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==Introduction==
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'''<span style="color:#ff0000;">This study guide is still work in progress. Stay tuned for further chapters.</span>'''
This Study Guide has been designed to give you all the information needed to start controlling as a Tower controller on the VATSIM network.
 
  
==Radio Communication - Basics==
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'' Prev: [[Study Guide:Ground]] - Overview: [[Study Guide]] - Next: [[Study Guide: Approach]]''
Because communication is crucially important for Air Traffic Control a fixed format and syntax is used, in order to minimize the risk of misunderstandings and to keep messages short. Worldwide English is the primary language in use, however in most countries you are also allowed to use the local language. In Austria VFR flights can choose their language whereas IFR flights are mostly conducted in English. Link: [[Buchstabiertabelle]]
 
===Basic Rules===
 
In order to achieve the goals set above the following rules important:
 
#''Listen before you talk''
 
#: It's impossible for two radio stations to transmit on the same frequency at the same time. If this is done, the radio signal will be blocked and this will result in a nasty noise on the frequency. Therefore it's important that every station monitors the frequency for about 5 seconds before transmitting, to make sure there’s no ongoing radio traffic. If you hear an ongoing conversation, wait until the conversation is over before you begin to transmit. Don’t start your communication if there is a read-back expected on the last transmission even if there is a short pause.
 
#''Think before you talk''
 
#: The radio traffic flow should be as smooth as possible. To achieve this it's vital to "think first" before transmitting so that a clear, concise and uninterrupted message can be sent.
 
#''As far as possible use standard phraseology and syntax''
 
#: To prevent misunderstandings and to maintain the radio traffic as effective as possible, stick to standardized phraseology and skip slang and of course private messages.
 
  
===Callsigns and Initial Contact===
 
Every participant on the network has his own Callsign. Controller Positions are identified by their location and their Function (e.g. Wien Radar, Graz Tower), Aircraft either by their Registration (e.g. OE-ALB) or an Airline Callsign followed by a combination of numbers and letters (e.g. AUA25LM, SWR387).
 
To pronounce these letters and digits the ICAO-Alphabet is used.
 
''
 
To initiate the contact between two stations an initial call has to be made. This call has the following structure:''
 
'''Station 1:''' Station 2, Station 1, Message
 
'''Station 2:''' Station 1, Station 2, Message
 
''Example - Austrian 251 is calling Wien Tower:''
 
'''AUA251:''' Wien Tower, Austrian 251, established ILS 34
 
'''LOWW_TWR:''' Austrian 251, Wien Tower, continue approach
 
In Subsequent calls the calling station part can be ommited. <br>
 
When a controller (or aircraft) transmits a message to a station it is very important that the receiving station acknowledge the message and reads back any required parts.. If the receiving station does not acknowledge, the transmitted message is considered as a lost transmission and the sender should resend the message or check if the receiving station got the message.
 
Items that must always be read back in full are all clearances (including altitudes, heaings, speeds, radials etc), runway in use, altimeter setting (QNH or QFE) and transition level, and all frequencies. For a controller, this is extremely important to remember, since if a pilot's readback is incorrect, the controller has to ask for confirmation, i.e a new readback. There are also items that should not be read back to reduce unnesessary radio transmissions. In short, this includes everything not mentioned above, but a few examples are: wind, temperature and other weather information (except altimeter settings) and traffic information in detail.
 
When giving an instruction the Callsign is stated at the beginning, when reading back you usually add it at the end of your transmission (although you are allowed to do it at the beginning too). <br><br>
 
'''Examples:'''
 
'''LOWW_APP:''' AUA251, turn left heading 290, descend to Altitude 5000 feet, QNH 1019.
 
'''AUA251:''' Turn left heading 290, descending to altitude 5000 feet QNH 1019, AUA251
 
<br> 
 
'''LOWW_GND:''' OE-DLT, taxi to Holding Point Runway 29 via Exit 12, M and A1, give way
 
to Speedbird Airbus A320 crossing you right to left on M.
 
'''OE-DLT:''' Taxiing to H/P Rwy 29 via Exit 12, M and A1, giving way to Speedbird
 
Airbus A320 on M, OE-DLT.
 
<br>
 
'''LOWW_TWR:''' NLY2678, wind 330 degrees at 6 knots, Rwy 29, cleared for takeoff.
 
