What happened
On September 2, 2017, a Cameron TR-77 hot air balloon, registration OY-NOI, was conducting a commercial flight southeast of Åbenrå under visual flight rules (VFR). The flight departed from a private residence near Åbenrå with a planned course toward Sønderborg. While the initial hour of the flight proceeded normally at altitudes up to 1,500 feet, the pilot encountered significant thermal turbulence while passing Vestre Sottrup. This turbulence disrupted the pilot's ability to control the balloon's altitude and direction.
In response to the unstable conditions, the pilot sought an immediate landing site southeast of Vestre Sottrup. The landing sequence involved multiple attempts. During the first landing, the pilot used the rip cord to vent hot air; however, the balloon briefly ascended to 5 meters before descending again. During the second attempt, the pilot vented more air to facilitate the landing. Due to the combination of reduced internal heat and strong winds, the envelope's shape changed, causing the basket to tilt and drag across the ground for over 55 meters.
The wind then caught the envelope, which acted like a large sail, lifting the balloon off the ground for approximately 150 to 200 meters. The balloon eventually struck a field hedge containing tall trees, which caused the aircraft to land a third time. There were no fatalities or serious injuries among the two occupants, but the aircraft sustained damage to 36 different areas of the envelope. A tree within the hedge had to be felled to extricate the balloon.
The investigation
The Danish Accident Investigation Board (Havarikommissionen) conducted an initial safety investigation. The investigation reviewed meteorological data, which indicated that conditions at takeoff were CAVOK with winds of 6 knots. The pilot had also consulted a flight meteorologist prior to departure, who suggested that thermal activity along the route was decreasing. The investigation concluded after establishing the sequence of events and the impact of the wind on the balloon's movement.