What happened
On September 30, 2018, a Balóny Kubíček BB37Z hot air balloon was conducting a commercial flight near Bottrop, Germany. The flight began at approximately 17:30 local time from a launch site in Oberhausen. After an initial ascent to an altitude of roughly 200 to 250 meters AGL, the balloon experienced a significant loss of altitude.
The pilot reported that a wind gust, caused by thermal activity, led to a deformation of the envelope, which reduced the balloon's lift. As the balloon descended, the pilot attempted to correct the altitude by activating the burners, but the response was delayed. Approximately 40 to 50 meters before reaching a 380-kV transmission tower, the balloon's rigging lines struck the neutral conductor near the pylon's lightning arrester. The basket became snagged on a bolt of the pylon, and the envelope became entangled in the line's vibration dampers. The pilot managed to secure the basket to the pylon using a throw line, preventing a further fall. The 5 passengers on board sustained minor injuries, specifically bruises and abrasions, and were rescued by fire department personnel.
The investigation
The BFU investigation examined the meteorological conditions, the pilot's actions, and the airworthiness of the aircraft. Investigators found that the flight took place during a period of declining thermal activity, which likely caused the turbulence and envelope deformation. The investigation also revealed that the pilot had not utilized official meteorological briefing services.
Technical inspections of the BB37Z uncovered several maintenance issues, including unserviceable gas hoses that were overdue for replacement, rusted eyelets for the envelope ropes, and uncertified fuel tanks. Additionally, the investigation noted that while the flight was conducted for compensation, the pilot was legally prohibited from performing commercial operations due to age-related regulatory restrictions, and the operator lacked the necessary passenger liability insurance and commercial authorization.