WPR15FA140

The pilot's failure to maintain control of the airplane while maneuvering, which resulted in an uncontrolled descent and structural failure. Contributing to the accident was the pilot's impairment from his use of diphenhydramine.

The student pilot was conducting a local area flight in daytime visual meteorological conditions. Multiple witnesses located near the accident site reported observing the airplane maneuvering over the area. Two witnesses reported seeing the airplane in a steep descent with the wings folded upward before it impacted the ground. Postaccident examination of the accident site and the airplane revealed signatures consistent with a high-speed, near-vertical impact with terrain. No evidence was found of any preexisting mechanical anomalies that would have precluded normal operation of the airplane. It's likely that while maneuvering, the pilot lost control of the airplane, which resulted in a steep descent from which the pilot did not recover. During the vertical descent, the airplane's structural capabilities were exceeded, and the wing spars failed in overstress. The pilot had applied for a medical certificate in 2003 and 2004: however, he did not provide all the information requested by the Federal Aviation Administration (FAA), and his application was denied. Review of FAA medical records revealed that the pilot had a history of a traumatic brain injury; however, based on a review of the information that the pilot provided in 2004, it is unlikely that the long term effects from the pilot's traumatic brain injury contributed to the accident. Postaccident toxicology testing identified tetrahydrocannabinol (THC), the psychoactive component in marijuana, in the pilot's blood and various tissues, and diphenhydramine, an over-the-counter allergy and sleep aid medication, in the pilot's blood The levels of THC found in tissues suggested that it was not used recently. Therefore, it is unlikely that the pilot's use of marijuana caused impairment or contributed to the accident. However, the level of diphenhydramine found suggested that, at the time of the accident, the pilot was likely impaired by his use of diphenhydramine.

