Airspace by country

Alert areas flag high training volume or unusual activity; everyone shares responsibility for see-and-avoid.

Class A airspace from 18,000 ft MSL to FL600 is IFR-only — what that means and why it exists.

Class B surrounds the busiest US airports and requires an explicit ATC clearance to enter — even under VFR.

Class C airspace, its two-way-radio and transponder requirements, and its typical 5-/10-nm shape.

Class D surrounds smaller towered airports; two-way radio contact is required to enter.

Class E is the controlled airspace that fills the gaps so IFR traffic stays protected; what VFR pilots must know.

Class G airspace is uncontrolled — the rules, weather minimums, and why it exists near the surface.

Why controlled firing areas aren't charted, and how they protect nonparticipating aircraft.

What an MOA is, whether VFR aircraft may enter, and how to stay safe near military training.

What prohibited areas are, why they exist, and the consequences of entering one.

Restricted areas contain hazards like artillery or missiles; how to check whether one is active.

What a special-VFR clearance is, when it's useful, and its limitations — especially at night.

An overview of special-use airspace — prohibited, restricted, warning, MOA, alert and controlled firing areas.

What TFRs are, the common types, and why checking for them is a non-negotiable preflight step.

Where a Mode C transponder and ADS-B Out are required, including the Mode C veil and the 10,000-ft rule.

A plain-English tour of the US airspace system — Classes A, B, C, D, E and G — and what each means for VFR and IFR pilots.

The visibility and distance-from-cloud requirements for VFR flight, by airspace class and altitude.

Warning areas resemble restricted areas but lie over international waters offshore.