Extreme athlete Joby Ogwyn will leap off the top of Mount Everest in a wingsuit live on television in May

For most adventurers reaching the summit of Mount Everest is the ultimate achievement, but for Joby Ogwyn it will be just the starting point.

After scaling the world's tallest mountain he intends to jump off it and fly to the ground wearing a nylon wing-suit.

The death-defying stunt will be broadcast live across the globe on television in May, when viewers will see Ogwyn say a quick prayer, take a few sucks from an oxygen mask, and throw himself into the void.

"I wish I had a nickel for every time I've heard I'm crazy," Ogwyn told The Telegraph moments after streaking across the California sky like Superman in a test flight of his wingsuit, a special nylon jumpsuit with webbing between the legs and arms.

"But there's a lot more to this than a crazy person jumping. It will be very well executed, it's like a shuttle mission in some ways. This is something I dreamed about as a little kid. Everything I've done for the last 20 years has been practice for this and now the technology has made flight possible.

"I believe it will be one of the most exciting adventures in the world and I want people to see it. Sure, I'm very scared. Jumping from a mountain is really, really scary, much more so than jumping from a plane. But I'm not afraid to die."

He added: "Everest is the ultimate, it's the pinnacle, the biggest stage in the world. I can't think of anywhere better to make the ultimate mega-jump of all time. I've done most of the things I wanted to do and this is the blasting cap at the end."

Within the rarified worlds of both mountain climbing and extreme skydiving Ogwyn, 39, is already a legend. If anyone can jump safely off a mountain he can.

In 2008 he climbed Everest in just nine and a half hours when it usually takes a least three days. He has practiced by flying his wingsuit around the Matterhorn, and jumped off the Eiger three times in one day. Fine tuning of the suit is happening at Perris airfield in California before he sets out for the Himalayas.

His jump will be broadcast live to more than 200 countries by the Discovery Channel, which previously aired Felix Baumgartner's freefall from the edge of space in 2012, and Nik Wallenda's tightrope walk across the Grand Canyon in 2013.

A 40-strong back-up team will accompany Ogwyn to base camp at 17,800ft, and four high altitude cameramen will join him on the three day trek to the summit. at 29,035 ft.

Once there the daredevil will, very quickly because of the intense cold, change out of his heavy climbing gear and put on the wingsuit.

"I will visualise the jump in my mind a thousand times before I do it" he said. "The last thing I will say is probably 'A little help God, that'd be great.' Five to 10 steps and then I'll be out of there. It will be a running jump.

"The biggest challenge will be launching off. Altitude and cold could affect the wingsuit and I have to be a little lucky with certain wind conditions."

Ogwyn, who is from the famously low altitude US state of Louisiana, could be blown back into the side of the mountain, or he could be swept into China.

"I'm prepared for landing in China," he said. "I will definitely have some cash and my passport in my wingsuit."

Travelling at up to 150mph on the descent he will use his body to steer the wingsuit and propel himself away from jagged cliff faces as he falls for 10 minutes before reaching base camp.

There he will slow himself down dramatically by arching his body in a motion called "the cobra."

He will not be wearing a traditional parachute and the landing will involve a so-far secret new piece of equipment designed specifically for such a high altitude jump.

His Italian wife Flaminia, 34, a lawyer, will be watching on television. "She probably worries about me like any good wife," said Ogwyn. "She freaks out every once in a while, but she knows I'm conservative in my approach and I will make the right decisions. My goal is, no matter what, to come back and spend the rest of my life with her."

About two dozen people are known to have died last year flying wingsuits, mostly by "pushing the envelope" and flying too close to mountains. There are only around 10 making a professional living from the new and dangerous extreme sport which began in t he late 1990s.

"A lot of people see the videos me and my buddies make and they want do it really bad," said Ogwyn. "It's a very intoxicating feeling but you can try to do it too quickly. I discourage people from getting into this business. It takes a long time to learn how to do it right."