Tower Study Guide

From VATSIM Germany
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Depending on when you read this manual, you will have received your Basic Lesson or will receive it in the future. Regardless, this guide should be read and learned before the TWR or GND lesson. If your Regional Group starts with a GND lesson, you may want to read down to the GND section and leave the TWR section for later.

The Tower Study Guide and later the Approach Study Guide are not meant to be read like a novel. Instead you should make sure that you understand each sentence. I am fully aware that this takes longer than reading a novel but it is essential to understanding this guide. However, you don't need to read everything at once. You should take your time and read it step by step. If you have to reread a section later in order to fully understand it, don't hesitate!. This guide is meant to support you and to teach you the basics of controlling.

Always remember: Have fun!

Basic Knowledge

This section is meant as an introduction for people with very little or no previous knowledge about aviation. It cannot give a complete picture but builds the very basis that is required to advance to the later sections about controlling. If you feel like this knowledge is too basic for you, you may want to skip this part. However, reading this section cannot hurt either ;)

Controller Positions

Broadly speaking the controller positions consist of:

  • Clearance Delivery

provides enroute and startup clearances.

  • Ground/Apron Controller

is responsible for all traffic on the ground and generally speaking for traffic in taxiways. The difference between an apron controller and a ground controller is that the apron controller is working directly for the airport instead or working for DFS. That means that officially apron controllers are not allowed to give enroute and startup clearances. However, on Vatsim this rule does not have to be followed.

  • Tower Controller

is responsible for all traffic on the runways and for airborne traffic within the boundaries of the airport‘s control zone (CTR). On some airports the tower controller is also responsible for some taxiways.

  • Approach Controller

is responsible for sequencing arriving and departing traffic to and from the airport.

  • Center Controller

is providing enroute ATC and sequencing of aircraft before they reach the approach controller

All of these positions can be divided into certain areas of responsibility, e.g. north and south ground control. In the beginning of the training you will only focus on the first three positions. On Vatsim you will have to provide Top-Down service which means that if you are connected as a tower controller, you will have to take over all other tower positions, all apron/ground positions and delivery. Therefore, you will have to know how to control each position before you can do your controller practical test (CPT) and pass onto the approach training.

What is the difference between VFR and IFR Traffic?

If you already know the difference between VFR and IFR, feel free to skip this section. This section is meant as an introduction for people without previous knowledge about this topic.

VFR means visual flight rules while IFR means instrument flight rules. One would think that a VFR pilot only navigates by looking out of his window and an IFR pilot only navigates by using his instruments and GPS or any ground based navigation equipment like VORs and NDBs. However, isn't necessarily true. A VFR pilot is always free to use GPS or tune up any VOR or NDB whenever he wants. The visual flight rule revers to the fact that he needs to be able to navigate visually but he is by no means required to do it 100% of the time. Similarly, IFR traffic has to be able to navigate by using instrumentation but for example during a visual approach or visual departure the IFR traffic may navigate visually.

In order to perform visual navigation the weather has to be good enough to allow for that which means that a VFR pilot is always bound by weather as he/she is not allowed to fly through clouds and the visibility has to be above a certain threshhold. In such a case the IFR pilot may not be able to perform visual approaches or visual departures but will be able to follow any standard SID, STAR or instrument approach. The advantage of the VFR pilot is of course that he/she does not need follow any SID, STAR or airway but can choose the route a lot more freely. Once we discuss handling VFR traffic you will find that even for controllers handling VFR traffic is less restricted than handling IFR traffic and it can be fun to come up with new and inventive solutions.

You see that neither flight rule is always better than the other, they are just different and it's a question of practicability.

Basics Of Controlling

Clearance Limit

Controlling can be described as directing aircraft to fly/roll or hover along a certain path until reaching a clearance limit at which the aircraft has to hold. The clearance limit of an aircraft can be a taxiway, a runway, a waypoint or even the stand/gate. On ground for example an aircraft can be instructed to taxi via L and hold short of L6. In that case the clearance limit is L6 and the aircraft is not allowed to taxi onto L6. On ground ATC should use clearance limits to maintain the safety at all times. This could be done by giving a hold short instructions in order to prevent aircraft from crashing into each other.

In the air the clearance limit is more difficult to explain as it varies depending on the route and the airport. Often the clearance limit is explicitly noted in charts, however, this is not always the case. For the purpose of this guide we will stick to a this simple example: An aircraft is instructed to fly a STAR and does not receive another instruction by ATC. In that case the clearance limit is the endpoint of the STAR.

This guide will mention clearance limits repeatedly. Please make sure you come back to this section in case you forget what clearance limits are.

Airspace Classes in Germany

The seemingly endless airspace has been divided into different classes in order to give it more structure and make it controllable. This is necessary to allow VFR and IFR traffic to coexist.

