NTSB Identification: LAX06FA031.
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Accident occurred Wednesday, November 09, 2005 in Geyserville, CA
Probable Cause Approval Date: 08/30/2007
Aircraft: Beech F33A, registration: N9204Q
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.

After visually identifying his home base airport on a night VFR approach, the pilot initiated a descent and the airplane struck the top of a ridgeline at the 2,834-foot level. The pilot was en route home from a trip between two airports that he made often. He had been receiving VFR flight following services from ARTCC and had cancelled when he reported the airport in sight. Recorded radar data showed the airplane descending from its cruise altitude in a straight line toward the airport and the accident site. Investigators identified two marks along the ridgeline that were similar in dimension to the distance between the main landing gear on the airplane. The airframe and engine examinations revealed no preimpact anomalies that would have precluded normal operation. Two drug substances were found in toxicological tests of the pilot's specimens, Diphenhydramine and Cetirizine. Diphenhydramine was found at a level that indicates usage within the past 8 hours of the accident flight. The Cetirizine that was found in the urine, but not the blood, and indicated that the pilot more than likely ingested the drug within the previous 48 hours, but not within the previous 12 hours of the accident. Diphenhydramine can result in drowsiness, and has measurable effects on performance of cognitive and motor tasks. Studies have shown that individuals' performance of tasks has been degraded even though they feel normal after ingesting the drug; however, in this case it is unclear the extent to which the pilot may have been sedated and/or impaired. Studies of individuals taking Cetirizine have not found any significant impairment from the medication.

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

the pilot's failure to maintain an adequate terrain clearance altitude profile during the descent that resulted in controlled flight into terrain.

Full narrative available

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