The ADS-B system assigns a unique 24-bit code (the ICAO address) to every aircraft's transponder. These address assignments are made by national government aviation authorities, such as the United States' Federal Aviation Administration or Transport Canada. To determine exactly which aircraft is being tracked, the registration databases can be downloaded from the authorities and used to look up the human-readable identity of the aircraft.
Currently, only the US FAA and Transport Canada registries are supported, identifying US- and Canadian-registered civilian aircraft. The current public registries are updated periodically, so the YAAC user can download an updated copy of the registries; the downloaded copies are kept with other local YAAC data so it can be used offline.
The menu choice File->Load->Aircraft Database checks the date of the last-downloaded registry database (if any), and confirms the user wants to download the latest version from the FAA or Transport Canada website. Because the websites use secure encrypted HTTP (HTTPS), these menu choices will not be available if use of encrypted HTTPS is disabled in the YAAC configuration.