ICAO allows for a total of seven airspace classes (named A to G). These airspace classes differ from each either in one or more of the following points:

  • Minimum weather requirements in order to fly VFR
  • Flight rules restrictions (only VFR or only IFR)
  • Instrumentation and equipment requirements (transponder, com radio, nav)
  • Contact with ATC and clearance requirements
  • (Separation requirements)

The specific weather minima required for VFR traffic will be ignored in this guide as they are less relevant to Vatsim. We can assume that every VFR pilot automatically complies with the required weather minima that he/she set up in his flight simulator.

The following picture shows the airspace structure within Germany.

Airspace structure Germany.

Above FL100 (exception FL130 in some places around the Alps) you find airspace C. Below airspace C there is usually an airspace E followed by airspace G close to the ground. In highly congested areas of airspace G and/or close to uncontrolled airfields you will find TMZs and/or RMZs

Around controlled airports you will usually find either airspace C or airspace D followed by a control zone (CTR) consisting of airspace D. As a tower controller this will be your playing field and thus we will ignore all other airspaces. If you want to learn more, you can take a look in the approach study guide where this topic is explained more elaborate.

In airspace D every aircraft needs a clearance to enter and a clearance to fly to certain points. With IFR that concept is easy to understand but this also applies to VFR. No VFR traffic may enter or fly within the CTR without your instruction/clearance.

Another aspect of airspace D is that VFR traffic is not separated to other VFR or IFR traffic by ATC but the pilots have to visually identify the traffic and make sure they keep their distance. We have not talked about separation yet so after you learned about separation you might want to reread this section. However, for now we just say that separation is the minimum distance between two aircraft. IFR and other IFR traffic has to be separated by you, the controller thus you have to ensure that the minimum distance is maintained. As stated before, this is not true for VFR traffic because they separate themselves visually. You will support the pilot by giving traffic information and may intervene to prevent a crash but that usually isn't necessary.

Principles Of Controlling

For this chapter please note that I, the author of this article, has no real life experience of controlling. However, this guide needs to explain "controlling" to people that might only know ATC from their time as a Vatsim pilot or not at all. Therefore, it is essential, that we establish main goals that we can work towards. These goals are safety and efficiency.


It could be argued that we only control on Vatsim and safety is not as important. We can't really cause harm to any person so we can only focus on efficiency in order to make traffic flow. However, looking at efficiency without looking at safety is a farce. It would be efficient to leave no space between two aircraft and make all aircraft take off right behind each other. That would be terribly efficient but also unsafe. Therefore, before improving efficiency we need to establish safety.

In order to establish safety we have the following types of separation. They will be applied depending on the circumstance and in some cases have to be applied at the same time. When two of these separations have to be applied at the same time, the bigger number is the one we go by.

Runway Separation

Runway separation means that at every point in time there must only be one aircraft on or above the runway. An aircraft can be considered "off the runway" when it has left the runway to the side like aircraft (a) and (c) in the picture below or has crossed the end of the runway like aircraft (b) in the picture below. Every aircraft airborn but still above the runway has to be considered on the runway! In this case aircraft (c) can only be considered clear of the runway once it has crossed the yellow hold line. There is a way to reduce this separation and is described in the article "reduced runway separation". For now though we stick with the rule: Only one aircraft on the runway.

Visualisation of runway separation.
Wake turbulence separation (WTS)

As soon as a wing produces lift it also produces a wing tip vortex. That means they are only created once the aircraft has rotated and they stop being created once the aircraft has landed and touched down with the front wheel. These turbulences are incredibly strong and can easily flip a smaller aircraft on its head. Therefore, if one aircraft is crossing or following the flight path of another aircraft on the same altitude or less than 1000ft below, additional horizontal separation needs to be applied. This separation also needs to be applied when two aircraft are approaching different runways less than 760m apart. WTS is applied between all aircraft, including VFR. However, it does not need to be applied between

  • Arriving VFR aircraft and
  • Arriving IFR aircraft on a visual approach.

However, if the pilot requests sufficient WTS to the preceeding aircraft, ATC has to ensure the spacing listed below. Note: WTS has to be applied for departing VFR aircraft. Aircraft on a touch and go/low approach are first considered arriving and are then considered departing once they cross the threshhold. So in such a case you will have to tell the pilot to follow a preceeding aircraft visually but once it has crossed the threshhold, you have to ensure that there is enough separation between it and the preceeding departure. If that is not the case, you have to tell the pilot to perform an early left or right turn.

For this purpose the aircraft are divided into the categories Light/Medium/Heavy/Super depending on the Maximum Takeoff Weight.

Category MTOW Examples
Light MTOW ≤ 7000kg C172
Medium 7000kg < MTOW > 136000kg A320
Heavy MTOW ≥ 136000kg B753
Super A388/AN225 A388

The B752 is the only exception to this rule as it is counted as a Medium when following and a Heavy when preceeding another aircraft.

