CEN21FA334 · Air Tractor Inc AT-802

The agricultural airplane was operating from a private grass airstrip that was 2,164 ft long and 100 ft wide. The airplane had just been fueled with 225 gallons of fuel and loaded with 635 gallons of chemicals before takeoff. Witnesses stated that the takeoff roll was normal but that, at the departure end of the runway, the airplane struck an embankment, nosed over, and came to rest inverted in a field. The airplane sustained substantial damaged to both wings, the empennage, and fuselage. A postaccident examination of the airplane showed no preaccident mechanical failures or malfunctions that would have precluded normal operation. Based on the airplane’s weight, the field elevation, the field type (turf), and the weather conditions at the time of the accident, the airplane’s planned takeoff ground roll would have been about 2,460 ft, which exceeded the length of the airstrip. Neither witness reported observations consistent with the pilot attempting to abort the takeoff. Thus, the pilot exceeded the airplane’s performance limitations during the takeoff. Toxicology testing detected ethanol at .189 g/dL in the pilot’s blood, .252 g/dL in his vitreous fluid, and .141 g/dL in his urine. Based on available medical evidence, it is likely that the pilot had consumed ethanol. The extent to which measured ethanol levels were affected by postmortem ethanol production is unknown, preventing reliable estimation of the pilot’s blood ethanol level at the time of the crash. Toxicology testing also found gabapentin and doxepin in the pilot’s specimens, both of which can cause impairment, especially when combined with ethanol. The evidence was not sufficient to determine whether doxepin was exerting some effects during the accident flight. However, given the concentration of gabapentin in the pilot’s blood and urine specimens, gabapentin was likely exerting some performanceimpairing effects, such as sedation and dizziness, which would have been more likely to occur in the presence of ethanol. Thus, the pilot was most likely impaired by the effects of the combined substances in his system.

Verbatim NTSB analysis and probable cause from the NTSB dataset