Son's birthday ends in unimaginable tragedy

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Photo: Kalev Saar / Postimees

Preparing for the birthday party this Sunday, parents must have been happy to see the morning starting out sunny and rather calm for the otherwise windy Tõrvandi.

Going to be a nice day, obviously agreed the other parents who left their offspring for a day of fun at the Aasa St home yard. A prominent feature, heard Postimees, was supposed to be a red inflatable trampoline – allowing a slide down a «slope». The centre of the thing, as befits boys, sported a car.

As measured at the Tartu Airport less than 500 metres away, at 7:40 pm the wind was 5 metres a second with gusts of 6.7 metres a second. In a word, nothing notable.

Nevertheless, at that very instant a phenomenon occurred which the most careful of parents could not have foreseen in her worst of nightmares. The trampoline, partly covered with a roof, was lifted high into the air, flew across the street and landed some 30 to 40 metres from where it once stood, in a field. Two of those on it – a girl of five and the son in the family (7) – perished. The other three were severely injured, as of yesterday one remained in a critical condition.

Inflatable trampolines have seen accidents before: kids fall off, hurt some joint while jumping, or slide to collide. But a trampoline going airborne was difficult even to imagine – before Sunday. Even so, Googling does provide such stories and videos from other corners of the world. In such instances, kids have been severely injured and have occasionally met their end. Still, initial searches yielded no earlier occasion with two deaths.

To the family in Tartu, the trampoline was rented by a local company Airfun OÜ which, according to initial information by prosecutor’s office, failed to fasten it to the ground.

As evident in explanations by Airfun chief Alger Vedler, the company trusted in the fair weather forecast. «In case of strong winds or thunderstorm hazard, there’s the issue if it is safe to install it or not,» said Mr Vedler. He affirmed the weather forecast was very positive regarding the trampoline that day – including the afternoon. At that, one understands the shock of the man who added this was a one in a million or a billion event, such as might have occurred to any other trampoline.

Not the Estonian first

In reality, Estonia has seen this before. According to Algo Laidvee managing an attractions rental company Ceelia, it was some three or four years ago. «On the stadium in Kanepi, a covered elk-shaped trampoline flew for about 50 metres in the middle of the stadium, but it had no kids on it at the moment, thankfully,» he said. «That was the only moment that a wind rose, the weather was calm before that. Between houses, wind corridors can occur and one never knows what may happen.»

Mr Laidvee said a trampoline will fly until the air in it from the ventilator on the ground runs out. «If a trampoline is full, it flies further,» he explained. «With surface acting like wings, it flies. Once the air runs out, it falls down.»

At that, Mr Laidvee’s airborne trampoline had been fastened to the ground at four places by ropes. «The wind broke one rope, a corner got loose, and thereafter the other poles were pulled out.»

Mr Laidvee said that most of their company’s trampolines are made of material thicker and heavier than the widely used Chinese trampolines which weigh a lot less. «I do have one Chinese trampoline which I am able to lift up, but I can’t lift the others,» said Mr Laidvee. In the case of Airfun, the trampoline was made in China.

At that, trampolines with roofs come with added risks, and the one used in Tõrvandi was partly covered. «The wind must be towards the «back» of a trampoline,» said Mr Laidvee. «If the wind blows under the roof, it swells. And even with the ventilator no longer engaged, the trampoline will fly.»

As the ventilator got separated from the trampoline, the latter may have leaned into the wind thus forming a «bag» which the wind was able to carry away.

Some locals say the wind was indeed stronger in the area, during the accident. The discrepancy between what airport says and what the locals testify may indeed be explained by wind corridors occurring between houses resulting in the exceptional localised gusts.

Mr Laidvee says covered trampolines are especially prone to fly, but if not properly fastened it may happen with others. «If a trampoline is not fastened, this is a mistake by the one who installed it,» he added.

Local gust

Postimees asked a well-known physicist Jaak Kikas what may have happened in Tõrvandi. With the Sun heating up the trampoline’s surface, may the air in it gotten warmer that external air? «I doubt that,» said Mr Kikas. «There does exist a thing they call the sun ball: a very thin dark film inflated with air. In sunlight it heats up so it may actually get airborne.»

With trampolines, this will not easily happen. «Inside the trampoline, air cannot swell too much, unlike in a balloon which can be blown so full that it bursts,» explained Mr Kikas. «Even if the Sun heated the trampoline, it did not swell significantly. And with the trampoline not swelling, the heating means nothing – the air mass and weight of the trampoline remain the same.»

As assured by Mr Kikas, a wind of six to seven metres a second is indeed nothing noteworthy. Meanwhile, the ventilator being separated from inflation point could not have caused it to lift into the air. «The inflation hole was hardly so large as to cause reactive force. Rather, the ventilator got loose from the trampoline and as the trampoline was no longer attached to the ground, nothing hold it back,» reasoned Mr Kikas.

Mr Kikas proceeded to point towards how roofs on houses go flying at times. «In the air that moves pressure goes down and the greater pressure under the roof presses the roof up,» said the physicist.

As confirmed by Mr Kikas, the accident does seem highly exceptional considering the airport wind data. «Possibly, local gusts developed which were stronger that measured at the airport,» he explained.

Postimees extends its condolences towards parents of the children who perished.

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