The required separation for different categories of aircraft can be found in the following tables. Preceding aircraft: Medium

Following Aircraft WTS
Medium -
Light 5NM

Preceding aircraft: Heavy

Following Aircraft WTS
Heavy 4NM
Medium 5NM
Light 6NM

Preceeding aircraft: A388 (only in and below FL100, otherwise A388 counts as Heavy)

Following Aircraft WTS
Super -
Heavy 6NM
Medium 7NM
Light 8NM

This separation can also be applied by using time instead of a distance. However, since you all have a radar scope in front of you, you can use distance and achieve WTS that way.

Visual Separation

Visual separation is what is used between VFR and IFR traffic in airspaces E and D. Usually this is supported by ATC by giving traffic information. A common misconception is that only VFR has to stay away from IFR however the responsibility is shared equally between both pilots. An IFR A320 has to avoid a VFR C172 if necessary and vice versa.

Visual separation can be applied between IFR however this is a bit more complex and should not be done during your tower training. For now just accept that you have to make sure that there is enough separation between two IFR aircraft (that could be WTS if required, radar separation and/or runway separation)

Radar Separation

Radar separation usually isn't interesting for tower controller as you will have no training on how to identify aircraft and how to use a radar for separation (except for departure separation). Radar separation means that you either need 1000ft vertically or 3NM horizontally between aircraft (above FL245 it's 5NM). Using runway separation properly usually results in radar separation so you do not need to worry about radar separation right now. This is just to give you the complete picture.

Procedural Separation

Procedural separation is the reason why some aircraft are allowed to be closer than 3NM but are not considered to be a conflict. This is because the IFR procedures (the instrument approach or SID) can be used simultaniously and the situation will always be safe. Of course these aircraft have to be on their procedure before this can be applied. This is the case in Munich, Frankfurt and Berlin when the ILS are used independently. During the trainings the mentors will tell you what procedural separation applies to your training airport so you don't need to be worried about this for now.


We have already established that without safety we shouldn't even look at efficiency. However, with safety established it becomes increasingly more important to improve traffic flow and minimize wait times. The following guidelines should help you achieve that goal.

General Guidelines for traffic movement
  • Keep traffic moving at all times - That sounds obvious at first, however, you might be surprised how many controllers disregard that fact that aircraft are extremly heavy objects and it takes a lot of energy and time to overcome inertia. Once they are rolling, interia isn't a problem anymore. Therefore, you should only give hold shorts when you have to for safety reason and if possible don't let the aircraft stop at the hold short. If safety allows it, you should instruct the aircraft continue taxi even before it has stopped so it doesn't have to accelerate from standstill. The same is true for aircraft vacating the runway. If possible give them the taxi instruction before they stop so the pilot can keep the aircraft rolling.
  • Avoid unnecessary delays for departures - In the previous section we have given you minimum distances between departing aircraft by using runway separation or WTS. On some airports you have to apply additional separation to achieve separation or sequencing of aircraft. However, you should never go above the minimum number unless there is a very good reason for that. As a busy tower controller you need to get rid of aircraft as soon as possible because it will reduce your workload. You can only do that by releasing departures as early as possible.
  • Avoid unnecessary go Arounds - This one almost goes without saying. When go arounds are required for safety reason, don't hesitate to instruct a go around. Go arounds are your fallback whenever it otherwise isn't possible to maintain safety. But they should only be a fallback protection and you should never willingly give instructions that will likely end in a go around.

Efficient Frequency

Here are a few guidelines for you. Always remember: The frequency is yours to manage, you are in command. Do not leave any pauses on frequency when you have lots of instructions to give. Only you know who needs the next instruction and if you have things to say, pilots have to wait. Of course sometimes you have to make sure to allow pilots to call in.

  • Stick to standard phraseology - it is designed to be as short as possbible and as clear as possible which is why you should use it.
  • Avoid triggering say agains - if you have a beginner pilot, speak slowly. If your instruction includes numbers like "contact xy on *frequency*", speak slowly - it's great if you can speak fast and gain time but it becomes absolutely useless if you spend all the gained time with answering "say agains". Also try to maintain a constant speed on frequency. it will be much easier for the pilot to follow your instruction.
  • Use "standby" and "blocked" - these two words are the easiest way tell pilots what's going on. Standby means: Controller is busy, wait, he/she will call you back. Blocked means: You have transmitted together with another stations. You may go again after one another or the Controller will call you one by one. All this information and you spend no time saying it. Especially standby is important as it prevents the pilot from calling agian and wasting frequency time. If DLH is calling and you want to give an instruction, simply say: "Standby, SWR123, turn left HDG 320". Now DLH knows that it was heard and the Controller will respond eventually.
  • Be calm on frequency - This is your hobby and you are doing it in your free time. If you are uneasy/pressured/triggered look for a replacement or go offline. You won't be happy, the pilots won't be happy and even worse you tend to become more difficult to understand the more uneasy you become which results in more "say agains" which will trigger you even more.
  • Be friendly but decisive - This goes together with standard phraseology. If the pilots think there is a party going on on your frequency, you won't really be able to control. Through your instructions it needs to become clear that this frequency is busy and the pilots should behave accordingly. If necessary, remind them but if you stick to standard phraseology this shouldn't be necessary.


