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2. ATC POSITION OVERVIEW
2.1 Choosing your ATC position
2.1.1 Tower Positions
2.1.2 Radar Positions
2.2 List of ATC Positions in VATSIM
2.3 Visual Ranges
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2.1 Choosing your ATC position [S]

When first
getting introduced to Virtual Controlling the various positions and call signs
used can look very intimidating at first glance. The easiest manner to decipher
these is to divide them into three distinct categories:
While the exact terminology varies from country to country, there are
generally three different types of ATC.
- Control Towers
- Approach controllers
- Centre
controllers
As a new
member to VATSIM and depending on the local restrictions in use at your vACC,
Student Controllers will usually start controlling at a Ground or Tower
position and then move up to Approach and Departure positions and from there to
Area Control positions and eventually once the required rating has been
achieved will be able to control the Euro Control Areas if interested.
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2.1.1
Tower Positions [S]

The primary
method in real life of controlling the immediate airport area is by means of
visual observation from the control tower. The tower is a tall, windowed
structure located on the airport. Tower controllers are responsible for the
separation and efficient movement of aircraft and vehicles operating on the
taxiways and runways of the airport itself, and aircraft in the air near the
airport.
Radar displays
are also available at some airports (on VATSIM at all airports). Tower uses
radar to display airborne traffic on final approach and for departing traffic
once they are airborne.
Some airports
(on VATSIM all airports) also have radar designated to display aircraft and
vehicles on the ground. This is used by Ground controllers as an additional
tool to control ground traffic.
The areas of
responsibilities for tower controllers fall into three general operational
disciplines:
- Clearance
Delivery
- Ground
Control
- Local Control
(Actual Tower
position)
The following
provides a general concept of the delegation of responsibilities within the
tower environment.
Clearance Delivery, the position responsible for
verifying a flight plan and issuing IFR clearance.
Ground, responsible for controlling traffic on the airport “movement”
areas, this generally include taxiways and holding areas and giving traffic
information and suggestions (for example approving pushback) to traffic on
aprons.
Tower, responsible for movements on the runways and
traffic in the control zone, (CTR) which surrounds the aerodrome and normally
extends around 5 to 10 NM from the aerodrome and from the ground up to
normally, 1500-2000ft. The tower is the position that clears aircraft for take
off or landing and ensures the runways are clear for these aircraft.
As in real life and in dense
traffic, at certain large airports more than one of these positions may be
opened, for example S or N for South or North.
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2.1.2
Radar Positions [S]

Even
though as described above Tower and Ground also use radar displays, we
will refer to the following as Radar Positions since they rely 100% on
radar in order to control and separate traffic.
These positions are not located in the actual tower; these facilities on
the other hand can be located in buildings adjacent to an airport or even in
buildings totally separated from it. A radar position as the name implies uses
Radar scopes to track and follow the movement of traffic in the air. These
teams are in turn subdivided into:
Approach Control (APP)
Area Centre Position (ACC)
Flight Information Service (FIS)
- Approach Position, the position
responsible for controlling, separating and sequencing arriving and
departing aircraft. APP is usually responsible for the terminal control
area (TMA). At small airports, the TWR and APP position is often combined.
On the contrary, at large airports or in complex TMAs, APP is usually
divided into several sectors. APP positions may have different radio
callsigns depending on the function, such as Departure, which as the name
implies controls departing aircraft, Arrival or Director, which usually
handle vectoring of arriving aircraft.
- Area Control Centre, the
position responsible for controlling traffic in the control areas (CTA)
and upper control areas (UTA) within the centre’s area of responsibility.
The area of responsibility is generally a FIR or part of a FIR, so ACCs
cover large areas, and therefore may be divided into several sectors, both
horizontally and vertically.
- FIS,
Flight Information Service is not used much
in VATSIM and seldom in Europe, but should it be on line then it is
responsible for providing traffic information, flight following and
providing
information to VFR flights. It is not a Control Position and can not
give instructions to aircraft but only advisories and information. As
FIS is not a standard
Designator on VATSIM, controllers providing this service usually log in
with
XXXX_I_CTR call-sign
FIS in essence is the most basic form of air traffic
service that is provided to aircraft.
However, the FSS suffix is used in Europe
as part of the different Euro
Control positions which even though they use FSS
as part of the log-on to the net work are proper Control positions in the Upper Airspace from FL245
and above
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2.2. List of positions in VATSIM [S]

