ERA19LA263

The agricultural pilot was initiating an aerial application flight over a cotton field. On the first pass, in controlled flight, he approached the field in a westerly direction and struck power lines, a large tree, then crashed onto a corn field. The pilot was killed, a postcrash fire ensued, and the airplane was destroyed. An examination of the wreckage did not reveal evidence of a preexisting mechanical anomaly or malfunction. Agricultural pilots routinely perform risky low-altitude maneuvers, and interactions with powerlines are not uncommon; these lines are difficult to see and avoid at the speeds of these flights. The pilot's traumatic injuries would not have been immediately fatal, but he had no evidence of breathing during the postcrash fire (no soot and no carboxyhemoglobin). As a result, the medical examiner placed the primary cause of death as hypertensive cardiac disease. This disorder increases the risk of a cardiac arrhythmia, which can cause palpitations, shortness of breath, or fainting. Such an event would not be expected to leave any evidence at autopsy. However, the operational evidence points to controlled flight into the power lines rather than loss of control as might be expected with an acute cardiac event. In addition, given the thermal injuries sustained, whether or how much the pilot's heart disease contributed to this accident could not be determined from the available evidence although it likely contributed to his immediate death. Additional medical findings included the pilot's monocular vision, obstructive sleep apnea, and prior use of cannabis in the hours or days preceding the accident. Although the pilot’s monocular vision could have made it even more difficult for him to see and avoid the powerlines, he had thousands of hours safely flying agricultural operations; therefore, it is unlikely his visual defect contributed to this accident. Concerning the pilot’s treated obstructive sleep apnea, all evidence he provided to the Federal aviation Administration demonstrated excellent compliance with his treatment regimen. Therefore, it is unlikely the pilot’s treated sleep apnea contributed to the accident. Finally, the absence of any psychoactive component or active metabolite of cannabis in the pilot’s blood with a reporting cut off of 1 ng/ml suggests his use was many hours before the accident and that it is unlikely he was impaired by the effects of the drug at the time of the accident.

The aircraft maintenance records were not located during the investigation. On September 2, 2019, about 0922 central daylight time, a Weatherly Aviation Company 620B, N90104, was destroyed when it was involved in an accident near Russellville, Alabama. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The local flight originated from a private, grass airstrip about 0915. According to the Federal Aviation Administration (FAA) inspector who responded to the accident site, the pilot was applying insecticide and plant regulator to a cotton field. The orientation of the field was east to west. During the first pass of the flight, the airplane overflew a road and collided with power lines, breaking two of the four wires. The airplane then struck the top of a tree, breaking several limbs. The airplane then collided with the ground and caught fire. There were no known eyewitnesses. The pilot reported monocular vision with use of a prosthesis for his right eye to the FAA and obtained a statement of demonstrated ability (SODA) in 2005 for monocular vision. In addition, he had reported having obstructive sleep apnea with the use of a continuous positive airway pressure (CPAP) device to the FAA. At his last FAA medical exam, he provided a report from July 2019 that demonstrated 99.7% usage of his CPAP device during the preceding 378 days with an average of 9 hours and 12 minutes of sleep per night. His average Apnea Hypopnea Index (AHI) was 2.1 with use of the device. According to the autopsy performed by Alabama Department of Forensic Sciences, the cause of death was hypertensive cardiovascular disease complicated by blunt force trauma and the manner of death was accident. Although there was a significant post impact fire, there was no soot in the airways. The pathologist remarked the heart weighed 640 grams with the left ventricular wall and interventricular septum each at 1.8 centimeters in thickness and the right ventricular free wall at 0.6 centimeters in thickness. Average heart weight for a man of his weight is 460 gm with a range from 346 to 602 gm; average wall thickness is 1.3 cm for the left wall and septum and 0.3 cm for the right ventricular wall. In addition, there was a single area of stenosis of about 50% in the left anterior descending coronary artery. The visual inspection of the heart was otherwise unremarkable; no microscopic evaluation was performed. Toxicology testing performed by the FAA's Forensic Sciences Laboratory identified Carboxy-Delta-9-tetrahydrocannabinal (THC-COOH) at 11.1 ng/mL in cardiac blood and at 66.1 ng/mL in urine. THC-COOH is an inactive metabolite of tetrahydrocannabinol (THC), the primary psychoactive component in marijuana. However, none of the parent compound was identified. An active metabolite, 11-Hydroxy-Delta-9-THC was found in urine at 4.6 ng/mL but was not detected in blood. No significant carboxyhemoglobin was reported(reporting cutoff is 10%). Personal medical records from the pilot's primary care provider for the 3 years preceding the accident contained only a telephone consult for a referral to his sleep center. The pilot’s logbook was not located during the investigation. Flight times were derived from his latest FAA second class physical application, dated January 17, 2019. The airplane was traveling in a westerly direction when the first point of impact occurred with power lines. The total length of the wreckage path was about 500 ft. The right wing tip was located immediately south of the broken power lines. After the initial impact with the ground, the main wreckage continued for about 40-50 ft before coming to a stop. Several unidentified sections of the airframe were lodged about 20 to 30 ft up a tree. The fuselage, from the engine to the empennage, was consumed by the postaccident fire. Flight control continuity was confirmed from the cockpit controls to the ailerons, rudder, and elevator. The engine sustained extensive fire damage. No evidence of engine case rupture was observed. One of the three propeller blades separated during the ground impact and was found adjacent to the wreckage. All propeller blades exhibited twisting signatures and chordwise scratching. The examination of the wreckage did not reveal evidence of a mechanical malfunction or failure.