Director of Public Prosecutions v Rosemary Gamble T/A Taz-Zorb [2025] TASMC 3

Director of Public Prosecutions v Rosemary Gamble T/A Taz-Zorb [2025] TASMC 3 | Case summary | Zoe

[11]

On Thursday 16 December 2021, students and staff of Hillcrest Primary School (the School), situated at 5 Lawrence Drive Devonport, were celebrating the end of the school year with an activities day called the "Big Day In". The Big Day In was held at the School with various activities split between four separate zones at the School, with students rotating through the activities over the course of the day. One of the zones was on the School oval. A teacher at the School had engaged the defendant, Rosemary Gamble (Ms Gamble), to provide and operate an inflatable jumping castle and zorb balls together with an inflatable border (the zorb ball arena) which was used to contain the zorb balls when in use. Ms Gamble was assisted in the operation of the inflatable devices at the Big Day In on the School Oval by Robert Monte and Jesse Barrett.
The jumping castle had been inflated and pegged down to the ground in four places. The jumping castle was connected to a yellow fan (the blower) which was used to inflate the jumping castle. The blower was plugged into a power socket in a nearby classroom using an extension cord. In addition to the jumping castle, Ms Gamble provided four zorb balls, which were contained inside an inflatable zorb ball arena or barrier which was inflated and not connected to a blower. The zorb ball arena was pegged down in six places. The defendant also set up a three metre by three metre gazebo between the jumping castle and zorb ball arena, to sit under and use as a workstation. This was secured by four pegs. At the time the inflatable devices and the gazebo were setup, it was calm and sunny, there was no wind, just dry heat, with perhaps the slightest breeze.
At approximately 10:00am witnesses describe a strong wind which came out of nowhere. The prosecution case is that at this time, three students, namely JW, DB and AP, were in zorb balls in the zorb ball arena. The fourth ball, a purple one, was being repaired by Mr Monte and it was ripped out of his hands by the wind. The three balls containing the students were lifted into the air. The pink zorb ball containing DB landed heavily near the soccer goals, JW's zorb ball landed on the western side of the oval and AP was assisted out of her zorb ball by friends. At the same time, Jye Sheehan, Jalailah Jones, Zane Mellor, Chace Harrison, Peter Dodt, LR and BM were on the jumping castle when it was lifted into the air by the wind. BM fell from the slide of the jumping castle as it became airborne. Master Sheehan fell from the jumping castle shortly afterwards, and the remaining children were carried on the jumping castle by the wind to the eastern side of the oval where the castle landed. In addition, the prosecution allege Addison Stewart was lined up to take a turn on the zorb balls when the jumping castle became airborne. As that occurred the blower attached to the jumping castle was also lifted and it hit her in the head. Tragically six children died in this incident and others suffered serious injuries to varying degrees (the incident).
Prior to the commencement of the hearing, I conducted a view at the School Oval and of the jumping castle, zorb ball arena, zorb balls and blower on 4 November 2024.

[21]

(a) At all material times Ms Gamble operated a business trading as Taz - Zorb.

(b) At all material times Ms Gamble was a person conducting a business or undertaking within the meaning of the Act who owed health and safety duties to ensure that others were not put at risk from work carried out as part of the conduct of the business or undertaking.

(c) At all material times Ms Gamble operated a business or undertaking that provided inflatable amusement devices for hire.

(d) At all material times Ms Gamble was engaged by the Crown in right of Tasmania (Department of Education) to operate inflatable amusement devices at Hillcrest Primary School for the end of school year celebrations.

(e) On 16 December 2021 Ms Gamble and two workers arrived at Hillcrest Primary School and set up the inflatable amusement devices, comprising an inflatable jumping castle model number E2 - 030 Crayon jumping castle "inflatable jumping castle", zorb balls and a zorb ball arena.

(f) The inflatable jumping castle was inflated by an electric blower which was attached to the device and provided continuous airflow in order for the device to remain inflated.

(g) The inflatable jumping castle had eight anchorage points to secure the device to the ground.

(h) The inflatable jumping castle was tethered to the ground using pegs at four of the anchorage points.

(i) Students of Hillcrest Primary School were allowed to take turns to play on the inflatable jumping castle.

(j) At approximately 10:00am on 16 December 2021 seven students were on the inflatable jumping castle when a significant weather event occurred which lifted the inflatable jumping castle causing it to become dislodged from the anchorage points and to become airborne. Students playing on the inflatable jumping castle were carried on the device and lifted into the air by the wind.

(k) Students fell from the inflatable jumping castle and suffered serious injury and/or death. Further, the blower was lifted from its position and hit a student in the vicinity of the inflatable jumping castle.

(l) The hazard[3] giving rise the risk, was the failure of the anchorage system to anchor the inflatable device to the ground.

(m) The risk[4] arising out of the said hazard was the risk of death or serious injury associated with falls from height and/or being struck by the inflatable device or any part attached thereto, due to the inflatable device becoming dislodged from the anchorage points and becoming airborne.

(n) Ms Gamble failed, so far as was reasonably practicable to ensure the health and safety of other persons was not put at risk from work carried out as part of the conduct of the business or undertaking, in that she failed to:

Ensure the provision and maintenance of safe systems of work, in that Ms Gamble failed to ensure that the anchorage system was sufficient to prevent lift of the inflatable device, in that she failed to do one or more of the following;

(i) Failed to ensure a peg was installed at each of the anchorage points on the inflatable jumping castle, in accordance with the manufacturer's instructions; and/or

(ii) Failed to ensure that each face of the inflatable jumping castle was secured by installing pegs at each anchorage point; and/or

(iii) Failed to use the pegs recommended by the manufacturer for use on the inflatable jumping castle or a suitable alternative as recommended by a competent person; and/or

[98]

A number of statements or transcripts of video recorded statements which describe the incident, the Wind Event, and its aftermath were tendered on the hearing by consent as the evidence of each witness. Those exhibits were marked P11 to P69 and they appear in Annexure "A".
On 24th February 2022 Detective Senior Sergeant Simon Conroy attended the School with Constable Wotherspoon (drone pilot) to ascertain the height the jumping castle reached in reference to the perspective of witness Lisa Shepherd. Constable Wotherspoon and Detective Senior Sergeant Conroy assessed where the jumping castle would have had to have been when she observed it and Constable Wotherspoon deployed a drone to lift vertically from that location. The officers ascertained that from the position that Ms Shepherd stated she was at, the drone came into vision at a height of 16 metres from where it was launched. The line of sight included across the School hall which is how Lisa Shepherd described her observations. Tendered on the hearing and marked P70 is a photograph of the position that Ms Shepherd was standing in when she made her observations.
Police investigations revealed that there was no CCTV footage of the incident available from the School.
First Class Constable Colin Wilcox assisted forensics at the scene where the jumping castle had been located on the western side of the oval, prior to the incident. He observed a number of pegs, both still in the ground and also on the ground. There were also carabiners and broken strapping on the ground. Constable Wilcox assisted with marking the locations of these items of relevance.
Senior Sergeant Russell Judges led a team who conducted a line search of the area of and surrounding the oval where the jumping castle was situated. He and his team were tasked with locating any evidence that may relate to the jumping castle. They were particularly briefed to be alert for small metal objects such as eyelets. The search was conducted as a close quarters line search. Officers were within one metre of one another. Several items which may have been associated with the jumping castle were located. When this occurred Forensic Services members of Tasmania Police were notified, and the position was marked by them, and the item catalogued by them.

