What happened
On July 16, 2013, a Lindstrand 180 A hot air balloon, registration F-GSAE, was conducting a commercial flight near Angervilliers, France. The flight, operated by Aerfun Montgolfières, carried a pilot and eight passengers. During the final approach to a landing site, the balloon experienced a sudden loss of altitude while overflying a field of rapeseed.
The side of the basket struck the ground with significant force before reaching the intended landing area. This initial impact caused the balloon to bounce and enter a longitudinal oscillation. Approximately 55 seconds later, the basket made a second contact with the ground in a stubble field. During this second impact, the basket tilted forward, causing three passengers from the rear compartment to be ejected forward, where they were struck by the basket.
The investigation
The investigation examined the flight parameters, the aircraft's configuration, and the pilot's actions. The aircraft was within its maximum takeoff mass, weighing 1,261 kg against a limit of 1,306 kg. The basket was configured in a 'T' shape with three compartments, where passengers are instructed to adopt a crouched position facing backward during landing.
Investigators analyzed data from the onboard altimeter/variometer, which showed a moderate descent rate of 0.6 m/s prior to the incident, though the rate increased significantly during the impact. The investigation also reviewed the pilot's briefing procedures and the environmental conditions, noting a 15 km/h north wind and a temperature of 27°C.
Findings
- The first contact with the ground was violent, causing the balloon to rebound and oscillate.
- The basket likely tilted forward during the second impact, leading to the ejection of the passengers.
- The pilot's choice of a landing site immediately following a tall crop of rapeseed left no margin for managing unexpected aerodynamic variations.
- While the pilot had briefed the passengers on landing positions and the possibility of bouncing, it is possible that some passengers released their handholds during the initial bounce without the pilot noticing.
- The investigation could not definitively determine if the sudden loss of altitude was due to a local loss of lift or an improper approach technique.