'''NLY2678:''' Rwy 29, cleared for takeoff, NLY2678.
 
  
==Aircraft and basic Flying Principles==
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== Introduction  ==
===Producing Lift===
 
For an aircraft to fly the lift force produced by (mostly) the wings has to outweigh the gravitational force that affects the aircraft.
 
  
Basically a wing produces lift by deflecting the air it moves through into one direction. According to Newton's third law of motion the lift is produced into the opposite direction. This lift grows with the speed the aircraft has in relation to the air and with the angle the wing draws with the direction of movement. This angle is called Angle of Attack (AoA). [[Bild:Angle_of_attack.png|framed|Angle of Attack]]
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This Study Guide is designed to give you all the information you need to become an efficient Tower Controller within VACC Austria. We assume that you have already read the [[Study Guide:OBS]], [[Study Guide:Delivery]] and [[Study Guide:Ground]].
  
The principle only works as long as a steady airflow around the wing exists. As soon as the airflow seperates from the wings surface the lift starts to decerease. The AoA at which this occurs is called critical Angle of Attack. It depends on the profile of the wing and it's dimensions but for subsonic aircrafts it typically lies between 8 and 21 degrees.
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Tower's main responsibility is to make efficient use of all available RWY's.
  
Think of an level flying aircraft that reduces it speed. In order to compensate the reducing lift the pilot has to raise the nose. However at some point the Angle of Attack will cross the critical angle of Attack and the pilot will find himself in a stall. So the speed of an aircraft is limited on the lower side by the so called stall speed. Because the stall speed depends on the profile most aircraft are equipped with devices that alter the profile during flight such as flaps or slats.
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The tower is therefore responsible:
  
On approach pilots have to fly in a certain speed range in order to conduct a safe landing. The lower boundary is called landing reference speed and is often a fixed multiple of the stall speed. As a result of this the approach speed also depends on weight an aircraft configuration (Flap/Slat setting). For safety the Approach Vapp is higher than Vref and the difference depends mostly on the weather conditions.
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- for all movements on the runways
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- for all movements within the control zone (see "Airspace Structure" below).
 +
 
 +
Euroscope visibility range for Tower should not exceed 50nm (regarding Vatsim CoC C12)
 +
 
 +
== Aircraft Categories  ==
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 +
A/C are categorized by their respective weight and approach IAS
 +
 
 +
=== Weight Categories  ===
 +
 
 +
Aircraft are categorized into four weight categories:
  
Generally you can say that bigger aircraft also have a bigger approach speed however at some point this rule does not work anymore because the Vref depends largely on the aircrafts weight in relation to it's maximum takeoff weight (MTOW). The speed ranges from 50 knots in a C150 up to 170 knots with a fully loaded 747. However for example it is possible that a light 747 is slower than a fully loaded 737.
 
===Aircraft Categories===
 
The most important ways of categorizing aircraft in aviation are by weight or by approach speed.
 
====Weight Categories====
 
Aircraft are categorized into three weight categories:
 
 
{| class="prettytable"
 
{| class="prettytable"
|'''Category'''||'''MTOW'''
 
 
|-
 
|-
|Light Aircraft (L)||< 7 000 kg
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| '''Category'''
 +
| '''MTOW'''
 
|-
 
|-
|Medium Aircraft (M)||7 000 – 136 000 kg
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| Light Aircraft (L)  
 +
| &lt; 7 000 kg
 
|-
 
|-
|Heavy Aircraft (H)||>136 000 kg
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| Medium Aircraft (M)
 +
| 7 000 – 136 000 kg
 +
|-
 +
| Heavy Aircraft (H)  
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| &gt;136 000 kg
 +
|-
 +
| Super Aircraft (S)
 +
| is only one: the A380
 
|}
 
|}
Weight depicted is MTOW.
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====Approach Speed====
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You can find a list of aircraft in this link [http://www.skybrary.aero/index.php?title=Category:Aircraft&until=D228] <br>Weight depicted is MTOW.
Aircraft are categorized by their reference approach speed (Vref) at maximum landing weight:
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 +
=== Approach Speed ===
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 +
Aircraft are categorized by their reference approach speed (Vref) at maximum landing weight:  
 +
 