[157]

Mr Barrett gave evidence he was inside the zorb ball arena when the weather event unfolded. He became aware of the wind going "around and around", heard a flapping sound and yelling. He noticed Ms Gamble holding the gazebo down and the fabric roof was flapping around. He then looked over his right shoulder and observed the jumping castle 10 metres high in the air and "probably 15-20 metres" towards the middle of the School oval.[73]
Mr Monte and Mr Barrett ran after the jumping castle. Mr Barrett noticed the jumping castle and the zorb ball arena spiralling in the air while he was running. As Mr Barrett was running, the zorb ball arena came down and hit Mr Monte and the wind knocked Mr Barrett to the ground and he was also hit by the zorb ball arena.[74] The zorb ball arena came back to the ground, and "came around again but I managed to duck it. Then I got up and started running after the castle again."[75]
Mr Barrett described how the jumping castle was going "around and around but further towards the outside of the oval."[76] The jumping castle touched the ground "for a little, for a split second" and that is when the children fell out of the jumping castle, and then the jumping castle went back up.[77] Mr Barrett was directed by Mr Monte to see whether there were any children remaining inside the jumping castle once it landed. He checked and noted there were no children remaining inside the jumping castle. Mr Barrett noticed the zorb ball arena landed in "one of the trees."[78] Upon walking past the original position where the jumping castle had been erected, Mr Barrett noticed one of the jumping castle pegs still in the ground, along with a folded out piece of metal.[79] What he saw is consistent with the photograph which is depicted at page 41 of Court Book Volume 2.[80]
LW, a student, in her record of interview conducted on 21 December 2021 says,[81] she was at the volleyball area when she felt a big gust of wind which knocked over the volleyball net. Her friend was unable to pick it back up because the wind was too strong. She said:

[178]

Dr Nicholas Earl-Jones gave expert evidence on behalf of the prosecution. He was the only weather expert to give evidence in this case. He was eminently qualified to do so.[103] His expertise and evidence was not disputed. Dr Earl-Jones and his colleague Mr Ben Weeding provided a detailed meteorological report dated 15 December 2022[104] (the report) and Dr Earl-Jones provided an undated supplemental proof of evidence, which was served on Ms Gamble's legal representatives on 1 November 2024.[105]
Dr Earl-Jones says in the report the evidence he reviewed by way of witness statements[106] suggests a tornado like feature although he says an actual tornado would be impossible given the weather conditions. In addition he says the weather conditions, together with the local nature of the extreme winds and evidence of other dust devils in the area, by which he refers to evidence from the Devonport airport,[107] indicate that a dust devil was the only realistic possibility.[108] He was "absolutely certain" that this Wind Event was a dust devil.[109]
As to wind speed the report says "[i]t is almost impossible to accurately measure the speed within a dust devil...as dust devils are very small and the wind speed within varies greatly in time and space, and from one dust devil to the next." However Dr Earl-Jones estimated that wind speeds can reach 100 km/h or faster and that "the Devonport dust devil would have been at least 60-80 km/h."[110] He goes on to say "[i]t was not the speed of the winds however which is what provided the lift, but the pressure drop in the middle of the vortex, which is up to 1000 Pa... lower than the immediate surrounding atmospheric pressure. This had the effect of sucking the inflatables into its centre of the dust devil and up off the ground in the associated updrafts."[111]
Based on the eyewitness statements, the direction of travel of the inflatables and the direction of the sea breeze as it moved over the School grounds Dr Earl-Jones concluded the dust devil was travelling from the north-west of the oval, from the school car park, parallel to the direction of the sea breeze, which was moving over the area from the north-west. He says the dust devil then moved across the oval to the eastern side of the oval in an east - south-east direction. It is likely to have dissipated in the trees to the east of the school as dust devils need a constant source of heat/energy to be maintained or it moved along the sea breeze towards the south-east.[112] In addition he says the dust devil is likely to have formed at a point at which the north westerly winds from the sea breeze met the southerly winds from the synoptic flow which he says Devonport experienced throughout the morning. He says there are many different land use types in the vicinity of the school such as the hot asphalt car park and nearby wooded areas and this could have triggered the intense convection and updrafts which formed the dust devil.[113]
In the report Dr Earl-Jones says:

[188]

In his supplemental proof Dr Earl-Jones says the winds of the dust devil would not have been coming from a single direction. They are very chaotic and variable as it pulls in the air around it. "The dust devil would likely have pulled air underneath the jumping castle."[126]
In his evidence Dr Earl-Jones said dust devils form when there is a huge temperature contrast "between the surface and higher up" causing a "big temperature contrast" similar to boiling a pot and "the bubbles" come up. The air is warm below which rises and if that air becomes "disturbed then it can start spinning and um that can form a dust devil which then sucks in the energy from around it" as it pulls in air from around it.[127] If there is cooler air around the dust devil, the energy it gains is "from that bottom half a metre, above the surface". The scale is "very small" between one metre diameter and the biggest is 50 metres in diameter.[128] The dust devil moves around picking things up and it moves to different heat sources[129] and once it moves to cooler ground, it loses energy, such as when you have trees creating shade on the ground.[130] If the dust devil collects no debris, it is invisible.[131] Exhibit P95 demonstrates the lifecycle of a dust devil.
Dr Earl-Jones said that the conditions that give rise to a dust devil are predictable however whether a dust devil will form in these conditions is "very unpredictable."[132] A video taken in America in 2023 or 2024[133] demonstrated a jumping castle being lifted into the air vertically rather than horizontally and how localised the dust devil was because only metres away, there was no wind visible at all.[134] This exhibit demonstrates how powerful and destructive the vertical suction force of a dust devil can be.
Dr Earl-Jones referred to an article in his report[135] which noted that between 1 January 2000 and 31 December 2021, there had been 132 reported incidents worldwide involving jumping castles and wind events, which resulted in 479 injuries and 28 deaths.[136] This article and the associated website does not refer to any reported jumping castle incidents involving wind events in Tasmania.[137]
Dr Earl-Jones said with respect to the predictability of dust devils that "[i]t's not completely impossible because they do form- in other parts of the world...at certain types of times of day... scientists have studied these in places like ah the Arizona desert where the conditions are very often ideal for the formation of dust devils...in that kind of situation they can be predicted. But in Devonport it's impossible to predict a dust devil in my opinion, with any kind of accuracy."[138]
Dr Earl-Jones said in evidence that at 10:00am on 16 December 2021, north westerly winds from the sea breeze met southerly wind from the background weather conditions at that boundary and it was at that boundary the dust devil formed.[139] A dust devil forms when the:

[190]

Dr Earl-Jones was of the view the thermal "gained energy from the large tarmacked road in front of the school as it was coming from the north west and um and of the carparks in the er associated with the school."[141] Dr Earl-Jones said the dust devil travelled from the carpark, travelling northwest which was parallel to the sea breeze and then it dissipated in the trees,[142] gaining energy from the dark tarmac of the carpark which "would've been very warm um compared to the other areas around it so that would've had lots of... energy, lots of heat energy and it would've sucked in that energy and that would've given the dust devil a boost."[143]
Dr Earl-Jones estimated the speed of the dust devil moving along with the sea breeze was approximately 10 - 20 kilometres per hour.[144] As to the wind speed inside the dust devil, Dr Earl-Jones said it is "very difficult to estimate" because dust devils are "highly variable" and "vary along their own life cycle" and "vary between dust devils". Dr Earl-Jones said, consistent with his report, "people have measured within dust devils, um I believe around 60 to 80 kilometres an hour" which is described as a "pretty typical um wind speed within the dust devil itself".[145] He said it is impossible to estimate how far the dust devil actually travelled[146] however it's duration was likely short because there is evidence of "multiple dust devils on this ah sea breeze front, so I believe that this specific one um is likely to have dissipated after ah leaving the school oval."[147]
Dr Earl-Jones said it was hard to say how the dust devil picked up the amusement devices because he had not seen a video of this particular dust devil however its scale may have grown once it got onto the oval because it "would've got some energy from that dry hot area. So it could've been metres across [in diameter]. So yeah technically it could've picked up both" the zorb ball arena and jumping castle.[148] The dust devil was a chaotic system moving along the sea breeze and to where the source of energy was so it would pick up some things and not others and so while it travelled the 75-metre distance across the School oval, the dust devil could have picked up both the jumping castle and zorb ball arena which he noted was implied from the witness statements.[149] Over that journey, the dust devil would gain energy, lose energy and regain energy again. This explains some of the evidence that the jumping castle was observed to come back down to the ground before rising into the air again.[150]
Dr Earl-Jones said if an anemometer was available at the time, it would have read light southerly winds and then as the dust devil and sea breeze front approached, air would have sucked into the anemometer, sending it into chaos and it too would have likely lifted with the dust devil if it was not tied down.[151] He said that an anemometer would have been "useless in the circumstances."[152]

[407]

