Our technology allows safe operation of drones by non-expert users. The drone is only allowed to fly inside a 3D tube, defined by a virtual rail with a certain radius around. This new concept has a lot of potential for the commercial market as for example the filming industry. Our system can be used to emulate existing hardware such as spider cams and camera dollys. The technique applies also for surveillance and delivery. The algorithm is applicable to any drone and protected by a patent (ETH).