 
{| class="prettytable"
 
{| class="prettytable"
|'''Category'''||'''Vref'''
 
 
|-
 
|-
|A||<= 90 knots
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| '''Category'''
 +
| '''Vref'''
 +
|-
 +
| A  
 +
| &lt;= 90 knots
 
|-
 
|-
|B||91 - 120 knots
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| B  
 +
| 91 - 120 knots
 
|-
 
|-
|C||121 - 140 knots
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| C  
 +
| 121 - 140 knots
 
|-
 
|-
|D||141 - 165 knots
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| D  
 +
| 141 - 165 knots
 
|-
 
|-
|E||>= 165 knots
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| E  
 +
| &gt;= 165 knots
 
|}
 
|}
  
==METAR and TAF==
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== Theoretical Knowledge ==
References for detailed information: [[METAR]], [[TAF]]
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 +
=== Producing Lift  ===
 +
 
 +
For an aircraft to fly the lift force produced by (mostly) the wings has to outweigh the gravitational force that affects the aircraft.
  
==How is an Aerodrome Organized?==
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Basically, a wing produces lift by deflecting the air it moves through into one direction. According to Newton's third law of motion, the lift is produced in the opposite direction. This lift grows with the speed the aircraft has in relation to the air and with the angle, the wing draws with the direction of movement. This angle is called Angle of Attack (AoA).  
[[Bild:Aerodrome_positions.png|framed|Aerodrome - Areas of Responsibility]]As airports grew bigger over time also the workload for the Air Traffic Controller handling the traffic got bigger. Soon it was necessary to distribute this workload onto more than one controller in order to be able to cope with the traffic.
 
  
So the Tower Position got divided into thre basic types with different areas of responsibility.
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The principle only works as long as a steady airflow around the wing exists. As soon as the airflow seperates from the wings surface the lift starts to decrease. The AoA at which this occurs is called critical Angle of Attack. It depends on the profile of the wing and it's dimensions but for subsonic aircraft, it typically lies between 8 and 21 degrees.  
  
* Clearance delivery (DEL), responsible for checking flightplans and issuing IFR clearances to departing aircraft.
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Think of a level flying aircraft that reduces its speed. In order to compensate for the reducing lift, the pilot has to raise the nose. However, at some point, the Angle of Attack will cross the critical angle of attack and the pilot will find himself in a stall. So the speed of an aircraft is limited on the lower side by the so-called stall speed but the aircraft is also limit by aerodynamics in the higher range of speed (buffeting). Because the stall speed depends on the profile most aircraft are equipped with devices that alter the profile during flight such as flaps or slats (Approach). In General, when an aircraft flies it will produce thrust but at the same time it produces drag. So if you fly just horizontal (cruise) you have at the same time Lift=weight and thrust=drag. Drag produce automatic noise and that is the big problem. to prevent this we have different procedures in the approach and a lot of research in aviation to reduce the sound of the aircraft but the main part are the engines.  
* Ground (GND), responsible for all traffic on the apron and the taxiways.
 
* Tower (TWR), responsible for movements on the runway and within its associated Control Zone.
 
Because Tower and Ground controllers rely very strongly on what they see out of their window, these are the positions which are situated within the airports control tower.
 
  
Apart from that there are the controllers who manage the traffic once it has left the control zone. They are again divided into:
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On approach, pilots have to fly in a certain speed range in order to conduct a safe landing. The lower boundary is called landing reference speed and is often a fixed multiple of the stall speed. As a result of this, the approach speed also depends on the weight and aircraft configuration (Flap/Slat setting). For safety, the Approach Vapp is higher than Vref and the difference depends mostly on the weather conditions.  
* APP Positions, managing the traffic within the airports vicinity (the so called TMA, Terminal Area). In Austria they are situated directly at the airports.
 
* ACC (Area Control Center, on VATSIM the abbreviation CTR is used) positions, which are responsible for enroute traffic. They reside in Vienna.
 
  
Since they all use their radar to control air traffic, they are also called Radar positions.
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Generally, you can say that bigger aircraft also have a bigger approach speed however at some point this rule does not work anymore because the Vref depends largely on the aircraft's weight in relation to its maximum takeoff weight (MTOW). The speed ranges from 50 knots in a C150 up to 170 knots with a fully loaded 747. However for example it is possible that a light 747 is slower than a fully loaded 737.
  