Mr Chen said the photograph of the jumping castle and accessories[296] included in East Inflatables s155 response depicted the same accessories provided with the E2-030 jumping castle.[297] He clarified that the E2-030 jumping castle came with an average four (4) to eight (8) pegs:[298] "in general, we provide four to eight pegs, uh it depends, uh it varies between customers. Some customers would like to purchase some more".[299] When asked when four pegs would be provided instead of eight, Mr Chen confirmed that "usually if it's below 20 square ah metres, it will be four, and over will be eight."[300] When asked specifically how many pegs would be provided with the E2-030 model, to which the interpreter clarified "So - so, do you mean like how many pegs were anchored?."[301] Before a response was provided, Mr Chen said "I think it would be eight, should be eight."[302]
Mr Chen said the dimensions of the pegs supplied are "roughly the same" as those shown in the photographs[303] provided with East Inflatables' s155 response.[304] When asked if at November 2015, East Inflatables supplied 300 millimetre by 10 millimetre J-shaped pegs, Mr Chen said "because it's been 10 years, a while, but now we use the seven - 47 centimetre one".[305] However East Inflatables' s155 response to WorkSafe represented eight 47 cm pegs were supplied with the purchase of a E2-030 Jumping Castle from which the inference is drawn that these pegs were supplied to Ms Gamble.[306]
Mr Chen confirmed the quality assurance examination (QA) on the jumping castle[307] was performed by a production manager by the name of "Jack"[308]. He accepted in cross examination that the date of the QA document was 15 November 2015 and that was the order date.[309] Mr Chen said that the QA included checks for sewing and reinforcement to ensure the product is "strong enough and can endure longer."[310]
East Inflatables s155 response provided test results with respect to European Standards.[311] Mr Chen also gave evidence that East Inflatables "produce our product in Australian Standard."[312] I do not accept this evidence given the evidence of Mr McDonald and Professor Eager that Ms Gamble's jumping castle did not comply with the Australian Standards. Mr Chen was cross-examined about whether a screen shot shown to him demonstrated the homepage for East Inflatables as at 19 September 2015[313] to which he responded, "...it seems like the one because that's the internet order IT Department, but for me, it seems like the one."[314] When asked whether sales representative "Fiona" of East Inflatables was authorised to represent that the E2-030 jumping castle model complied with Australian Standards, Mr Chen reiterated that "we produce the product according to Australian Standard".[315] Mr Chen eventually conceded that East Inflatables did not perform or arrange for their products to be tested or assessed to confirm they comply with Australian Standards.[316]
Mr Chen said "Fiona" from East Inflatables was using her private email to correspond with Ms Gamble when "Fiona" offered to amend the tax invoice to enable Ms Gamble to avoid paying tax in Australia.[317] Mr Chen later confirmed in answer to a proposition that "Fiona" was negotiating with Ms Gamble regarding the dry slide sold by East Inflatables that "So, ah generally we just - we will say if they can get order and then we will produce the product". This is in stark contrast to "Fiona's" email representations to Ms Gamble.[318]

[743]

Mr Monte gave evidence that on 16 December 2021, he picked up the trailer from Ms Gamble's home at 6:30am and drove to Devonport arriving at approximately 7:45am. Mr Monte walked around the School to find someone to plug in power for the Amusement Devices. He unpacked equipment and put out the power leads when Ms Gamble and Mr Barrett arrived at the school.[527] Mr Monte and Mr Barrett pegged down the jumping castle and zorb ball arena.[528] Mr Barrett and Ms Gamble inflated the zorb balls, and Mr Monte inflated the zorb ball arena. Mr Monte and Mr Barrett undid the straps and unrolled the jumping castle, opening the two halves up, did up the zippers and attached the blower. The jumping castle was blown up, positioned, and let down again before being pulled taut and pegged to the ground.[529] Mr Monte hammered in two pegs to anchor the jumping castle and Mr Barrett hammered in another two pegs.[530] Mr Monte inserted the pegs on the left side of the jumping castle, as he faced it, at points "C" and "E" identified on Exhibit P78,[531] and Mr Barrett hammered the pegs on the right side.[532] Mr Monte inserted at least one j-shaped peg[533] at the front left side of the jumping castle.[534] Mr Monte said he hammered in a peg similar to the one contained at photograph 545[535] which was described as a folded down peg on the back left side of the jumping castle.[536]
Mr Monte gave evidence that he ensured the ground was firm to support the weight of the jumping castle,[537] there were no drainage issues,[538] the ground was suitable to hold the anchoring system,[539] there was adequate clearance between the jumping castle and buildings, trees and powerlines,[540] and there was safe access for participants and emergency vehicles.[541]
The pegs inserted to secure the jumping castle were described by Mr Monte as "mixed" and approximately 300 mm in length.[542] He said the ground surface of the School's oval was "incredibly hard".[543] Mr Monte said that because the ground was incredibly hard, it made it difficult to insert the pegs at an angle.[544] The pegs were therefore hammered into the ground near vertically and flush to the ground.[545]
The zorb ball arena was secured with six pegs of a similar shape and size as the pegs used on the jumping castle.[546]
When Mr Barrett arrived at between 8.30am and 9.00am, he assisted Mr Monte unstrap and remove the Amusement Devices from Mr Monte's trailer and the tray of his ute.[547] Mr Barrett and Mr Monte unfolded and pulled the corners of the jumping castle, dragged it into position and started to inflate it with a big fan.[548]
Mr Barrett said in evidence the jumping castle tethers were pulled "taut", and four pegs were hammered into place on four of the eight tether points of the jumping castle by both Mr Barrett and Mr Monte.[549] Mr Barrett hammered pegs at points marked "G" and "H" on First Class Constable Wotherspoon's plan of the jumping castle (Exhibit P78).[550] Mr Barrett said he hammered a J-shaped peg and another "sort of folded down style hook"[551] peg through the D-rings on the jumping castle[552] and hammered the pegs into the ground using "a big mallet hammer."[553] Mr Barrett confirmed he pulled the anchorage ties of the jumping castle taut before hammering the pegs in.[554]
Mr Barrett also assisted with unfolding, moving into position and inflating the zorb balls and zorb ball arena, as well as setting up and securing the gazebo.[555] Mr Barrett confirmed the pegs with "folded down type ends" were used to secure the zorb ball arena and were the same length as the jumping castle pegs.[556]

[759]

The evidence of Mr Monte and Mr Barrett together with the evidence of First Class Constable Wotherspoon, who inspected the scene after the Wind Event, establishes only four anchor points using pegs hammered into the ground through a D ring attached to the jumping castle were used to anchor the jumping castle to the ground. The pegs used were two J shaped pegs which were 300mm long and had a diameter of 11.9mm and two folded V shaped pegs which were 345mm long and which had a diameter of 11.1mm.[573] They were inserted into the anchorage points at locations shown at C, E, G and H on P78.
In addition AS3533.4.1-2005 required that "each anchorage point on the inflatable and its stake or stakes shall withstand a minimum horizontal force of 1.6kN."[574] All but one of the pegs[575] tested by GeoTon, including three of the pegs used on the day to anchor the jumping castle, were found to be able to withstand the minimum horizontal force given the manner in which they were hammered into the ground on the day; that is the full length of each peg was hammered into the ground at near 90 degrees to the angle of the peg.
Mr McDonald advised the pegs used on 16 December 2021 were not compliant with the Standard because they were not 16mm in diameter[576] and not compliant with the manufacturer's instructions because they were of a mixed configuration (J and V pegs), nor was there a consistent approach to the set-up, that is Ms Gamble varied the pegs used from site to site.[577] However, he noted that there were some star pickets with carabiners in the toolbox on the back of the trailer, which was at the School, that were compliant with the Standard.[578]
Australian Standard AS3533.4.1-2005 dealing with anchorages also specified "[t]he anchorage system shall be designed so that the anchor ropes or straps are secured in a manner that prevents the device lifting off the ground."[579]
Mr McDonald said in his evidence there are a number of mechanisms associated with preventing lift in a jumping castle. The key one is "putting in anchorages" at all; and the other is related to the process and sequence of installation of the anchorages. As to this Mr McDonald specified that by laying the inflatable out in a deflated form and stretching the anchorages, inserting the pegs then (lastly) inflating the jumping castle creates tension within the bottom membrane of the castle and the anchorages. This changes the mechanism as to how the anchorages are loaded and helps to hold the castle down.[581]
The evidence is that on 16 December 2021 two anchorage pegs were inserted before the jumping castle was inflated to put it into position and then two anchorage pegs were hammered in after the jumping castle was inflated.[582] The effect of anchoring the inflatable after it was inflated means that, according to Mr McDonald "you wouldn't have that tension within the straps, and you're at risk of bringing... your anchorages into a vertical load pattern. So, part of the key to how you prevent lift is actually the installation or erection of the castle."[583] Mr McDonald has however proceeded on the basis of the Tasmania Police report regarding the order of installation which was the jumping castle was laid out, it was inflated and then anchored.[584] This is at variance with the evidence.
Further Mr McDonald said had all eight anchorages been used in the configuration provided by the manufacturer, then if the castle had been inflated correctly (i.e. the tension in the straps) then that would have prevented lift considering the wind loads within the Standard.[585] Mr McDonald was of the view the anchorage system in use on 16 December 2021 was not suitable because the method of installation did not provide the necessary tension and that the failure to anchor each face by anchoring the two sides left the front edge unrestrained and that, consequently, "the whole front of the mattress... can lift. There's nothing actually holding it"[586]
Mr McDonald's evidence was that the configuration of the anchorage on the jumping castle on the day, namely at C, E G and H (Exhibit P78) meant that the face that represents G and H would probably be reasonably secure, but the back, left and front sides would not be secure. The effect of his evidence on this point was that the anchorage system used on the day meant three of the four faces of the jumping castle were unsecured.[587]
Paragraph 6.2(i) of AS3533.4.1-2005[588] provides "[a]nchorage systems shall be consistent...". Mr McDonald said this means the same system was to be used each time. He said that the instructions from the downloaded manual, which is the 2 page manual Ms Gamble downloaded from the East Inflatables website, to "Locate all of the tie down straps on the bottom of the unit...., Extend the strap drive the provided stakes through the ring at the end of the strap"[589] conformed with the requirement to be 'consistent and reproducible' and the manufacturer's instructions did not allow for any deviation in the application of the anchorage system.[590] He reviewed material related to how the anchorage system was implemented by Ms Gamble and concluded she did not comply with AS3533.4.1-2005 as there were inconsistencies in the installation of the anchorage system, as installation depended on the weather and the retention pegs used were mixed up quite a bit. Different anchorage systems were devised and used on different occasions.[591]
Part 6 of AS 3533.4.1 is very specific regarding the anchorage system. Mr McDonald says the anchorage system:

