Incident Overview
On 30 July 2021, at approximately 13:30Z, a Cessna 172P aircraft, registration ZS-GDA, operated by an Aviation Training Organisation under Part 141, was conducting a circuit training flight at Wonderboom Aerodrome (FAWB). On board were a flight instructor and a student pilot.
Sequence of Events
Air traffic control instructed the crew to hold at the holding point of Runway 11 for 5 to 10 minutes due to airspace congestion. After being cleared for take-off, the flight instructor initiated the take-off roll and then handed control to the student pilot. During rolling checks, the airspeed indicator was noted to be unresponsive.
The flight instructor decided to abort the take-off and took control again. While reaching for the throttle, her right-front seat unlatched and rolled backwards, preventing her from reaching any controls. The aircraft yawed to the left. The student pilot then took control, steered back to the runway centreline, and the flight instructor moved her seat forward and re-latched it. The instructor then taxied the aircraft off the active runway via Runway 24 and returned to the flight line.
Injuries and Damage
Neither crew member was injured, and the aircraft sustained no damage.
Post-Incident Actions
The flight instructor recorded in the aircraft's flight folio: "Seat moved back during take-off." The aircraft was examined by an aircraft maintenance organisation, which could find no fault with the seat latching mechanism or the airspeed indicator. The aircraft was returned to service. A placard was placed on the instrument panel stating: "Ensure that seat is locked in position prior to taxi, take-off and landing. Failure to properly latch seat and failure to comply with all safety instructions can result in bodily injury or death."
Probable Cause
Following a decision to abort take-off, the flight instructor's seat unlatched and moved backwards, rendering her unable to reach the controls, whereupon the aircraft veered off to the left of the runway. Thereafter, the student pilot took control of the aircraft and steered it back onto the runway centreline.