What happened
On 5 March 2011, a Cameron Z-350 hot air balloon, registration G-VBFG, was conducting a commercial passenger flight over the Lake District. After an initial takeoff from Gilpin Bridge, the pilot attempted to land near Coniston Water. However, due to changing wind conditions, the pilot aborted the landing attempt and sought an alternative site in the Dunner anddale Valley.
During the descent into the valley, a sudden gust of wind pushed the balloon into the treetops. The basket struck deciduous trees, causing it to tilt significantly. During this impact, a tree branch protruded through a foot hole in the basket, striking a passenger in the ribs. The balloon continued to climb through the canopy, subsequently striking taller coniferous trees. The flight ended near Broughton-in-Furness, where the balloon landed on its side after hitting a barbed wire fence.
Among the 16 passengers on board, 2 sustained injuries (one serious and one minor). The crew remained uninjured.
The investigation
The AAIB examined video evidence from the flight, which captured the moment of impact. The investigation established that the Rapid Deflation System (RDS) parachute valve was open during the encounter with the trees. The pilot was observed making multiple adjustments to the venting line rather than utilizing the burners in a 'hands free' mode.
Investigators also reviewed the pilot's decision-making regarding landing sites. While the pilot avoided the coastal plain due to concerns regarding 'curlover' (turbulence caused by wind hitting terrain), the investigation noted that the gradient of the coastal plain was significantly shallower than the valley slope.
Findings
- The pilot closed the RDS parachute valve using the venting line without releasing it, which prevented the burners from heating the air in the envelope efficiently.
- The use of intermittent burner bursts rather than locking the burners in 'hands free' mode likely hindered the balloon's ability to climb away quickly.
- The passenger's injury was caused by the basket tilting and the passenger being pressed against the basket wall by the force of the impact.
- The pilot's decision to prioritize the recovery and packing of the balloon over the immediate medical assessment of the passengers was noted.