FIR (Flight Information Region)

Each FIR is managed by a controlling authority — typically a national air navigation service provider — that is responsible for flight information service (advisories and traffic information) and alerting service (initiating search and rescue) within its boundaries. FIRs are defined by ICAO in coordination with member states and are identified by a four-letter ICAO region code, such as LTAA for the Ankara FIR or EGTT for the London FIR.

Lower airspace is handled within the FIR, while higher-altitude airspace may be designated as an Upper Information Region (UIR) overlying one or more FIRs. Because FIR boundaries do not always follow national borders and extend over international waters, they are the practical unit for describing where a given authority's airspace warnings, closures and restrictions apply.

AeroVigil uses FIR and UIR geometry as a reference frame for geolocating airspace events. When a conflict-zone warning, closure or interference advisory is tied to an FIR, mapping it to that region lets operators understand which routes and overflights are affected rather than reasoning from coordinates alone.