What happened
On 10 June 2005, a Sky 90-24 Hot Air Balloon, registration G-VINO, was conducting a private pleasure flight near Mytholmroyd. After ascending to 2,000 ft and traveling west, the pilot identified a landing site within a field situated at the head of a steep-sided valley. The aircraft touched down in nearly calm conditions.
Following the landing, the pilot chose to keep the envelope inflated to help the ground recovery crew locate the craft. While the main burner gas supply was set to the OFF position, the pilot lights remained active. However, a downdraft caused by wind moving over the nearby trees and valley slope hit the balloon, causing the envelope to collapse onto the basket and burners.
Because the balloon had landed in a backward orientation, the flying wires from the fallen envelope draped across the burners, which had shifted into a horizontal position. One of these wires struck the gas supply control lever, momentarily opening the valve. The released propane ignited via the pilot lights, creating a flame that passed under the collapsed fabric. This incident resulted in one minor injury to a passenger, who sustained a minor burn to the face.
The investigation
The AAIB examined the sequence of events following the pilot's report. The investigation focused on the interaction between the wind patterns in the valley, the physical state of the burner controls after landing, and the mechanical movement of the flying wires during the envelope collapse.