Airspace Classification, ATS Services and Separation
What the exam tests
This domain tests ICAO airspace classes A to G, the services provided in each, and who is separated from whom. Questions often ask what a VFR flight can expect in Class C, D or E airspace.
Core rules
- Class A: IFR only; all aircraft are separated by ATC.
- Class B: IFR and VFR permitted; ATC separates all aircraft from all aircraft.
- Class C: IFR and VFR permitted; IFR is separated from IFR and VFR; VFR is separated from IFR, but VFR receives traffic information about other VFR and is not separated from VFR.
- Class D: IFR is separated from IFR; IFR and VFR receive traffic information about each other; VFR is not separated from VFR.
- Class E: IFR is separated from IFR; IFR and VFR receive traffic information; VFR is not separated from IFR or VFR.
- Class F is advisory; Class G is uncontrolled. Flight information service and alerting service are available in various classes, but are not the same as ATC separation.
- ATS units include area control, approach and aerodrome control. Separation minima depend on radar or procedural standards and on the airspace class.
Worked example
A VFR flight enters Class C airspace. ATC separates it from IFR traffic, so the VFR pilot can expect conflict avoidance against IFR flights. However, ATC does not separate that VFR flight from other VFR aircraft; it provides traffic information as far as practicable. The pilot remains responsible for see-and-avoid with respect to other VFR traffic.
Traps
Do not assume VFR always receives separation. Do not say Class E separates VFR from IFR. Do not confuse traffic information with a separation service. Do not treat flight information service as an ATC clearance.