==Working Delivery Positions==
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=== Transition Altitude/Transition Level  ===
Clearance Delivery is responsible for checking and correcting flightplans of departing aircraft and issue routing clearances to them.
 
===Flightplan Structure===
 
'''Flight plans''' are documents filed by pilots with the local Civil Aviation Authority prior to departure. They generally include basic information such as departure and arrival points, estimated time en route, alternate airports in case of bad weather, type of flight (whether instrument flight rules or visual flight rules), pilot's name and number of people on board.<br>
 
For IFR flights, flight plans are used by air traffic control to initiate tracking and routing services. For VFR flights, their only purpose is to provide needed information should search and rescue operations be required.
 
  
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Aircraft Altimeters use the air pressure around them to determine their actual altitude. In order to get correct readings, you have to use the actual local pressure in your area. As a memory hook, you can use this: The altimeter needle moves in the same direction you turn the rotary knob to adjust the pressure. If you turn it counterclockwise, the needle also turns counterclockwise and therefore indicates a lower altitude.
  
Aircraft routing types used in flight planning are: Airway, Navaid and Direct. A route may be composed of segments of different routing types.
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As ground pressure changes every hundred miles, aircraft would need to update their settings every few minutes. If ALL aircraft would need to do this, it would be terribly unpractical and dangerous. Guess what happens if one forgets? So the altitude is "sliced":
*'''Airway:''' Airway routing occurs along pre-defined pathways called Airways. Mostly aircraft are required to fly airways between the departure and destination airports. The rules cover altitude, airspeed, and requirements for entering and leaving the airway (SIDs and STARs).
 
*'''Navaid:''' Navaid routing occurs between Navaids (short for Navigational Aids) which are not always connected by airways. Navaid routing is typically only allowed in the continental U.S. If a flight plan specifies Navaid routing between two Navaids which are connected via an airway, the rules for that particular airway must be followed as if the aircraft was flying Airway routing between those two Navaids. Allowable altitudes are covered in Flight Levels.
 
*'''Direct:''' Direct routing occurs when one or both of the route segment endpoints are at a latitude/longitude which is not located at a Navaid. This is a routing from Vienna
 
  
===Issuing IFR Routing Clearances===
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* In lower areas (where the terrain is in close proximity), aircraft have to update local settings. Most aircraft are there only for takeoff and landing, so no big deal.
DEL gives routing clearances to all departing aircraft with the following information:<br>
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* In higher areas, aircraft all tune a standard-setting (QNH 1013 or 29.92 HG) - this setting may be "wrong", but as all aircraft have the same "wrong" setting, it does not matter.
'''Destination of aircraft'''
 
'''SID''' (= Standard instrument departure) Normally the filed SID is given
 
Initial climb altitude after departure (5000ft)
 
'''Squawk''' (Squawk assignments for LOWW are 4600 to 4620)
 
'''QNH''' (Local QNH of airport according to latest METAR)
 
CTOT (= Calculated take-off time) Slot time (Normally not used on the VATSIM network)
 
  
The '''bold''' marked points are mandatory, all other points are optional.<br>
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And where is the altitude where that changes?
<br>
 
Normal construction of a routing clearance:
 
Callsign, cleared to XXXX via XXXXX XX departure, (climb initially 5000ft), Squawk 46XX, QNH XXXX
 
Example:
 
Austrian 125, cleared to Frankfurt via LUGIM 1C departure, climb initially 5000ft,
 
Squawk 4601, QNH 1020.
 
Some Aircraft are not able to follow SIDs for various reasons, most of the time due to missing equipment. In these cases you should issue a so called vectored departure. A vectored departure clearance includes the same components as a normal clearance but instead of the SID you issue instructions to be carried out after departure. In this case the initial climb altitude is mandatory.
 
Callsign,cleared to XXXX, after departure rwy XX, XXXXXXX, climb initially 5000ft,
 
Squawk 46XX, QNH XXXX
 
Example:
 
Austrian 125, cleared to Frankfurt, after departure Runway 29, turn left heading 240
 
expect vectors to LUGIM, initially climb to 5000 ft, Squawk 4601, QNH 1020.
 
