What happened
On 25 July 2014, a Lindstrand, L/BL 90A hot air balloon, registration G-MUPP, was conducting a private flight originating from Silverstone Circuit. While the initial weather conditions and wind forecasts were favorable, the pilot observed that wind speeds had increased significantly to approximately 14 knots. Seeking a safe landing site, the pilot identified a long field near Silverstone Golf Club.
To protect the approach from the wind, the pilot descended behind a tree line. During the landing sequence, the pilot utilized the rip line to vent hot air from the envelope. Although the balloon initially made a positive touchdown, the gusty conditions caused the aircraft to become airborne a second time. During this period, the balloon drifted approximately 60 degrees to the left, directing the craft toward nearby electricity power lines.
As the balloon could no longer clear the lines due to the loss of heat, the pilot extinguished the pilot lights and fuel, instructing the passengers to prepare for a heavy impact. The balloon subsequently struck an electricity transformer post roughly 15 feet above the ground. The impact caused electrical arcing when the metal flying wires contacted the power cables. The three persons on board (one crew and two passengers) sustained minor injuries resulting from the electrical arcing. The balloon eventually rotated and settled on the ground, allowing the occupants to egress.
The investigation
The investigation examined the flight sequence, the weather conditions at the time of the accident, and the physical damage to the aircraft. The AAIB established that the balloon's flight path changed abruptly after the first contact with the ground. The investigation also reviewed the damage to the aircraft, which included 11 of the 24 flying wires, the scoop, the lower Nomex, and the basket's top bar, as well as minor burns to clothing and equipment.
Findings
- The primary cause of the accident was a local increase in wind speed that exceeded the initial forecast.
- The gusty conditions caused the balloon to lift off again after its initial touchdown.
- The shift in ground track toward the left placed the aircraft in the path of the power lines.