Priorities are meant as a guide for you. It should give you an idea about which instructions to give next on a full frequency. This will prevent you from losing control of your airport and should also tell you on what to concentrate on.

The priorities are:

  1. Emergency
  2. Landing
  3. Departing
  4. Vacating Runway
  5. Taxi
  6. Pushback
  7. Startup/Enroute Clearance

Apart from emergencies the most important instructions are landing clearances followed by take-off clearances and taxi clearances for traffic that has just landed. This does not mean that you always have to give the landing clearance first. Priorities should be applied whenever two or more instructions are time critical. Time critical means that it's only a few seconds until you have to give an instruction.

Imagine you have an aircraft that has just landed, vacated and will stop taxiing in a few seconds and you have an aircraft on the ILS with 10NM until touchdown. In this case the only time critical instruction is the aircraft that is taxiing because in a few seconds it will have to stop. Remember for efficiency sake we do not want aircraft to stop. So in that case it is better to not think about priorities but give the taxi clearance first so the aircraft keeps rolling. You still have a few munites until the aircraft on the ILS will reach the runway. However, you should not wait unnecessarily with landing clearances. Most of the time you want to give landing clearances as soon as possible unless you have a very good reason to withhold the landing clearance.

Let's imagine a different example: You have one aircraft on the ILS, 1 NM before touchdown which needs a landing clearance and another aircraft that is about to reach its point where it has to hold short. In this case both instructions are time critical because the first aircraft will have to go around in a few seconds and the second aircraft will have to stop in a few seconds. Now that both instructions are time critical, we need to apply priorities and first give the landing clearance and later the taxi instruction.

One last but very important point: Mistakes in priorities happen but you have to make sure that you don't accidentally give too many clearances when there are more important priorities to attend to. You have a limited capacity and at some point there will be too much traffic to handle for you. The only way you can get rid of traffic is by giving takeoff clearances. If you forget to give take off clearances but keep giving enroute clearances and pushbacks, you will get more and more traffic but no aircraft will leave your frequency and eventually you will be unable to handle the situation. That is why it is essential, that you follow priorities when there are multiple time critical instructions because otherwise you might end up making your life very difficult or impossible.


ATIS stands for Automated Terminal Information Service and generally speaking provides all necessary information for local airport. This information includes active runways, expected approach, weather information like QNH, winds, clouds and other weather phenomena. The ATIS is provided by your Euroscope package so you don't have to worry about it too much. You will only have to press a few buttons and all pilots will be able to hear or read the ATIS. Your mentors will show you how that works in your first training.

The main thing you should take away is that every ATIS has an identifier in form of a letter. Pilots flying IFR need to report the letter they received when listening to the ATIS to you and you have to check whether that is the current letter. If the pilot reported an outdated letter, you will have to correct him.

When you manually update your ATIS, you should increase the letter by one so that everyone can verify if they have the latest ATIS information. Here is an example of an ATIS:


Clearance Delivery

Delivery (if available at the airport) is usually the first station a pilot contacts for his flight. Delivery is primarily responsible for the start-up and enroute clearance of an IFR flight. This clearance contains all the important instructions that the pilot needs for the departure. Depending on the airport, VFR traffic may also have to report to Delivery for the initial contact (see the respective airport SOP).

Likewise, Delivery should check the flight plan for the basics (e.g. sensible route and altitude) and can make changes if necessary.

On Vatsim, the tasks of the Delivery controller in Euroscope are best handled with the Departure/Start-Up lists provided by the individual RGs.

Flight Plans

A flight plan indicates how the execution of a flight is planned. In addition to the call sign and aircraft type, the planned route, altitude and speed are also specified. This ensures that the pilot and the control are on the same planning level. Flights under instrument flight rules (IFR) must always file a flight plan, whereas flights under visual flight rules (VFR) are free to do so.

On Vatsim it should be noted that once a flight plan has been processed by a controller, the pilot himself is no longer able to change it! This also applies in the event that any controller has assumed the TAG. Even if the TAG is subsequently released again, the flight plan cannot be changed again by the pilot, unless the pilot logs out and then logs in again.

The format of the flight plans is identical worldwide and prescribed by ICAO. It is therefore possible that a flight plan is not displayed with the classic input fields, but in the following format. This contains all the important information that air traffic control needs to know from the pilot.


