CEN20LA271

The pilot was conducting his second aerial application flight of the day. According to a witness, the airplane had been topped off with fuel before the first flight and 165 gallons of chemical just before the accident flight. The witness stated that the airplane became airborne later than he expected. After departure, the airplane angled left from the runway heading and its wingtip impacted a power pole. It then hit power lines and another pole before coming to rest inverted in a draw. A postaccident examination found no mechanical malfunctions or anomalies that would have precluded normal operation. Toxicology testing indicated the pilot had the sedating antihistamine diphenhydramine in his blood at the time of the accident. The levels detected were above the therapeutic level for diphenhydramine. Given the pilot’s years of experience and familiarity with the aircraft, it is reasonable to consider that his reaction time and flying performance were diminished due to the use of sedating medication, which resulted in the impact with the power pole.

WEIGHT AND BALANCE The witness stated that the airplane was loaded with about 165 gallons of pre-emergent weed control and the tanks had been topped off (52 gallons) prior to the previous flight. He estimated the weight of the chemical to be about the same as water (8 lbs per gallon) since it was a mixed solution. The airplane had an empty weight of about 2,214lbs and a maximum takeoff weight of 4,200lbs. The combined empty weight of the airplane (2,214lbs), chemical (1,320lbs), fuel (312lbs) and pilot (169lbs) totaled about 4,015lbs. Although the FAA Type Certificate Data Sheet lists the maximum gross weight of the Cessna 188 series airplanes as 3,300lbs, the following note is contained in the document, in part: NOTE 3. When operating in restricted category, operators may approve higher maximum weights as permitted by FAA Advisory Circular No. 20-33B and Civil Aeronautics Manual 8. With respect to this action, these aircraft have demonstrated satisfactory operation in the restricted category envelope given at 1500 ft. altitude and standard day at the following restricted gross weights: 188 Series 3,800 lb. T188C Series (Serials T18802839T, T18803307T, T18803308T, T18803325T and on) 4,400 lb. On July 10, 2020, about 1440 central daylight time (CDT), a Cessna T188C, N2690J, was substantially damaged when it was involved in an accident near Dustin, Oklahoma. The commercial pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 137 aerial application flight. According to another company pilot who witnessed the accident, after taking on a load of about 165 gallons of herbicide, the airplane began its takeoff run. After departure, the airplane impacted a utility pole with the wingtip. It then hit power lines and another pole before coming to rest inverted in a draw. The witness stated that the airplane became airborne later than he expected. Toxicology testing detected diphenhydramine in the pilot’s femoral blood at 226 (ng/mL) and urine. The non-sedating medication tamsulosin was detected in the pilot’s cavity blood and urine. Diphenhydramine is a sedating antihistamine (commonly marketed as Benadryl) and is available over the counter in many products used to treat colds, allergies, and insomnia. The therapeutic range is 25 to 100 ng/mL. It carries the warning that use may impair mental and/or physical ability required for the performance of potentially hazardous tasks. The density altitude was computed to be 2892ft MSL. The airplane’s right fiberglass wingtip initially impacted a utility pole located about 1,000 ft from the departure end of the turf runway just above the bottom power wire, then separated from the wing. A few small wood fragments from the utility pole were observed embedded under rivet heads common to the most outboard wingtip rib. After impact with the first pole and wires, a second pole was impacted. The airplane then traveled about 180 ft before it impacted the terrain inverted,which resulted in substantial damage to the fuselage and wings. (See figure 1). Figure 1: Map of Accident Location