"The jet was going to Tucson, Arizona and I'd never been there," he said. "So I took it."

That was three years ago and since then Lewis, chief executive officer of property management company Concept Seven, which operates on the West Coast of the US, has become a regular private jet flyer — for business and pleasure. He takes one or two trips every month.

The bargains come from what are known as "empty legs" or "empty sectors." That is, the one-third of private jet flights that wouldn't otherwise carry passengers because the planes are in the wrong place at the wrong time.