NoFlyZone is a free Android app developed by Paul Leischow that contains over 46,000 airports worldwide. This app can be particularly useful for RC model flyers, especially when flying commercially, as it provides information about no-fly zones around airports depending on your geographic location. For instance, when flying UAVs in Canada, Transport Canada has set a 9km no-fly zone around airports without proper legal authorization. By default, the app sets a 9km radius around airports and displays all airports within 30km of your marker. However, these settings can be adjusted based on your geographic location and local rules.

Overall, NoFlyZone is a handy tool for RC model flyers who want to ensure they are not flying in restricted areas. With its easy-to-use interface and vast database of airports, this app can help users stay informed and fly safely.