The Application of ICAO Airspace Classifications in UK FIRs

The purpose of CAS in the UK is to enhance the protection of Air Transport Movements (ATMs) operating under Instrument Flight Rules (IFR) during en-route flight and the critical stages of an Instrument Arrival or Departure, and to permit the safe and effective integration of such traffic with other IFR flights and flights operating under Visual Flight Rules (VFR). Such protection is principally established by means of a “known traffic” environment.