LAX02FA210 · Beech C35

During a nighttime cross-country flight in clear visual meteorological conditions, the airplane departed from controlled flight and broke up during a steep high speed descent. Wreckage was located over a 1,650-foot-long southerly path about 0.4 miles from the last recorded radar position, with the right wing and right stabalator found early in the debris field. The pilot had awakened at 0600 and reported for work at 0750, and he had flown five contract flights dispersing fire retardant chemical on wildfires for a total of 7.4 flight hours on the day of the accident. Upon completing his last flight about 1900, the pilot was overheard stating "we had a tough one today." He then laid his head down on the airplane's wing and said, "dang I'm tired." A second associate reported that the pilot had experienced difficulty completing the required end of day paperwork, making arithmetic errors during simple addition calculations. This associate thought the pilot was tired and "mentally exhausted." The pilot told this associate that he was going to spend the night in a local hotel, but instead he departed about 2022. The pilot requested and received VFR radar flight following service, and at no time did the pilot indicate he was experiencing any difficulties or request assistance. Following about an hour of cruise flight at 10,500 feet, during the last 19 seconds of radar-recorded flight, the airplane's average ground track changed from 241 degrees to 170 degrees, while its altitude increased from 10,900 to 11,000 feet. There were no further altitude readouts. The airplane broke apart in flight and impacted flat, desert terrain at an altitude of about 6,200 feet mean sea level. The right wing spar fractures were positive overload failures and evidence shows that it separated and impacted the right stabilizer, which also then separated.

Verbatim NTSB analysis and probable cause from the NTSB dataset