: 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 public aircraft accident report.
Tanker 11 departed the tanker base to conduct its second fire retardant drop of the day in the same location. Upon arriving in the fire traffic area, Tanker 11 followed the lead airplane into the drop zone, which was located in a shallow valley 0.4 mile wide and 350 feet deep. The lead airplane flew a shallow right turn onto final and then dropped to an altitude of 150 feet above the valley floor while approaching the intended drop zone. While making the right turn onto final behind the lead airplane, Tanker 11's right wing tip collided with terrain, which resulted in a rapid right yaw and subsequent impact with terrain. The wreckage created a 1,088-foot-long debris field, and a postimpact fire ensued.
Two witnesses took photographs of the accident sequence photos, and an examination of these photographs showed that the lead airplane was positioned ahead of the tanker throughout the flight; however, the orientation of the lead airplane compared to the orientation of Tanker 11 indicated that Tanker 11 did not directly follow the lead airplane's path to the final drop course. Rather, it was about 700 feet left of the lead airplane’s path and made a wider right turn as it attempted to align with the final drop course. The accident flight crewmembers had previously flown nearly the same exact drop and the lead pilot cautioned them about tailwind conditions during the flight; however, the wider turn suggests that they did not properly compensate for the wind conditions while maneuvering. In addition, the previous flight was conducted at an altitude above the ridgeline. GPS evidence indicates that the accident flight was conducted below the ridgeline, which would have made it more difficult to detect the rising terrain during the wider turn. A review of the airplane’s cockpit voice recorder audio information revealed that the flight crew did not recognize or attempt to correct the reduced clearance between Tanker 11 and the rising terrain until about 2 seconds before impact.