Introduction
On 22 January 2022, at approximately 10:00 local time (09:00 UTC), a Lindstrand LBL 150A hot air balloon, registered OO-BDI (Belgian), experienced an accident near the village of Ig, Ljubljansko barje, Slovenia. The balloon was privately operated and occupied by a pilot and five passengers.
Flight Preparation
The pilot and his family had traveled to Slovenia with the intention of conducting a formation flight of two hot air balloons near Bled. However, weather conditions in that area were unsuitable, prompting a decision to fly over Ljubljansko barje, where conditions were believed to be more favorable. The pilot reviewed weather forecasts using a mobile weather application.
Weather and Meteorological Conditions
Forecasts indicated generally favorable conditions for VFR flight, but actual conditions included stronger winds and turbulence. Meteorological data from the nearby Vrhnika station and sodar measurements showed increasing wind speeds during the morning hours. A radiosonde ascent at Bežigrad detected a strong westerly wind above a morning temperature inversion. The pilot's interpretation of the available weather information was later found to be incorrect.
Flight and Accident Details
After takeoff, the balloon ascended and was carried by the wind. According to radar track data, the flight trajectory deviated from the planned route. The balloon encountered stronger winds than forecast, leading to a rapid descent and collision with the ground. The impact caused minor surface damage to the basket. An examination of the burner system revealed no technical malfunctions.
Injuries
The accident resulted in three passengers sustaining serious injuries. The pilot and two other passengers sustained minor injuries or were uninjured.
Probable Cause
The investigation concluded that the direct cause of the accident was the balloon's collision with the ground at a high descent rate as a consequence of flying in adverse weather conditions. The indirect cause was the pilot's non-compliance with and incorrect interpretation of weather forecasts.