[762]

In addition Mr McDonald says part 18 of AS3533.4.1-2005 titled 'Operation' provides if the manufacturer's anchorage system is not suitable for use, for example the instructions are incomplete or the equipment is non-compliant, then the device is not to be used until appropriate direction has been sought from the manufacturer or a competent person has assessed and advised on the system.[593]
The evidence of Ms Gamble contained in the response to the s155 notice and Mr Monte's evidence was to the effect that she did not receive any manuals and she only received four pegs when she received the jumping castle from East Inflatables. The evidence of East Inflatables was there was a one page manual specific to the E2-030 jumping castle which indicated it had eight tie downs which "must be either staked to the ground with at least a 45cm long stake...", and that this manual was available at the time the jumping castle was purchased by Ms Gamble and could be sent electronically. However, this was not obtained by the defendant who only downloaded a two page manual from the website.[594] Interestingly on this point the one page manual[595] which I have found Ms Gamble did not receive talks about using 45cm stakes whereas the response of East Inflatables to the s155 notice says each stake or peg is 47cm.[596]
In any event, Mr McDonald was of the view that the manufacturer's instructions (based on the two page downloaded manual) required pegs to be driven through all the tie down locations that had been identified, and that the jumping castle had been designed, in accordance with the Standard, to have two anchorage points at each corner. However, Ms Gamble did not follow those instructions as she oversaw a system on the day where only four pegs were inserted into the anchorage points at C, E G and H depicted in Exhibit P78. The prosecution questioned the reasonableness of Ms Gamble's interpretation irrespective of her assertion she was only provided with four pegs, given the obvious eight anchor points on the jumping castle, and the fact that she did, on other occasions, peg all eight anchor points. This is to be contrasted with the evidence at paragraphs 210 to 213 including that of Mr McDonald.
Further, it is apparent those instructions were open to different interpretations, so in the absence of clear instructions, Mr McDonald says it was incumbent on Ms Gamble to engage a competent person to advise her on the appropriate anchorage system. This is discussed in more detail below.
Mr McDonald says the effect of the anchorage system in place on the day was that it was inadequate to address the lateral load requirements under the Standard and it did not secure the leading edge on three of the four faces of the jumping castle. This enabled air to infiltrate the mattress and put the jumping castle into vertical lift, which was the configuration which offered the least retention capacity for the pegs that were in use. Those pegs were themselves not compliant with the Standards or the manufacturer's instructions.
Mr McDonald also considered the requirements Section 13 of AS 3533.4.1-2005 imposed on the manufacturer and supplier in relation to information they are to provide. He compared the three manuals that were said to be in existence at the time, namely the downloaded manual (two pages), the E2-030 specific manual (one page) and the generic manual (13 pages).[597] Each of the three manuals contained instructions about the method of anchorage and the number of anchorage points. In particular he concluded that each of the manuals provided that each of the tie down straps were to be staked - see Exhibit P112 (CB V5 p52).[598] The one page specific manual contained instructions to use eight pegs and specified that the pegs to be used were to be 45cm in length.[599] Further, Mr McDonald said none of the three manuals provided for an alternative staking set up.[600] He concluded that all three manuals were deficient in the provision of information in respect of certain elements of Section 13.[601]
Section 17 of AS 3533.4.1 provides:

[767]

