# Radio Navigation In the past, pilots often used basic radio navigation along with INS. They flew from one waypoint to the next using VORs and NDBs. These navigation aids still exist today, but they are not used as much anymore. Because it costs money to keep VORs and NDBs running, many of them have been shut down or taken out of service. So if you want to use classic radio navigation in the current version of the flight simulator, your options are quite limited. That’s why we recommend this free addon. It gives you access to about 500 old VORs and 4.000 old NDBs. You can expand your navigation database for free and explore the old days of radio navigation. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.flightsim-studio.com/boeing-727/navigation-options/radio-navigation.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.