What happened
On June 22, 2008, a Cessna 182 S, registration HB-CQP, was conducting a night flight between Cannes-Mandelieu and Bastia-Poretta. While cruising at flight level 95 over the sea, the pilot observed a "LOW VOLTAGE" warning light. Believing a short circuit was occurring, the pilot proactively disconnected most electrical systems to preserve the battery charge.
As the aircraft approached the NORKA waypoint, the aircraft suffered a total electrical failure. To maintain navigation, the pilot relied on a portable GPS unit and used a flashlight to read the magnetic compass. Because the nearby Calvi aerodrome was closed, the pilot continued toward Bastia-Poretta. During the approach, the pilot attempted to contact the tower via radio on several occasions, but received no response. After performing several 360-degree turns near the NA waypoint to ensure the area was clear, the pilot landed the aircraft at Bastia-Poretta and proceeded to the parking area to notify personnel of the arrival.
The investigation
The investigation focused on the cause of the electrical failure and the pilot's response to the initial warning. Investigators found that the alternator circuit breaker had tripped during the flight, an event the pilot did not notice. The specific cause of the breaker tripping could not be determined.
Furthermore, the investigation noted that the aircraft's flight manual was stored in a pouch in the rear of the cabin, making it inaccessible to the pilot during the emergency. The manual's troubleshooting procedures for such an event included instructions to turn the avionics master switch off, verify the alternator field circuit breaker status, and then cycle the master switch.