AFIS on the Network

The RADIO position

At Vatsim Brasil, AFIS is provided by positions with the suffix _R_TWR, such as SBBU_R_TWR (Bauru Radio) and SBTT_R_TWR (Tabatinga Radio). The _R_ marks the RADIO and is a Vatsim Brasil convention. The _TWR is just the connection type: the VATSIM Code of Conduct lists the suffixes accepted on the network, and none of them is for AFIS¹.

Three practical consequences:

• Rating: under the GCAP table, _TWR positions require the S2 rating (Aerodrome Controller)². Opening a RADIO requires the same rating as a tower.
• Approved positions: only approved positions and frequencies may be opened (Code of Conduct item C6)¹. Use the callsign and frequency from the aerodrome page in the MOP.
• Range: the maximum range of a tower position is 50 NM (item C8)¹. That is more than the 27 NM radius of AFIS with no published FIZ.

Where the RADIOS are

The pages of AFIS aerodromes are in the afis folder of each FIR, in the Aerodromes section, tagged Não-Controlado. The "ATC Units" table on each page gives the position, the abbreviation, the callsign and the frequency. The table note says when AFIS is provided by another unit, as in Bauru, where AFIS is provided by Bauru APP (SBWU_APP) on the same frequency.

The terminal area pages list the aerodromes of each TMA and, in the top-down coverage diagram, show which position each RADIO falls back on.

Real-world hours

In the real world, many units change with the time of day: the tower that becomes AFIS overnight, the approach that closes and leaves a FIZ in place of the TMA, the RADIO that only operates on weekdays. The MOP pages record this as "In the real world".

On the network, the position in the sector package applies, at any time. If the aerodrome has a tower in the package, it is a tower. If it has a RADIO, it is a RADIO.

Top-down coverage

The GCAP establishes that VATSIM positions cover the airspace and positions below them when those are not staffed. This is the top-down principle. It applies to positions providing control service, and the division may extend it to other positions (GCAP 4.6 and 4.6(a))². At Vatsim Brasil, RADIOS are part of the coverage: in each TMA's diagram, the _R_TWR sits below the APP, and the APP sits below the center.

With the RADIO disconnected, the position above provides the Flight Information Service in the FIZ³. The arrangement has a real-world parallel: at an uncontrolled aerodrome where an APP is based, the APP itself provides AFIS (Art. 784 of ICA 100-37)⁴. This has an effect that catches many people out:

With no one connected, either directly or top-down, pilots use the network traffic frequency. The Code of Conduct requires monitoring the designated frequency in airspace with no controller, and using 122.800 where there is no specific frequency¹.

Opening and closing the position

When you open the RADIO, someone was probably covering the aerodrome top-down. Tell the approach or center, ask about traffic already in the FIZ or arriving, and only then start answering calls.

When closing, do the reverse: tell whoever will cover, and tell the pilots on the frequency whom they will talk to from then on. If no one will cover, say that the aerodrome is left without an ATS unit and that the traffic frequency becomes the network one.

These steps follow the same pattern as the handover between any positions, covered in the Coordination and Transfer Manual.

Coordination with approach and the center

The RADIO neither receives nor transfers control, because there is no control to transfer. A flight departing an AFIS aerodrome enters the control chain at the unit with jurisdiction over the airspace ahead, not at the tower. What the RADIO coordinates with that unit is information:

ATIS

The Code of Conduct only allows voice ATIS at aerodromes that have ATIS in the real world, always with a text version in English (item C7(a))¹. Some AFIS aerodromes have ATIS in the package, such as SBBU_ATIS. If the aerodrome has ATIS, the aerodrome information may quote the information letter, but known traffic is still given on the frequency.