The 37-year-old will fly over 22,800 nautical miles across 13 different countries including France, Lithuania, Russia, Canada and Greenland, before arriving back in England in around six months.
The gyrocopter travels at just 70 knots, with a range of just 700 nautical miles.
During his trip he will stop at schools in every country he visits in order to give motivational talks and raise money for two charities, Kindled Spirit – which supports victims of trafficking, and Over The Wall – which supports children and young people facing serious health challenges.
Adventurer James Ketchell takes off for the first leg of his bid to fly round the world (Steve Parsons/PA)On Sunday, crowds gathered at Popham Airfield in Hampshire to wave him off before he leaves to fly across the Channel from Goodwood, Sussex, on Monday.
Mr Ketchell, from Basingstoke, Hampshire, told the Press Association: “I had no idea three or four hundred people were just going to turn up to wave this lunatic off, it’s all a bit surreal really.
“It’s doable – but I’m just taking it day by day. It’ll probably take me about six months, that’s the plan.
“Hopefully I can achieve my objective of speaking at a school in every country, trying to inspire some young kids to believe in themselves and do things – that’s the mission.
“I enjoy working with kids and for some reason they listen to me. Maybe it’s because I’ve done a few cool things. Maybe they won’t listen to me in 10 years when I’ve lost my hair or gone grey.
“I don’t have a family of my own. I’m not sure if that’s in my destiny. I’ve got a little nephew so, I can try and be a cool uncle.
“Maybe if the time is right and I meet the right person – but right now I’m focusing on my thing really.”
All of his adventure can be tracked in real-time online through his website as he sets out to inspire “one million young people” on his journey.
Asked what had motivated him to be so involved with inspiring children, Mr Ketchell said: “When I was a young teenager I just really struggled. I had no motivation, I left school without one qualification.
James Ketchell starts his bid to become the first person to fly solo round the world in an open cockpit gyrocopter (Steve Parsons/PA)“I didn’t really have any ambition or drive, I was lazy. When I left school I got fired from jobs, left, right, and centre – I spent a lot of time just lying around in bed.
“I never really believed in myself or wanted to anything. I was probably a bit depressed really, but didn’t know or understand how the brain works.
“I had a very nasty motorcycle accident and that was really the catalyst for rowing across the Atlantic – I’d always wanted to but never had the guts to do it.
“I was very insecure when I was younger and always worry about what other people would think of me.
“But when I had that accident and the doctor said: ‘well mate, you may never walk again’, I thought that I needed something to aim for and I did it.
“People who had never rowed the Atlantic before, all of a sudden were experts, telling me why I shouldn’t be doing it, why I should focus on my job instead of ‘silly dreams’.
“Human beings have a terrible habit of telling other people what they think they should do, and if I had listened to those people, I wouldn’t be where I am today.”