This Standard also requires the device to be set up in accordance with "the manufacturer's instructions with all device anchor points connected to ground anchor stakes in the correct positions. Where the manufacturer's instructions are not clear or cannot be complied with, the anchorage system shall be designed by a competent person."[605]
In addition AS3533.1-2005 requires that ground stakes be installed in accordance with the manufacturer's instructions and they are to withstand a horizontal force of 1.6kN, that weather conditions are continuously monitored and the use of an anemometer is recommended.[606]
Mr McDonald advised the manufacturer's instructions Ms Gamble downloaded from the website contained the key information regarding anchorage but it was not a complete manual. He said that if there is a risk that the information was ambiguous or incomplete then the Standard required the operator to consult with a "competent person" and he stressed the importance of using someone who understands the requirements of the Standard (locally), within the local environment and with the people who are using the device.[607]
Mr McDonald indicated if there is reinterpretation, redesign or modification of an engineering control system, such as what anchorages should be used, a "competent person" needs to be someone of a similar competence to a designer and in Australia that is seen as being a tertiary qualified engineer. He said there were 26,000 mechanical engineers alone in Australia and he expected the cost of an engineer conducting an investigation and providing the necessary advice to be in the vicinity of $1,000-$2,000 on 2020 rates.[608]
Mr McDonald also reviewed AS3533.2-2009 which covers operations and maintenance with respect to amusement rides and devices.[609] In relation to organisational arrangements and planning Mr McDonald advised it was difficult to discern any consistent policies and procedures of Ms Gamble which were invariably applied, adhered to and undertaken at each hire, set-up, operation, dismantling and storage of the jumping castle.[610] He reviewed some of the risk assessments Ms Gamble had undertaken and acknowledged she had identified wind as a hazard and she had imposed a limit of 25kph which was lower than that required in Section 6 of AS3533.1-2005.[611] However she did not have a system for monitoring wind speeds and she did not use an anemometer.[612] Further in one assessment the defendant had identified the use of star pickets (there were several located in the toolbox on the trailer on the day of this incident) as a control measure to address the hazard of wind. However, the lack of consistency of practice meant that the control measure was not adequately implemented and therefore it cannot be said that the risks posed by wind had been adequately addressed.[613]
In addition Mr McDonald was not satisfied Ms Gamble adequately addressed the requirement in AS3533.2-2009 to train workers.[614] In particular, he found no evidence from the material supplied to him of training records or procedures. This, combined with the numerous examples of non-compliance with the Standards, led Mr McDonald to conclude Ms Gamble was not competent to train the staff as they were consistently inconsistent with everything: "[t]here's no consistency in anchorage, there's no consistency in knowing what the wind speed was, there's no consistency in the number of patrons. There's no evidence of things like ...practising the emergency evacuation." His conclusion therefore was there was insufficient training of staff.[615]
Mr McDonald also noted from the evidence supplied to him that it was highly likely that a copy of the instructions developed in accordance with Section 3.1(a) and (c) of AS3533.2-2009[616] were not available at all times to the workers. He also concluded that there was evidence pegs had been previously damaged and replaced and the replacement pegs did not match the specifications of the manufacturer or the jumping castle's design, and that the defendant was not competent to change the system in so far as it related to the pegs used.[617]
Mr McDonald was asked a number of questions in the letter of instruction he received from WorkSafe Tasmania which he addressed at p168 onwards in his report.[618] In particular, he examined the three versions of the manufacturer's instructions and concluded there had been critical non-compliance by Ms Gamble in respect of the jumping castle, in so far as it related to the pegs used in the anchorage system and the number of pegs utilised (specifically the failure to install eight pegs) on the date of the incident.[619]
Mr McDonald was also asked whether the jumping castle complied with the relevant Australian Standards at a component level; that is the fine detail of the pegs, anchorage, the material it was made out of, corner stitching, the size of the emergency exit and the like.[620] The main areas where there was non compliance on the day of this incident with AS3533.1-2005, related to design and manufacture, and were in respect of anchorages; that is the supplied stakes did not comply with the Australian Standard's requirement that they be of a diameter of 16mm, nor did the anchorage system used by Ms Gamble on the day, comply with the requirement to install eight pegs in accordance with both the manufacturer's instructions and the Australian Standards.[621]
There were also a number of non-compliance issues related to the deficiencies in the information to be provided by the manufacturer, supplier or "competent person".[622] Mr McDonald said if information is missing then you go back to the manufacturer and if you still fail to obtain the necessary information you engage a competent person. He said a competent person would also be required to advise on information which was incorrect for the Australian context and/or was incomplete. This is to all occur before the jumping castle is used. Accordingly in the absence of receiving an operating manual, Ms Gamble should have made the necessary enquiries to obtain complete, correct and appropriate information before using the jumping castle.[623] In the case of deficiencies, a competent person with engineering qualifications should have been engaged to advise on remedies with respect to the non-compliance issues.[624]
Mr McDonald was asked to determine if Ms Gamble operated the jumping castle, on the day of this incident, in accordance with the relevant Australian Standards. He set out his findings in Exhibit P112 at pages 190 to 193. In evidence Mr McDonald described the deficiencies in the defendant's operation of the jumping castle as "systemic."[625] He made observations of particular failures in respect of AS3533.1-2005 regarding anchorages and operations. Mr McDonald advised that the jumping castle, as set up on the day, was not compliant with the manufacturer's instructions, primarily due to the failure to follow the manufacturer's specification (or the Australian Standard) as to the type and number of pegs used to anchor the jumping castle.[626]
It follows as the set up did not comply with the manufacturer's specifications then Mr McDonald found the jumping castle was not operated in accordance with the manufacturer's instructions, namely to anchor using eight pegs and to use the manufacturer's pegs. Nor had the defendant engaged a competent person, to address the absence of fundamental components and required information.[627]
Mr McDonald was then asked to determine the impact of these failures on maintaining control over a hazard such as wind. In his evidence Mr McDonald explained the hierarchy of controls[628] and identified wind as a hazard in the use of inflatable amusement devices.[629] At pp 201-205 of his report,[630] Mr McDonald says the effect of wind on the jumping castle is an ever-present risk when it is set up outside. During his evidence he acknowledged that in those circumstances wind as a hazard cannot be eliminated, and therefore it is the operator's duty to minimise the risks that are associated with the hazard. He identified that an engineering control was required to restrain the inflatable device. AS3533.1-2005 requires the use of a formula that enables the calculation of wind loads imposed on the jumping castle in order to determine the minimum number of anchorages to withstand a minimum wind speed of 40kph.[631] In this case that was calculated to be eight pegs. Further, the pegs were required to be 16mm in diameter and fit for purpose. This took into account the diameter, peg length, length to achieve penetration into the soil and whether the pegs are "V" or "J"-style pegs or star pickets.[632]
Mr McDonald also noted that continuous accurate local wind monitoring was required and that the use of an anemometer was recommended. He also referenced AS3533.1-2005 Section 18(b) and the requirement for the device to be "set up in accordance with the manufacturer's instructions (in this case eight pegs) with all device anchor points connected to ground anchor stakes in the correct positions. Where the manufacturer's instructions are not clear or cannot be complied with, the anchorage system shall be designed by a competent person."[633] Mr McDonald noted the manufacturer's instructions provided specified that all anchor points (of which there were eight) were to be used and he noted that the documentation provided to him for his review (including Safe Work Australia Amusement Device Operator Checklists and the defendant's completed risk assessments which referenced wind and the use of star pickets), establish Ms Gamble knew wind was a hazard.[634]
Mr McDonald said the installation of the anchorage system on the day of this incident did not comply with the manufacturer's instructions or the Standard and as such it provided significantly lower restraint to wind which he says was effectively half the capacity recommended by both the manufacturer and the Standard. He noted that there was a sequence of failures, the first being that by virtue of the anchorage configuration, the defendant failed to prevent horizontal wind from penetrating underneath the castle which in turn changed the desired loading behaviour of the pegs by changing the load from a horizontal force to a vertical force resulting in the pegs sequential failure.[635]
In addition Mr McDonald says Ms Gamble was not competent to design the anchorage system and by extension, was not competent to make changes to the anchorage system by installing a reduced number of pegs.[636] The effect being that the change reduced the capacity of the engineering control; ie the anchorage system. In addition the anchorage system which she used on this day increased the likelihood of its partial or full failure and as such it could not adequately prevent lift, which likely magnified the potential consequences through reaction to wind gusts or events; namely the dust devil.[637]
The capacity of the changed design of the anchorage system used by Ms Gamble on this day was dependent on relatively calm wind or weather for the duration of the event at the School and/or sufficient warning of a change in wind conditions so she could act if wind increased. However, there was no evidence Ms Gamble continuously and accurately monitored local wind speeds in order to adhere to the identified control to cease operations if the wind speed reached the specified limit of 25kph.[638] This significantly increased the exposure of patrons to the adverse effects of wind.
Finally, the reliance by Ms Gamble and Mr Monte on weather applications meant that the information received was based on regional forecasts that did not account for localised terrain influences on wind.[639]
Mr McDonald concluded by saying Ms Gamble's decision to alter the anchorage system was made without the competence, qualifications, knowledge, training and specific experience of or from a competent person, with the effect that the hazards and risks associated with wind were not properly controlled.[640] He went on to say:

[769]

