What happened
On August 20, 2019, a Cessna 120 was performing a local flight training mission at Aeródromo Presidente João Batista Figueiredo (SBSI) in Sinop, Mato Grosso. The aircraft, registered as PP-DFM, was operated by a flight school with an instructor and a student pilot on board.
During the takeoff roll on runway 21, the student pilot lifted the tail at the recommended speed of 40 mph. However, due to a crosswind component (wind from 080° at 7 knots), the aircraft began to veer to the left. Although the student attempted to correct the deviation using right rudder, the control effectiveness was insufficient. As the aircraft approached the left edge of the runway, the instructor took control and applied full right rudder while reducing engine power. This intervention induced oscillating skidding motions to the left and right. These oscillations caused the right landing gear to collapse and the right wing to strike the ground, resulting in a runway excursion and substantial damage to the aircraft. Both occupants were unharmed.
The investigation
CENIPA's investigation focused on the sequence of control inputs and the decision-making process during the takeoff phase. Investigators examined the aircraft's maintenance records, which were up to date, and confirmed the airworthiness certificate was valid. The crew's medical certificates and licenses were also found to be valid.
The investigation analyzed the aerodynamic characteristics of the conventional gear Cessna 120 under crosswind conditions, noting that rudder effectiveness is reduced at low speeds. The investigation also reviewed the student's training records, which indicated previous difficulties maintaining the centerline during takeoff. Finally, the investigators evaluated the instructor's experience, noting that while the instructor was highly qualified, they had only 42 hours of flight time in this specific model.