Read the FAA's comma-delimited MASTER file from its downloadable ZIP with Python, compare two snapshots by N-number, and decide when a maintained aircraft registry API is worth using.
Daily FAA registry snapshots can show what public registration state was observed and what changed between observations. They do not automatically prove the exact legal effective time of a change.
N-numbers and Mode S / ICAO24 addresses identify related parts of a U.S. aircraft registration, but they are not interchangeable and neither should be treated as permanent physical-aircraft identity.
The FAA makes the registry downloadable. Turning seven public files into a reliable developer API still requires validation, normalization, identity rules, atomic publication, provenance, history, and privacy controls.