He expanded on this in his oral evidence and explained that as the anchorage system was already reduced (by virtue of only having half the number of required pegs), this had a bearing on the retention capacity of the existing pegs, which was critical in light of the likely exposure of the castle to the extreme weather event of 1-2 seconds. In particular, if configured properly, there was the potential to minimise the consequences of the Wind Event passing over the jumping castle by the pegs not completely coming out and there not being a total failure of the anchorage system.[642]
Mr McDonald prepared some calculations to determine the point at which the retention of the pegs in the soil started to fail, in other words, the ultimate capacity of this jumping castle if properly anchored.[643] Mr McDonald determined the ultimate capacity of the unladen jumping castle on its front and back face, side faces and underside of the mattress in lift. He determined that at the time the Wind Event occurred the jumping castle was already in lift. In a lift situation, in addition to the forces from the retention pegs, the mass of the inflatable device and the mass of the patrons on board would act against the vertical lift force. Upper and lower measurements were provided for each of these factors to determine that the ultimate theoretical capacity of the E2-030 jumping castle in lift was between 87.1- 100.4kph, noting that this was based on an even loading of all anchor points and pegs and therefore does not consider the load distribution within the jumping castle at the time of the incident which he said is unknown and cannot be accurately estimated. Furthermore he says the structural stiffness of the jumping castle is treated as being even in his calculations. As structural stiffness varies and specifically changes between the jumping compartment and the climb/slide space - he says it is likely that the jumping castle would not lift evenly or in a level manner. Other influencing variables include wind direction, weakest capacity peg, load distribution and structural mass distribution.[644]
Mr McDonald also reviewed the evidence of a lack of peg shaft bending failure and the absence of evidence of hole structural failure, combined with witness accounts of the event to determine that the failure of the anchorage system was due to the defeat of three fundamental serial controls brought about by a significant reduction in the capacity and restraint of the anchorage system in installation. These were 1) the installation of only four pegs which facilitated the infiltration of air pressure under the mattress and activated the risk of device lift, placing the jumping castle into a state of abnormal operation. 2) As a result, preventing full lift was reliant on the anchorage system in place on the day. With only half the required pegs, the retentive capacity of the anchorage system was also halved. 3) Lastly, the pegs used did not have the required capacity under the Standard owing to the pegs having a diameter of less than 16mm.[645] Further the evidence supported a finding that the complete failure of the anchorage system was while it was in vertical lift.[646]
The combined force of the weight of the castle and its patrons and the retention capacity of the four pegs installed on the day meant that the total force acting on the jumping castle to resist lift was between 5256N and 7849N. The minimum pressure required to lift those forces was between 218-333Pa. This translates to a minimum wind speed of between 71-87kph to achieve static equilibrium between lift and restraint.[647]
Mr McDonald advised both the Standard and the manufacturer's instructions specified that eight pegs be used to anchor the device. He then compared, in table 10.9.2 of his report, the retention capacity of the four mixed pegs used on the day, with the retention capacity of eight pegs of the same dimensions as those Ms Gamble says she received, eight pegs which were compliant with AS3533.4.1, eight pegs matching the manufacturer's specifications[648] (J shape, 470mm shaft length, 10mm diameter) and eight star pickets (450mm length, 30mm leg). Had any one of the final three configurations been used on the day, then he says any of those configurations would have had the capacity to resist lift of the jumping castle.[649]
Table 10.9.3 on page 226 of Exhibit P112 illustrates that based on a comparison of half of the same configurations as above (i.e. four pegs only) that only four star pickets with rated carabiners would have had the capacity to defeat the loss of retention of the pegs and lift of the jumping castle.
Importantly, Mr McDonald noted that the above calculations were based on static equilibrium and did not take into account the time exposure of the wind event to the jumping castle.[650] Based on witness accounts (and the evidence of Dr Earl-Jones) it is likely that the wind event passed over the jumping castle in a matter of seconds. Had star pickets been used then they would have had greater retention capacity than other configurations which means that it would take the application of a sustained wind of sufficient force and duration to force a peg from the ground. In circumstances where the exposure to the wind event was fleeting, the use of star pickets potentially could have significantly affected whether failure occurred at all, or the behaviour of failure and the magnitude of potential consequences and harm.[651]
However the actual anchorage system in use on the day, which was significantly under the required capacity, did not have the base restraint strength nor the endurance capability to sustain retention in a dynamic situation.[652]
In summary Mr McDonald concluded that the jumping castle had not been anchored or operated in accordance with the applicable Australian Standards at the time of the incident nor was the jumping castle or its operation compliant with the manufacturer's specifications. In particular, the jumping castle had only been anchored at four anchorage points using non-compliant pegs. Further the configuration of the anchorage system meant that the jumping castle did not meet the horizontal wind load rating which facilitated pathways for air pressure to infiltrate and fill under the jumping castle's mattress providing the impetus for lift. Calculations of wind speeds required in these circumstances to defeat the anchorage system in place on the day showed the jumping castle was likely exposed to wind speeds of 71-87 kph. However had the jumping castle been set up and operated in accordance with the Australian Standards it would have likely had the capacity to withstand speeds of 87.1-100.4kph. Further if star pickets had been used (in fact, the only peg/stake that met the Australian Standard peg specification requirement), as foreshadowed in Ms Gamble's risk assessments, the jumping castle would have likely had the capacity to withstand 109.8-119kph. In his evidence Mr McDonald said he believed that "if the full eight star pickets had been used, it would have endured the event".[653]
In addition Mr McDonald concluded that the reductions in risk controls and the substantial reduction in capacity of the jumping castle anchorage system contributed to this rapid failure and its catastrophic consequences. Further, the anchorage system failure was not instantaneous and had the anchorage system been correctly installed it would have likely prevented complete anchorage system defeat or at least slowed failure of the anchorage system during the short event. The slowing of the failure would have likely resulted in a reduction in the magnitude of the consequences.
In his evidence Mr McDonald said that the (force of the) dust devil was not the failure.

[853]

his explanation for the mechanism of the failure of the anchorage system was not corroborated by witness accounts;
despite his involvement in the development of the relevant Australian Standards he was not previously aware of the University of Illinois tent study, despite it being published in 2004 with a guidebook being available since 2017;
he was clearly sympathetic to Ms Gamble and it was suggested this infected many of his responses in cross examination. In addition his answers were often unresponsive whereby he repeatedly and earnestly justified her actions;
he only spent two hours examining the jumping castle and three weeks working on his report whereas Mr McDonald said he spent 2 ½ days inspecting the inflatable devices and six months preparing his report;
he was an academic with little or no practical experience in applying the Australian standards to the inspection of inflatable amusement devices;
Mr McDonald was eminently qualified to give his opinion on the failure of the anchorage system of the jumping castle given his many academic qualifications and memberships and relevant practical experience applying the Australian standards to the inspection of inflatable amusement devices; and
Mr McDonald was an impressive witness who was measured and gave his evidence impartially. His evidence was coherent and considered and his opinion was based on clear reasoning.[709]
As to the first, sixth, ninth and tenth reasons I take the view Professor Eager was very passionate about the engineering aspects of this case and he put his views across forcefully. He clearly believed in his hypothesis and where he disagreed with what was being put to him he unequivocally and clearly said so. This is demonstrated in his very thorough cross examination by Mrs Wilson SC whereby she sought his agreement with Mr McDonald's hypothesis that all the "significant Wind Event" did was amplify what occurred after the anchorage system had already failed.[710] In my opinion this does not mean Professor Eager lacked impartiality. In any event the methods used by factfinders to resolve conflicts in evidence given by lay witnesses such as the manner in which a witness gives his or her evidence and demeanour do not help when resolving conflicts between experts. In this case the opinions of the experts are directed towards issues which assist in the determination of Ms Gamble's guilt. In such a case I am only permitted to accept Mr McDonald's opinion to the exclusion of Professor Eager's opinion if I am satisfied beyond reasonable doubt that Mr McDonald's opinion is correct. Authority for this proposition is the decision of the Victorian Court of Appeal in R v Anderson [2000] VSCA 16 where the Court said at [61]:

[855]

This decision was recently followed in R v AN; R v LM [2022] NSWSC 776[711] which is a case which concerned a conflict between experts as to the cause of death of the victim. In addition "in exceptional cases, I may be incapable of resolving a conflict between experts on matters of science. If the conflict relates to an area where I cannot resolve that conflict in a manner which would eliminate reasonable doubt, the accused must be acquitted: Velevski v R (2002) 187 ALR 233; [2002] HCA 4; Ussher-Clarke v R [2018] NSWCCA 61."[712]
Insofar as the second reason is concerned Professor Eager said that in determining the cause of the failure of the anchorage system he first looked at the hypothesis that lateral forces lifted the jumping castle but he did not think that was the cause. He thought there must be some other way and that is when he looked at the possibility of the dust devil lifting the jumping castle and he used his expertise in engineering to explain the mechanics of the failure by reference to calculations relating to the force of the dust devil and how that operated on the anchorage system.[713] Hindsight reasoning which is the basis of the criticism of Professor Eager appears to have been the same process which Mr McDonald used to inform his opinion as to the wind speed of 71 km/h - 87 km/h which led to the failure of the anchorage system.[714] He has started with the failure of the anchorage system, he has noted the configuration of the pegs which were used, the forces resisting lift namely the mass of the jumping castle and the patrons using it, the retention strength of the various pegs, relying on the GeoTon report, and the pressure required to lift the jumping castle, patrons and the pegs. He has then performed a calculation to determine the minimum wind speed, in the range of 71 km/h - 87 km/h, which he says would have led to the failure of the anchorage system. In my experience experts quite often start with the result and work backwards using all the available evidence in order to form an opinion as to the cause of the event which is being examined. I do not criticise either expert for working in this manner.
In relation to the third reason there appears to be a reference to the one page manual[715] in Professor Eager's report.[716] It is referenced at page 147 and in appendix A at page 148 in the schedule of documents attached to the second letter of instruction dated 26 June 2024 at document number six. He said in evidence[717] though he had never seen it and there were a number of photographs he did not think he had seen. If one looks at appendix A to his report and the schedule of documents contained in the letter of instruction of 15 June 2022 and those in appendix A to the letter of instruction of 26 June 2024 and those in appendix B to the letter of instruction of 27 August 2024 then the following items refer to photographs provided to him: item 1 in the first letter, items 1, 31, 34, 52, 54, 125, 140, 142, and 144 which appear in appendix A to the second letter and items 2, 3, 4, 5, and 6 which appear in appendix B to the third letter. On the assumption the photos were sent he has examined a large number of photos. It is not clear to me what photographs he has not seen or if he has seen all the photographs in evidence. If Professor Eager has not seen the one page manual, and it is not clear from the evidence whether that is the case, then in my view this makes no difference to his opinion. That opinion is essentially based upon the two page manual which is the only manual I have found Ms Gamble had access to. I cannot make any assessment of the effect on Professor Eager's opinion of him not considering some photographs when it is not clear to me whether he considered them all and if he did not which ones he did not consider. I can say from considering his report that it appears he has considered the photographs relevant to his opinion. I therefore conclude there is no substance to this criticism.
As to the fourth reason Professor Eager said in evidence the effect of the dust devil resulted in the repeated twisting and releasing of the jumping castle like it was a coiled spring and it would have been violently fluttering. He accepted that there was no eyewitness account which corroborated the movement of the jumping castle in this way.[718] The evidence of Ms Shepherd was discussed with Professor Eager in relation to this issue. She described the jumping castle as "all crumpled and mixed up" but it was put to Professor Eager this was not the jumping castle because she described the inflatable device which she saw as blue and the jumping castle was not blue. It was suggested what she saw was the zorb ball arena because that was blue. Professor Eager attempted to reconcile this discrepancy by deducing Ms Shepherd either got the colour of the jumping castle wrong or she did not observe the jumping castle but instead what she observed was the zorb ball arena. However if one considers her statement carefully the conclusion I have come to is that the device she observed in the air was the jumping castle because she goes on to say she saw a child fall out of the jumping castle while it was in the air. The evidence is a boy fell from the jumping castle and no child fell from the zorb ball arena. I therefore conclude the device which Ms Shepherd observed was the jumping castle although she was wrong about the colour. Having said that both Mr Boutcher and Ms Brown also describe the jumping castle as blue[719] and parts of it are in fact blue.[720] Ms Shepherd's description of it being all crumpled and mixed up is not inconsistent with the jumping castle repeatedly twisting and violently fluttering. There is also evidence from other witnesses as to the jumping castle lifting straight up and spinning, twirling and twisting while in the air.[721] This criticism does not affect the veracity of Professor Eager's opinion.
There is no substance in the fifth criticism of Professor Eager's opinion. Professor Eager is specifically asked about that study, which he refers to in his report, during cross-examination.[722]
In relation to the seventh criticism it does not follow, without more, that because Professor Eager spent less time than Mr McDonald in examining the jumping castle and preparing his report that Professor Eager's opinion is wrong or that Mr McDonald's opinion ought to be preferred.
As to the eighth reason while it is clear Professor Eager is indeed an academic the evidence discloses he has vast practical experience including experience in the impact of wind in dynamic circumstances upon structures including amusement devices.[723] This, given his background of being on the committees responsible for numerous standards including AS3533.4.1.2005,[724] would include the practical application of the relevant standards. Professor Eager also has some patents[725] which implies the practical application of relevant standards.
In so far as Mr McDonald's opinion is concerned I note he said in evidence he chose not to rely on the contents of Dr Earl - Jones' report because he only had a preliminary version of that report when he produced his own report.[726] Dr Earl - Jones was the only meteorological expert called to give evidence at the hearing of this Complaint and his opinion was not challenged. Unlike Dr Earl-Jones, Mr McDonald is not a meteorological expert and therefore, given s79 of the Evidence Act 2001, he is not able to provide an admissible opinion with respect to the direction, force, nature and characteristics of the dust devil. He has no expertise in meteorology, specifically wind, which is outside his field of specialised knowledge and training.
Mr McDonald's opinion as to the cause of the anchor failure[727] is provided in response to the following question:

