This paper considers the problem of integrating unmanned aircraft into low altitude airspace above urban environments, including major terminal areas and helicopter landing sites. A simple set of data-driven modelling techniques are used to explore, visualise and assess existing air traffic in a manner more informative to the unmanned aircraft community. First, low altitude air traffic data sets (position reports) are analysed with respect to existing exclusion/no-fly zones. Second, an alternative geometric approach to defining and comparing various exclusion zones is derived based on set theory. The analysis is applied to a region of south-east Queensland, Australia including Brisbane International Airport and three helicopter landing areas. The results challenge some of the current unmanned aircraft regulations, and should help to motivate a more rigorous scientific approach to safely integrate unmanned aircraft.