What happened
On July 27, 2020, a BB42Z hot air balloon was conducting a skydiving operation near the Klatovy airport (LKKT) in the Czech Republic. The flight, carrying a pilot and five skydivers, reached an altitude of approximately 2,200 meters AGL. Following the pilot's instructions, the aircraft began a controlled descent to 1,800 meters AGL.
At this altitude, the pilot commanded all five skydivers to exit the basket simultaneously. This sudden loss of 440 kg of weight caused the balloon to enter an extreme ascent. During this rapid climb, the top of the envelope deformed, and the paravent control line became disloded and tangled within the vent lines. This led to a total collapse of the envelope, rendering the balloon uncontrollable. The aircraft entered a high-speed descent, falling at an estimated two to three times the vertical speed of the skydivers' parachutes, before impacting the ground in a field near Ostřetice. The pilot sustained serious injuries in the crash.
The investigation
The ÚZPLN investigation examined the aircraft, the pilot's qualifications, and the operational procedures used during the jump. Investigators reviewed witness statements, including video footage from a bystander, and performed technical inspections of the balloon's envelope, basket, and burners. The investigation also looked into the weight and balance calculations and the compliance of the jump organizer with skydiving regulations.
Findings
- The pilot was experienced and qualified to fly the BB42Z, but failed to follow established procedures for skydiving operations.
- The flight was conducted in violation of the balloon's flight manual; the pilot did not perform the necessary weight and balance calculations prior to the jump.
- The total takeoff weight exceeded the maximum allowable load by approximately 128 kg, and the minimum landing weight was significantly below the required limit by approximately 119 kg.
- The jump was performed as a group exit, which contradicted the manufacturer's flight manual.
- The pilot was not equipped with a reserve parachute during the flight.
- The primary cause of the accident was the improper execution of the skydive jump while failing to maintain the minimum landing weight, which triggered the extreme ascent and subsequent envelope collapse.