What happened
On July 5, 2023, an Aero Commander S2R Thrush, registration HK-5253, was performing agricultural spraying operations over a banana plantation in Zona Bananera, Magdalena, Colombia. During the second flight of the day, the pilot completed a spray pass and attempted to climb by deploying flaps and adjusting the elevator trim to relieve nose weight.
During this maneuver, the pilot experienced an immediate loss of engine power at a low altitude. The pilot declared an emergency on the company's internal frequency and identified a nearby plantation for an emergency landing. As the aircraft approached the ground, the pilot realized the throttle had been inadvertently closed and moved the lever forward abruptly, causing engine detonation. The aircraft struck several palm trees, resulting in substantial damage to the airframe, wings, and engine mount, before coming to a stop. The pilot, who was uninjured, evacuated the aircraft on his own.
The investigation
The GRIAA investigation focused on the cockpit ergonomics and the pilot's operational history. Investigators found that the pilot frequently operated a Piper PA-36-375 but only operated the Aero Commander S2R Thrush occasionally. The investigation examined the physical layout of the cockpit, noting that the design and positioning of the throttle and trim controls were highly similar, which could lead to confusion for pilots transitioning between different aircraft types.
Furthermore, the investigation reviewed the operator's safety management systems and internal regulations. It was noted that the company lacked specific policies regarding pilot currency or experience verification when a single pilot is authorized to fly multiple different aircraft types within the same fleet. The investigation also looked into the pilot's familiarity with the specific spray plots, finding that unfamiliarity with the terrain acted as an additional stressor during the complex operation.
Findings
- The primary cause of the emergency landing was the involuntary and mistaken reduction of the throttle by the pilot, who confused the lever with the elevator trim control.
- The physical similarity in shape and position of the throttle and trim controls in the Aero Commander S2R facilitated this error.
- The pilot lacked recent flight continuity and sufficient experience on this specific aircraft type.
- The low altitude at which the power reduction occurred left insufficient time to recover the flight profile.
- The operator's internal regulations allowed pilots to operate various aircraft types simultaneously without verifying recent proficiency or flight continuity in each specific model.
- Inadequate risk management and hazard identification by the operator regarding flight operations.