What happened
On June 26, 2014, at approximately 06:30 UTC, an Aerospool WT9 Dynamic Speed, registration OK-KUU 75, crashed near the village of Kondrač, Czech Republic. The aircraft was part of a group flight consisting of two ultralight aircraft traveling from České Budějovice toward Pula, Croatia.
Witnesses on the ground reported hearing an irregular engine sound followed by the activation of a ballistic parachute system. They observed the aircraft entering a right-hand spin before impacting the ground. The impact, which occurred with the right wing first, resulted in the total destruction of the aircraft. Both the pilot and the passenger sustained fatal injuries.
The investigation
The ÚZPLN investigation examined the aircraft's technical state, the pilot's qualifications, and the meteorological conditions at the time of the accident. Investigators analyzed the aircraft's weight and balance, noting that the aircraft was equipped with an unauthorized auxiliary fuel system.
Technical examination of the engine and propeller showed the engine was operational until impact. However, the investigation focused on two primary hypotheses for the loss of control: potential carburetor icing due to specific atmospheric conditions, or a loss of spatial orientation caused by flying into cloud cover. The investigation also reviewed the pilot's medical and flight qualifications, as well as the flight's group coordination.
Findings
- The aircraft was overloaded by 132.8 kg, exceeding its maximum allowable weight by 28.1%.
- The center of gravity was located at 34.95% SAT, which was beyond the rear operational limit by 4.95% SAT.
- The pilot was flying with an invalid medical certificate and lacked the necessary language proficiency for controlled airspace.
- Meteorological conditions presented a high probability of carburetor icing and could have led to a loss of spatial orientation.
- The pilot activated the ballistic parachute system too late, likely only after regaining visual contact with the ground, which was at an altitude too low for effective deployment.
- The aircraft featured an unauthorized installation of additional fuel tanks.
Safety action
- It is recommended that the LAA ČR notify pilots of this accident and establish standardized procedures for maintaining radio communication between aircraft flying in a group.