Narrative:

While en route (VFR) to ack at 3;000 ft; I noticed a discharge in the electrical system. I had the strobe lights; navigation lights and the beacon light on due to hazy conditions and because of traffic in the area. Cape approach lost my mode C transmission which has happened before due to weak signal around the cape area which did not alarm me. Within a minute or so they also lost all radar contact; and then I lost all instrument panel power; which got my attention. I could receive transmissions from cape approach but could not transmit; I squawked 7600 hoping they received it. I also turned off all electrical equipment not needed; keeping one radio on hoping that there was enough power remaining to transmit. I was not able to reestablish communications; and also lost the ability to receive transmissions from cape approach. By this time I was out over the water about 20 miles from ack. I continued my flight without electrical power and headed to the north east side of the island which is about ten miles from the airport and the lowest area of aircraft traffic. At this point I used my cell phone to call the airport tower to explain the problem I was having; and got clearance to land runway 24. No other traffic was affected at the time due to low traffic in the area and I ended the call once I was on final. [I] landed without any incident cleared the runway and called the tower back to get taxi instructions. I am unsure as to why the aircraft lost electrical power as the aircraft started without any issues and had a normal run up. The aircraft will be sent in for maintenance.

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Original NASA ASRS Text

Title: A C172 lost power at 3;000 FT on a VFR flight to ACK. Cell phone contact with the Tower was established and a clearance to land received.

Narrative: While en route (VFR) to ACK at 3;000 FT; I noticed a discharge in the electrical system. I had the strobe lights; navigation lights and the beacon light on due to hazy conditions and because of traffic in the area. Cape Approach lost my Mode C transmission which has happened before due to weak signal around the Cape area which did not alarm me. Within a minute or so they also lost all radar contact; and then I lost all instrument panel power; which got my attention. I could receive transmissions from Cape Approach but could not transmit; I squawked 7600 hoping they received it. I also turned off all electrical equipment not needed; keeping one radio on hoping that there was enough power remaining to transmit. I was not able to reestablish communications; and also lost the ability to receive transmissions from Cape Approach. By this time I was out over the water about 20 miles from ACK. I continued my flight without electrical power and headed to the north east side of the island which is about ten miles from the airport and the lowest area of aircraft traffic. At this point I used my cell phone to call the airport Tower to explain the problem I was having; and got clearance to land Runway 24. No other traffic was affected at the time due to low traffic in the area and I ended the call once I was on final. [I] landed without any incident cleared the runway and called the Tower back to get taxi instructions. I am unsure as to why the aircraft lost electrical power as the aircraft started without any issues and had a normal run up. The aircraft will be sent in for maintenance.

Data retrieved from NASA's ASRS site as of July 2013 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.