Indoor skydiving

"Stretch out your arms and legs to the same level, and then just let the wind take you up," Shi Lisi was told before she jumped into the air and started to float.

"The way that you are able to float in the air is magical," said Shi after she experienced her first ever indoor skydiving session at the UFLY Skydiving Club in Shanghai.

Simulated skydiving takes place in a cylinder wind tunnel around six meters tall and with a diameter of four meters. The floor is a trampoline, and the walls are made of glass. With the wind whisking through it from below, the cylinder's wind speed can reach 70 meters per second, and can be enough to make anyone under 100 kilograms airborne.

"This wind force can make people fly if they adopt the right postures," said Wang Yingjun, Shi's indoor skydiving coach. "So for Shi who weighs 50 kilograms, we set the wind at 40 meters per second.

An indoor simulated skydiving experience might lack the thrills of actually jumping out of an airplane and rocketing steadily towards the earth below. But it has earned a following in China.

"It is estimated that at least 5,000 people in China have experienced indoor skydiving by now," said Gao Miao from the General Administration of Sport of China.

Gao said that compared to other extreme sports, indoor skydiving is safe, but there are still risks of hurting one's neck and waist by colliding with the glass wall, or falling awkwardly.

"Facing the strong wind, I panicked and forgot the training I learned beforehand," said Shi. "Luckily my coach was inside the tunnel and told me what to do. The gesture is like swimming," she added.

Seeing that Shi had maintained her balance in the air, Wang decided to take it up a notch. "Now lower one of your arms, and raise the other one, so you can do a flip in the air," shouted Wang to Shi through the noise of the wind.

As Shi started to flip over, she slid away half a meter. "Stop sliding, your head will clash with the glass wall," warned Wang.

Wang introduced that all indoor skydivers need to wear a helmet, wristbands and kneecaps to prevent an injury if they collide with the glass wall. The other necessary items include a flying suit, goggles and gloves. "The flying suit increases the force area, making it easier for skydivers to remain airborne," said Wang.

After two-minutes experimenting, Wang asked Shi to withdraw her arms and bend her calves to 90 degrees in order to land. "Remember to land with your arms and legs, not your waist, or you will strain yourself," he warned.

After her first indoor skydiving session, Shi said that she planned to come back regularly to practice more complicated positions.

"I have always wanted to go to Switzerland to sky-dive, but imaging all the buildings and mountains I could hit when falling freaks me out, so I will do indoor skydiving first," said Shi.

According to Gao, indoor skydiving has the advantage of being safer and having no age restrictions. The popularity of the sport is soaring in China, with four credible indoor skydiving facilities having now opened to the public, including UFLY in Shanghai, and Happy Valley Chengdu in Sichuan Province.

"Indoor skydiving can also improve a skydiver's balance, and his or her reactions in air. Practicing on indoor simulators helps people prepare for real skydiving," said Gao.

Despite the advantages, Gao noted that indoor skydiving still faces some obstacles in China, such as the price.

According to UFLY, it costs 280 yuan ($46) for one session, and it only lasts two minutes. The high pricing is mainly due to the costs of powering the machine, with 1000 watts of electricity needed to run the machine for one hour.

Besides, indoor skydiving for some skydivers still lacks the excitement of a real sky-dive.

"The sensation of seeing the landscape from above, along with the relief when the parachute opens, just can't be replicated indoors," added Gao.