What happened
On September 22, 2007, an AB-115 aircraft, registration PP-GRN, was conducting a flight instruction mission departing from Ribeirão Preto, Brazil. The flight involved an instructor and a student pilot. Following takeoff, the crew performed a simulated emergency procedure.
During the subsequent traffic pattern for runway 18, the instructor directed the student to execute a power-off approach. The student utilized a sideslip maneuver to manage the descent rate. However, at an altitude of approximately 3 meters and a speed of 60 mph, the aircraft began to sink rapidly. The student attempted to correct the descent by pulling back on the control column, which increased the aircraft's pitch but failed to reduce the sink rate. The instructor intervened by applying full power and maintaining a three-point landing attitude, but the aircraft struck the runway forcefully. The aircraft slid approximately 100 meters before coming to a complete stop. The two crew members were uninjured, but the aircraft sustained heavy damage to the landing gear and propeller, along with minor damage to the fuselage.
The investigation
CENIPA's investigation focused on the sequence of maneuvers and the instructional environment. Investigators noted that the student had not flown for over a week, necessitating a more gradual reintroduction to flight maneuvers. The investigation also revealed that the pre-flight briefing lasted only about 30 minutes, which was deemed insufficient for a complex instruction session. Furthermore, the investigation found a lack of standardized instructional orders at the flight school, as the crew was using a simple summary sheet rather than a structured syllabus.
Findings
- The student pilot's improper control inputs allowed the aircraft to acquire an excessive sink rate at low altitude.
- The instructor's decision-making regarding flight planning contributed to the accident, as the high-difficulty power-off maneuver was introduced immediately following an emergency simulation without a period of adaptation.
- The instructor's delayed intervention prevented the aircraft from achieving a positive aerodynamic response to the power application.
- Inadequate flight planning and instruction sequencing were primary contributing factors.
- Lack of standardized instructional documentation and oversight at the flight school hindered student preparation.