Both aircraft were owned by Hawkins & Powers Aviation of Greybull, Wyoming and operated under contract to the United States Forest Service (USFS).

[3][4][5] Unusually, the aircraft was being filmed by a passing tourist during the retardant drop and at the moment the wings separated,[6] providing valuable video evidence for the subsequent investigation by the National Transportation Safety Board (NTSB).

[3] The NTSB investigated the crash and determined that the accident was caused by a structural failure that occurred at the wing-to-fuselage attach point, with the right wing failing just before the left.

The investigation disclosed "evidence of fatigue cracks in the right wing's lower surface skin panel, with origins beneath the forward doubler.

The origin points were determined to be in rivet holes which join the external doubler and the internal stringers to the lower skin panel.

"[3][7] The second crash occurred on July 18, 2002 near Estes Park, Colorado, also as a result of structural failure, in this case in the wing's spar adjacent to the left side of the fuselage.

The aircraft continued to roll left, impacting the ground at a 45° nose down attitude, starting a large fire at the wreck site.

The FAA and the DOI subsequently developed an action plan to address many of the same inspection and maintenance issues seen in the most recent C-130A and P4Y accident investigations.

Since that time the DOI has dropped its restrictions on the C-130A....[7]On August 13, 1994, a 1957-built C-130A, registration N135FF with call sign Tanker 82, crashed near Pearblossom, California while fighting a fire in the San Gabriel Mountains.

[13] Due to the extremely rugged terrain, the NTSB recovered only a small portion of the wreckage, and its preliminary conclusion that an explosion caused by a fuel leak led to the wing separation was based largely on eyewitness statements.

"[1] In March, 2003, the panel released its report, which included eight key findings ...critical for planning a safe and effective fire aviation program.

[1] Almost two years after the summer 2002 crashes, and as a direct result of the ensuing investigations, on May 10, 2004 the Forest Service abruptly terminated the contracts for the entire large tanker fleet.

To continue to use these contract large airtankers when no mechanism exists to guarantee their airworthiness presents an unacceptable level of risk to the aviators, the firefighters on the ground and the communities we serve.