Controlled and uncontrolled airspace

ICA 100-12 defines controlled airspace as "airspace of defined dimensions within which Air Traffic Control Service is provided in accordance with the airspace classification" — a generic term covering ATS airspace of classes A, B, C, D and E². ICA 100-37 reaches the same idea by another route: Control Areas and Control Zones are "the parts of the airspace within the FIR where Air Traffic Control Service is provided to IFR or VFR flights, in accordance with the airspace classification"¹.

Outside these areas the airspace still exists — it remains within the FIR — but the nature of the service changes: instead of control, flight information and alerting are provided¹. This change has a direct practical consequence for who is responsible for separation between aircraft: whenever the ATC unit is not responsible for providing separation in the airspace class concerned, it is up to the pilot in command to provide their own separation from other aircraft (Art. 24)¹.

The next chapter details the airspace classes and what changes in each one. Here, the distinction that matters is binary: either there is control, or there is not.

Controlled airspace is not the same as a controlled flight

These are two neighboring concepts that are easy to confuse, and the rest of this manual uses both. Controlled airspace is an attribute of the airspace: classes A, B, C, D and E, where Air Traffic Control Service is provided in accordance with the classification². Controlled flight is an attribute of the flight: item CI of Annex VII to ICA 100-12 defines it as "any flight subject to an air traffic control clearance"².

The test is different in each case — the first asks where the aircraft is; the second, whether that flight depends on an ATC clearance. They almost always coincide, but not always:

• a VFR flight in Class E airspace is inside controlled airspace and is not a controlled flight: Art. 115 of ICA 100-12 states that, in Classes E, F and G, "VFR flights are not subject to air traffic control clearance, receiving from ATS units only flight information and alerting services"²;
• a Special VFR flight is a controlled flight by definition, because Annex VII to ICA 100-12 describes it as a "VFR flight cleared by air traffic control" within a CTR or the ATZ of a controlled aerodrome².

This distinction is what underpins two statements that appear later: that a VFR flight in Class D is still a controlled flight, and Art. 77 of ICA 100-12, which requires a clearance "before operating a controlled flight, or a portion of a controlled flight"².

FIR

Art. 15 of ICA 100-37 is direct: "Flight Information Regions are the parts of the airspace where Flight Information and Alerting Services are provided."¹ ICA 100-12 defines the same concept almost word for word: "airspace of defined dimensions within which flight information service and alerting service are provided"².

The FIR is the container for the other divisions, not an alternative to them. Art. 19, sole paragraph, is explicit: "Control Areas, Control Zones and Aerodrome Traffic Zones located within a Flight Information Region form part of that Flight Information Region."¹ In other words, UTA, CTA, TMA, CTR and ATZ do not sit beside the FIR — they sit inside it.

Control Areas: UTA, CTA and TMA

Art. 16 establishes the general category: "Control Areas and Control Zones are the parts of the airspace within the FIR where Air Traffic Control Service is provided to IFR or VFR flights, in accordance with the airspace classification."¹ Art. 17 divides Control Areas into three types, each "as defined in the AIP-Brasil"¹:

• UTA — comprises the upper airways and other parts of the upper airspace;
• CTA — comprises the lower airways and other parts of the lower airspace;
• TMA — comprises parts of the lower airspace.

The boundary between upper and lower airspace is not a local variable — it is national and fixed: the upper airspace begins above FL 245 (exclusive) and has no upper vertical limit; the lower airspace extends from the ground or water up to and including FL 245 (Art. 12 and 13)¹. It is this division that separates UTA from CTA.

The TMA gets an additional description in ICA 100-12: it is the "control area normally established at the confluence of ATS routes in the vicinity of one or more aerodromes"² — the airspace that concentrates the arrivals and departures of one or more neighboring aerodromes before they join the airways.

CTR

ICA 100-12 defines a Control Zone as "controlled airspace extending upwards from the surface of the earth to a specified upper limit"². It follows the same control logic as Art. 16 — within the CTR, Air Traffic Control Service is provided to IFR or VFR flights according to the airspace class¹ — but with a difference in where it starts: while a Control Area "extends upwards from a specified limit above the earth"², the CTR starts at the ground itself. It is the controlled airspace that surrounds an aerodrome from the surface up.

ATZ

Art. 19 designates as Aerodrome Traffic Zone "the parts of the airspace around an aerodrome within which special requirements have been established for the protection of aerodrome traffic"¹.

The ATZ is not an airspace class. Annex II to ICA 100-37, referenced by Art. 22, records this: "An ATZ has no classification under the [airspace class] table, its practical effect being to protect VFR traffic operating at an aerodrome."¹ What does — or does not — guarantee traffic control at that aerodrome is another provision: Art. 20 states that "aerodromes where Air Traffic Control Service is provided to aerodrome traffic are designated as controlled aerodromes."¹

Vertical overlap

When two ATS airspaces overlap vertically — one directly above the other —, Art. 23 resolves the conflict with a single rule: "flights at a common level shall comply with the requirements of, and be provided with the services applicable to, the less restrictive airspace class."¹ The sole paragraph sets the order of restrictiveness: "Class B airspace shall be considered less restrictive than Class A airspace; Class C less restrictive than Class B, and so on."¹

In practice: if a Class D TMA has a Class C CTA overlapping above it, at the exact level where the two coincide the Class C rules apply — the less restrictive of the two. The airspace classes are detailed in the next chapter; what matters here is the resolution principle for when two structures coincide at the same level.

Summary of the divisions

The actual lateral and vertical limits of each FIR, TMA, CTR and ATZ are published in the AIP-Brasil and on aeronautical charts — they vary by location and change with each AIRAC cycle. For the current limits of each area, see the portal's Operational Manuals section.

Vertical cross-section of the airspace