However, as this is somewhat confusing and error-prone for manual input, there are various visualisations for the flight plan available to the controller on Vatsim. One of these visualisations is the flight strip in Eurscope. This can be displayed with the F6 key and is shown below.

ATD Flugstreifen.png

Euroscope flightplan window
Topsky flightplan window

Another visualisation of the flight plan consists of the flight plan window in Euroscope. In most cases, the standard Euroscope flight plan window is used for editing flight plans. It can always be opened using the ".am" command before clicking on the relevant aircraft.

With the use of the Topsky plugin, there is also a separate flight plan window for the controller. The contents are mostly identical, only displayed differently. The following list refers primarily to the flight plan window of Euroscope. It is important to note that this differs from official flight plan form of ICAO!

Euroscope Topsky Meaning
Callsign Callsign Callsign
IFR/VFR FRUL Flight rule
AP data ATYP Aircraft type and equipment
Origin ADEP Departure airport
Destination ADES Destination airport
Alternate ALTN Alternate airport
TAS TAS True Air Speed
Altitude RFL Requested (Cruise) Flight Level
Squawk ASSR Squawk code
Dep EST EOBT Estimated Off Block Time
Actual -- Actual Off Block Time
Temp alt PEL/CFL Temporary Altitude
Enroute EET Estimated Enroute Time
Fuel -- Fuel On Board
RFL -- ?
Route RTE Route
Remarks Other Remarks

Enroute and Startup Clearance

The main purpose of Delivery is giving the enroute clearance. This clears the aircraft to fly along a certain route (usually the route filed in the flight plan) to a waypoint or to its destination. It always includes a clearance limit along the route although this does not mean that the aircraft can start moving towards that clearance limit. The aircraft will have to wait for pushback, taxi and takeoff clearance. But once the aircraft has departed the airport and assuming it does not receive further clearance limits, it will have to hold latest at the clearance limit mentioned in the enroute clearance. Besides the clearance limit the enroute clearance has to include departure instructions (usually SID), a route (usually flight planned route, although it may be amended completely or in parts by ATC), the initial climb and a squawk.

The startup clearance is usually included in the enroute clearance and it means that in theory the aircraft is allowed to start the engine. In practice though this is only allowed on stands that do not require pushback. Instead the phrase startup approved is used to indicate to the pilot that he can expect taxi/pushback within the next 20 minutes. This of course also means that startup should not be approved if the expected delay until taxi/pushback is more than 20 minutes. In reality the engine start also requires the approval of the ground crew.

An example of an enroute and startup clearance is given below with additional explanations of each part.

Enroute and Startup Clearance
"EDDF_DEL, DLH123, info A, request clearance to EDDM."
"DLH123, EDDF_DEL, hallo, , info B now current, startup approved, cleared München, ANEKI9L, flight planned route, climb via SID FL 130, Squawk 1000"
"DLH123, info B, startup approved, cleared München, ANEKI9L, flight planned route, climb via SID FL 130, Squawk 1000"
"DLH123, readback correct"

The first action of both radio stations is to establish radio contact. This is done by saying the callsign of the station that is being called followed by the callsign of the calling station. ATC has to confirm this by also first saying the station that is being called followed by ATCs own callsign. This is to ensure that both parties talk to the correct station. After that every party only uses the aircraft's callsign.

In our example the pilot requests a clearance and reports that he has received ATIS info A. The first action of ATC is to confirm this information. ATC is only required to mention the ATIS information if the pilot has not reported the correct ATIS letter or has no reported any letter at all. However, it is recommended to always mention the current ATIS info. This can either be done by saying "Info A correct" if the pilot has reported the right letter or by correcting the pilot like in our example. The next part of the clearance includes the startup clearance mentioned above. Now the enroute clearance starts.

  • "cleared München" clears the aircraft to its destination (the only exception is a Y-Flightplan mentioned below). The actual clearance limit though is not the airport but a waypoint on the route that can be found in the charts.
  • "ANEKI9L" is the departure route that the aircraft will have to fly.
  • "flight planned route" means that the aircraft will fly along the planned route for the flight including the requested flight level for cruise. "Flight planned route" can be substituted by a description of a route in case the route the pilot filed is not appropriate for ATC.
  • "climb via SID" indicates the initial climb. "Climb via SID" should be used if there are level or speed restrictions on the SID otherwise "climb" should be used.
  • "Squawk 1000" mentions the squawk code the pilot has to set.

Notice that in our example the pilot reads back the clearance word for word as required by standard phraseology. On vatsim most pilots will not do this and you do not need to force them to do so. Instead you should make sure that the pilot understood the SID, the initial climb and the squawk.

Radar Vectored Departure

Radar vectored departures are departures where the pilot flies a certain HDG until further instructed by ATC. This only exists on Vatsim in order to make our lives easier in case the pilots do not have up to date NAV data. An example of this clearance is given below.

