Aircraft Accident/Incident Report

Mammoth Lakes, California 93546
Monday, September 3, 2007 9:30 PDT

The pilot departed from a private airport at Flying M Ranch on a local personal flight, which ground personnel thought would last about 2.5 to 3 hours. When the airplane failed to return, it was reported missing and a search was started. No emergency locator transmitter (ELT) signal was received from the airplane. The Civil Air Patrol suspended its search activities after about 1 month. About 1 year later, a hiker found some of the pilot’s personal effects, and an aerial search located the airplane wreckage about 0.5 mile from the personal effects. The accident occurred in remote mountainous terrain at an elevation of 10,000 feet. After the wreckage was discovered, a review of radar data from September 3, 2007, revealed a track that ended about 1 mile northwest of the accident site. This 20-minute track showed the airplane flying south along the crest of a mountain range with elevations greater than 13,000 feet. During the search efforts, aircraft had flown over the accident location but did not see the wreckage. Additionally, the 20-minute track had been ruled out as the accident flight due to a witness report of seeing the airplane near Yerington at the time of the track. The witness reported the time of his sighting based on a telephone call with a friend. The search team initially used the time provided by the witness. Later, it was determined from the telephone company’s time log that the witness-reported time was off by 1 hour. Examination of the accident site revealed that the airplane was on a northerly heading at impact, indicating that the pilot had executed a 180-degree turn after radar contact was lost. Ground scars and distribution of the heavily fragmented wreckage indicated that the airplane was traveling at a high speed when it impacted in a right wing low, near level pitch attitude. A postimpact fire consumed the fuselage, with the exception of its steel frame. The wings were fragmented into numerous pieces. The ELT was destroyed. Damage signatures on the propeller blades and the engine crankshaft indicated that the engine was operating at impact. Examination of the airframe and engine revealed no evidence of any malfunctions or failures that would have prevented normal operation. Visual meteorological conditions existed in the accident area at the time of the accident. Mean winds at 10,000 feet were from 220 degrees at 15 to 20 knots; some gusts of 25 to 30 knots may have occurred. Moderate turbulence and downdrafts of at least 400 feet per minute probably occurred at the time and in the area of the accident. The magnitude of the downdrafts likely exceeded the climb capability of the airplane, which, at a density altitude of 13,000 feet, was about 300 feet per minute.

The pilot’s inadvertent encounter with downdrafts that exceeded the climb capability of the airplane. Contributing to the accident were the downdrafts, high density altitude, and mountainous terrain.