Casa Grande

The commercial pilot and the pilot-rated passenger were flying the biplane to a fly-in gathering in another state. Witnesses saw the airplane flying over a frozen lake at a low altitude and low airspeed. One witness saw the airplane "listing" left and right before it entered a left turn, and he lost sight of it. Other witnesses saw the airplane turn left and nose-dive into the ground. A postimpact fire consumed most of the airplane. Damage to the wreckage indicated that the airplane impacted the ground in a nose down attitude. The examination did not reveal evidence of any preimpact anomalies with the airframe, engine, or the control system of the airplane. A witness reported that, at the time of the accident, the wind was from the south about 30 miles per hour. However, a burnt area extending east from the airplane's impact point indicated the wind was from the west. Additionally, although wind information from nearby weather stations varied in direction and intensity. One station, about 14 miles west-northwest of the accident site reported calm wind., However, another station, located about 11 miles south of the accident site, recorded wind from the west at 11 knots with gusts to 27 knots about the time of the accident and wind from the west at 33 knots with gusts to 48 knots about an hour after the accident. Further, the forecast for the accident area called for wind gusts to 40 knots from the west-northwest. Therefore, it is likely that strong gusty west winds prevailed in the accident area at the time of the accident. Although some witnesses speculated that the pilot may have been attempting to land the airplane on the frozen lake, the airplane was not equipped to land on ice, and the reason the pilot was maneuvering at a low altitude in strong gusty winds could not be determined. Based on the witness observations and the damage to the wreckage, it is likely that the pilot allowed the airspeed to decrease to a point where the critical angle of attack was exceeded, and the airplane entered an aerodynamic stall/spin. Although the pilot was known to have heart disease, it is unlikely that his medical condition contributed to the accident. The witness observations indicate that the pilot was actively flying the airplane before the loss of control. Toxicology testing showed the presence of chlorpheniramine in the pilot's blood at a level that was likely in the therapeutic range. Chlorpheniramine is a sedating antihistamine available in a number of over the counter products, and it carries the warning, "May impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery)." Because of its sedating effect, chlorpheniramine may slow psychomotor functioning and cause drowsiness. It has also been shown in a driving simulator (after a single dose) to suppress visual-spatial cognition and visual-motor coordinating functions when compared to placebo. Such functions would have been necessary for the pilot to maintain control of the airplane while maneuvering close to the ground in the strong gusty wind conditions. Therefore, it is likely that the pilot's ability to safely operate the plane was impaired by the effects of chlorpheniramine.

The lineman who spoke with the pilot/owner of the accident airplane before its departure reported that the pilot stated that he and the flight instructor were going out to practice for about an hour. The flight instructor had given the pilot/owner his initial instruction in the airplane and flew with the pilot/owner regularly. The flight instructor had also given the pilot/owner about 58 hours of dual instruction in the accident airplane. The pilot/owner had accumulated about 51 hours of pilot-in-command time in the airplane make and model. It is likely that the pilot/owner was the pilot flying. Several witnesses reported observing the accident sequence. One witness reported seeing the airplane pull up into vertical flight, bank left, rotate nose down, and then impact the ground. One witness reported observing the airplane go from east to west, turn sharply, and then go north of the runway. He subsequently saw the airplane hit the ground. One witness, who was a pilot, stated that he observed the airplane enter a left bank and then a nose-down attitude of about 75 degrees at an altitude of about 300 feet above ground level, which was too low to recover. It is likely that the pilot was attempting a go-around and pitched up the airplane excessively and subsequently lost control, which resulted in the airplane impacting flat desert terrain about 100 feet north of the active runway at about the midfield point in a steep nose-down, left-wing-low attitude. The airplane was destroyed by postimpact forces and thermal damage. All components necessary for flight were accounted for at the accident site. A postaccident examination of the airframe and both engines revealed no anomalies that would have precluded normal operation. Additionally, an examination of both propellers revealed rotational scoring and twisting of the blades consistent with there being power during the impact sequence. No anomalies were noted with either propeller that would have precluded normal operation. Toxicological testing of the pilot was negative for drugs and alcohol. The flight instructor’s toxicology report revealed the presence of tetrahydrocannabinol (THC). Given the elevated levels of metabolite in the urine and kidney, the absence of quantifiable THC in the urine, and the low level of THC in the kidney and liver, it is likely that the flight instructor most recently used marijuana at least several hours before the accident. However, the effects of marijuana use on the flight instructor’s judgment and performance at the time of the accident could not be determined. A review of the flight instructor’s personal medical records indicated that he had a number of medical conditions that would have been grounds for denying his airman medical certificate. The ongoing treatment of his conditions with more than one sedating benzodiazepine, including oxazepam, simultaneously would also likely not have been allowed. However, none of the prescribed, actively sedating medications were found in the flight instructor’s tissues, and oxazepam was only found in the urine, which suggests that the flight instructor used the medication many hours and possibly several days before the accident. The toxicology findings indicate that the flight instructor likely did not experience any impairment from the benzodiazepine medication itself; however, the cognitive effects from the underlying mood disturbance could not be determined.

The crew departed Chandler-Stellar Airpark on a local flight. En route, one of the engine failed. The pilot attempted an emergency landing when the airplane crashed in flames in an open field. The aircraft was destroyed and all four occupants were killed.