Radar vectored departure
"DLH123, info A correct, startup approved, cleared München via radar vectors to ANEKI out of RWY 18, climb 5000ft on runway heading, flight planned route, Squawk 1000"

As you can see, most parts of the standard enroute clearance can also be found in the radar vectored departure clearance. The most important part in this clearance is a HDG, a climb instruction and a waypoint. The waypoint is important as it tells the pilot that he can expect to fly a direct to ANEKI at some point. In case of communication failure the pilot knows exactly what to and ATC knows what they can expect from the pilot.

Y-Flight Plan

A Y-Flight plan is used when an aircraft wants to switch from IFR to VFR at some point during the flight. This is mainly done in order to land on airfields that do not have IFR procedures like Egelsbach. In this case the clearance is issued until the last waypoint on the route. As an example a clearance using this route:


Y-Flight Plan
"DLH123, info A correct, startup approved, cleared SPESA, ETASA2H, flight planned route, climb 5000ft, Squawk 1000"

Ground Control


Ground/Apron is responsible for the pushback and the entire taxi guidance at the airport. Ground and Apron differ in that in reality Ground is managed by DFS and Apron by the airport operator itself. In Germany, there are four airports with the Apron station: Berlin, Frankfurt, Hamburg and Munich. The respective areas of responsibility are regulated in the respective SOP of the airport.

Taxiing on the ground should not be underestimated, as it requires a great deal of attention and foresight, depending on the airport!


Since aircraft cannot taxi backwards, they usually have to be pushed back from the parking position onto a taxiway by a tug. Sometimes there are also parking positions where the pilot can taxi out under his own power (taxi positions). Whether a pushback is required for a position can be seen in the Ground Movement Charts of DFS by means of a small symbol next to the parking position.

As a rule, the pushback always takes place on a taxiway. If there are several options for the pushback, the controler must inform the pilot how it is to be carried out. Most frequently, the direction in which the pilot should face after the pushback is indicated (e.g. face west). Likewise, deviating taxiways can be indicated (e.g. a taxiway which is not directly behind the gate or, if available, a blue/orange line). For this purpose, the control should have a plan for the subsequent taxiing prior to the pushback in order to work as efficiently as possible.

Pushback Instruction
"München Apron good day, DLH5KC, stand 205A, request pushback."
"DLH5KC, München Apron good day, pushback approved, face south."
"Pushback approved, face south, DLH5KC."

It should be noted that a taxiway will be blocked for several minutes due to the pushback (varies depending on the aircraft type and pilot). For this reason, it is particularly important to keep an eye on the entire taxiway and to work in advance, especially at large airports.

If the pushback is not possible immediately (e.g. because there is already an aircraft behind it or an inbound still has to be waited for), the pilot must be informed of this with a hold position and ideally a short information about what he still has to wait for. If there are two waiting outbounds on the frequency, both of which are ready for pushback, it may be advantageous to deviate from the "first come, first serve" principle, depending on the situation, if this reduces the overall waiting times.


example taxi route

It should be noted that a taxiway will be blocked for several minutes due to the pushback (varies depending on the aircraft type and pilot). For this reason, it is particularly important to keep an eye on the entire taxiway and to work in advance, especially at large airports.

If the pushback is not possible immediately (e.g. because there is already an aircraft behind it or an inbound still has to be waited for), the pilot must be informed of this with a hold position and ideally a short information about what he still has to wait for. If there are two waiting outbounds on the frequency, both of which are ready for pushback, it may be advantageous to deviate from the "first come, first serve" principle, depending on the situation, if this reduces the overall waiting times.

Taxi Instruction
"DLH5KC, request taxi."
"DLH5KC, taxi to entry S8 via W2 D2 O2."
"Taxi to entry S8 via W2 D2 O2, DLH5KC."

Hold Short

Hold shorts are used to stop rolling traffic in front of another taxiway. It is important to note that the further taxiing guidance is cancelled after the hold short. If the aircraft is to continue taxiing, it must be informed (again) of the complete further route. If it is foreseeable that the aircraft will have to wait at a certain point, it should only be given the taxiways necessary to get there.

Taxi Instruction
"TUI4PH taxi to holding point runway 18 via L N1 N, hold short of N5."
"TUI4PH continue taxi via N."
"RYR1ME taxi to holding point runway 24 via B A A3, hold short of runway 14L."

If a sequence of taxiing aircraft is to stop at a certain point, it is sufficient to give the first aircraft the hold short. All following planes will inevitably have to stop behind it. However, it is important to note that as soon as the first aircraft rolls again, the complete sequence will start moving again.

If the way to the active runway leads over another runway (e.g. in Cologne and Hamburg), an explicit permission to cross this runway is always necessary. If the runway is outside the own area of responsibility, a hold short must be instructed.

