The following excerpt comes from the investigation report of the crash of a U.S. Navy pilot flying an F-18C strike fighter jet during a May 1992 training run in the Sierra Nevada mountain range: Opinions #9 and #10

9. The most probable cause factor of the mishap is pilot error in that LCDR [Lieutenant Commander] McGuire executed a high G, level turn around a canyon bend without knowledge of the terrain that lay only seconds ahead of him. LCDR McGuire did not recognize his worsening situation until after a point at which his aircraft performance was insufficient to prevent ground impact.

10. Visual illusions resulting from the combined effects of multi- colored rock, morning shadows, and a sloping canyon floor existed at both the canyon bend and the first impact site. These illusions, when coupled with the lack of any reported pre-flight terrain study, contributed to the mishap by delaying LCDR McGuire’s recognition of the rising canyon floor and rock outcroppings for a brief, but critical, instant of time.

(Rondestvedt, 1992, p. 20)