What happened
On November 28, 2020, a Neiva 56-C-1, registration PP-HRH, was conducting a local flight for instruction and flight re-adaptation at the Catanduva Aerodrome (SDCD) in São Paulo, Brazil. The flight involved an instructor and a student who had not flown for approximately one year.
During the third landing attempt, which was intended to be a touch-and-go maneuver, the aircraft encountered a crosswind. As the student attempted to correct the wing position, the aircraft began to drift from the runway centerline. The instructor, recognizing the deviation, verbally announced that he was taking control of the aircraft to level the wings and return to the centerline. However, the student continued to apply flight controls. This resulted in the simultaneous and antagonistic application of forces on the controls, causing the aircraft to yaw approximately 70 degrees to the left. The aircraft exited the runway and the left landing gear struck an uncovered drainage ditch, resulting in substantial damage to the aircraft. Both occupants were unharmed.
The investigation
CENIPA's investigation focused on the coordination between the two occupants and the procedures for transferring flight controls. The investigation established that the instructor was properly qualified and the aircraft was airworthy and within weight and balance limits.
Investigators noted that the aircraft was not equipped with headsets, meaning all communication relied on verbal commands. During the go-around, increased engine noise likely hindered the student's ability to clearly hear the instructor's announcement. Furthermore, the investigation found that the flight club's safety manual lacked specific, detailed instructions regarding the procedures for the transfer of controls between pilots, nor did it require these procedures to be reinforced during pre-flight briefings.
Findings
- Conflicting control inputs: The primary cause of the excursion was the simultaneous application of opposing forces on the flight controls by the instructor and the student.
- Cockpit coordination: Inadequate coordination between the crew members during the critical phase of the maneuver.
- Communication barriers: High engine noise levels during the go-around likely prevented the student from clearly understanding the instructor's verbal takeover of the controls.
- Lack of standardized procedures: The absence of detailed protocols for the transfer of controls in the operator's manual contributed to the lack of clarity during the incident.