Annex 7 foreword and definitions; common and registration marks; certificate of registration and aircraft nationality.
This topic is ICAO-framework material — the content below is a study aid, not cited regulation. Always verify against the current ICAO documents and national AIP.
ICAO Annex 7 establishes international standards for aircraft nationality and registration marks. Its purpose is to ensure that every aircraft operating internationally carries markings that identify the State in which it is registered and assign it a unique designator within that State's registry. This allows air traffic control, accident investigators, border authorities, and search-and-rescue services to unambiguously identify any aircraft, anywhere in the world.
State of Registry — the contracting State on whose register a specific aircraft is entered. An aircraft may only be registered in one State at a time.
Nationality mark — the letter or letter group assigned to a contracting State by ICAO, forming the first element of the full registration. Finland holds OH, Germany holds D, the United Kingdom holds G, and so on. These marks derive from the International Telecommunication Union (ITU) letter series allocated to each State.
Registration mark — the alphanumeric characters assigned by the State of Registry to a specific aircraft, appended after the nationality mark. Nationality mark + hyphen + registration mark form the complete designation (e.g., OH-ABC, D-EATF).
Common mark — a mark assigned directly by ICAO Council for aircraft that cannot be registered by any contracting State (for example, certain internationally-operated aircraft or unmanned systems in special categories). It consists of two ICAO-assigned letters instead of a State nationality mark.
Marks must appear in Latin alphabet characters and Arabic numerals, in a colour contrasting with the background, and meeting minimum character height requirements. For fixed-wing aircraft the marks are placed on:
The marks must not be liable to confusion with distress signals or with the aeronautical communication signals Q, X, or PAN, nor with the letters SOS.
The State of Registry issues a certificate of registration for each registered aircraft. This certificate must be carried on board at all times when the aircraft is operated. It contains at minimum:
The certificate is not transferable. When an aircraft is sold, re-registered, or permanently exported, the original certificate is returned to the issuing authority and a new one obtained in the new State of Registry.
Registration marks are the aircraft's permanent legal identity. They appear on the certificate of airworthiness, all maintenance records, flight plans, and every piece of official documentation throughout the aircraft's life. Pilots use the registration as the radio telephony callsign (or as the basis for a company callsign) and must know it for flight plan filing and ramp inspections. If an aircraft is re-registered in a different contracting State it receives a new nationality prefix and a new registration mark, reflecting the change of registry — the old certificate lapses immediately.
This block connects to your school's own Operations Manual (OM-A/B/C/D). In the full product it shows, cited to your manual, how YOUR organisation implements the regulation above — private to your school. (Demo placeholder.)
The cases below are labeled illustrative context only and are not regulatory sources.
Registration marks as aircraft identifiers across official records CASE-1
A 2026 FAA notice on renewing information-collection requirements for maintenance, preventive maintenance, rebuilding, and alteration highlights that every maintenance action — including FAA Form 337 for major repairs and alterations — must record who, what, when, where, and how of the task performed. The aircraft's nationality and registration marks are the primary identifier on all such documentation. This underscores a direct practical consequence of Annex 7 standards: the registration mark is not merely a visual marking on the airframe; it is the linking key that ties the airworthiness certificate, the maintenance record, the flight plan, and the ownership record into a single auditable chain. An error or gap in registration documentation — for example, operating after a change of ownership without an updated certificate of registration — can break this chain and create legal and airworthiness complications that surface during ramp checks or accident investigations.
1. How many contracting States may simultaneously hold the registration of a single aircraft under Annex 7?
The lesson defines the State of Registry as the one contracting State on whose register a specific aircraft is entered, and states explicitly that an aircraft may only be registered in one State at a time.
2. What does an ICAO "common mark" consist of, and who assigns it?
The lesson states that a common mark consists of two ICAO-assigned letters and is assigned directly by the ICAO Council for aircraft that cannot be registered by any contracting State.
3. On a fixed-wing aircraft, Annex 7 requires registration marks on the lower wing surface to be placed under which wing?
The lesson specifies that marks on the lower surface of the wing are placed normally under the left wing.
4. When must the certificate of registration be carried on board the aircraft?
The lesson states that the certificate of registration must be carried on board at all times when the aircraft is operated, with no exceptions listed.
5. What must happen to the original certificate of registration when an aircraft is re-registered in a different contracting State?
The lesson states that when an aircraft is re-registered, the original certificate is returned to the issuing authority and a new one obtained in the new State of Registry, with the old certificate lapsing immediately.