Working the Frequency

The rhythm of the frequency

At the tower, the controller leads: clears, instructs and waits for the readback. At the RADIO, the pilot leads. The pilot calls, says where they are and what they intend, and reports each phase. The RADIO answers with roger, adds what the pilot needs to know and requests the next report.

The MCA 100-16 examples for AFIS always follow the same pattern (Arts. 153 to 158)¹:

1. the pilot calls and identifies;
2. the RADIO answers with its own callsign;
3. the pilot gives origin, position, level and intention, or requests information;
4. the RADIO gives roger and the aerodrome information, and asks for intentions or a report;
5. the pilot reports each phase, and the RADIO acknowledges with roger, with traffic information when there is any.

Aerodrome information

The RADIO's first answer to an arriving or departing aircraft is the aerodrome information. The items are in Art. 788 of ICA 100-37, detailed in AFIS Fundamentals². In the MCA 100-16 examples, it comes in roughly this order¹:

• wind, in degrees and knots, or "wind calm";
• runway used by other aircraft, when applicable;
• altimeter setting (QNH);
• temperature;
• aerodrome conditions: "aerodrome under visual conditions", "aerodrome under IMC" or "aerodrome below visual minima", with estimated ceiling and visibility when relevant;
• aids out of service, such as an NDB off the air, and obstacles on the movement area, such as machines beside the runway;
• known traffic, or "no reported traffic";
• time check, for those about to depart;
• and, for arrivals, "advise intentions".

The RADIO does not assign the runway. It gives the runway and circuit other traffic is using. The pilot is expected to use that runway, but may choose another, provided they say so before entering the circuit or starting to taxi (Art. 158 of ICA 100-37)².

Traffic information

Traffic information is the most valuable thing the RADIO has, because the pilot will use it to separate themselves. It says who the traffic is, what it is, where it is and what it will do. MCA 100-16 gives this example, for an arrival with two traffics (Art. 154)¹:

Give the information when it changes the pilot's decision: on the initial call, when new traffic joins the circuit or calls on the frequency, and when two aircraft will converge on final or on the runway. The MCA 100-16 examples mark this point with "[traffic information]" after the roger, in the base leg and final reports (Arts. 154 and 155)¹.

ICA 100-37 gives the pilot the rules to resolve the conflict: the aircraft on final approach normally has priority over the one in the circuit (Art. 159)². MCA 100-16 also shows traffic with priority, such as an aeromedical flight or an organ transport, and the pilot who, once informed, gives way (Art. 158, III)¹.

VFR arrival

The pilot calls with origin, position, level and intention. The RADIO gives the aerodrome information and asks for intentions. From then on, each leg generates a report (Art. 154 of MCA 100-16)¹:

The following reports are downwind, base, final and on the ground with runway vacated. On base leg, the pilot also reports the landing gear down and locked, as Art. 791 of ICA 100-37 requires².

Joining the circuit. The preferred join is via the upwind leg sector (Art. 154 of ICA 100-37). At an AFIS aerodrome, since two-way communication is mandatory, the pilot may also join aligned with the start of the downwind leg, at the midpoint of the downwind leg at 45°, or aligned with the base leg, after making sure with the RADIO that there will be no conflict (Art. 163). With no other traffic and a crew familiar with the aerodrome, VFR may join straight in on final, and IFR may fly a straight-in approach (Art. 164)². MCA 100-16 has an example of a join via long final (Art. 155)¹.

The circuit altitudes and layout are in the Traffic Circuit Manual.

VFR departure

The pilot calls when starting to taxi, with the runway and destination, and requests information. The RADIO gives the aerodrome information, with known traffic and time check, and requests a report at the holding point. The following reports are holding point, entering the runway, lined up and airborne (Art. 156 of MCA 100-16)¹.

Note what the pilot says at the holding point: "maintain position, waiting for Xingu landing". The pilot is the one who decides to wait. The RADIO only gave the information that made the decision possible.

After take-off, the pilot reports the level reached and the estimates. If the route enters controlled airspace, the RADIO gives the frequency of the next unit: "entering Terminal, contact Vitória Control 119,8, if negative, Vitoria Tower 118,1"¹.

IFR arrival

ICA 100-37 has a section on instrument descent at an aerodrome provided with AFIS, which "must have an IFR approach procedure in force" (Art. 140)²:

• In controlled airspace, the aircraft obtains from the ATC unit clearance to descend to the minimum level of controlled airspace, proceeds to the procedure and transmits on the RADIO frequency the levels or altitudes and the procedure phases as it reaches them (Art. 141).
• Outside controlled airspace, there is no clearance to obtain: the aircraft determines the minimum descent level using the criteria of Art. 142, flies the procedure and transmits the same information on the RADIO frequency (Art. 142)².

MCA 100-16 gives two situations, both with the aircraft descending under Amazônico Center (Art. 153)¹:

1. Still with the center, the pilot calls the RADIO and requests the aerodrome conditions. The RADIO gives the wind, the runway used by other aircraft, the setting, the aerodrome condition, the visibility, the ceiling and the temperature.
2. The pilot states the procedure to be flown, and the RADIO asks them to report when cleared by the center.
3. The pilot comes back to the RADIO: "cleared by Center, passing FL 120 IMC". The RADIO gives roger and the altimeter setting.
4. The RADIO requests the procedure reports. On a conventional procedure: initial altitude, outbound, base or procedure turn, final approach and MDA with the aerodrome in sight. On an RNAV procedure: each fix (CZ009, CZ011, CZ012). On final, the pilot reports the gear down and locked.
5. The RADIO gives the wind and requests the on the ground and runway vacated reports.

The descent clearance belongs to the center or approach. The RADIO does not repeat it as if it were its own. It follows the procedure and keeps the pilot informed about traffic, especially VFR traffic in the circuit. The MCA 100-16 example does this for an IFR aircraft on an RNP procedure: "IFR operation, lowest layer at 600 feet, PT KLN traffic is a Cessna 182, departed 2 minutes ago climbing to FL 060, radial 337, report starting procedure" (Art. 158)¹.

IFR departure

The IFR clearance is issued by the control unit with jurisdiction over the airspace ahead, never by the RADIO. When the clearance comes through the RADIO frequency, it is a relay (Art. 788, VII, of ICA 100-37)², and the RADIO says where it came from: "after passing FL 040, cleared by the Center to climb en route, report passing FL 040 to the Amazônico Center, frequency 123,95" (Art. 158 of MCA 100-16)¹.

In the MCA 100-16 IFR departure example (Art. 157)¹, the pilot calls when starting to taxi, stating the departure to be flown ("I will execute SID RNAV AGIL 1A"). The RADIO gives the aerodrome information with a time check, requests the holding point, lined up and airborne reports, and then the report passing the first fix of the departure. Only then does it send the pilot to the center: "contact now Amazônico Center 124,55, if negative, 134,15".

See also Coordination with approach and the center.

Aerodrome below minima

The RADIO does not close the aerodrome. It gives the conditions, and the decision is the pilot's. In the MCA 100-16 example, the RADIO reports "aerodrome below visual minima, estimated visibility 2.000 meters, ceiling 600 feet, advise intentions", the pilot decides to proceed to the alternate, and the RADIO requests a report "5 minutes out of Aeroxingu" (Art. 158, II)¹.

Aircraft without radio

ICA 100-37 prohibits the operation of aircraft without radio, or with the radio inoperative, at AFIS aerodromes. The exceptions are ferry flights, agricultural flights, and gliders and aircraft of flying clubs and training centres based at the aerodrome, always with prior coordination and at times that do not disrupt traffic (Art. 789)².