Definition
The letters and numbers displayed on the exterior of an aircraft that identify the country in which it is registered and its unique registration number. For aircraft registered in the United States, the nationality mark is the letter 'N', followed by the registration number assigned by the FAA (for example, N1234A). These marks must be displayed in the size, location, and manner specified by 14 CFR Part 45.
Plain English
The painted letters and numbers on the outside of an aircraft that show what country it belongs to and which specific aircraft it is. In the U.S., every registered aircraft starts with the letter 'N' followed by its own unique number.
Context Anchor
Seen on the outside of the aircraft and on aircraft documents such as the airworthiness certificate and registration certificate.
Derivation
Nationality' identifies the country of registry; 'registration' refers to the formal recording of the aircraft with that country's aviation authority. The 'N' prefix was assigned to the United States by international agreement after World War I, when countries were given unique radio call-sign letters that became the basis for aircraft nationality marks.
Why Pilots Care
These marks are mandatory for legal flight and allow authorities to identify the aircraft and its owner.
Analogy
Like a license plate on a car: the country tells you where it is registered, and the number tells you which specific aircraft it is.
Intuition Check
Do not read “nationality” as where the airplane was built or who owns it. Here it means the country where the aircraft is officially registered.
Example Sentence 1
Before departure, the pilot confirmed the nationality and registration marks on the tail matched the N-number listed on the aircraft's registration certificate.
Example Sentence 2
The inspector checked the nationality and registration marks against the aircraft's airworthiness certificate during the ramp check.