Introduction

Airspace is the invisible framework that governs how aircraft operate. In real-world aviation, it creates order, safety, and efficiency. On VATSIM, this structure is simulated to mirror ICAO principles, allowing pilots and controllers to interact realistically.
Because each state designs its airspace differently, the best way to understand any airspace is through its rules, not assumptions about altitude or location. Pilots should rely on official charts and tools such as VATGlasses for accurate, local information.

What Is Airspace?

Airspace is a defined portion of the atmosphere where rules specify:

• Whether IFR and/or VFR flights can operate
• What ATC services are provided
• What separation is ensured
• What pilots are responsible for

The implementation of each class varies globally, but the core rules remain consistent.

Airspace Classes (A–G)

Class A

• IFR flights only.
• Full ATC separation provided.
• Can begin at high or low altitudes depending on the country—sometimes as low as 1500 ft.
• VFR entry may be prohibited by local procedures.

Class B

• IFR and VFR permitted.
• Full separation between all aircraft.
• Associated with high-density, complex airspace, typically around major airports.

Class C

• IFR and VFR permitted.
• IFR separated from all traffic.
• VFR separated from IFR; receive traffic information regarding other VFR.
• Common in medium-complexity terminal areas.

Class D

• IFR and VFR permitted.
• ATC separates IFR from IFR; VFR receive traffic information as possible.
• Typical for smaller towered aerodromes.

Class E

• IFR receives ATC services and separation.
• VFR receive no separation and are responsible for their own see-and-avoid.
• Provides transitional or lower en-route structure.
• Services to VFR are workload permitting.

Class G

• Uncontrolled airspace.
• Pilots are responsible for their own separation.
• May contain FIS or AFIS at or near aerodromes.
• With no ATC online on VATSIM, pilots coordinate using the local advisory frequency or CTAF where published.

Special Airspace Types

Prohibited Areas (P-areas)

No flight allowed due to national or security restrictions.

Restricted Areas (R-areas)

Entry requires permission from the controlling authority.

Danger Areas (D-areas)

Activities hazardous to aviation may occur. Exercise caution.

RMZ — Radio Mandatory Zone

Two-way radio communication required prior to entry.

TMZ — Transponder Mandatory Zone

Aircraft must operate an active transponder.

ATZ — Aerodrome Traffic Zone

Low-level protection for aerodrome traffic, typically around smaller or non-controlled aerodromes.

FIS and AFIS

Flight Information Service (FIS)

• Provides information, not control.
• Includes weather updates, QNH, traffic information, and basic navigation support.
• No separation or clearances issued.
• On VATSIM, FIS is often hosted under the _CTR suffix because no dedicated _FIC or _FSS suffix exists under GCAP.

Aerodrome Flight Information Service (AFIS)

• Used at aerodromes without a full ATC tower.
• Offers runway, traffic, and weather information.
• Cannot issue take-off, landing, taxi, or crossing clearances.
• Pilots self-separate while following AFISO advisories.

ATC Structure on VATSIM

Delivery | _DEL

• Issues flight plan clearances
• Provides initial departure instructions
• Assigns transponder codes

Ground | _GND

• Manages pushback and taxi
• Controls apron and taxiway movement

Tower | _TWR

• Handles takeoff and landing clearances
• Manages runway operations
• Controls the ATZ where applicable

Approach | _APP / Departure | _DEP

• Provides terminal area control
• Manages SID/STAR flows
• Conducts vectoring and sequencing

Center | _CTR

• Controls en-route airspace
• Coordinates between sectors
• May provide FIS services, depending on local vACC structure

Operations Without ATC

When no controller is online, pilots self-announce position and intentions on the local advisory frequency (122.800MHz), including CTAF where applicable.
Messages should be brief and strictly operational.