Airspace and ATC services communications
This section covers airspace and ATC services communications: what a clearance means in each class, which services ATC provides, and how to ask for them.
Core rules
- Controlled airspace (Classes A–E) requires an ATC clearance for IFR; VFR requires clearance in Classes B, C and D, and VFR is not permitted in Class A. Class G is uncontrolled: no clearance is required, but other rules still apply.
- ATC services include aerodrome or tower control, approach control, area control, flight information service and alerting service.
- In Class G, ATC may provide traffic information and a flight information service, but it does not provide separation between VFR aircraft. Do not treat “traffic information” as a clearance or as a separation guarantee.
- Transponder requirements vary by airspace; if a code is assigned, read it back and set it.
- When requesting a service, state callsign, position, altitude and what you want: for example, “request traffic service” or “request flight information”.
Worked example
A VFR pilot in Class G calls “Lagos Information, 5N-ABC, 20 nm north of LOS, 2,500 ft, request traffic service.” The controller replies with known traffic and suggests a frequency. The pilot may use the information but remains responsible for see-and-avoid and terrain clearance; no clearance or separation is implied.
Traps
Assuming ATC separates all traffic in Class D or G; entering Class C without a clearance; confusing “traffic in sight” with “cleared to enter”; and failing to read back an assigned squawk.