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Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the ATSB to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation. The statement is published as a report in accordance with section 25 of the TSI Act, capturing information from the investigation up to the time of discontinuance. |
Overview of the investigation
On 28 March 2022, the ATSB commenced an investigation into a hard landing involving a E-240 Kavanagh balloon, registration VH-ZON, which occurred at Moorabbin Airport, Victoria, on 27 March 2022.
The balloon was being operated on a scenic passenger flight between Reservoir and Moorabbin Airport with a pilot and 10 passengers on board. The pilot provided the operator’s standard safety briefing to the passengers before take-off, while the passengers were in the basket, to explain and demonstrate the position to adopt during normal landings and emergencies. The position was facing opposite to the landing direction, standing with slightly bent knees, holding on to the rope handholds in front, and back rested against padding on the basket. Passengers were to remain in that position until the basket stopped.
There were several other balloons operating the same scenic flight route, and the pilots had collectively decided the departure point and that the weather was suitable for their respective flights (all along the same route). The pilots reviewed several sources of weather information, including the Bureau of Meteorology aerodrome forecasts (TAF) for Melbourne, Essendon and Moorabbin. The Moorabbin TAF forecast the wind to be 11 kt from the north-east at the time the balloons were due to land.
The pilots had also obtained information about the actual wind conditions prior to departure by releasing 2 piballs[1] in different locations to assess the speed and direction of the wind at different levels. Following this assessment, the balloons departed at about 0700 local time.
The pilot had about 30 years experience as a balloon pilot and had been operating balloons in the area for about 18 years, with extensive knowledge of the planned route.
On approach to Moorabbin Airport, VH-ZON was travelling in a south-easterly direction and was about 500 m to the west of the other balloons. The pilot obtained automatic terminal information by radio for Moorabbin, and it advised of a 4-kt north-easterly surface wind.
The pilot reported that they had commenced the descent into Moorabbin Airport after the other balloons and found the wind to be faster at the lower levels than expected. Data collected via another balloon pilot’s navigation equipment post-accident showed the wind was about 38 kt at 1,400 ft and 35 kt at 1,000 feet, which was significantly faster than the pilots had anticipated. This meant that the pilot had to conduct a faster than usual descent to ensure they could land the balloon in a suitable area.
When the balloon reached 300–400 ft, it travelled through a temperature inversion (where temperature increases with altitude, which is a reversal of typical atmospheric conditions) and the balloon rotated 120°. Although the passengers had been instructed to adopt the landing position, the pilot did not have time to rotate the balloon to the correct orientation (with the passengers facing opposite to the landing direction) before reaching the ground. On landing, the balloon impacted the front right corner of the basket and bounced. The basket was then dragged for a short distance, coming to rest in a culvert at the end of a runway within the airport boundary.
As a result of the hard landing and the orientation of the basket, 1 passenger was seriously injured and 2 passengers received minor injuries.
As part of its investigation, the ATSB interviewed the pilot and passengers and reviewed:
- weather information including observations and forecasts used by the pilot
- air traffic control recordings
- recorded navigation information used in-flight by one of the other balloon pilots (data could not be retrieved from the equipment used on the accident balloon)
- the operator’s procedures for passenger briefings
- photographs taken in-flight by the balloon operator and others that were provided by passengers and a witness on the ground.
The ATSB notes that, due to unexpected wind speed on descent (which was much higher than the surface wind information that the pilot had previously obtained), and the limited landing site options, the pilot decided to land as soon as possible. This resulted in a faster and harder landing than normal. The balloon’s abnormal orientation after passing through the temperature inversion meant that although the passengers were in the correct position for landing, there was a greater risk of injury.
Reasons for the discontinuation
Based on a review of the available evidence, the ATSB considered it was unlikely that further investigation would identify any systemic safety issues or important safety lessons from this specific occurrence. Consequently, the ATSB has discontinued this investigation.
However, the ATSB is concerned about the number of accidents that have been occurring in commercial balloon operations and has listed the reduction of passenger injuries in commercial ballooning operations as one of its Safety Watch items. The evidence collected during the investigation involving VH-ZON will be used in a safety study further examining these types of accidents.
[1] Piball: an abbreviation of ‘pilot balloon’, which is a small, helium-filled free balloon with a light attached. It is released and visually tracked to determine the wind at different altitudes.