What happened
On 30 January 2008, a Piper PA23-250 involved in a twin-engine conversion training flight collided with two vehicles at the Benoni/Brakpan Aerodrome. The flight, consisting of a flight instructor and a pilot under training, had just completed a session in the East Rand general flying area. After landing on runway 18 and taxiing to the apron, the aircraft came to a stop at a designated parking area in front of the flying school clubhouse.
As the pilot under training began the engine shutdown sequence and applied the parking brake, the aircraft unexpectedly began moving forward. Despite the instructor's urgent commands to apply the brakes, the aircraft continued its forward motion. The instructor attempted to mitigate the movement by closing the fuel mixture controls on both engines, but the aircraft ultimately struck two vehicles parked on and adjacent to the apron. The impact caused damage to the aircraft's left-hand wing, both engines, and both propellers, as well as damage to the parked vehicles. No injuries were reported.
The investigation
SACAA AIID investigators examined the aircraft's mechanical state and the operational circumstances of the flight. Post-accident inspections of the braking system confirmed that the brakes were fully functional and serviceable, with no hydraulic leaks detected. The investigation also noted that the aircraft's right rudder pedal was found in a slightly forward position and the parking brake had been left released.
Investigators also reviewed the organizational status of the flight school and the maintenance facility. While the maintenance organization held a valid approval, the investigation revealed that the aviation training organization (ATO) had operated for a 14-day period without a valid accreditation certificate due to a delay in the SACAA audit and renewal process.
Findings
- The primary cause of the collision was that the pilot under training stepped on the rudder pedals instead of the toe brakes.
- A lack of concentration by the trainee pilot may have contributed to the error, potentially exacerbated by the instructor conducting a flight debriefing while the aircraft was still taxiing.
- The instructor was unable to intervene directly with the brakes because the Piper PA23-250 is only equipped with brake pedals on the left-hand side, where the trainee was seated.
- While the aircraft was parked within the required ICAO clearance distances, the presence of the vehicles in the immediate path of the aircraft contributed to the collision.