You can find the instructions for each Airport within the [[Study Guide:Airport Details]]
 
If the pilot responds with a correct readback you should answer with the following phrase:
 
Callsign, readback correct.
 
Afterwards you either hand the pilot over to GND or wait for his startup request, depending on local procedures.
 
  
===Special Situations (High Traffic, Slots, ...)===
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* For climbing aircraft, it is the Transition Altitude, where they change from local to standard pressure.
====Slots====
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* For descending aircraft, it is the Transition Level, where they change from standard to local pressure.
In order to guarantee a safe flow of traffic and to minimize delays in the air so called slots are being used. A slot is a timeframe of five minutes before to ten minutes after the CTOT mentioned before. The aircraft has to depart within this timeframe from its departure airport.
 
On the VATSIM network this system is only used on special occasions.
 
  
==== Verhalten in Situationen mit erhöhtem Verkehrsaufkommen ====
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Between the two, there is a safety layer (called "Transition Layer") which compensates for the difference between local and standard pressure, which is 1000ft minimum, so the stack is:
Sometimes one of your neighboring sectors has to stop accepting traffic. In these cases you should delay an aircrafts start-up clearance.
 
  
If possible you should inform the pilot about the expected delay:
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Upper airspace: measured in Flight Levels (FL220 = Altitude 22.000ft at standard settings)
  Austrian 125, readback correct, expect startup in 10 minutes.
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Transition Level: the lowest Flight Level
  Austrian 125, startup approved, expect departure in 10 minutes.
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Transition layer (to keep distance)
 +
  Transition Altitude (TA): the highest altitude cleared at local pressure settings
 +
  Lower airspace, where the altitude is given (you write "A5000ft").
  
== Working Ground Positions ==
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As the difference between TA and TL varies with pressure (the lower local pressure, the thinner), the size of the Transition Layer varies (the lower local pressure, the thicker). Use the following table to calculate your TRL:  
Ground is responsible for all movements of aircraft on ground, except the movements on the runway.
 
Ground takes over responsibility for Delivery if he is not online.<br>
 
<br>
 
'''Start-up clearance'''<br>
 
Start-up clearance can be given if no other aircraft is taxiing behind the starting-up aircraft and if the take-off is expected in 20 minutes or less.
 
Austrian 125, start-up approved, (Temperature Minus 3)
 
'''Push-back clearance'''<br>
 
Push-back clearance can be given if no other aircraft is passing behind and the parking position requires push-back (i.e. position at the gate, … [refer to charts])
 
Austrian 125, push-back approved”
 
'''Combination of both phrases'''<br>
 
During low traffic you can use these two phrases together<br>
 
Austrian 125, start(-up) and push(-back) approved
 
===Taxi Instructions===
 
The pilot pushes back and starts the aircrafts engines. As soon as he is ready for taxi he will call you:
 
AUA125:AUA125, ready for taxi.
 
Depending on traffic you can give him the taxi instruction to his departure runway:
 
GND:AUA125, taxi to holding point Rwy 16 via taxiways Exit 4, L and F.
 
AUA125:Taxiing to holding point runway 29 via L and F, AUA125.
 
Sometimes it is necessary to hold an aircraft in front of another taxiway:
 
GND:AUA125, hold short of taxiway L.
 
AUA125:Holding short of L, AUA125.
 
When an aircraft is approaching its assigned holding-point (and clear of possible traffic-conflict) a hand-off to next higher position (i.e. TWR) shall be initiated as soon as possible.
 
GND:AUA125, contact now Salzburg Tower on frequency 118.10, bye bye!
 
AUA125:contacting Tower on frequency 118,10 bye!
 
  
===Ground Traffic Management===
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  QNH      &lt; 0977: TA + 3000 ft.
To organise the traffic on ground different techniques are available, some of them relying on the pilots seeing each other. Generally you should avoid clearing two aircraft onto crossing pathways, unless you are sure they will never meet each other. To achieve this you should instruct aircraft to hold short of taxiways in the way stated above. Consider the following situation:
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  QNH 0978 - 1013: TA + 2000 ft.
{|class="prettytable"
+
  QNH 1014 - 1050: TA + 1000 ft.
|-
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  QNH 1051 &gt;    &nbsp;: TA = TL
|You are the Ground Controller at Vienna Airport. Runways active are 34 for landing and 29 for departure. DLH6KM has vacated rwy 34 and requests taxi to its parking position. LZB421 is ready for taxi at stand 7Q.
 
|}
 
  GND:DLH6KM taxi to stand 40 via taxiways D and L.
 
