Cable-less avionics implementation will clearly improve the efficiency of aircraft while reducing weight and maintenance costs. Therefore, with the technological progress of wireless technologies, an alternative avionic communication architecture based on Ultra WideBand (UWB) technology is proposed to fulfill these new needs. To adapt this wireless technology to safetycritical avionics, first, the tuning process of theMAC layer and the integration of accurate reliability mechanisms to achieve timely and reliable communications are presented. Then, an efficient timing and reliability analysis of such a communication network based on Network Calculus is detailed. This analysis integrates the impact of non-preemptive message transmission, various service policies in end-systems, e.g., First In First Out (FIFO) and Fixed Priority (FP), and transmission errors. Third, this general analysis is illustrated in the case of a realistic avionic application to replace the AFDX backup network with our proposed UWBbased network to support timely and reliable communications.