The present disclosure provides systems and methods that enable flexible access of internal data of an avionics system (e.g., a Flight Management System). Aspects of the present disclosure enable enhanced, flexible and robust recording of flight test data, testing, debugging, and analyzing in-service problems. One example system includes a Configuration Tool that generates a Loadable Configuration File and a Configuration File based on user selections, structure of data in Data Stores, platform information, processor information, and Receiving Component requirements; a Data Access Component that subscribes to data in the Data Stores based on the Loadable Configuration File and outputs the data; and a Receiving Component receives the data, and decodes the data based at least in part on the Configuration File. Aspects of the present disclosure provide the ability to change which data gets output by the avionics system without the need to recompile and recertify the avionics system software.