Just steps from where I stand, I watched office workers leap to their deaths from the flaming upper floors of the World Trade Centre. Now I am perched high above the ground and about to jump into thin air myself.

The first and most improbable addition to the Ground Zero area since the attacks is an open-air trapeze school set up in Hudson River Park, just north of the site.

For just under £30, visitors of all ages can learn to swing from the flying trapeze, hang from their knees, do a back-flip dismount and even leap into the hands of a professional catcher just like in the circus.

“Some people come to get over their fear of heights; some for exhilaration; some because they are stressed. Some people come because this is their dream of flying,” says Jonathan Conant, 42, the school’s founder. “The first year people came just to get through their sadness at seeing people fly through the air.”

Standing atop the 23ft-high (7m) platform, one looks straight over Ground Zero — although buildings obscure the actual pit.

The flying trapeze may look graceful high above the circus ring, but it is surprisingly arduous, as you heave your legs over your head to hook your knees over the bar. It’s a cross between Pilates and bungee-jumping.

More than a dozen people a week balk at making their first jump — although they all succumb finally. In my class of nine, it was a young Korean-American woman — supple enough to be the best of the first-timers — who stalled. It took her several false starts before she was airborne.

There is a safety net, and you’re hooked up to safety lines that ensure a smooth fall, so danger is minimal. Even so, the first leap is one into the unknown. Although I suffer from mild vertigo, my first experience was less one of fear than one of a sudden stretching as my spine elongated as I hung from the bar. The school’s slogan is “Forget Fear: Worry about the Addiction.”

Many people return class after class to hone their technique. “I saw this when I was on a bike ride. It looked like so much fun, but I was scared,” says Ross Maclean, 50, a playwright. “I watched for a few weeks.

“Then I thought — I can watch for the rest of my life or find out. It gave me a great sense of achievement. I have been weightlifting for years, but even if you can lift weights, where’s the achievement?” The school, which stands on the bicycle path along the Hudson River, achieved a certain cachet recently when Sex and the City filmed an episode there to show Sarah Jessica Parker’s character trying to loosen up in life.

My class ran the gamut from a 55-year-old stagehand to a nine-year-old boy whose mother was trying to get him interested in something — anything.

“I have done skydiving, bungee-jumping, scuba diving, rock climbing, raced America’s Cup boats in the Virgin Islands, gone hang-gliding and run three marathons,” bragged Tom Fagan, the oldest member of the group. “With parachuting and bungee-jumping, it’s ‘Go!’ and gravity takes over. With this, you have to think a little bit. But it’s not as scary.”

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