What happened
On May 25, 2012, at approximately 20:3 and 30 local time, a Thunder and Colt Ltd. AX 7-77 Z balloon, registration PH-ZOZ, was conducting a flight from Saint-Saud Lacoussière toward the Nontron region. While the pilot was attempting to land in a field, the basket collided with an electrical power line.
An electrical arc occurred during the impact, causing one of the two basket supports to fail and the basket to tilt. During the ensuing chaos, one passenger was ejected from the basket. A fire broke out on the balloon's skirt. Fearing a potential explosion of the gas cylinders, the pilot instructed the remaining passenger to jump; however, the passenger remained in the basket. The balloon continued its descent, resulting in a hard landing approximately 1,000 meters from the initial collision site. The incident resulted in three injured (the pilot and two passengers) and significant damage to the aircraft, including three severed sections of the power line.
The investigation
The investigation focused on the visibility of the hazard and the mechanical failure of the basket. Investigators found that one of the two steel cables connecting the basket to the load frame had melted due to the electrical arc. Evidence of fire was found on the base of the envelope, the balloon skirt, and one of the gas cylinders. The wicker basket and steel load frame sustained deformation from the impact.
Regarding environmental factors, the investigation established that the concrete pylons supporting the power lines were completely obscured by very dense vegetation. Furthermore, at the time of the accident, the sun was at an elevation of only 8.67° and an azimuth of 291°, placing it in the front-right sector of the approach path. The passengers noted that the setting sun significantly hindered their vision during the descent.
Findings
- The primary cause of the accident was the late detection of the power lines by the pilot.
- The dense vegetation masking the pylons prevented early identification of the hazard.
- The low angle of the setting sun caused glare and impaired the pilot's vision.
- The inertia of the balloon prevented the pilot from maneuvering away in time once the lines were spotted.