Radio frequency (RF) communications provide navigation and communication capabilities that are essential to safe operation of the current and future airspace systems. Loss of C2 and navigation links is a significant hazard even for current generation systems, and future systems that will operate with a high level of automation and autonomy, often without a highly-skilled operator onboard, will be even more susceptible to lost links. NASA has identified “Critical system failure…including loss of C2 link, loss or degraded GPS” as a key safety-critical risk relevant to future aviation systems. The proposed research effort will develop tools to analyze RF link coverage and support decision making that enhances system safety by minimizing the likelihood of lost links. The proposed tools will also enable intelligent responses to lost links that maximize the likelihood links are quickly and safely restored. The approach builds on an existing commercial software tool for RF propagation analysis, adding features to address challenges unique to the operation of future aviation systems, specifically features to enhance the accuracy of RF propagation analysis at low altitudes and to compute time-varying satellite-based-navigation coverage maps. Very low altitude operations play a significant role in future aviation system concepts, including UAS operations such as those envisioned to occur within the UAS Traffic Management framework, and emerging Urban Air Mobility concepts. The proposed research would enhance RF propagation modeling capabilities near and below the tops of obstructions including buildings and vegetation. The work will also build on risk-based path planning tools for UAS currently being developed by the team, integrating RF coverage analysis as an additional consideration in generating minimum-risk paths.