[858]

Mr McDonald said the calculations he performed in this section of his report,[730] and on which his opinion was based, were qualified[731] as his "...calculations represent the theoretical ultimate capacity and configuration..." based upon the requirements of AS 3533.4.1 and assume an "...even loading of all eight anchor points and pegs...". He also said "...the structural stiffness of the jumping castle is treated as being even in the above calculation" but that "...it is likely that the jumping castle would not lift evenly or in a level manner". He noted "other influencing variables include wind direction, weakest capacity peg, load distribution and structural mass distribution."
Although Mr McDonald accepted that the wind event was a dust devil[732] he said, contrary to the evidence of Dr Earl-Jones, that it was horizontal forces that put the jumping castle into lift.[733] Further in his evidence Mr McDonald advised references to wind speed in his report[734] were to horizontal wind speed,[735] which, on his analysis, caused the "lift" by horizontal wind entering underneath the leading edge of the jumping castle. The initial failure of the anchorage system was caused by the entry of horizontal wind under the mattress which put the jumping castle into lift. This was prior to the vertical suction forces of the dust devil acting upon the jumping castle.[736] That is the anchorage system had already failed before the dust devil was over the jumping castle.[737] The difficulty with this theory is that it does not appear anywhere in Mr McDonald's very thorough and lengthy report. It only came to light during his evidence. It was not suggested to be his evidence in the DPP's opening however it became his position in closing submissions.[738] It is difficult to accept this theory bearing in mind it was Mr McDonald's evidence that it only took 1-2 seconds for the anchorage system to fail and for the jumping castle to become airborne.[739] His opinion ignores the likelihood of dynamic suction forces, as distinct from static horizontal forces, having anything to do with the loss of retention. Having said all of that Mr McDonald went onto concede:

[876]

Therefore according to Dr Earl-Jones it is not the speed of the winds but the pressure drop in the middle of the dust devil which sucked the jumping castle into its centre and up off the ground.
Mr McDonald's opinion also appears to be based upon the order of installation reported by Tasmania police that being the castle was laid out, it was inflated and then anchored. He says if you do it the other way around by laying it out, stretching it out, anchoring it and then inflating it you tension the bottom strap which pulls the pegs horizontally. The first method produces slackness in the strapping which enables air to infiltrate under the mattress which puts the castle into lift and allows the straps to pull vertically.[748] The evidence however is that the straps were pulled taut before the pegs were hammered in and therefore there was no slackness which would enable air to infiltrate under the mattress which puts the castle into lift.[749]
In addition there was criticism by the DPP that "significant aspects of Dr Peiris' evidence were not put to Mr McDonald."[750] The reason for this was, as explained by counsel for Ms Gamble in his submissions in reply, because Dr Peiris' evidence related to the application of vertical wind force, relying on the opinion of Dr Earl-Jones, which was a completely different mode of failure to the opinion expressed by Mr McDonald. Mr McDonald's opinion was that horizontal wind caused the anchorage system to fail before the dust devil arrived, that is "before the dust devil commenced its vertical suction on the jumping castle."
The DPP also submitted Dr Peiris' calculations were simplistic and they do not engage with Mr McDonald's opinion that the anchorage system failed before the weather event.[751] Just because these calculations were characterised as simplistic does not mean, without more, they were wrong. While the mathematical calculation or process is not difficult the calculation of the various components of the equation is not simplistic. In any event Dr Peiris was not challenged on his calculations and he included an analysis of Mr McDonald's upward and downward force figures bearing in mind Mr McDonald's position is the horizontal wind had already caused the anchorage system failure. When applying a dynamic force which was agreed to be 5 to 7 times greater than a static force Dr Peiris' calculations were not inconsistent with Professor Eager's view that 50 to 74 pegs would not have held the jumping castle down.
The final point to mention is the anchorage system consisting of the pegs did not entirely fail. One peg remained embedded in the oval. It was the D ring which was attached to that peg which catastrophically failed.
For the reasons expressed in paragraphs 388 to 436 I am not satisfied beyond reasonable doubt that the anchorage system failed because of the application of a horizontal wind force prior to the dust devil commencing its vertical suction on the jumping castle. The evidence does not permit me to exclude, as a reasonable hypothesis, the possibility that Professor Eager's opinion is correct.

[879]

There are a number cases which have discussed the nature of offences such as the charge in this case which qualify the duty, as appears in s19 of the Act, with words such as "so far as is reasonably practicable". Such cases include National Foods Milk Ltd v Smith [2006] TASSC 24 and Kent v Gunns Limited (supra), from this jurisdiction, Chugg v Pacific Dunlop Ltd [1990] HCA 41; (1991) 170 CLR 249 at 262 - 263, Chugg v Pacific Dunlop Ltd (No 2) [1993] 3 VR 934 at 940 - 945, R v Australian Char Pty Ltd (above) at 846 - 847, Slivak v Lurgi (Australia) Pty Limited (supra) at 319 [39], 324 [58] and 322 [88] - 336 [98] and Dinko Tuna Farmers v Markos [2007] SASC 166; (2007) 98 SASR 96 at 104 [26] - 109 [44].
From these authorities the following propositions with respect to the charge emerge:[755]
- the primary element of the offence is the failure to ensure so far as is reasonably practicable that each employee, or in this case "other persons'" health and safety is not put at risk. The obligation imposed on the defendant is not absolute;
- there is no test or general rule by which it can be determined whether the obligation has been met;
- the onus is on the prosecution to establish such a failure;
- the determination of whether there has been a failure involves a value judgment;
- "reasonably practicable" means something narrower than physically possible or feasible;
- what is reasonably practicable is to be determined on the basis of what was known at the relevant time;
- what is reasonably practicable is a question of fact;
- to determine what is reasonably practicable, it is necessary to balance the likelihood of the risk occurring, against the cost, time and trouble necessary to avert that risk;
- while it may be expected similar considerations to those which arise in the determination of a breach of the common law duty, may also arise when considering a breach of the section, common law requirements should not be imported as elements of the offence; and
- foreseeability of risk of injury is a likely consideration when reaching a determination as to whether the element of ensuring safety so far as was reasonably practicable has been made out. However, such a consideration does not import common law requirements into the legislation as an element of the offence.
In Laing O'Rourke (supra) in considering what was "reasonably practicable" Murphy JA said:[756]

