Following the flight path demonstrations by the bird dog aircraft, the Electra proceeded to carry out the retardant drop on the fire. After delivering the specified retardant load, the Electra was seen turning right initially then entering a turn to the left. At 12:21 MST, the Electra struck the terrain on the side of a steep ridge at about 3 900 ft above sea level. The aircraft exploded on impact and the two pilots were fatally injured. An intense post-crash fire consumed much of the wreckage and started a forest fire at the crash site and in the surrounding area. The on-board ELT was damaged by the impact forces and did not activate.

Findings as to causes and contributing factors

1. For undetermined reasons, the Electra did not climb sufficiently to avoid striking the rising terrain.
    
2. Given the flight path and the rate of climb chosen, a collision with the terrain was unavoidable.
    
3. The characteristics of the terrain were deceptive, making it difficult for the pilots to perceive their proximity and rate of closure to the rising ground in sufficient time to avoid it.

Other findings

1. Performance calculations show that the Electra - in the absence of limiting mechanical malfunction - could have climbed at a rate that would have allowed the aircraft to avoid the terrain.
    
2. Although a functional cockpit voice recorder (CVR) was installed in the aircraft, it was not required by regulation and it was not used; as a result, vital clues that could have shed light on the circumstances of this accident were not available.
    
3. The ELT could not transmit a signal as a result of severe impact forces that exceeded the design criteria.