Jeb Corliss doesn’t look insane. In his flying kit he has the chiselled looks and sculpted hair-style of an extra from Top Gun, aviator shades and all. However, when he explains what he is planning to do, disbelief mounts to the point where the only question that seems to make any sense is: “Have you been certified yet?”

“I get asked that a lot,” Corliss says. “But this isn’t crazy. It’s all about pushing the boundaries, looking again at what people believe is possible. I want to prove we are capable of doing anything and that we have no limits.”

This month Corliss was training in Switzerland in preparation for a stunt in which he will fall 2,500ft from a helicopter without a parachute and, if all goes to plan, live to tell the tale. He will be wearing a wingsuit, which he believes will allow him to glide to the ground at a shallow enough angle to be able to land safely.

The key to surviving the stunt is to fly. In freefall, Corliss will reach a velocity of 120mph to 200mph. By controlling his wingsuit, he can reduce his rate of descent to about 70mph – slow enough to survive the impact with the ground, provided he lands on a special runway.

“I made the breakthrough about two years ago when I realised that I’d need a special runway,” says the 32-year-old from Malibu, California. “An aircraft can land on flat ground because it can match the angle of that ground as it comes in. Planes can also regain altitude if needs be.

“A wingsuit gives you a ‘glide ratio’ of between two and three to one; in other words you’re moving up to 3ft forward for every foot you fall, so you need something to match that angle to land on. Imagine a ski slope at a constant 45-degree slant for more than 1,000ft – it’s a runway that’s perfectly matched to a wingsuit glide ratio.

“Look at the Olympic downhill skiers, who fly for three or four seconds before making contact with the slope – at just the right angle. People are already doing this; it’s just that they’re doing it ground to ground whereas we’re doing from a few thousand feet up in a plane.” Corliss isn’t the first man to dream of unaided flight, of course. Ever since Icarus came unstuck, men have been trying to imitate the birds. However, it wasn’t until the 1930s that technology enabled them to try it. Early wingsuits were made of materials such as canvas, wood, silk, steel and whalebone.

The idea was to create enough drag and lift to enable the bird-men, as they became known, to glide laterally rather than plummet as with a conventional parachute jump. The contraptions were not reliable. According to wingsuit lore, between 1930 and 1961, 72 of the 75 bird-men died testing their wingsuits, although the exact number is disputed.

What isn’t in doubt is that it was a dangerous pastime. Clem Sohn, an American air-show daredevil, claimed to have perfected the art by using cloth strung between steel tubes to form a web between his legs and arms. Although initially successful, he died in 1937 when both his chutes failed to open.

Wingsuits came on in leaps and bounds in the late 1990s, thanks to the popularity of extreme sports and new strong, lightweight materials. Modern suits are modelled on the flying squirrel, with layers of material that spread between the outstretched arms of the jumper and the hips as well as another web triangle between the legs. The fabric traps a layer of air, making it rigid like a wing. The technology has meant that vast distances can be covered.

In 2003 John “Chuck” Berry, a stuntman, completed an unassisted flight in his native New Zealand, covering four miles. Then in June this year, Ueli “the Sputnik” Gegenschatz, a Swiss skydiver, travelled 11 miles across the sky above Co Gal-way, Ireland.

All jumpers carry a parachute, which they deploy at the end of their descent – something Corliss won’t have.

He says he is still researching and fundraising for the construction of his specially angled runway and so won’t give much detail. With the jump scheduled for early next year, he’s raised about 70% of the $12m (£6m) he estimates he will need. He’s hoping that Sir Richard Branson, a pioneer of extreme ballooning, could be persuaded to open his wallet.

Branson might be encouraged to learn that one of Corliss’s partners is an engineering firm that creates deceleration systems for Nasa. The company was sceptical when Corliss first approached it. “The boss’s immediate reaction was: ‘You’re gonna die’, but he said he’d give me 30 minutes of his time. Five hours later he’s saying, ‘Not only is this quite possible but I can’t believe that no one has done it before – I’m on board’,” says Corliss, who as well as doing hundreds of skydives has jumped with a parachute from the Eiffel Tower and the Golden Gate Bridge. “I’ve been arrested five times in four countries,” he boasts.d

Earlier this month in Switzerland he was practising “proximity flying” on the Eiger – a hair-raising activity that entails descending while keeping 10ft-15ft away from the side of the mountain, using eddies and currents and his arms and legs to maintain the safe distance. “Controlling my fall is crucial: I have to be accurate in order to hit the target ramp.”

The “wingsuit landing project”, as he calls it, marks a return to action for Corliss after he broke his back in three places when a jump from the top of a South African waterfall went wrong, but he remains sanguine about the risks.

“My life is about risk evaluation,” he says. “I spend days and weeks doing the most thorough preparation imaginable. B a s i -cally, I take things that are very dangerous and make them as safe as possible.

“Crossing the street can be dangerous if you do it the wrong way. If you don’t follow the rules, you’ re going to get hit by a car and die.”

Maybe so. But for his latest trick he has one chance only to get it right.

JEB CORLISS – THE FACTS

Claim to fame He aims to become the first person to land safely after freefalling from 2,500ft without a parachute. A wingsuit will enable him to control his descent and land on a specially constructed ramp.

Why? Corliss claims he is pushing the barriers of what is possible and that the stunt is the “Everest of skydiving”.

So he’s an adrenaline junkie? Seems likely. As a child he caught rattlesnakes for fun, then graduated to diving with sharks, “because I had always been terrified of them”.

At 16 he saw someone base-jump for the first time and decided to take it up.

What’s base jumping? Jumping off a tall structure or mountain, freefalling for a bit, then parachuting to the ground. So far he has base-jumped off Mount Eiger, the Eiffel Tower and the Golden Gate Bridge.

Sounds dangerous It is. Corliss is currently claiming damages for emotional distress against the owners of the Empire State Building after security guards apprehended him attempting to base-jump from the 86th floor.

That’s a bit rich isn’t it? Well, he is American.

FREEFALLERS WHO LIVED TO TELL THE TALE

VESNA VULOVIC, a 22-year-old Yugoslav air hostess, survived a 33,316ft fall in 1972 after her plane had exploded – possibly as a result of a bomb planted by a Croatian terrorist group. Trapped in the wreckage of the aircraft, she landed on a mountainside in Czechoslovakia, was knocked unconscious and remained in a coma for three weeks before coming round. She holds the world record for surviving a fall.

FLIGHT SERGEANT NICHOLAS ALKEMADE jumped 18,000ft from his burning bomber in 1944. The RAF tail gunner fell into a German pine forest, then rolled into a snowdrift. Curiously, he suffered nothing more than a twisted ankle.

MICHAEL HOLMES, from Jersey, suffered a punctured lung and a broken ankle in 2006 after plummeting 12,000ft over New Zealand when his parachute became tangled and his reserve chute failed to open. Fortunately for him, he landed in a blackberry bush.

KLINT FREEMANTLE, a New Zealander then aged 22, plunged 3,000ft into a 3ft-deep duck pond in 1993 when his parachute failed to open, and emerged with only a small cut near his eye. “Klint went for that pond like a guided missile,” said Tim Russell, his instructor. “The Grim Reaper had got him, but then Klint gave the Grim Reaper a headbutt in the face. It’s a freak, one-in-a-billion accident.”