Countries are categorized by ICAO membership as follows:
The term Contracting States refer to States which have ratified or adhered to the Chicago Convention in accordance with the provisions of its Chapter XXI. There are currently (Aug. 2020) 193 Contracting States.
The term non-Contracting States refer to those States which have not ratified nor adhered to the Chicago Convention but that are Members of the UN or of a Specialized Agency. The only non-Contracting States are the Holy See and Liechtenstein.
In addition, there are States which are not signatories to the Chicago Convention and which are not members of the United Nations nor of any of its Agencies.
Providers and Users
For purposes of planning and facilitating the follow-up of implementation of the required air navigation services and facilities, States have been categorized into two main groups: