What happened
On 31 March 2024, a Cessna 172RG, registration ZS-LLY, departed Goodside Private Airfield in Mpumalanga, South Africa, bound for Hoedspruit Civil Airfield. The flight was being conducted under visual meteorological conditions as a private operation. During the takeoff roll on the grass runway, the aircraft experienced sluggish acceleration.
As the aircraft approached the 700-meter mark, the pilot attempted to increase lift by deploying 10° of flaps; however, this action increased drag and further reduced airspeed. The pilot attempted to rotate the aircraft at approximately 50 knots, which was below the required speed. This maneuver resulted in a left-wing stall. To prevent a more serious accident, the pilot pushed the nose down, but the aircraft could not stop within the remaining runway length. The aircraft overran the end of the runway and struck a perimeter fence, causing the aircraft to veer sharply to the right and skid sideways. While the aircraft sustained substantial damage, there were no injuries to the two occupants.
The investigation
SACAA AIID investigators analyzed the environmental conditions and aircraft performance data. The investigation established that the airfield elevation was 4,537 feet, and due to the temperature and pressure, the density altitude had risen to 10,961 feet. This high density altitude significantly reduced the engine's effective power output, making the required takeoff performance difficult to achieve.
Investigators also reviewed the takeoff procedures and the pilot's actions. It was noted that the pilot reached the 700-meter decision point without having achieved the necessary airspeed for a safe climb. Furthermore, the investigation examined the aircraft's maintenance records, finding the Cessna 172RG was airworthy and had no reported defects prior to the flight.
Findings
- The primary cause of the accident was the failure to abort the takeoff at the 700-meter decision point despite insufficient airspeed and engine performance.
- High density altitude (10,961 ft) resulted in an engine power output that was inadequate for a standard takeoff.
- The pilot applied 10° of flaps late in the takeoff roll, which increased drag and further hindered acceleration.
- There was a lack of adequate pre-flight planning regarding the impact of high density altitude on aircraft performance.
- The pilot rotated the aircraft at 50 knots, which was 13 knots below the recommended obstacle clearance speed.