[928]

The submission by Ms Gamble with respect to paragraphs n) a. (i), (iii), (v) and (vi), n) b. (i), (iii), (v) and (vi); and n) c. (i), (ii) and (iii) is that, if the Court does not accept that Ms Gamble was provided with "manufacturer's instructions" by East Inflatables or was able to access material from East Inflatables which provided the instructions alleged, namely requiring her to install a peg at each anchorage point of the jumping castle, she cannot be held to have breached s32 in the manner particularised.
I have found that no instruction manual was supplied to Ms Gamble by East Inflatables and she only received four pegs. I accept the interpretation placed on clause seven by Ms Gamble and Mr Monte contained in the two page manual downloaded by Ms Gamble. I have also found only two pegs supplied by East Inflatables and two other V shaped pegs were used on the day. I do not think this means the defendant's submission ought to be accepted although strictly speaking on the evidence it is correct. This is because it is also clear on the evidence that on occasions eight pegs had been used by Ms Gamble to anchor the jumping castle due to the prevailing weather conditions. So without knowing it Ms Gamble had complied in the past with what the DPP says were the manufacturer's instructions. She had applied common sense to the operation of the jumping castle. It is also plainly common sense to use eight pegs if there are eight anchorage points. If you bought a tent with eight anchorage points which was supplied with four pegs and no manual would you only use four pegs? I suggest not. The prudent person would source four more similar pegs and use eight pegs.
Accordingly was the use of eight pegs on 16 December 2021 at the School reasonably able to be done in relation to ensuring health and safety given the hazard and risk? The hazard being the failure of the anchorage system, due to the application of wind on the jumping castle, to anchor the jumping castle to the ground and the risk being the risk of death or serious injury associated with a fall from height and/or being struck by the inflatable device or any part attached thereto, due to the inflatable device becoming dislodged from the anchorage points and becoming airborne. Turning to the s18 factors:

[941]

Where these particulars refer to a competent person, namely n) a. (iii), (v), (vi) and n) b. (iii), (v) and (vi) they are not applicable. This is because I am of the view that changes made to the anchoring system are more likely to be operational rather than design issues; that is I am not satisfied beyond reasonable doubt the definition ascribed to this term by Mr McDonald ought be favoured over that used by Professor Eager. Being an operational issue it is clear on the evidence, having considered in detail her system of work at paragraphs 223 to 324, Ms Gamble was a competent person.
Returning to s32 Ms Gamble accepts she had a health and safety duty under subsection (a) and I have found she has failed to comply with that duty under subsection (b) by not using eight pegs. However I am not satisfied this failure exposed the students to a risk of death or serious injury under subsection (c). This is because the weather forecast, the eyewitness evidence of the weather conditions before the Wind Event, and the exhibit which shows those weather conditions prior to the Wind Event, all establish the weather conditions were benign. If those conditions had continued it is likely this tragedy would have been avoided. In addition, I am not satisfied beyond reasonable doubt, for the reasons discussed in paragraphs 388 to 436, the anchorage system failed in the manner proposed by Mr McDonald. It is more likely the anchorage system failed due to the significant upward force of the dust devil acting upon the jumping castle. In those circumstances the evidence is that eight pegs would not have prevented the failure of the anchorage system and therefore the failure to comply with the duty was not a substantial or significant cause of the children being exposed to the risk of serious injury or death.[773]
Application of the s18 factors to particulars n) a. (viii) and n) b. (viii) namely a failure to use a continuous monitoring anemometer is the same as previously stated for s18(a), (b) and (c), as set out in paragraph 462. As to s18(d) an anemometer has a distinct advantage over using weather apps on phones because the forecasts provided on weather apps are general over a region and do not take into account localised terrain and land features which affect wind. Accordingly weather apps do not enable the user to accurately monitor local wind speeds and accordingly Ms Gamble would not know when a wind speed of 25 km/h had been reached which was when she would cease operations. It appears Mr Monte previously used such a device but had difficulty converting the reading he received from his device from miles per hour to kilometres per hour. He was however, at the time of this incident, in the process of trying to source a new device. Such devices, for the purposes of s18(e) were commercially available and affordable. So again s32(a) and (b) are satisfied. The Wind Event was described by eyewitnesses as coming on "all of a sudden" and Dr Earl Jones said it was likely invisible to the naked eye. He and Professor Eager said such a device was useless in the circumstances. Accordingly, the failure to comply with the duty and use an anemometer was not a substantial or significant cause of the children being exposed to the risk of serious injury or death.[774] Section 32(c) has not been made out.
Application of the s18 factors to particulars n) a. (ix) and n) b. (ix) namely a failure to apply the controls identified in previous risk assessments, namely the use of star pickets, is the same as previously stated for s18(a), (b) and (c), as set out in paragraph 462. As to s18(e) there was no additional cost to the defendant in using star pickets as there were in excess of eight star pickets available for use on site on the day of the incident. Contrary to Ms Gamble's submissions[775] there is evidence that a risk assessment had identified the control of using star pickets[776] however as to s18(d) while available, I do not consider the use of star pickets was a suitable method by which to eliminate or minimise the risk because of the reasons set out in paragraph 462(d). In addition on the DPP's case, based on Mr McDonald's report, it was not suggested the Australian Standards advised or required the use of star pickets. I am therefore satisfied s32(a) has been made out but not s32(b). There is also evidence that the failure to use of eight star pickets was not a substantial or significant cause of the children being exposed to the risk of serious injury or death.[777] Therefore s32(c) has also not been made out.
The remaining particulars are n) a. (ii), n) b. (ii) and n) c. (iv) which provide in summary Ms Gamble failed to ensure safe systems of work and the safe use, handling and storage of plant and structures by failing to ensure that each face of the inflatable jumping castle was secured by installing pegs at each anchorage point and by failing to ensure the provision of any information, training, instruction or supervision that is necessary to protect all persons from risks to their health and safety by ensuring the provision of adequate supervision during the set up of the jumping castle.
The first two particulars can be dealt with together. Application of the s18 factors to these particulars is as previously stated for s18(a), (b) and (c), as set out in paragraph 462. As to s18(d) there were pegs available to secure each face and Ms Gamble had previously secured each face when operating the jumping castle. I find Ms Gamble knew or ought reasonably to have known about the hazard or the risk and that this was a method which was reasonably able to be implemented and which at least minimised the risk. As to s18(e) there was no additional cost to the defendant in installing pegs at each anchorage point as there were in excess of eight pegs available for use on site on the day of this incident. I am therefore satisfied s32(a) has been made, as has s32(b). However s32(c) has not been made out because I am not satisfied beyond reasonable doubt that had each face been secured by installing eight pegs that measure would have made any difference to the tragic outcome; that is the breach was not a substantial or significant cause of the children being exposed to the risk of serious injury or death.[778]
The final particular to consider is n) c. (iv) which alleges a failure to adequately supervise during the set up of the jumping castle. In my view the evidence discussed at paragraphs 223 to 324[779] establishes Ms Gamble did adequately supervise Mr Monte and Mr Barrett. If I am wrong about that then the inadequacy had no, or no material, effect on the elimination or reduction of the risk, for the reasons stated in paragraph 439 from Baiada Poultry Pty Ltd v The Queen (supra). In addition any breach in this regard was not a substantial or significant cause of the children being exposed to the risk of serious injury or death.[780]
Finally I need to consider the "reasonably practicable" measures particularised under subparagraph o) of the Complaint which are as follows:

At a glance

Court

Decision date

Source

Judgment (1252 paragraphs)

Director of Public Prosecutions v Rosemary Gamble T/A Taz-Zorb [2025] TASMC 3 (6 June 2025)

Parties

Legislation Cited (1)

Cases Cited (15)