Narrative:

As I approached the airport; I listened for ATIS and tried contacting tower. I could not contact the tower on one of the radios; but I was able to contact the tower on the second radio. Thinking back; that was probably the first sign of failing power; although I didn't think of it that way at the time. Tower told me to report right downwind for runway 32 which I acknowledged and proceeded to execute. As I was getting closer to the reporting point; the voices on the radio kept getting fainter. When I joined right downwind; I repeatedly tried to contact the tower but with no result on either radio. I squawked 'lost communication' and continued on downwind; trying to determine the radio issue and looking back for possible light gun signals. As I was closing in on the inner shoreline (still on right downwind); I noticed that all electrical lights were dim and the transponder light was not flashing. I recycled all electrical devices but the transponder never came back on and the radio displays came on for a second or two and quickly faded. At that time I decided that I was dealing with electrical failure and squawked 'emergency' realizing that the tower was probably unaware of my situation because of non-functioning transponder. I was almost at the inner shoreline when I decided to get on final and land thinking that being on a long final should give the tower enough warning time to move other planes around me. I noticed one plane on final and I waited for that plane to pass my right wing before turning base and final behind it. On final; I kept switching the transponder from 'emergency' to 'lost communication' and I kept trying to get at least 1 radio working; but with no results. I didn't notice any other planes near me on final until I got closer to the runway when I noticed a plane positioned for takeoff. I decided to watch that plane and I moved to the right edge of the runway. I was thinking that if that plane started rolling; I would land on the grass parallel to the runway on its r-hand side. The plane didn't move though because it was probably held by the tower. When I got far enough ahead of it to be sure that the other pilot saw me; I moved back over the runway centerline and landed. Because of lack of electrical power; my flaps didn't work (I tried using them) and the landing was longer than normal but safe. I turned the plane off the runway at taxiway C and stopped it just past the runway threshold. I immediately shut down the engine and cut off the fuel. After shutting down the engine; I could hear a fairly loud crackling noise coming from the bottom r-hand side of the engine compartment. That noise eventually faded away after about 10-15 seconds. I got out of the plane and waved at the tower pointing at the plane. I also called the owners of the plane to tell them what had happened and to ask for a tug. A few mins later; a ground vehicle arrived and I briefly explained the situation to the person in it. He contacted FBO to speed up the towing and eventually drove to FBO to escort the tug back to my plane. After the plane was put in the hangar; I called the control tower; who I believe was the shift supervisor at that time. I explained the situation and gave shift supervisor my contact information and my certificate number. She indicated that she would call me if there were any further questions. Because of all the events surrounding my landing; I never called to close my flight plan and flight service eventually called me as I was speaking with tower. I told them that I had an emergency landing but that I was safe on the ground and they could close my flight plan. The WX at the time was solid VMC with very good visibility and was not a factor at all. I also had about 3 hours of fuel left at the time of the incident. At the time of the incident; I understood from my ground training that in the event of an electrical failure; a pilot can only assume 30 mins of flight time and the plane should land as soon as possible. When I realized I had an electrical failure and I thought back about the symptoms; I estimated that I had been about 15-20 mins into those 30 mins; making an emergency landing justified in my mind. After researching the issue more; inow realize that I probably had much more engine time left and because of that I could have tried either circling the airport to get tower's attention or fly to an uncontrolled airport and land there. Second critical element was a lack of communication with the tower. If the tower knew about my situation; I'm sure they would have helped me land the plane much safer and I wouldn't be breaking any rules. Because of that; I will now always carry a backup handheld radio while flying.

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Original NASA ASRS Text

Title: LOW TIME PRIVATE PILOT OF C172 SUFFERS ELECTRICAL FAILURE IN PATTERN. CONTINUES TO A SAFE LANDING OVER AN AIRCRAFT AWAITING DEPARTURE ON THE RUNWAY.

