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Flight Information Region (FIR)

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An airspace of defined dimensions within which flight information service and alerting service are provided.

Source: ICAO Doc 4444 PANS-ATM


Generally, flight information regions (FIRs) are the largest airspace structures in use. There are no rules regarding their size but in most cases smaller countries tend to have one FIR and larger countries usually divide their airspace into several FIRs. While there is an ICAO recommendation in Annex 11 that the delineation of airspace, wherein air traffic services are to be provided, should be related to the nature of the route structure and the need for efficient service rather than to national boundaries, in most cases the national boundaries coincide with FIR boundaries.

It is possible to define portions of Controlled Airspace within an FIR. These structures are called control zones (CTZs) if their lower limit is the ground and control areas (CTAs) otherwise. Within this airspace, air traffic control (ATC) service is provided in addition to flight information and alerting services. Depending on the airspace class, ATC service may be provided to IFR flights only or to both IFR and VFR.

It is also possible for a control area to include (parts of) the airspace of several FIRs.

An FIR includes all airspace within its lateral limits, except as limited by an upper flight information region (UIR). In this case, the lower limit of the UIR is the same as the upper limit of the FIR and coincides with a VFR flight level (e.g. FL 245). The procedures applicable in the UIR need not be identical with those in the underlying FIR.

The provision of service in an FIR (excluding the parts that are designated as controlled airspace) is done by an ATS unit called Flight information centre (FIC). This unit is normally identified by the name of a nearby town or city or geographic feature and the FIR is normally identified by the name of the unit having jurisdiction over the airspace.

FIRs and UIRs are considered "locations" in terms of ICAO Doc 7910 Location Indicators and, as such, are assigned four-letter codes. Sometimes an FIR and a UIR share the same location indicator.

Oceanic airspace is divided into Oceanic Information Regions and ATS is provided by authorities bordering those regions.

Europe - FIR/UIR lower airspace chart - 2019
Europe - FIR/UIR upper airspace chart - 2019

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Further Reading

  • ICAO Annex 11: Air Traffic Services
  • ICAO Doc 7910 Location Indicators