Aircraft Accident/Incident Report

Myton, Utah 84052
Thursday, November 6, 1997 19:04 MST

The pilot was on a return flight via the same route when the accident occurred. Recorded radar data revealed two transponder-equipped airplanes. The first target, the accident airplane, was tracked between 1902:51 and 1904:07, flying in a southeast-to-northwest direction at an encoded altitude of 12,600 feet mean sea level (msl). The second airplane, an unidentified aircraft squawking a transponder code of 1200, was tracked between 1907:00 and 1912:07, flying in a northwest-to-southeast direction at an encoded altitude of 13,600 feet msl. The unidentified airplane was estimated to have been 14 miles from the accident airplane at the time of the accident. At 1904, the accident airplane disappeared from the radarscope. No distress calls were received. Between 1906 and 1926, the controller tried to reestablish radio contact with the pilot, but to no avail. Search and rescue operations were initiated, and the wreckage was located the following afternoon. According to the metallurgist's factual report, the left wing, right horizontal stabilator, and vertical stabilizer spar fractures were 'consistent with overstress separations' and failed under 'negative loading.' There was no evidence of 'preexisting cracking such as fatigue or stress corrosion.' Dark night visual meteorological conditions prevailed at the time of the accident.

The pilot exceeded the design stress limits of the airplane which resulted in an in-flight airframe overload failure. A related factor was the dark night.