What happened
On 30 July 2021, a flight instructor and a student pilot were preparing for circuit training at Wonderboom Aerodrome (FAWB). After being held briefly by air traffic control due to congestion, the crew received clearance for takeoff on Runway 11. The instructor initially managed the takeoff roll before handing control to the student pilot once the aircraft was stabilized.
During the performance of rolling checks, the crew noticed that the airspeed indicator was not functioning correctly. The instructor decided to abort the takeoff. As the instructor reached for the throttle to terminate the roll, her seat unlatched and slid toward the rear of the cockpit. This movement prevented her from reaching any of the flight controls. Consequently, the Cessna 172P, registration ZS-GDA, began to yaw to the left. The student pilot immediately took control, steering the aircraft back onto the runway centerline. Once the instructor had successfully repositioned and re-latched her seat, the aircraft vacated the runway via Runway 24 and returned to the flight training organization's line. There were no injuries and no damage to the aircraft.
The investigation
SACAA AIID examined the sequence of events following the serious incident. The investigation noted that the aircraft had undergone a maintenance inspection approximately three weeks prior to the event. Following the incident, the instructor recorded the seat movement in the aircraft's flight log. The aircraft was subsequently inspected by a maintenance organization, which was unable to identify any mechanical fault with the seat latching mechanism or the airspeed indicator. The aircraft was subsequently returned to service.
Findings
- The primary cause of the loss of directional control was the unlatching of the instructor's seat during the aborted takeoff attempt.
- The movement of the seat rendered the instructor unable to manipulate the aircraft's controls.
- The student pilot's intervention prevented the aircraft from departing the runway surface.