Portions of the left and right wing spars were sent to the NTSB Materials Laboratory for further examination. A senior metallurgist examined the spars, and reported that the right spar exhibited a separation about 53 inches from the inboard end. The deformation pattern of the spar tubes at and adjacent to the separation were consistent with bending deformation. Optical examination of the fracture at the separation revealed features consistent with overstress separations following approximately 45 degrees of deformation. No indications of preexisting cracking or corrosion were apparent. The left wing spar was fractured about 96 inches from the inboard end. The fracture and adjacent deformation were consistent with a tension bending separation. No indications of preexisting cracking or corrosion were apparent. An autopsy performed at the request of the Sonoma County Coroner's Office by Forensic Medical Group determined the cause of death was multiple extreme blunt force injuries due to a light plane crash, and the manner of death was an accident. No significant natural disease was identified, however, the examination of the brain was limited by the extent of injury. In a note regarding the death investigation, the investigator reported they had interviewed the pilot's ex-wife who believed the decedent changed his name due to the fact he really wanted to fly, and could not due to a traumatic brain injury he received, which would exclude him from getting a pilot's license. The investigator also noted that the pilot was receiving supplemental security income disability benefits under the social security number and the different name than what the airplane and student pilot certificate were issued under. Toxicology testing performed by NMS Laboratories at the request of the Coroner identified tetrahydrocannabinol (THC, the psychoactive component in marijuana) at 3.3 ng/ml in cavity blood. Levels of the primary metabolite, tetrahydrocannabinol carboxylic acid (THC-COOH) were less than 5.0 ng/ml. Toxicology testing performed by the FAA's Bioaeronautical Research Laboratory identified diphenhydramine, tetrahydrocannabinol (THC), and tetrahydrocannabinol carboxylic acid (THC-COOH; 0.0873 ug/g) in liver. In addition, diphenhydramine (0.634 ug/ml), THC (level below 1 ng/ml), and THC-COOH (0.004 ug/ml; 4 ng/ml) were identified in cavity blood. THC (level below 1 ng/g) and THC-COOH (0.0059 ug/g; 5.9 ng/g) were identified in the lung. Diphenhydramine is a sedating antihistamine used to treat allergy symptoms and as a sleep aid. It is available over the counter under the trade names Benadryl and Unisom. Diphenhydramine carries the following FDA warning: may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery). Compared to other antihistamines, diphenhydramine causes marked sedation; this is the rationale for its use as a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed. In fact, in a driving simulator study, a single dose of diphenhydramine impaired driving ability more than a blood alcohol concentration of 0.100%. The therapeutic range for diphenhydramine is 0.0250 to 0.1120 ug/ml. Diphenhydramine undergoes post mortem redistribution where after death, the drug can leech from storage sites back into blood. Central post mortem levels may be about two to three times higher than peripheral levels. Although now available for medicinal use in some states and has been decriminalized in limited amounts in others, marijuana continues to be labeled as a Schedule 1 Controlled Substance by the Drug Enforcement Administration. It has mood altering effects including inducing euphoria and relaxation. In addition, marijuana causes alterations in motor behavior, perception, cognition, memory, learning, endocrine function, food intake, and regulation of body temperature. Specific performance effects include decreased ability to concentrate and maintain attention, impairment of hand-eye coordination, and is dose-related over a wide range of dosages. Impairment in retention time and tracking, subjective sleepiness, distortion of time and distance, vigilance, and loss of coordination in divided attention tasks have been reported. Interpreting post mortem blood and tissue results for marijuana is complex for several reasons. First, the drug is lipophilic, and gets stored in fatty tissues; it undergoes post mortem redistribution, and may leech back into blood from liver, lung, and brain after death. Thus, post mortem testing may not indicate ante-mortem levels. Marijuana has been demonstrated to have clinical effects at levels as low as 0.001 ug/ml. While significant performance impairments are usually observed for at least 1-2 hours following marijuana use, and residual effects have been reported up to 24 hours, even when the blood level is undetectable. Examination of the accident site revealed that the airplane impacted an open field adjacent to a tree line about 1.3 miles southeast of runway 29. The airplane came to rest in a near vertical position. All major structural components were present at the accident site. Debris, including the engine and one propeller blade, were located within about 15 feet of the main wreckage. The left wing remained partially attached to the airframe via both the flying wires and landing wires, however, it was separated at the forward spar attach point. The forward spar was separated about mid span. The fracture surface was consistent with overload and impact damage. In addition, all of the internal braces for the left wing were separated. One of the internal brace wires was found separated, and exhibited splayed signatures, consistent with overload. The wing covering was mostly intact, but torn in various areas. No scuffing or transfer marks were observed on either the top or bottom side of the wing. The left aileron remained attached to its respective mounts. The right wing remained attached to the airframe via the forward spar mounts and all of the flying and landing wires. The forward spar was bent and twisted in numerous areas, consistent with impact. In addition, all of internal braces for the right wing were separated. The wing covering was mostly intact and turn in various areas. No scuffing or transfer marks were observed on either the top or bottom side of the wing. The right aileron remained attached via its respective mounts. The empennage remained intact and undamaged. The horizontal and vertical stabilizers remained attached to their respective mounts. The rudder and elevators remained attached to their respective mounts. Flight control continuity was established from all primary flight controls to the cockpit controls. The airframe was mostly impact damaged. The instrument panel was separated with numerous instruments dislodged. The right side flying wires remained attached to the seat structure; however, the left side flying cables were separated by first responders. The airframe was equipped with a ballistic parachute system. The parachute was found dislodged from one half of the parachute case; however, it was extended about 15 feet from the main wreckage. The envelope of the parachute remained stowed within the opposing half of the case. The engine was separated from the airframe, and located about 15 feet from the main wreckage. The carburetors and the propeller gearbox were separated from the engine. The propeller hub and one of the two propeller blades remained attached to the propeller gearbox and located within the main wreckage. The separated propeller blade was found about 10 feet from the main wreckage. The separated propeller blade exhibited a nick in the leading edge near the blade tip. The nick was found consistent with the size of a landing wire utilized on the airplane. Both the left and right carburetors were separated. When the float bowls w