What happened
On June 2, 2012, a CZAW Sport Cruiser, registration CS-UQC, was participating in the "Tojeira Air Meet 2012" at the Tojeira airfield in Sintra, Portugal. The aircraft had departed from Portimão earlier that morning with one pilot and one passenger on board.
While performing a landing on runway 17, the pilot maintained a normal approach speed but utilized a glide slope slightly shallower than recommended. As the aircraft approached the threshold, it encountered a sudden loss of altitude. This sudden sink caused the left main landing gear to strike a grassy slope just before the runway surface. The impact was severe enough to fracture the left main gear leg, causing the aircraft to veer left and exit the runway. The aircraft came to a stop a short distance from the runway. The occupants were able to exit the aircraft uninjured, though the aircraft sustained minor damage to the landing gear, flap, and the underside of the left wing.
The investigation
The GPIAAF investigation examined the aircraft's weight, the meteorological conditions, and the pilot's approach profile. The investigation noted that the aircraft's takeoff mass at the time of the incident was approximately 495kg, which exceeded the 450kg maximum takeoff mass (MTOM) certified by the National Civil Aviation Authority, although the manufacturer's manual allows for up to 600kg.
Investigators also reviewed the airfield information, noting discrepancies between the VFR Manual and other local guides regarding runway dimensions, which may have contributed to the pilot's cautious approach. Meteorological analysis focused on thermal activity over the agricultural fields surrounding the airfield.
Findings
- The aircraft was operating at a mass exceeding the certified MTOM for ultralight aircraft.
- The pilot was performing a landing approach with a glide slope shallower than recommended, which limited the ability to recover from altitude changes.
- The aircraft encountered localized convective currents; as the aircraft moved from an area of stronger upward thermals to weaker ones near the runway threshold, it experienced a sudden sink.
- The pilot's lack of familiarity with the airfield, compounded by conflicting runway dimension information, likely influenced the landing technique.
- The force of the impact during the touchdown was sufficient to fracture the left main landing gear leg.