON A TFC WATCH FLT CIRCLING ABOVE TOLL PLAZA BAY BRIDGE AT 2000 FT MSL, I LOST MY ELECTRICAL PWR. THE LAST THING I HEARD WAS THE ATC ANNOUNCING THAT HE LOST MY XPONDER. WHEN I TRIED TO RESPOND THE RADIO TOTALLY DIED. AT THIS POINT, I LOOKED AT THE AMMETER AND SAW THAT THE NEEDLE WAS JUST A LITTLE BIT OFF TO THE NEGATIVE SIDE. I TOUCHED THE LOW VOLTAGE AND IT ILLUMINATES. DURING THIS TIME I DECIDED TO LEAVE THE CLASS C AIRSPACE TO THE NE BECAUSE OF LOST RADIO COMS WITH THE ATC. WHILE LEAVING THE CLASS C AIRSPACE I STARTED TO TROUBLE-SHOOT. I TURNED OFF ALL ELECTRICAL EQUIP AND RECYCLED THE MASTER SWITCH. THE AMMETER SHOWED A STRONG POSITIVE LOAD AND THE LOW VOLTAGE LIGHT GOES OFF. TO BE ON THE SAFE SIDE I DECIDED TO FLY BACK TO HAYWARD ARPT AND LAND. I TURNED ON THE RADIOS JUST OUTSIDE THE CLASS D AIRSPACE AND PICKED UP THE ATIS AND TALKED WITH THE TWR AND LANDED. WHAT I MISSED ON MY RUNUP WAS TO RECYCLE THE ALTERNATOR SWITCH AND TO CHK THE AMMETER PROPERLY. SO BY FOLLOWING THE CHKLIST AND NOT LETTING ANY PRIVATE PROBS INTERFERE WITH THE FLYING, A PROB LIKE THIS SHOULD NOT OCCUR AGAIN.

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.