What happened
On June 6, 2007, a Schroeder Fire Balloons hot air balloon, registration PH-BAF, was conducting a passenger flight near Geldermalsen, Netherlands. The flight, which began in Amersfoort, was operating at low altitudes due to cloud cover. As the balloon approached its intended landing site, the pilot determined the field was unsuitable due to the presence of livestock and initiated a go-around.
During this climb, the pilot attempted to replace a gas cylinder because one was running low. However, the pilot was unable to successfully connect the new cylinder to one of the three burner systems. As the pilot focused on the connection issue, the balloon began to lose altitude rapidly. At approximately 21:50, the balloon struck a storage container on a residential property, causing the basket to tilt. During the impact, a passenger fell from the basket and was subsequently dragged beneath it. The balloon eventually came to a halt against a shed wall, and the remaining passengers and crew evacuated.
The investigation
The investigation examined the technical state of the aircraft, the pilot's experience, and the procedures used during the gas cylinder exchange. While the aircraft's maintenance records and documentation were valid, the investigation focused on the mechanics of the connection failure. The Schroeder Fire Balloons model utilized quick-release couplings, which differ from the screw-type couplings the pilot was more accustomed to using on other aircraft types.
Investigators found that the primary difficulty arose because the gas line had not been properly depressurized. According to the flight manual, the pilot should have closed the valve on the cylinder being disconnected and burned off the remaining gas in the line before attempting a new connection. Because the line still contained pressure, the quick-release coupling failed to engage, and the pilot's attempts to force the connection distracted him from monitoring the balloon's descent.
Findings
- The pilot failed to successfully connect a full gas cylinder to one of the three burners.
- The pilot's focus on the connection issue prevented the timely use of the two remaining functional burners.
- The pilot likely deviated from the manual's procedure by failing to depressurize the gas line before attempting the swap.
- The pilot had limited experience with the specific quick-release coupling system used on this aircraft.
- The decision to attempt a gas cylinder change during the critical landing/go-around phase increased the risk of an uncontrolled descent.
- The pilot did not implement the established emergency procedure to continue the flight using only two burners.
Safety action
- The investigation noted that the pilot's training should emphasize more experience with various coupling types, specifically moving beyond a heavy orientation toward Cameron-style screw couplings.