Flight information region

In aviation, a flight information region (FIR) is a specified region of airspace in which a flight information service and an alerting service (ALRS) are provided. It is the largest regular division of airspace in use in the world today. FIRs have existed since 1947 at least. In aviation, a flight information region (FIR) is a specified region of airspace in which a flight information service and an alerting service (ALRS) are provided. It is the largest regular division of airspace in use in the world today. FIRs have existed since 1947 at least. Smaller countries' airspace is encompassed by a single FIR; larger countries' airspace is subdivided into a number of regional FIRs. Some FIRs encompass the territorial airspace of several countries. Oceanic airspace is divided into Oceanic Information Regions and delegated to a controlling authority bordering that region. The division among authorities is done by international agreement through the International Civil Aviation Organization (ICAO). There is no standard size for FIRs – it is a matter for administrative convenience of the country concerned. In some cases there is a vertical division of the FIR, in which case the lower portion remains named as such, whereas the airspace above is termed an upper information region (UIR).