The machine should propel him at about 118 miles (190 kilometers) an hour, making it a 12- to 15-minute trip.

Failure is not an option, as the Channel is one of the world's busiest shipping lanes, and Rossy's jet pack is not designed for landing on water.

"He will be wearing a fire-proof flight suit, 120 pounds [54 kilograms] of wings, fuel, engines, and parachutes, so staying afloat for any length of time could be difficult," said Tom Benson, an aeronautical engineer at the NASA Glenn Research Center in Cleveland, Ohio.

(Watch video of Rossy's debut flight over the Alps in May 2008.)

Rossy's support team is confident that he can carry out his Channel-hopping feat—but that likely won't stop them biting their fingernails when he sets off.

"The first five seconds will probably define whether he is going to make it or not," said Markus Zipperer, an engineer with the German company JetCat, which helped build the machine.

"The biggest challenge for him is to get into a stable flying configuration once he has left the plane."

Fly Like a Bird

Like many other aviation enthusiasts before him, Rossy wanted to find a way for people to get as close as possible to flying like birds.

He started working on the project about 15 years ago, building prototypes in his garage. He first created an inflatable wing that enabled him to glide, but Rossy was really after powered flight.
With the help of JetCat and Swiss firm ACT Composites, Rossy built a prototype and began improving upon his jet-wing design.

A few weeks ago he carried out his longest flight yet, covering 22 miles (35 kilometers) in 12 minutes, but tomorrow's scheduled event will be the first time he will try to cross a major body of water.
The 49-year-old Swiss pilot will be following the route taken by Louis Bélriot 99 years ago, when he became the first person to fly an airplane across the English Channel.

Although Bélriot's route is the shortest, Rossy could be hampered by winds blowing from England toward France.

"With a trailing wind, he can fly farther across the surface than with no wind using the same amount of fuel," said NASA's Benson, who is not involved in the attempt.

"With a headwind, he will fly a shorter distance across the surface before exhausting his fuel. With a cross wind, he could be pushed off course, again making the crossing distance longer."

Already the weather has forced Rossy to delay his flight by a day, and the team has an additional three-day window of opportunity if unfavorable conditions persist.

"The best conditions are likely to be a calm, cold day when the air density is high. This will assist the wing and the jets to produce more thrust," said Glenn Martin, a jet pack inventor from Christchurch, New Zealand.

When the attempt happens, it will air live on the National Geographic Channel.