Flight Information Region

A Flight Information Region (FIR) is an airspace of defined dimensions within which flight information service (FIS) and alerting service are provided. FIRs cover the entire surface of the earth, including oceanic areas, ensuring that every point in the world falls within some FIR's area of responsibility.

FIRs are designated by ICAO and managed by the state responsible for the airspace. Each FIR is identified by a four-letter ICAO indicator (e.g., SBCW for Curitiba FIR in Brazil, EGTT for London FIR). Above a specified altitude (usually FL245 or FL460), an Upper Information Region (UIR) may be established.

FIR boundaries are significant for flight planning because crossing from one FIR to another may involve changes in:

• Communication frequencies
• Altimeter setting procedures (QNH vs. standard pressure)
• Separation standards
• Language requirements
• Overflight fees and permits