  DLH6KM:Taxiing to stand 40 via D and L, DLH6KM.
 
LZB421:Wien ground LZB421 stand 7Q, ready for taxi.
 
GND:LZB421, taxi taxiway W, hold short of taxiway L.
 
  LZB421:taxiing via W holding short of L.
 
{|class="prettytable"
 
|-
 
|The aircraft are now both approaching the intersection L/W.
 
|}
 
GND:LZB421, give way to the DLH B737 crossing left to right on L, thereafter continue
 
taxi to holding point runway 29 via taxiways Exit 2, M and A1.
 
  LZB421:Giving way to the 737 from left to right, then continuing taxi to holding point
 
runway 29 via Exit 2, M and A1.
 
Of course you have to make sure that this instruction is unambiguous, so there shouldn't be two DLH B737s in the area. Also in low visibility operations this procedure might not work very well, in this case you might have to give the aircraft the instruction to continue taxi when the other aircraft has passed.
 
In some cases it is also useful to let one aircraft follow the other:
 
GND:LZB421, follow the Austrian DASH 8 crossing you right to left on M to holding point runway 29.
 
LZB421:following the DASH 8 crossing us right to left on M to holding point runway 29.
 
===Intersection take-off===
 
Some flights do not need the whole length of their given departure runway so they might request takeoff from an intersection somewhere down the runway. This procedure is called a intersection takeoff. You should only grant this in coordination with Tower and if traffic situation permits.
 
Also at some airports intersections are used to be more flexible in the departure sequence (see section [[Study Guide:Tower#Departure_Seperation_-_Based_on_Type_of_Aircraft_and_departure_route|Departure Seperation]]).
 
  
===Special Situations (High Traffic, Slots, ...)===
 
====Slots====
 
In case the above mentioned slot regulations are in force ground has the responsibility to set up a departure sequence in a way that the aircraft do not miss their slot.
 
====Opposite runway operations====
 
At some austrian airports it is very common to use opposite runway configurations (departure and arrival runway are opposite to each other). In these situations it can happen very fast that you have two aircraft facing each other nose to nose. Special attention should be paid to avoid this situation.
 
  
==Working Tower Positions==
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==Before you start controlling==
Tower is responsible for all movements on the runways as well as for all movements within the control zone (CTR), (10NM radius, GND to 2500ft MSL). Tower is also responsible for ground and delivery if they are not online. He also decides which runways are in use.
 
===ATIS===
 
ATIS stands for Automatic Terminal Information Service and is a usually automatically generated broadcast that contains essential informations for pilots. It is continuously broadcasted on a dedicated frequency. On initial contact with the controller, pilots should already have listened to the ATIS and state the identifying letter.
 
  
A ATIS broadcast has to consist of:
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Tower decides which runways are in use and maintains the ATIS. The tower is also responsible for ground and delivery if they are not online or if they are not defined for that particular airport (LOWS has DEL, but no GND; LOWI, LOWG and LOWK have only TWR).
* Name of the Airport
 
* Identification Letter
 
* Time of Observation
 
* Active Runways
 
* Transition Level
 
* Wind direction and velocity
 
* Visibilities
 
* Special weather conditions (such as rain)
 
* Cloud ceiling
 
* Temperature and Dewpoint
 
* QNH
 
* Trends
 
  
It is updated every 30 minutes or as soon as significant changes occur.
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=== Airspace Structure around Major Airports  ===
  
===Determination of active Runways===
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Major airports in Austria are surrounded by a control zone (CTR) which is class D airspace. This means that A/C need clearance for entry. So either they are cleared for an approach or they are cleared into the control zone. Details will be discussed in the VFR part later on.
Pilots normally prefer to takeoff and land the aircraft with the nose into the wind because it shortens the Rwy length required to safely operate the aircraft. The wind direction given in the METAR is the direction the wind is coming from, so it is easy to compare this wind to your given runways. <br>
 
'''Example:'''
 
