What happened
On February 11, 2023, at approximately 10:3 and during an aerial firefighting mission, an Air Tractor AT 802 A aircraft crashed in the rural sector of Chamizal Alto, within the Hualqui commune of the Biobío Region, Chile. The aircraft, operated by a commercial pilot, was engaged in forest fire suppression maneuvers when it struck the treetops of a forested area. Following the initial impact with the vegetation, the aircraft plummeted to the ground on a hillside. The pilot sustained injuries, while the aircraft suffered extensive structural damage.
The investigation
DGAC Chile investigators analyzed the wreckage, engine, and propeller, as well as flight data and video evidence. The investigation included a detailed teardown of the Pratt & Whitney PT6A-67F engine and the Hartzell propeller by specialists from the manufacturer.
Investigators utilized video footage captured by a ground observer, which recorded the aircraft approaching the drop zone. Analysis of the audio from this footage allowed investigators to estimate the propeller's RPM and the aircraft's airspeed using Doppler effect calculations. Furthermore, data from the aircraft's fleet control device helped reconstruct the flight path from Aeródromo Carriel Sur (SCIE) to the final impact site.
Physical inspection of the wreckage revealed severe damage: the fuselage was severed at the cabin level, the landing gear was torn away, and the engine was fractured into three distinct sections. The propeller also sustained significant damage, with three blades being torn from the hub and found embedded in the terrain.
Findings
Analysis of the video evidence provided critical insights into the sequence of events. The footage showed that during the approach to the drop zone, the water payload failed to release as intended. Consequently, the aircraft was unable to clear a line of trees located beyond the intended release point, leading to the collision with the treetops.
Technical analysis of the engine and propeller indicated that the engine was producing power at the moment of impact, with an estimated propeller speed of approximately 1704 RPM and an airspeed of roughly 130 KTAS.