What happened
On August 23, 2001, an M-18A Dromader, registration PT-WCV, operated by Radar Agro-aérea Ltda., was engaged in an aerial firefighting mission in the mountainous, forested region of Bonito, Mato Grosso do Sul. The aircraft was carrying 2,500 liters of water and was accompanied by a passenger serving as an observer.
During the operation, the pilot executed a water drop over a fire on a mountain slope. Following the release, the pilot attempted a sharp right-hand turn to avoid rising terrain. During this maneuver, the aircraft entered a stall and lost control, impacting the ground in a level attitude. The pilot sustained fatal injuries, while the passenger suffered minor injuries. The aircraft was destroyed.
The investigation
CENIPA's investigation focused on the aerodynamic performance of the aircraft during the turn and the environmental conditions present at the time. Investigators found that the aircraft was operating with engine power at the moment of impact and that the engine was functioning normally.
The investigation also examined the cockpit environment. It was noted that the pilot's helmet shifted backward upon impact because the chin strap was not properly adjusted. Furthermore, the weight of the passenger, who was seated in a rear-facing seat, caused the pilot's seatback to deform during deceleration, contributing to the pilot's head striking the instrument panel.
Findings
- The pilot performed the water drop in a direction from the valley toward the mountain, utilizing a tailwind, which increased the risk of a stall.
- The pilot made an erroneous choice regarding the flight path, which necessitated a recovery turn exceeding the aircraft's aerodynamic capabilities under the existing conditions.
- The execution of high-amplitude pitch and bank commands during the turn, combined with G-loading, led to the aerodynamic stall.
- Visibility was restricted due to heavy smoke from the ongoing fires.
- Strong winds, estimated at approximately 30 knots, were present, acting as a tailwind during the approach.
- The aircraft's maintenance records showed inadequacies, specifically regarding uncertified inspections and unupdated propeller logs.