{| class="prettytable"
 
|-
 
|You are the Tower controller at Salzburg Airport. The only runway at Salzburg is runway 16-34 so  you have two directions available (roughly 160° and 340°.) The wind is coming from 180° at 5 knots. So the usual Runway in use would be rwy 16 for takeoff and landing.''
 
|}
 
However, at most airports a preferred runway configuration is defined (Find them here: [[Study Guide:Airport Details]]) which should be used if traffic situation and weather permits. Aircraft have certain limitations they can operate in, so normally the tailwind component should not exceed 5-10 knots (again depending on airport). Also the allowed crosswind is limited (This depends very much on the aircraft).<br>
 
Be aware that it is the pilots responsibility to accept a certain wind component and that this decision is often based on performance issues, so one pilot might accept the next one refuses to take a certain runway.
 
  
So back to our example above:
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== Tower Workflow  ==
{| class="prettytable"
 
|-
 
|At Salzburg, due to the terrain in the vicinity and city of Salzburg around the airport, runway 34 is preferred for departures and rwy 16 for landing. So the indicated configuration would be DEP 34, ARR 16.
 
|}
 
  
===Transition Altitude/Transition Level===
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===Setting the right priorities===
[[Bild:3-Pointer Altimeter.png|framed|Altimeter]]Knowing the altitude you are flying is one of the most important informations you need in order to safely operate an airplane. Aircraft Altimeters use the air pressure around them to determine their actual altitude. In order to get correct readings you have to use the actual local pressure in your area. As a memory hook you can use this: The altimeter needle moves in the same direction you turn the rotary knob to adjust the pressure. If you turn it counterclockwise, the needle also turns counterclockwise and therefor indicates a lower altitude.
+
The moment you are responsible for more than one aircraft you will have to set priorities in your handling. As a general guideline:
  
On the other hand it would not be very practical to use the local pressure while flying at higher altitudes, since terrain is not an issue here and you would have to set a new pressure setting in your altimeter every few minutes.
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#aircraft in the air have top priority - you take care of them first. Reason: They can't stop.
 +
#aircraft moving on the ground have next priority. They could bump into each other.
 +
#aircraft standing on ground have the least priority.
  
To avoid this pilots use the local pressure when departing from an airport until they pass the so called Transition Altitude (TA), where they set the so called standard pressure (QNH 1013 hpa or Altimeter 29.92 inHg). They continue to use this setting until they descend through the Transition Level (TRL) at their destination airport (or an airport on their route), where they set the local pressure again.
+
=== Runway Separation  ===
  
In airport charts only TA is given, whereas TRL has to be determined by ATC. Use the following table to calculated your TRL:
+
The runways are one of the most dynamic spots on an airport. Aircraft are travelling at high speed with little room to manoeuvre and most of the time no ability to stop at a reasonable distance. In general '''<span style="color:#ff0000;">only one aircraft may be cleared to use a runway at the same time.</span>''', nevertheless there are exceptions to this rule which will be described in the upcoming chapters.
QNH      < 0977: TA + 3000 ft.
 
QNH 0978 - 1012: TA + 2000 ft.
 
QNH 1013 - 1050: TA + 1000 ft.
 
QNH 1051 >    : TA = TL
 
  
The room between TA and TRL is called Transition layer. It ensures that the minimum spacing of 1000 ft between aircraft flying in lower part (with local pressure) and the upper part (using Standard pressure).
+
=== Departing Traffic  ===
  
===Runway Separation===
+
So now we are at the point where the pilot reaches the Holding Point of his departure runway and reports ready for departure. What are the things you should check before issuing the takeoff clearance?
The runways are one of the most dangerous spots on an airport because aircraft are travelling at high speed with little room to maneuver and most of the time no ability to stop at a reasonable distance. Because of this the general rule is that '''<span style="color:#ff0000;">only one aircaft may be cleared to use a runway at the same time.</span>''' What this means practically and exceptions from this rule are explained in the following chapters.
 
  
===Departing Traffic===
+
*Have a look at the Flightplan. Take note of the type of aircraft and the Departure Route.  
So now we are at the point where the pilot reaches the Holding Point of his departure runway and reports ready for departure. What are the things you should check before issuing the takeoff clearance?
 
*Have a look at the flightplan. Take note of the type of aircraft and the Departure Route.
 
