NTSB Identification: IAD99FA038.
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Accident occurred Monday, April 12, 1999 in SHAWSVILLE, VA
Probable Cause Approval Date: 05/08/2001
Aircraft: Beech BE-95A, registration: N3113K
Injuries: 4 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 was briefed on two occasions by a flight service briefer and was advised of a SIGMET for moderate to severe turbulence for the departure airport area and along the airplane's proposed route of flight. The pilot acknowledged receipt of a Hazardous In-flight Alert System (HIWAS) alert for moderate to occasional severe turbulence just prior to takeoff. After departure, the tower controller stopped the airplane's climb at 6,000 feet for traffic, then told the pilot to continue the climb to 8,000 feet. The controller had received Pilot Reports (PIREPs) about turbulence and asked the pilot what he was experiencing. The controller did not receive a response, and the airplane disappeared from the radarscope after reaching an altitude of 6,700 feet. Post accident interviews with other pilots revealed they experienced severe turbulence during the same time frame in the vicinity of the accident. Computer analysis of weather data indicated a 100% probability of severe turbulence at 6,000 feet, and at 7,000 feet, vertical motions of 3,153 feet per minute indicated a severe mountain wave. A PIREP placed the base of the cloud layer at 5,400 feet and the tops at 9,500 feet. The airplane's published maximum gross weight was 4,200 pounds, with a center-of-gravity (CG) range of 80.5 inches to 86 inches aft of datum. The airplane's calculated weight at the time of the accident was 4,566 pounds, with the center of gravity calculated at 90.68 inches aft of datum.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot's inadequate preflight planning which resulted in intentional flight into known severe turbulence and the subsequent loss of control. Factors in the accident were the turbulence in instrument meteorological conditions and an airplane loaded over the maximum allowable gross weight and outside the allowable center-of-gravity range. Full narrative available
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