What happened
On the morning of 24 February 2024, a pilot operating an L39C Albatros, registration ZU-IBN, attempted a takeoff from Middleburg Airfield (FAMB) in Mpumalanga. The flight was intended to be a local private operation under visual meteorological conditions. During the takeoff roll, the pilot attempted to rotate the aircraft at 105 knots. However, the aircraft failed to lift off as intended.
As the aircraft progressed down the runway, the rear canopy detached and struck the vertical stabilizer before falling to the ground. This separation created significant aerodynamic instability and drag. Unaware of the detached canopy, the pilot attempted to abort the takeoff by applying brakes. However, because the nose had lifted, the weight-on-fly microswitch had disabled the normal braking system. The subsequent use of emergency brakes caused a tire to burst, leading the aircraft to veer off the runway. The pilot attempted to pull back on the stick to clear an obstacle, but the aircraft ultimately struck a concrete perimeter fence and came to a stop 80 meters beyond it. The pilot sustained serious injuries to the face and hand.
The investigation
SACAA AIID examined the mechanical and operational circumstances leading to the excursion. The investigation focused on the aircraft's performance capabilities under the specific environmental conditions at the time, the mechanical integrity of the canopy latching system, and the functionality of the braking systems. Investigators also reviewed the pilot's recent training history and the airfield's safety infrastructure.
Findings
- The aircraft was rotated before reaching the required speed; while 81 knots is the standard minimum, the high-density altitude at the time required a rotation speed of approximately 130 knots.
- A broken push rod link on the left rear latch caused the rear canopy to separate from the airframe.
- The aircraft's normal braking was unavailable because the nose gear weight-on-wheels switch was disengaged during the rotation attempt.
- The pilot had not flown this specific aircraft type in over a year and lacked recent training on the L39C.
- The airfield lacked a sufficient Runway End Safe Area (RESA) to prevent the impact with the perimeter fence.
- The aircraft was not compliant with regulations regarding the decommissioning of military systems, specifically the absence of functional canopy jettison and ejection systems.