In this paper, we study the propagation characteristics of air-to-air (A2A) channels in a virtual urban scenario generated with the ITU-R model. Based on ray- tracing simulations, we explore the behavior of large- scale fading when taking the environmental setup into consideration. Our analytical results show that the large-scale fading statistics, e.g., pathloss exponent (PLE) and shadow fading variance, are associated with the receiver height and elevation angle. Furthermore, we derive an approximate expression for line-of-sight probability according to the deployment and distribution of buildings. The expression is characterized as a function of receiver height and elevation angle with the condition of high transmitter height. To efficiently evaluate the performance of unmanned aerial vehicle (UAV) communication systems, we then propose an empirical propagation channel prediction model, which can be easily extended to different scenarios in the ITU-R model.