In a preliminary NTSB report on the June 3 Lockheed P2V Neptune tanker accident 20 miles north of Modena, Utah, the board said, "While conducting its second retardant drop of the day, Tanker 11 followed behind the lead airplane into the drop zone. The drop zone was located in a shallow valley that is 0.4 miles wide and 350 feet deep.

"The lead airplane flew a shallow right-hand turn on to final, and dropped to an altitude of 150 feet above the valley floor over the intended drop area. While making the right turn on to final behind the lead plane, Tanker 11 hit rising terrain that was about 700 feet left of the lead airplane's flight path."

The accident claimed the lives of two Neptune Aviation Services pilots.