What happened
On February 3, 2002, a commercial hot air balloon flight departed from the ice of Lake Walchsee, Austria, carrying the pilot and 22 passengers, including four children. The flight proceeded northeast toward the mountains, eventually descending to approximately 400 meters above ground level near the border of the mountains.
As the pilot approached a landing field near Übersee, Germany, he noted a sudden increase in both horizontal and vertical descent rates. During the landing attempt at approximately 12:00, the basket struck the ground with an increased sink rate and tipped over. The impact was violent enough to eject five passengers from the basket. Following this initial contact, the balloon briefly lifted off the ground. However, the pilot was unable to stabilize the aircraft because the "Superchute" rapid deflation system had partially opened during the first impact and could not be resealed. This led to a continuous loss of hot air and buoyancy. The balloon subsequently descended at an increasing rate, striking the ground a second time approximately 3ered 375 meters away. The entire sequence resulted in 5 serious injuries and 9 minor injuries.
The investigation
The BFU investigation examined the aircraft's airworthiness, the pilot's credentials, and the meteorological conditions. Investigators found that the aircraft, a Lindstrand LBL400A, was not in an airworthy state at the time of the flight. Specifically, the investigation identified that the burner system's performance was limited due to technical defects and low operating pressure in the gas cylinders. Furthermore, the investigation scrutinized the loading of the balloon, finding that the aircraft was significantly overweight and over capacity.
Findings
Several critical factors contributed to the accident:
- Overloading: The balloon was carrying 23 people, despite being certified for a maximum of 19. Additionally, the takeoff mass exceeded the maximum allowable weight by approximately 160–190 kg.
- Loss of Lift: The pilot entered a layer of warmed air near the ground, which caused a loss of buoyancy. This, combined with the reduced performance of the burner system, led to an uncontrolled descent.
- Equipment Failure: The rapid deflation system was unable to be closed after the first impact. The investigation also noted that unauthorized modifications to the balloon envelope components had compromised the reliability of the deflation system.
- Safety Violations: Several gas cylinders had expired inspections, and one cylinder was found improperly secured in a passenger compartment, posing a direct injury risk. Furthermore, the passengers had not been adequately instructed on proper landing procedures, which exacerbated the severity of the injuries.
Safety action
Following the accident, the BFU issued recommendations for a technical inspection of all aircraft operated by the involved company and called for an audit of the company's compliance with aviation regulations regarding the commercial transport of passengers.