These days, the charismatic businessman is developing his fifth major airline startup. Once again, Neeleman is looking to fill a market niche left open by others in the industry.

Code-named Moxy, his next endeavor wants to transform low-cost air travel for smaller cities in the US in very much the same way Azul did in Brazil. According to Neeleman, as costs increase for airlines, they have a tendency to retrench their network to focus on their hubs and operate larger planes. Thereby leaving behind smaller, less trafficked destinations.

"We think there's a market where you can go with a smaller plane with a lower trip cost and service these cities that have been forgotten or neglected," he said.

Neeleman posits that there are enough neglected routes in the US that his new airline could grow substantially without any direct competition.

"I would be very surprised if a single Moxy route had nonstop service competition," he told us. "There are literally hundreds and hundreds of city pairs that are crying out for nonstop flights."