Give Way

Another way to resolve potential conflicts on the ground is to use the give way instruction. This involves giving the pilot the task of giving right of way to other rolling traffic. It is important to tell the pilot where he has to let his colleague pass (at D3), what other traffic he has to watch out for (company - Lufthansa A320) and where the traffic is coming from. To avoid misunderstandings, only the direction from which the other traffic is coming should be indicated, not where it is heading.

Give Way Instruction
"DLH5KC, at D3 give way to company A320 from left."
"UAL988, give way to opposit outbound British Airways A319, thereafter taxi to A23 via N5."

Combinations of hold short instructions (e.g. if a taxiway is blocked for a longer time by a pushing aircraft) and later give way instructions can also be used to make better use of the time on the frequency.

Intersection Departure

On Vatsim, traffic is usually distributed from Ground or Apron to the different intersections of the runways. Ideally, the pilot announces which intersection he is ready for when he is ready to taxi or when he makes the initil call for further taxiing.

Taxi Instruction
"München Ground hallo, DLH5KC Entry S8, able B12."
"DLH5KC, hallo, taxi to holding point runway 26L, intersecton B12, via B12."
"DLH5KC, hallo (no benefit), taxi to holding point runway 26L via S and B13."

If it is advantageous for the tower or the pilot (e.g. time saving), the intersections can be assigned. However, there is no obligation to do so, so the pilot can also be taken on to the beginning of the runway as normal. For the pilot, it is always safer the more runway he has available. If he has to wait longer for take-off due to landing traffic, wake turbulence or generally because of the departure sequence, this time should also be used to taxi to the beginning of the runway.

If the use of an intersection is not part of the published standard procedures of an airport (AIP), the pilot must always be asked beforehand whether he can use the intersection. Details on this can be found in the respective SOP of the airport.

Likewise, ground/apron controllers should always take care not to block their main taxiways by assigning the same intersection if they do not know the departure sequence of the tower (e.g. taxiway L in Frankfurt). If in doubt, coordinate with the tower or give a handoff as early as possible so that the tower can take the aircraft into the intersection itself if necessary.

Revision of Taxi Instructions

Especially at large airports, the traffic situation on the ground changes continuously. For this reason, it may be that there is a potential conflict on the route communicated to the pilot or that longer waiting times become necessary (e.g. due to a pushback). In this case, the control can change the route of the aircraft on the ground in addition to the instructions already known.

Taxi Instruction
"DLH5KC revision, continue via W2, hold short of D4."

Advanced Taxi Instructions

Especially when there is a lot of traffic on the ground, it is important to work efficiently and keep the frequency load as low as possible. It is important to maintain the flow of traffic, reduce unnecessary waiting times and radio messages (few hold shorts, short and concise instructions, early handoffs) and still ensure safety. Enclosed are a few tips that can make the job easier.

NOTE: Only use these procedures if you feel comfortable with them and can handle them! Also, it is always possible that a pilot may not understand your instructions exactly and will not ask for them.

Push and Pull

It doesn't always have to be the classic push back, especially pilots with X-Plane are easily able to pull forward and disconnect the tug at a certain point. This is useful, for example, when two aircraft are pushing next to each other or you want to clear the taxiway promptly for another aircraft.

Push and Pull
"DLH123, pushback approved, then pull foreward, disconnect (tug) short of D2 / abeam stand 217."

Conditional Pushback

As with the Give Way instructions, the responsibility can be transferred to the pilot. This is especially useful if the pilot has to wait for another aircraft to pass behind him.

Push and Pull
"DLH123, when clear of outbound company A320 behind, pushback approved."
"DLH123, when space permitts, pushback approved."
"DLH123, when clear of the inbound British Airways A319 for V117, pushback approved, orange line, facing west."

Intersections First

Aircraft leaving or crossing a runway should be prioritised if possible. This will enable the tower to allow aircraft to cross the runway more efficiently and with less waiting time for outbounds.

Give Way Instruction At Intersections
"DLH123 give way to the vacating Condor A320 from runway 25C."
"Giving way to the vacating traffic, DLH123."
"CFG789 number one, taxi right via L, hold short of N8."

Give Directions/Progressive Taxi

If you need to move quickly or the pilot is not familiar with the airport, it is always helpful to tell the pilot whether to turn left or right onto a taxiway (left, right, straight ahead).

Progressive Taxi
"DLH123, taxi next right on L, hold short of N8."

Tower Control

The Tower part is not complete. It is recommended to look to the old pdf version of this guide for further information.

General Introduction

Tower has two main duties. One is the responsibility for all active runways and the traffic on the ground handed over to him by ground control. The other one is the management of airborne traffic within his control zone.

Runway In Use

Tower is also responsible to set the active runway(s). Determining the active runway(s) is generally depending on the wind direction and strength. On some airports a specific runway is prefered up to a certain tailwind component (usually 5 kts). If there is no prefered runway direction, you should make sure aircraft will land into the wind and not with the wind.

