NTSB Identification: LAX98FA306.
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Accident occurred Saturday, September 26, 1998 in HAWTHORNE, NV
Probable Cause Approval Date: 04/20/2000
Aircraft: Beech 95-B55, registration: N554MB
Injuries: 1 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot called the flight service station and obtained a weather briefing prior to the flight. He was told several times that VFR flight was not recommended due in part to IFR conditions along a portion of his route, mountain obscurment along the entire route, and moderate rime and mixed icing along the route between 8,000 and 18,000 feet. Additionally, he was told there were thunderstorms over the Sierra Nevada Mountains, Southern California, and throughout Utah and Nevada. The pilot picked up an IFR clearance moments before he told controllers that he had a "system's failure." The controller asked him what type of system's problem he had and he told the controller that he had lost control of the aircraft and was descending at 2,000 feet per minute. Ground units that were launched to locate the missing aircraft were hampered by inclimate weather, and an H-60 military helicopter that was conducting an airborne search entered clouds and crashed not far from the site of the downed aircraft. Teardown reports on both engines concluded that there were no mechanical malfunctions noted that would have caused an operational problem. The left propeller was found feathered prior to impact, with no preimpact discrepancies noted on either propeller that would have precluded normal operation. The right propeller had indications of rotation and power development on impact. The airplane was not equipped for flight into icing conditions and did not have any propeller or wing deicing boots. Analysis of meteorological data showed that the aircraft entered the clouds where significant light to moderate clear/mixed airframe icing was present, and, encountered a convective cell in the minutes prior to the accident.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's disregard of the weather briefing information and his decision to attempt flight into forecast adverse weather conditions, which led to an encounter with icing conditions beyond the performance capability of the aircraft. The pilot's disregard for the pilot operating handbook prohibition against flight into icing conditions is also causal.

Full narrative available

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