Instructor with spi had electrical failure. Continues with green light and lands.

Attributes
ACN	230148
Time
Date	199212
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : tol
State Reference	OH
Altitude	msl bound lower : 1500 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tol
Make Model Name	Small Aircraft
Flight Phase	descent : approach
Flight Plan	None
Person 1
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : cfi pilot : instrument pilot : commercial
Experience	flight time last 90 days : 100 flight time total : 700 flight time type : 7
ASRS Report	230148
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : student
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : unable none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Departed tol arsa no difficulties. Student's first lesson. Demonstrated and had student perform 4 fundamentals. Upon completion, headed back to tol for landing. Could not raise tol approach/departure on radio on way back. Continued in because we never switched from departure/approach control, and believed they had us on radar, if they were not receiving our xmissions. Approached tol from the north (in northwest practice area). Received steady green light from tower and made right traffic (normal traffic) and landed on runway 25. Taxied off, received flashing green and proceeded to parking. After shutdown and securing aircraft, talked on telephone to tower controller. Was told they lost us on radar and were getting ready to send a crew out to look for us. Received a call on the morning of the 28TH from mr. X, FAA cle. He told me it would be written up as an occurrence. As it turned out, the alternator was bad and the warning light was not bright enough to be seen during the day. We had used up the battery and lost all electrical power. We are working on the warning light problem.

Original NASA ASRS Text

Title: INSTRUCTOR WITH SPI HAD ELECTRICAL FAILURE. CONTINUES WITH GREEN LIGHT AND LANDS.

Narrative: DEPARTED TOL ARSA NO DIFFICULTIES. STUDENT'S FIRST LESSON. DEMONSTRATED AND HAD STUDENT PERFORM 4 FUNDAMENTALS. UPON COMPLETION, HEADED BACK TO TOL FOR LNDG. COULD NOT RAISE TOL APCH/DEP ON RADIO ON WAY BACK. CONTINUED IN BECAUSE WE NEVER SWITCHED FROM DEP/APCH CTL, AND BELIEVED THEY HAD US ON RADAR, IF THEY WERE NOT RECEIVING OUR XMISSIONS. APCHED TOL FROM THE N (IN NW PRACTICE AREA). RECEIVED STEADY GREEN LIGHT FROM TWR AND MADE R TFC (NORMAL TFC) AND LANDED ON RWY 25. TAXIED OFF, RECEIVED FLASHING GREEN AND PROCEEDED TO PARKING. AFTER SHUTDOWN AND SECURING ACFT, TALKED ON TELEPHONE TO TWR CTLR. WAS TOLD THEY LOST US ON RADAR AND WERE GETTING READY TO SEND A CREW OUT TO LOOK FOR US. RECEIVED A CALL ON THE MORNING OF THE 28TH FROM MR. X, FAA CLE. HE TOLD ME IT WOULD BE WRITTEN UP AS AN OCCURRENCE. AS IT TURNED OUT, THE ALTERNATOR WAS BAD AND THE WARNING LIGHT WAS NOT BRIGHT ENOUGH TO BE SEEN DURING THE DAY. WE HAD USED UP THE BATTERY AND LOST ALL ELECTRICAL PWR. WE ARE WORKING ON THE WARNING LIGHT PROB.

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.