What happened
On April 25, 2013, at approximately 7:45 p.m., a Cameron C-90 hot air balloon, registration F-HIAG, was attempting a recreational takeoff from a private field in Saint-Prypt-Saint-Loup (Saint-Péran), France. The pilot was accompanied by two passengers.
As the balloon ascended and the vent line was released, a sudden wind gust from a direction opposite to the estimated wind hit the aircraft. In response to the unexpected shift, the pilot immediately initiated an aborted takeoff by activating the rapid deflation system. The balloon landed approximately 40 meters southeast of the takeoff site, during which the envelope collided with overhead electrical cables. The pilot and both passengers evacuated the basket without injury, though the balloon's envelope was torn and the power lines sustained minor damage.
The investigation
The investigation focused on the meteorological conditions and the pilot's flight experience. Prior to the flight, the pilot had consulted a weather forecaster and used a helium balloon to confirm a light southeasterly wind. However, a localized change in air mass was occurring in the region.
Investigators analyzed meteorological data from the nearby Rennes aerodrome. While the initial conditions were favorable, a transition from a warm, humid air mass to a cooler, north/northwesterly flow was underway. This shift caused the wind to change from a light southeast breeze to a northwesterly wind of approximately 8 knots, with gusts reaching between 14 and 16 knots. This change occurred between 7:30 p.m. and 8:00 p.m., coinciding with the time of the accident. Localized wind maps and forecasts (TEMSI) had not detected this specific local shift in wind direction and intensity.
Findings
- The pilot was likely caught by surprise by a sudden change in wind direction and intensity caused by a localized air mass transition occurring between the flight preparation and the actual takeoff.
- The pilot's ability to manage the sudden instability was likely hindered by limited flight experience, as she had accumulated only 9.5 hours of pilot flight time at the time of the accident.
- The takeoff site was located near obstacles, with the first obstructions situated approximately 20 meters from the takeoff area.