What happened
On August 27, 2017, at approximately 19:27 local time, a motorized hang glider, registration ES-KTT, crashed near the Kuusiku airfield in Estonia. The flight, which began around 17:00, was conducting recreational flights in the vicinity of the airfield.
As the aircraft approached the airfield from the direction of Rapla at an altitude of approximately 400–50 and entered a dive, the wing structure failed. During the maneuver, the aircraft's wing broke apart, causing the glider to plummet from roughly 200 meters into a spruce forest. The impact resulted in a post-crash fire, and both occupants—the pilot and a passenger—were killed.
The investigation
The Estonian Safety Investigation Bureau (OJK) examined the structural damage to the aircraft's airframe. The investigation focused on the integrity of the wing components following the impact. Physical evidence revealed that the trapezoid tubes (1 and 2) within the airframe had bent and fractured, and the tension cables (A and B) had snapped.
Findings
- The aircraft was a motorized hang glider with a valid certificate of airworthiness.
- The pilot held a valid ultralight (UL) class A license with approximately 183 hours of flight experience.
- Weather conditions at the time were CAVOK (ceiling and visibility OK) with light winds.
- The execution of an inappropriate maneuver caused a significant increase in airspeed during the dive.
- The resulting imbalance between lift and weight forces placed excessive stress on the trapezoid tubes, causing them to fail. This structural failure allowed the wing to shift to a much larger angle of attack, leading to the snapping of the tension cables and the deformation of the wing structure.