Executive summary
At 0639 on Saturday 7 January 2012, a Cameron Balloons Limited A210 hot-air balloon lifted off from near Carterton in the Wairarapa area for a commercial flight. There were one pilot and 10 passengers on board. The weather conditions were fine with a light and variable wind, which was suitable for the flight. The balloon had been airborne for about 35 minutes when the pilot began to descend the balloon in preparation for landing in the Somerset Road area.
The balloon changed direction several times as it descended to lower levels. At about 0720 the balloon descended to between 5 and 7 metres (m) from the ground as it drifted over a silage paddock. The paddock was bounded on 2 sides by 33-kilovolt (kV) power lines with an average height of about 9 m. The balloon had earlier drifted near that paddock at a height of between 30 and 60 m, heading in the opposite direction.
The balloon was drifting towards the power lines on the far road-end boundary when the wind changed and took it towards power lines closer to the adjacent boundary. The pilot applied the burners to try to out-climb the power lines, but the basket of the balloon became entangled in them.
About 15-30 seconds later, at 0722, an intense electrical arcing occurred and fire erupted in the lower part of the basket. One of the balloon’s liquefied petroleum gas (LPG) fuel cylinders was ruptured by the electrical arcing, and escaping fuel intensified the fire.
Two of the passengers jumped while the basket was still caught on the wires and continuing to climb. The height was about 20 m by this time and they died from their injuries. Heat from the fire further raised the air temperature in the balloon envelope to a point where it broke the wire that was restraining it. The balloon rapidly ascended to a height of between 110 and 150 m before the balloon envelope caught fire and collapsed, and the balloon fell to the ground. The pilot and 8 remaining passengers died from their injuries.
The Transport Accident Investigation Commission (Commission) concluded that the pilot had not intended to land in the paddock bounded by the power lines and that it had been an unsafe manoeuvre to allow the balloon to descend below the level of the power lines and remain at low level as it crossed the paddock. The Commission also concluded that when the balloon flew towards the power lines and collision was unavoidable, the pilot should have followed the balloon manufacturer's advice and rapidly descended his balloon instead of making it climb. Had he done so, the balloon occupants would have had a better chance of survival.
Post-mortem toxicology tests revealed the pilot had a tetrahydrocannabinol (THC) level of 2 micrograms per litre (ug/l) of blood. THC is an active ingredient of cannabis. The Commission concluded that this THC level had been caused by both long-term and recent use of cannabis. While it is difficult to say how much each type of use contributed to the result, cannabis is known to affect a person's judgement and decision-making ability. Poor judgement and poor decision-making were factors contributing to this accident. The Commission found that the pilot's use of cannabis could not be excluded as a factor contributing to his errors of judgement, and therefore to the accident.
Recommendations
The Commission has already made recommendations to the Government about passing legislation to address the safety issue of the use of performance-impairing substances in all transport modes. The Commission makes a further recommendation on this matter.
The Commission also found that the practices of the maintenance provider for the balloon were not in accordance with Civil Aviation Rules. An urgent recommendation was made to the Director of Civil Aviation to address any maintenance issues with the balloon industry. The Director has already taken sufficient action to close that recommendation. However, the investigation found no maintenance issues or mechanical defects with the balloon that contributed to the accident.
Although not relevant to this accident, the Commission also expressed concern at the lack of regulation covering private ballooning. The Civil Aviation Authority of New Zealand (CAA) has already issued a notice of proposed rule-making (NPRM) to address this safety issue.
Key lessons
Both long-term and recent use of cannabis may significantly impair a person's performance of their duties, especially those involving complex tasks. Under no circumstances should operators of transport vehicles, or crew members and support crew with safety-critical roles, ever use it.
Power lines are a well recognised critical hazard to hot-air balloon operations. Balloon pilots should give them a wide margin and if they ever inadvertently encounter them, they should follow the balloon manufacturers' advice and best industry practice to mitigate the possible consequences.
Related Recommendations
The post-mortem toxicology results for the pilot in the Carterton hot air balloon showed that he had a positive result for tetrahydrocannabinol (a constituent of cannabis). It was likely that this was due to 2 factors: first, the pilot smoking cannabis shortly before the accident flight; and, second, residual tetrahydrocannabinol, from ingesting cannabis over a longer term, redistributing in the pilot’s blood after his death.
(a) conduct an urgent check of all maintenance organisations and licensed engineers approved to maintain hot-air balloons to ensure that their balloon maintenance practices fully comply with Civil Aviation Rules, and (b) satisfy himself that all New Zealand-registered hot-air balloons are airworthy.