|
Call sign
|
Designator
|
Short Description
|
|
Delivery (Clearance)
|
DEL
|
Responsible for issuing IFR clearances
|
|
Ground
|
GND
|
Responsible
for movements on the ground on the manoeuvring area.
|
|
Tower
|
TWR
|
Responsible for
traffic on the runways and in the CTR..
|
|
Departure
|
DEP
|
Responsible for separation
and flow of departing traffic at certain airports.
|
|
Arrival/Approach
|
APP
|
Responsible for
separating and sequencing arriving and departing traffic in TMA’s
|
|
Final/Director
|
APP
|
Responsible for final
vectoring of arriving traffic at busy airports.
|
|
Control/Radar
|
CTR
|
Responsible
for en-route traffic and traffic in CTA/UTA
|
|
Euro
Control
|
FSS
|
Responsible
for control of upper airspace from FL245 when no local CTR is on line.
|
Euro Control in VATSIM was specially created to ensure ATC cover over
large geographical areas when no local ATC is on line.
A further position is AFIS
|
AFIS (Aerodrome Flight Information Service
|
TWR
|
Gives information about traffic and weather at
some uncontrolled airports.
|
In VATSIM AFIS must log on with a TWR call-sign but the controller information
(ATIS) will state when it is an AFIS
ESSA_DEL : Arlanda Clearance Delivery
LTBA_GND : Ataturk Ground
EDDF_TWR : Frankfurt Tower
EPWA_DEP : Warsaw Departure
LIPZ_APP :Venice Tessera Approach
LEBL_CTR :Barcelona
Control
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2.3 Visual Ranges [S]

The VATSIM
community relies on a network of computers interlinked to provide position
updates to controllers and pilots alike. The network is donated by third
parties. In an effort to avoid any wasting of bandwidth the following Maximum ranges have been imposed.
|
Position
|
Range
|
|
DEL/GND
|
10 to 20 nm
|
|
TWR
|
30 to 50 nm
|
|
APP/DEP
|
100 to 150 nm
|
|
CTR
|
300 to 600 nm
|
|
FSS
|
1500 nm
|
When a user logs on
to network, it is important that the visual range slider be set to the
appropriate range depending on the position being manned, the main reason is to
limit the waste of bandwidth. Bear in mind that a user will receive information
packets every few seconds, so a GND controller having a range of 400nm will
also be receiving traffic information in a radius of 400nm from the position
being manned this is an absolute waste of bandwidth and should be avoided at
all cost.
Unfortunately some
controllers forget to change their facility type when switching to another ATC
position. Setting a correct facility type is important; since it affects the
radio range of the controller. Therefore in some cases a wrong facility type
could affect the text communication between a controller and a pilot.
RANGE is the visual range
set by the controller in ASRC/VRC options using the range slider. There is one
exception: visual range for FSS facilities is hard coded to 1500nm (since this
is much more then the slider is allowed to be set to). This range defines from
which distance the controller gets aircraft position reports, so which traffic
is shown at the radar scope and which not. It’s obvious it should be adjusted
to the service the controller is providing. The best situation is when
controller is capable to see the traffic within his sector plus a small margin.
Therefore the visual range should be adjusted to the size and shape of the
sector
(NOTE that the visual range is calculated from the point where the radar
scope is actually centered, unless the .vis command has been used to set a different visibility point).
If
you use VRC as radar
client, it is a good practice to configure it for the facility you are
manning
and then save the profile with its callsign to make sure that all
settings are appropriate for your position. (i.e.: LEBL_TWR, EGKK_APP,
etc.)
There are some situations,
when extended range is justified, for example a very large or an irregular
shaped sectors or some special operations.
(NOTE: for irregular shaped sectors, you can use multiple visibility
points in order to have a “radar antenna” at the significant points of your sector,
so that it’s not needed to increase range. Multiple visibility points are
available on both VRC and ASRC1.2)
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