The two main classifications of airspace
What are the two main classifications of airspace?
In Australia, there are two major types of airspace: controlled, and uncontrolled. Controlled airspace in Australia is actively monitored and managed by air traffic controllers. To enter controlled airspace, an aircraft must first gain clearance from an air traffic controller.
Uncontrolled airspace has no supervision by air traffic control so no clearance is required to operate in uncontrolled airspace. The large majority of light aircraft and helicopters operate outside or underneath controlled airspace.
In uncontrolled airspace, pilots are often not visible to air traffic control but must still follow flight rules.
Further classifications of airspace
As well as being broken into controlled or uncontrolled airspace, Australian airspace is further divided into different classes, where internationally agreed rules for flying apply.
Depending on how far and how high an aircraft wants to fly, it will pass through different classes of airspace, in which different rules will apply to it.
Figure 1: Australian Airspace classes (diagram taken from airsevicesaustralia.com).
Class A: This high-level en-route controlled airspace is used predominately by commercial and passenger jets. Only IFR (‘Instrument flight rule’) flights are permitted and they require an ATC (Air Traffic Control) clearance. All flights are provided with an air traffic control service and are positively separated from each other.
Class C: This is the controlled airspace surrounding major airports. Both IFR and VFR (Visual flight rule) flights are permitted and must communicate with air traffic control. IFR aircraft are positively separated from both IFR and VFR aircraft. VFR aircraft are provided traffic information on other VFR aircraft.
Class D: This is the controlled airspace that surrounds general aviation and regional airports equipped with a control tower. All flights require ATC clearance.
Class E: This mid-level en-route controlled airspace is open to both IFR and VFR aircraft. IFR flights are required to communicate with ATC and must request ATC clearance.
Class G: This airspace is uncontrolled. Both IFR and VFR aircraft are permitted and neither require ATC clearance.
Note: At towered airports, the class of airspace may change subject to the time of day.
| Class | Controlled | IFR | VFR | ATC Clearance | Separation |
|---|---|---|---|---|---|
| A | Controlled | Yes | No | Required | Provided for all flights |
| C | Controlled | Yes | Yes | Required | Provided for all IFR to IFR/VFR |
| D | Controlled | Yes | Yes | Required | Provided for IFR to other IFR |
| E | Controlled | Yes | Yes | Required for IFR | Provided for IFR to other IFR |
| G | Uncontrolled | Yes | Yes | Not provided | Not provided |
Figure 2: Australian Airspace classes and services
Planning flight operations
There are a number of different air charts available to people when planning flight operations. These detail various factors including restricted areas, airports and more. Your organisation’s Chief Pilot (or delegate) is responsible for ensuring all flights are conducted in accordance with the law and you should have policies in place that support this.
As a general rule, whenever there are operations proposed that are outside the SoCs in regards to not flying within 5.5km of a controlled aerodrome, this should prompt you to seek advice from your Chief Pilot (or delegate), or the sub-contractors relevant manager to ensure someone has been in contact with air-traffic control and has received permission to fly. Drones around airports are a particularly sensitive issue and you definitely don’t want your organisation being the star attraction in an incident.
