This chapter presents key regulatory problems related to sub-orbital flights. Some observers have noticed that the private sector was already active in outer space in the 1960s. Richard Branson, the founder of Virgin Galactic, has even predicted that a sub-orbital flight from Singapore to London can take 30 minutes. However, the very high cost of such flights is a barrier for regular traffic. There are several legal issues that may interfere with the development of commercial use of outer space. The use of airspace and outer space are covered by two entirely different legal regimes – the Chicago Convention and the Outer Space Treaty respectively. The issue of status of sub-orbital flights also implicates the question of whether ships engaged in such flights shall be registered as space objects and if their operations shall be notified to the United Nations Office for Outer Space Affairs.