CEN16LA260 · Air Tractor Inc AT-602

The pilot was performing an aerial application flight to a field that was intersected by powerlines. There were no witnesses to the accident, but the wreckage path consisted of broken power lines consistent with an in-flight collision. In addition, the ground scarring was consistent with the airplane operating at a normal speed before the collision, followed by an uncontrolled descent. Examination revealed no mechanical anomalies that would have precluded normal operation.

The 48-year-old pilot had reported multiple orthopedic surgeries and use of medication for high cholesterol to the FAA. At the time of his last aviation medical examination, he was diagnosed with diabetes and began treatment with metformin. The aviation medical examiner (AME) who performed the examination questioned the pilot's records from a recent hospitalization that stated the pilot had anxiety/depression. The pilot told the AME this was not a current diagnosis and that he had not been on medication for these conditions in years.

Toxicology testing identified acetaminophen, an over-the-counter analgesic; chlorpheniramine, a sedating antihistamine available over-the-counter in many cold, cough, and allergy preparations; citalopram, a prescription antidepressant medication; and dextromethorphan, an over-the-counter cough suppressant, in liver. Acetaminophen and chlorpheniramine were found in cavity blood and the rest were found in muscle. Acetaminophen was identified in urine.

It is likely that the pilot did not see the power lines while spraying the field, which resulted in the in-flight collision with the power lines. While treated diabetes can result in hypoglycemia, this is an unusual occurrence when metformin is used as a single agent for the disease. Thus, it is unlikely that the pilot's diabetes or its treatment contributed to this accident. Because the status of the pilot's depression symptoms around the time of the accident were unknown, whether effects from it contributed to his inability to avoid the powerlines could not be determined from the available information. The pilot's use of chlorpheniramine, dextromethorphan, and acetaminophen suggests that he had cold or allergy symptoms and was using an over-the-counter product to treat them. When severe, such symptoms may be quite debilitating; however, the extent to which he had symptoms at the time of the accident and the effectiveness of the treatment could not be determined. As a result, whether his underlying symptoms or the use of medications contributed to the accident circumstances could not be determined.

Verbatim NTSB analysis and probable cause from the NTSB dataset