What happened
On February 23, 2017, at approximately 09:00 local time, a Piper PA-25-260, registration HK585, was performing agricultural spraying operations near Ambalema, Tolima. The aircraft, operated by Sanidad Vegetal Cruz Verde, had previously completed several spraying tasks at a nearby estate before departing for the Pajonales estate to continue its mission.
During the eighth flight of the day, while maneuvering over lot 3 and following the application of solid fertilizer, the aircraft experienced a sudden and severe leftward bank. This led to a rapid loss of control, causing the aircraft to impact the terrain at a high angle and high velocity. The impact resulted in the total destruction of the cockpit, the left wing, and the horizontal and vertical stabilizers. The engine was separated from the firewall, and the propeller detached upon impact. The pilot, the sole occupant, sustained serious injuries and was hospitalized in a medically induced coma for ten days.
The investigation
The GRIAA investigation focused on determining whether mechanical failure, environmental factors, or pilot error contributed to the crash. Investigators examined the aircraft's maintenance records, which showed the plane was fully airworthy and compliant with all required service bulletins. A technical inspection of the Lycoming engine and the flight control systems (cables and pulleys) ruled out engine failure or mechanical control malfunctions.
Meteorological data indicated that weather conditions were appropriate for VFR flight, with only minor changes in wind speed that did not pose a hazard. The investigation also reviewed the operator's manuals and the pilot's flight history, noting that while the pilot was experienced, there had been a previous incident involving an obstacle strike in the days prior to the accident.
Findings
- The primary cause of the accident was an aerodynamic stall induced by the pilot during a 90–270 degree reverse turn, a standard maneuver in agricultural spraying used to reposition the aircraft over the crop.
- The stall occurred at a low altitude, leaving the pilot with insufficient time or altitude to execute recovery techniques.
- A significant contributing factor was the lack of clarity and standardization within the operator's manuals regarding the specific stall speeds and characteristics of the Piper PA-25-260 during low-altitude spraying maneuvers.
- The operator's documentation lacked specific guidance on preventing and recovering from stalls during high-load, low-altitude turns.