Definition

A worldwide system of aeronautical fixed circuits provided, as part of the aeronautical fixed service, for the exchange of messages and/or digital data between aeronautical fixed stations having the same or compatible communications characteristics.

Source: ICAO Annex 10 Vol II

Description

The AFTN uses two types of aeronautical fixed stations - AFTN communication centres and AFTN stations. The AFTN communication centre is an AFTN station whose primary function is to relay AFTN messages to or from a number of other interconnected AFTN stations.

At the majority of aerodromes where ATS is provided, there is an AFTN station. A number of such stations grouped together and around an AFTN centre form an AFTN circuit.

An example of an AFTN circuit

Several AFTN communication centres, when connected to each other, form a network of fixed aeronautical telecommunication lines through which every AFTN station can be reached. Sometimes AFTN stations are connected to more than one centre or to other stations.