DEN08GA076 · Air Tractor AT-602

A state forest service representative contacted the operator, who had two single-engine air tanker (SEAT) airplanes, and requested aerial support to a wildfire, which was identified by local authorities as the TA25 wildfire. The interagency dispatch system coordinated flight following of the two SEATs from the operator’s airfield directly to the wildfire. Prior to the flight, the accident pilot checked the weather for the area and declined support to the TA25 wildfire, due to high winds, but accepted a mission to another wildfire, approximately 55 nautical miles east, because of its location relative to wind activity and terrain. While en route, the dispatch system informed the accident pilot that the airplanes were not needed for the other wildfire, but inquired whether they could support the TA25 wildfire. Being halfway into their flight, the pilots decided they would at least check out the flight conditions at the TA25 wildfire rather than cancel the mission. After arriving to the TA25 wildfire, the accident pilot coordinated the drop area with a ground contact, and the second pilot maintained aerial observation support. The accident pilot performed a dry run over the area and then told the ground contact that the winds and turbulence were too strong to do a drop. The drop zone was then moved to another location at the TA25 wildfire. Gusty winds and power line hazards were reported to the accident pilot by the ground contact. Witnesses observed the airplane drop the load, then enter a vertical climb, stall, and impact terrain. The last calculated groundspeed of the airplane was 81 miles per hour (mph), and estimated winds at the time of the accident were at least 30 knots and gusting from the southwest. Examination of the airframe and engine revealed no pre-impact anomalies. The flaps were found in the full-extended position, and the airplane flight manual for fire control operations recommended a flap setting of 10 degrees. Representatives of the land management agencies reported to the NTSB that due to the local procurement arrangement for this flight, several levels of personnel typically involved in the decision making and dispatch processes for wildfires, were not involved, and the airplane was not properly configured for aerial fire support.

Verbatim NTSB analysis and probable cause from the NTSB dataset