The Australian Transport Safety Bureau has issued a Safety Advisory Notice to commercial hot air balloon operators recommending they review their operational practices to reduce the risk of passenger injury when using vehicles to assist with balloon deflations.
The Safety Advisory Notice arises from an ATSB investigation into a 16 March 2019 incident near Coldstream, Victoria where two passengers sustained injuries when the basket of a Kavanagh B-400 balloon operated by Picture this Ballooning tipped over when a vehicle was being used to assist the deflation of the balloon envelope.
Due to the lack of wind and the large size of the envelope, after the completion of a scenic flight the crew elected to use the recovery vehicle to assist in pulling the envelope over during deflation by attaching the crown line-a rope attached to the top or crown of the balloon-to the vehicle then slowly driving forward.
During this process, with 16 passengers and the pilot on board, the vehicle inadvertently pulled the basket over, resulting in one passenger sustaining broken ribs and another being knocked unconscious.
The ATSB's investigation into the accident found that the operator had not conducted a risk assessment concerning the use of vehicle-assisted deflations.
The ATSB advises all commercial balloon operators utilising vehicle‑assisted deflation to review their current operational practices with the aim of mitigating the safety risks associated with the procedure.
ATSB Director Transport Safety Dr Stuart Godley said while not required by regulation, the lack of a risk assessment for vehicle-assisted deflation likely left the operator and crew unaware of the risks associated with the process and without appropriate procedures to control those risks.
"As a result, when communication broke down between the pilot and vehicle driver leading to the basket tipping over, the passengers were unprepared and not in the landing position, increasing their likelihood of injury."
This accident was the third time in Australia since 2016 where occupants of a commercial balloon have been injured during a vehicle‑assisted deflation, prompting the ATSB to issue a Safety Advisory Notice regarding the practice.
"The ATSB advises all commercial balloon operators utilising vehicle‑assisted deflation to review their current operational practices with the aim of mitigating the safety risks associated with the procedure," Dr Godley said.
The number of large hot air balloons with envelopes of 350,000 cubic feet or greater registered in Australia has increased by around eight to nine balloons each year since mid-2015, the ATSB notes (the B-400 has a 400,000 cubic foot envelope and is certified to carry up to 22 passengers and crew).
"The average size of these larger balloons has also increased resulting in a corresponding increase in the number of passengers per balloon flight, making it likely that the number of passengers at risk of injury will also increase," said Dr Godley.
"Regulatory guidance on the mitigation of the potential risk from vehicle-assisted deflations will be important to help educate commercial balloon operators and assist them to mitigate risk as the number of passengers in these larger balloons continues to increase."
The Civil Aviation Safety Authority has advised the ATSB of their intention to produce an advisory circular on deflation of hot air balloon envelopes using vehicle assistance.
Meanwhile, the operator has developed and implemented a new vehicle-assisted deflation procedure with improved communication instructions for pilots and ground crew.
You can find here the investigation report AO-2019-014: Ground handling event involving Kavanagh B-400 Balloon, VH-LNB, near Coldstream, Victoria, on 16 March 2019
You can find here the ATSB's safety advisory notice: Potential for injury during vehicle-assisted deflation.
