An
aircraft registration is a unique
alphanumeric string that identifies a
civil aircraft, in similar fashion to a
licence plate on an automobile.
Military aircraft typically use tail codes and serial numbers. In accordance with the
Convention on International Civil Aviation, all aircraft must be registered with a
national aviation authority and they must carry proof of this registration in the form of a legal document called a
Certificate of Registration at all times when in operation. Most countries also require the aircraft registration to be imprinted on a permanent fireproof plate mounted on the
fuselage for the purposes of post-fire/post-crash aircraft accident investigation.