NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The flight instructor and passenger, departed on a flight with two other airplanes to conduct simulated air-to-air combat maneuvers. Two airplanes at a time would maneuver against each other, while the other airplane observed from a higher altitude and safe distance. Examination of onboard video and audio recordings revealed that this portion of the flight was uneventful, however, following the series of aerobatic maneuvers, the passenger began experiencing air-sickness.
While returning to the airport, the airplanes flew a planned low-level flight (minimum altitude of 30 ft agl) in trail formation to simulate a bombing run. The accident airplane was the last airplane in the formation. During this time, the pilot communicated to the passenger, that he would fly the airplane "nice and easy." After climbing over a ridgeline, and descending back towards the desert floor, the airplane approached a small hill. Video indicated that the passenger, who was seated in the front seat, likely knew that a ground collision was imminent but was unable to communicate effectively with the pilot, since his microphone was out of position. The airplane subsequently impacted terrain near the top of the hill. The video showed the airplane flying at a normal speed and attitude before the impact occurred, with no indication of an evasive maneuver. Postaccident examination of the airplane revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
Although the airplane encountered precipitation during the low-level portion of the flight, the precipitation did not appear to reduce forward visibility or obscure the terrain. However, the tandem seating configuration of the airplane made it difficult for the rear-seated flight instructor to see the areas directly in front of and below the airplane. As such, pilots normally conducted "check turns" during low-level operations to ensure obstacle and terrain clearance. Video from the accident airplane and another airplane in the formation indicated that the accident pilot performed 4 check turns during the approximate 2-minute low-level flight; the other pilot performed 8 check turns during this time. It is likely that the accident pilot intentionally conducted fewer check turns, to clear for terrain and obstacles, because of the passenger's airsickness.
Toxicology testing of the pilot detected tetrahydrocannabinol (THC, the primary psychoactive component of marijuana) in tissue sample; however, because the antemortem blood levels of THC could not be directly computed and because there is no direct relationship established between blood levels of THC and impairment, whether the pilot's use of marijuana contributed to the accident could not be determined from the available evidence.