Private aviation distribution platform Returnjet is turning its attention to the managed corporate travel space. It runs a booking platform for private jets and helps fills "empty legs"?flights in which aircraft depart with no passengers for positioning reasons?which account for about 40 percent of flights in private aviation and can offer attractive rates, according to aviation director Steve Westlake. About five years old, Returnjet has 7,500 aircraft of all sizes signed up. Those planes fly to 6,000 airports around the world.