UIR (Upper Information Region)

Airspace is divided vertically as well as horizontally. Lower-altitude traffic is handled within Flight Information Regions (FIRs), while the airspace above a defined level may be organized into Upper Information Regions (UIRs). This division lets states and air navigation service providers manage dense high-altitude jet traffic separately from the more varied operations found at lower levels. Like FIRs, UIRs are established by ICAO in coordination with member states and are identified by ICAO region codes.

The boundary at which an FIR transitions to its overlying UIR is a published flight level that varies by region, and a single UIR is frequently drawn to span several underlying FIRs. Because high-altitude airspace is where most international airline cruise occurs, the UIR is often the practical unit for describing where en-route warnings, restrictions and overflight conditions apply to long-haul traffic. Not every region defines a separate UIR; some authorities manage the full vertical extent within one FIR.

Conflict-zone advisories, GNSS interference reports and airspace restrictions frequently bear on the cruise levels that fall inside a UIR. AeroVigil uses FIR and UIR geometry as a reference frame, mapping such events to the regions they affect so operators can reason about exposure to overflight risk at the altitudes their aircraft actually transit.