As we know the wind direction in the ATIS is always the direction where the wind comes from and the runway direction is always the direction the runway faces. For example runway 32, will face roughly heading 320 and if there is a wind of 32005kts the aircraft will have 5 kts headind when landing on runway 32.

It's important to note that we always talk about headwind or tailwind components. If the wind direction differs from the runway direction they are not equal to the absolut wind speed. A wind of 35005kts on runway 32 will cause a headind component of 4.33 kts instead of 5 kts. You can calculate this with the following formula: headind component = cos(difference between runway direction and wind direction)*wind speed in our example: cos(350-320)*5kts = 4.33kts

If the number is negative, there will be a tailwind on the runway.

It is important to note that the wind direction might change throughout the course of the evening. In that case it could be worth looking at the TAF. If the wind starts at 18004kts and turns to 32007kts, it might be worth opening runway 32 right away in order to prevent runway changes during times of high traffic. Sometimes though, they are unavoidable.

Handling IFR Traffic


Although on some airports tower controllers are responsible for taxiways, we will concentrate on the duties involving the runway. IFR traffic will eventually end up on the holding point of the runway. If there is no other traffic on the runway or on approach for that runway, there is no reason to hold back the take-off clearance at that point:

Take Off Clearance
"Köln Tower, DLH123, hallo, holding short of runway 14L"
"DLH123, Köln Tower, hallo, wind one one zero degrees, five knots, runway 14L cleared for takeoff"
"DLH123, runway 14L cleared for takeoff"

Please note that it is very important to never use takeoff unless it involves the takeoff clearance. It is strictly forbidden to be used in any other context. In any other clearance you should use "departure clearance"

The pilot will now taxi onto the ruwnay and depart and stop his climb latest at the initial climb altitude. On some airports you will have to transfer the aircraft to the next controller which should be done before the aircraft levels out. It's best to do this as early as practical (possibly as soon as the aircraft is passing 1000ft).

If the pilot should only taxi onto the runway and wait for the departure clearance the following instruction should be used.

Line Up Clearance
"DLH123, Köln Tower, hallo, line up runway 14L"

Please note that the "and wait" in the more common phraseology of "line up runway 14L and wait" is optional. It is recommended that you do not say "and wait" as it unnecessarily wastes time and accomplishes nothing.


Of course you will have to give landing clearances as well.

Landing clearance
"Köln Tower, DLH123, hallo, final runway 14L"
"DLH123, Köln Tower, hallo, wind one one zero degrees, five knots, runway 14L cleared to land"
"DLH123, runway 14L cleared to land"

A landing clearance can be issued anytime before the aircraft crosses the runway threshhold, but should be given as early as possible. It is important to note that only one aircraft can be on the runway at one time and aircraft count as on the runway as long as they want to use the runway and end up above it. That means even aircraft above runway 14L count as on the runway. So the latest point at which you may give the landing clearance is when the aircraft crosses the very beginning of the runway. If you cannot give the landing clearance by then, the aircraft will have to go around.

Go Around
"DLH123, go around, I say again, go around."


Although most airports have dedicated landing and takeoff runways, sometimes you will have landing and departing traffic on the same runway. When there is one aircraft on final and one aircaft on the holding point, you will always have to decide if the takeoff traffic can depart before the landing traffic or if it will have to depart behind. As a general rule of thumb: If the aircaft is on a 6NM final, the departure traffic can line up and takeoff in time. However, the pilot should know that he is expected not to waste time. Either by giving an immediate takeoff or by simply telling him "No delay" after the takeoff clearance. Especially the second option is not official phraseology but clearly states what you want from the pilot which is always the most important thing. Please note that sometimes 5 NM or even 4 NM final are enough to perform line up and takeoff but it is highly dependent on the departing aircraft. You cannot be certain that it will always work.

takeoff clearance for immediate takeoff
"DLH123, Köln Tower, hallo, wind one one zero degrees, five knots, runway 14L cleared for takeoff, no delay"

If you cannot give the takeoff clearance, you will have to let the departure wait and eventually give the takeoff clearance as soon as the landing aircraft has vacated. However, you can make sure the aircraft lines up behind the landing traffic.

conditional line up clearance
"DLH123, Köln Tower, hallo, behind next lanidng Eurowings A320, line up runway 14L, behind."
"DLH123, behind next landing Eurowings A320, line up runway 14L, behind."

In some cases you first have to ask the pilot if he has the arriving traffic in sight. After that you can give the conditional line up clearance as described above. You will have to do this, whenever the runway intersection is more than 90° to the runway. VISUALISATION MISSING

Parallel Configuration

Intersecting Runways

Handling VFR Traffic


Airspace Classifications

Traffic Circuit

VFR Within The CTR

Departing VFR Aircraft
Arriving VFR Aircraft

VFR Traffic Circuits

General VFR Topics