ATC Department

Tower (TWR)



The duties of the Tower controller are multiples. This ATC position is responsible for runways selection, take-offs & landings clearance, VFR traffics inside the CTR (please note CTR in real has a different meaning from CTR on Ivao) and runway occupation.

This is the position at the heart of each airport and the leading ATC. He/she is responsible to take traffic airbones or back to the ground. This position requires good coordination skills with both GND, APP and DEP controllers. As Tower has to deal with traffic flying as well as traffic on the ground he/she should always be able to see situation in advance and plan accordingly.

At the same time, the Tower position requires a deep knowledge of several subjects.


Basic Knowledge Requirements

A TWR controller must be perfectly familiar with:

  • All the Basic Knowledge Required to control DEL position and GND position
  • Runway selection criterias
  • VFR chart interpretation and VFR handling
  • Airspace Classes and set up
  • Missed approach procedure (MAP)
  • Emergencies handling
  • Wake turbulence separation
  • Important weather phenomena and visibility constraints (such as RVR)
  • TORA


Controller in Action

The first step for the virtual controller that wants to act as TWR would be to be sure he/she is in line with the knowledge requirements highlighted above.

As this is done, the controller should load the sector file for the airport in which he/she wants to control. The sector file can be found on the quicklinks tab of the Home page.

The second step is to check the latest Handy Sheet, available on the airport page, where all the necessary information are summarised in a single document. VFR Charts are mandatory!

In the IVAC's COMM Box the controller has to set his primary frequency in line with GND frequency for that airport. In order to do so just type //199.999  where 199.999 stands for the frequency one wants to set up.

The next step is the setup of the altitude filter. As the TWR controller is responsible for movement on the ground as well as airborne and VFR traffics, the filter should be set up in such a way that he excludes all the traffics that are above its CTR. In order to do so under the menu "PVD" (top left) select "PVD Options..." the controller will set Primary filter from 0 to 1000 ft above CTR upper limit. This is for example 5'500ft at Zurich.

Once IVAC is ready, it is time to connect.

As soon as the controller is online the first priority is to create the TS channel followed by the filing of a correct ATIS. Please remember, the Tower is responsible (always) for runway selection! 

The station name and frequency have to be in line with guidelines from ATC Department and can be found here: LSAZ and LSAG. The remarks box must be left empty unless a special situation requires to be communicated to pilots. This is the case for "LOW VISIBILITY PROCEDURE ACTIVE" or "ALL RWYS CLOSED DUE TO EMERGENCY" or also "ALL RWYS CLOSED DO TO SNOW CLEARING". Personal message or greetings to pilots are not allowed.

Always inform nearby controllers of your presence online.

There are three kind of traffic that joins the frequency of an Tower controller: outbound, inbound and VFR. Despite the latter can follow into any of the first 2 categories, VFR are handled in a different way and thus requires a specific classification.

Outbound. When a traffic reaches, or is about to reach clear of any potential conflicts, the holding point of the active runway for departures the Apron controller transfers it to the Tower. The duty of the Tower controller is to clear the traffic to enter the runway and take-off. Obviously this should be done without putting the departing traffic in any risks of conflicts with others such as traffic s cleared to cross the active runway or traffic about to land. A runway can be occupied by only one traffic departing or only one landing. Once the traffic is airborne, the Tower transfers it to DEP controller.

Inbound. Tower controller receives inbound traffics from ARR. Arrival controller positions traffics for a stable approach to a runway whatever it will be instrumental or visual. When confirmed stable for the assigned approach, Arrival transfers to Tower. Tower receives the traffic and according to the current flow situation clears the inbound traffic to land or to continue the approach. Once on ground and runway vacated (or about to vacate), Tower controller will transfer the traffic to Apron. In some cases this will happen automatically without requests from Tower to contact Apron.

VFR. This is a separate category as includes inbounds, outbounds and local circuit traffics. Tower is responsible for all VFR traffics operating within its CTR (please note the meaning of CTR is different from IVAO's defiinition of CTR). Tower instructs VFR traffics to designated VFR routes within its airspace and keeps separation between all other traffics. Depending on airspace classification, different power (and duties) are given to Tower controller. A good knowledge of VFR rules is mandatory to keep a "clean" airspace around an airport.


Phraseology Examples


Runway Line Up and Take Off Clearance

 Pilot  ATC

Zurich Tower good morning, Swiss 57PU, approaching A rwy 28, ready for departure


Swiss 57PU Tower hello, [continue taxi], line up and wait rwy 28


Traffic aligns with runway


Swiss 57PU wind 320 degrees 12 knots, rwy 28, cleared for takeoff

Cleared for takeoff rwy 28, Swiss 57PU


Traffic takes-off


Swiss 57PU contact departure [on 125.950]



Conditional Clearance

Pilot ATC

Zurich Tower good morning, Swiss 57PU, approaching A rwy 28, ready for departure 


Swiss 57PU Tower hello, BEHIND Airbus 320 on short final, line up and wait rwy 28, BEHIND

BEHIND Airbus 320 on short final, line up and wait rwy 28, BEHIND, Swiss 57PU





Pilot ATC

Zurich Tower Grüezi, Swiss 215, [7 miles out] ILS 14


Swiss 215 Tower hello, wind check 200 degrees 15kts, continue approach

Continue, Swiss 215


Traffic continues the approach 


Swiss 215 Jumbolino about to vacate, wind 200 degrees 14kts, rwy 14 cleared to land

Cleared to land, Swiss 215


Tower, Swiss 215, is H2 available?


Swiss 215, affirmative [on expedite]

Roger, Swiss 215




VFR - Outbound

Pilot ATC

Geneva Tower, good afternoon, HB-CQR, holding point Y, rwy 23, ready for departure, outbound via route November


HB-CQR, Geneva Tower, hello, outbound via route november, winds 220 degrees 11 knots, rwy 23, cleared for takeoff

outbound via route november, cleared for takeoff rwy 23, HB-CQR


HB-CQR N, 3500ft


H-QR, Frequency change approved, Goodbye

Frquency change approved, H-QR, Goodbye




VFR - Inbound

Pilot ATC

Zurich Tower, HB-CQR, Cessna 172, VFR from Geneva, Hallwilersee 3500ft, for landing, via route Whiskey, information X-RAY


HB-CQR, Zurich Tower, good day, [check Information X-RAY], enter control zone via Route W, QNH 1023

enter control zone via route W, QNH 1023, HB-CQR


HB-CQR, W1, 3500ft



H-QR, W2, 3000ft


H-QR join downwind RWY 28

Join downwind RWY 28, H-QR


H-QR, downwind RWY 28


H-QR wind 280 degrees 10 knots, RWY 28 cleared to land

RWY 28 cleared to land, H-QR