MOONEY M20J — Avalon, CA

What happened

The airplane was taking off from an airport on top of a mountain, at 1,602 feet mean sea level, on a runway surrounded on three sides by cliff-like precipitous drop-offs. Shortly after liftoff the airplane began to wobble and perform in an unstable manner, making contact again with the runway at about 2/3 of its length. The airplane then veered left off the runway, traveling through a gravel infield area in a nose-high attitude with the main landing gear still on the ground. The airplane continued through the gravel before veering back onto the runway surface just before the pavement ended and the terrain dropped away steeply at the departure end. The airplane descended into the valley and collided with downward sloping terrain. The airplane was destroyed by postimpact fire. The uphill slope of the first 2/3 of the runway made it appear much shorter than it actually was. No obvious preimpact anomalies were noted with the airframe. The engine intake valve cam lobes exhibited wear that could have resulted in a reduction of engine power, but this reduction would have occurred progressively over an extended period of time prior to the accident. It was unclear whether a reduction in engine power could have significantly affected the airplane's performance. The gross weight could not be determined with certainty; however, the airplane was loaded on the inbound trip with the same amount of passengers and baggage as the accident flight, and fueling facilities did not exist at the accident airport. The autopsy results were consistent with a cardiac event suffered by the pilot at some point around the time of the accident, but the pilot had not reported any symptoms and was actively controlling the aircraft and speaking with the surviving passenger during the accident sequence.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.