Narrative: AS I APCHED THE ARPT; I LISTENED FOR ATIS AND TRIED CONTACTING TWR. I COULD NOT CONTACT THE TWR ON ONE OF THE RADIOS; BUT I WAS ABLE TO CONTACT THE TWR ON THE SECOND RADIO. THINKING BACK; THAT WAS PROBABLY THE FIRST SIGN OF FAILING PWR; ALTHOUGH I DIDN'T THINK OF IT THAT WAY AT THE TIME. TWR TOLD ME TO RPT R DOWNWIND FOR RWY 32 WHICH I ACKNOWLEDGED AND PROCEEDED TO EXECUTE. AS I WAS GETTING CLOSER TO THE RPTING POINT; THE VOICES ON THE RADIO KEPT GETTING FAINTER. WHEN I JOINED R DOWNWIND; I REPEATEDLY TRIED TO CONTACT THE TWR BUT WITH NO RESULT ON EITHER RADIO. I SQUAWKED 'LOST COM' AND CONTINUED ON DOWNWIND; TRYING TO DETERMINE THE RADIO ISSUE AND LOOKING BACK FOR POSSIBLE LIGHT GUN SIGNALS. AS I WAS CLOSING IN ON THE INNER SHORELINE (STILL ON R DOWNWIND); I NOTICED THAT ALL ELECTRICAL LIGHTS WERE DIM AND THE XPONDER LIGHT WAS NOT FLASHING. I RECYCLED ALL ELECTRICAL DEVICES BUT THE XPONDER NEVER CAME BACK ON AND THE RADIO DISPLAYS CAME ON FOR A SECOND OR TWO AND QUICKLY FADED. AT THAT TIME I DECIDED THAT I WAS DEALING WITH ELECTRICAL FAILURE AND SQUAWKED 'EMER' REALIZING THAT THE TWR WAS PROBABLY UNAWARE OF MY SITUATION BECAUSE OF NON-FUNCTIONING XPONDER. I WAS ALMOST AT THE INNER SHORELINE WHEN I DECIDED TO GET ON FINAL AND LAND THINKING THAT BEING ON A LONG FINAL SHOULD GIVE THE TWR ENOUGH WARNING TIME TO MOVE OTHER PLANES AROUND ME. I NOTICED ONE PLANE ON FINAL AND I WAITED FOR THAT PLANE TO PASS MY R WING BEFORE TURNING BASE AND FINAL BEHIND IT. ON FINAL; I KEPT SWITCHING THE XPONDER FROM 'EMER' TO 'LOST COM' AND I KEPT TRYING TO GET AT LEAST 1 RADIO WORKING; BUT WITH NO RESULTS. I DIDN'T NOTICE ANY OTHER PLANES NEAR ME ON FINAL UNTIL I GOT CLOSER TO THE RWY WHEN I NOTICED A PLANE POSITIONED FOR TKOF. I DECIDED TO WATCH THAT PLANE AND I MOVED TO THE R EDGE OF THE RWY. I WAS THINKING THAT IF THAT PLANE STARTED ROLLING; I WOULD LAND ON THE GRASS PARALLEL TO THE RWY ON ITS R-HAND SIDE. THE PLANE DIDN'T MOVE THOUGH BECAUSE IT WAS PROBABLY HELD BY THE TWR. WHEN I GOT FAR ENOUGH AHEAD OF IT TO BE SURE THAT THE OTHER PLT SAW ME; I MOVED BACK OVER THE RWY CTRLINE AND LANDED. BECAUSE OF LACK OF ELECTRICAL PWR; MY FLAPS DIDN'T WORK (I TRIED USING THEM) AND THE LNDG WAS LONGER THAN NORMAL BUT SAFE. I TURNED THE PLANE OFF THE RWY AT TXWY C AND STOPPED IT JUST PAST THE RWY THRESHOLD. I IMMEDIATELY SHUT DOWN THE ENG AND CUT OFF THE FUEL. AFTER SHUTTING DOWN THE ENG; I COULD HEAR A FAIRLY LOUD CRACKLING NOISE COMING FROM THE BOTTOM R-HAND SIDE OF THE ENG COMPARTMENT. THAT NOISE EVENTUALLY FADED AWAY AFTER ABOUT 10-15 SECONDS. I GOT OUT OF THE PLANE AND WAVED AT THE TWR POINTING AT THE PLANE. I ALSO CALLED THE OWNERS OF THE PLANE TO TELL THEM WHAT HAD HAPPENED AND TO ASK FOR A TUG. A FEW MINS LATER; A GND VEHICLE ARRIVED AND I BRIEFLY EXPLAINED THE SITUATION TO THE PERSON IN IT. HE CONTACTED FBO TO SPEED UP THE TOWING AND EVENTUALLY DROVE TO FBO TO ESCORT THE TUG BACK TO MY PLANE. AFTER THE PLANE WAS PUT IN THE HANGAR; I CALLED THE CTL TWR; WHO I BELIEVE WAS THE SHIFT SUPVR AT THAT TIME. I EXPLAINED THE SITUATION AND GAVE SHIFT SUPVR MY CONTACT INFO AND MY CERTIFICATE NUMBER. SHE INDICATED THAT SHE WOULD CALL ME IF THERE WERE ANY FURTHER QUESTIONS. BECAUSE OF ALL THE EVENTS SURROUNDING MY LNDG; I NEVER CALLED TO CLOSE MY FLT PLAN AND FLT SVC EVENTUALLY CALLED ME AS I WAS SPEAKING WITH TWR. I TOLD THEM THAT I HAD AN EMER LNDG BUT THAT I WAS SAFE ON THE GND AND THEY COULD CLOSE MY FLT PLAN. THE WX AT THE TIME WAS SOLID VMC WITH VERY GOOD VISIBILITY AND WAS NOT A FACTOR AT ALL. I ALSO HAD ABOUT 3 HRS OF FUEL LEFT AT THE TIME OF THE INCIDENT. AT THE TIME OF THE INCIDENT; I UNDERSTOOD FROM MY GND TRAINING THAT IN THE EVENT OF AN ELECTRICAL FAILURE; A PLT CAN ONLY ASSUME 30 MINS OF FLT TIME AND THE PLANE SHOULD LAND ASAP. WHEN I REALIZED I HAD AN ELECTRICAL FAILURE AND I THOUGHT BACK ABOUT THE SYMPTOMS; I ESTIMATED THAT I HAD BEEN ABOUT 15-20 MINS INTO THOSE 30 MINS; MAKING AN EMER LNDG JUSTIFIED IN MY MIND. AFTER RESEARCHING THE ISSUE MORE; INOW REALIZE THAT I PROBABLY HAD MUCH MORE ENG TIME LEFT AND BECAUSE OF THAT I COULD HAVE TRIED EITHER CIRCLING THE ARPT TO GET TWR'S ATTN OR FLY TO AN UNCONTROLLED ARPT AND LAND THERE. SECOND CRITICAL ELEMENT WAS A LACK OF COM WITH THE TWR. IF THE TWR KNEW ABOUT MY SITUATION; I'M SURE THEY WOULD HAVE HELPED ME LAND THE PLANE MUCH SAFER AND I WOULDN'T BE BREAKING ANY RULES. BECAUSE OF THAT; I WILL NOW ALWAYS CARRY A BACKUP HANDHELD RADIO WHILE FLYING.

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.