Since I can't edit: I mean "Class B" airspace, which is mostly used in the USA. The ICAO definitions specify what the airspace classifications mean generally b

Since I can't edit: I mean "Class B" airspace, which is mostly used in the USA. The ICAO definitions specify what the airspace classifications mean generally but each country often has its own slight variations of the rules. Class B/C/D is airspace where contact with ATC is required but differs in separation policies. IFR traffic is always kept separated from other IFR traffic. A: IFR only B: All aircraft kept separated by ATC. IFR-VFR and VFR-VFR are all ATC's responsibility. C: IFR traffic kept away from VFR traffic. VFR must watch out for other VFR. D: IFR must watch out for VFR (only kept away from other IFR).