 
*Check the traffic approaching the runway.
 
*Check the traffic approaching the runway.
To give him the takeoff clearance the following phrase should be used:
 
  e.g.: TWR: AUA2CM, wind 320 degerees at 7 knots, Runway 29, cleared for takeoff.
 
  AUA2CM: Cleared for takeoff Runway 29, AUA2CM
 
The pilot lines up on the runway, advances the throttle and takes off. When he is well established in climb check he is squawking Mode C and the right Code. Afterwards he is handed off to the next Controller, in this case a radar position:
 
  TWR: AUA2CM, contact Wien Radar on frequency 128.20, bye bye!
 
  AUA2CM: Contacting Wien Radar on frequency 128.20, AUA2CM.
 
The next aircraft reports ready for departure. Again check the points above, but this time we cannot give the takeoff clearance straight away because the preceeding aircraft is still occupying the runway. Now you get to know the first exception to the Runway Seperation rule above. To speed things up you can instruct the next aircraft to line up behind the first one while this one is still in the takeoff roll occupying the runway:
 
  TWR: AZA639, behind departing Austrian Airbus A319, line-up rwy 29 behind and wait.
 
  AZA639: behind departing Airbus lining up runway 29 and waiting behind, AZA639.
 
  ''Note: The two times behind in this instruction is not a typing error but was implemented
 
to emphasize that part of the clearance.''
 
This type of clearance is called a conditional clearance. <br><br>
 
The earliest possible point where you can issue the next takeoff clearance is, when the preceeding aircraft has overflown the opposite runway end or has clearly turned onto either side of it.<br>
 
However in some cases this could be very close which leads us to the next chapter.
 
  
===Departure Seperation - Based on Type of Aircraft and departure route===
+
To give a takeoff clearance the following phrase should be used:
One of the main tasks of air traffic control is to keep aircraft at a safe distance to each other. So imagine the following situation:
+
 
 +
AUA2CM, wind 320 degrees, 7 knots, Runway 29, cleared for takeoff.
 +
 
 +
When the A/C is well established in climb check if squawking Mode C and the right Code. Afterwards, he is handed off to the next Controller, in this case, a radar position:
 +
 
 +
AUA2CM, contact Wien Radar frequency 134.675.
 +
 
 +
 
 +
The next aircraft reports ready for departure. Again check the points above, but this time we cannot give the takeoff clearance straight away because the preceding aircraft is still occupying the runway. Now you get to know the first exception to the Runway separation rule above. To speed things up you can instruct the next aircraft to line up behind the first one while this one is still in the takeoff roll occupying the runway:
 +
 
 +
  AZA639, behind departing Austrian Airbus A319, line-up rwy 29 behind.
 +
 
 +
''Note: you '''must''' add another "behind" at the end of the clearance!!
 +
 
 +
This type of clearance is called conditional clearance. <br> The earliest possible point where you can issue the next takeoff clearance is, when the Proceedings aircraft has overflown the opposite runway end or has clearly turned onto either side of it.<br>
 +
 
 +
 
 +
==== Take care! Phraseology around the runway is vital ====
 +
In 1977, at the Tenerife Airport, two 747 Jumbo Jets collided on the runway and burst up in flames, killing more than 500 people. There was a simple cause: misunderstandings in the takeoff phraseology: Tower said "standby for takeoff", the pilot understood "cleared for takeoff". So, there are two iron rules which you should never break as a Tower controller:
 +
 
 +
* '''Use the word "takeoff" only when you clear for takeoff: Say "<aircraft> cleared for takeoff" and nothing else.''' If you have to say anything else (like that the aircraft can leave in 2 minutes), then use the word "departure".
 +
* '''Use the word "landing" only when you clear for landing: Say "<aircraft> cleared to land" and nothing else.''' If you have to say anything else (like where to leave the runway after touchdown), use the word "arrival".
 +
 
 +
=== Departure Separation  ===
 +
There are several factors to take into consideration when deciding what the minimum separation between succeeding aircraft is. It is the tower controller's responsibility to decide which kind of separation to apply. The following types of separation shall be considered:
 +
*[[#Time Based Separation|Time Based Separation]]
 +
*[[#Radar Separation|Radar Separation]]
 +
 
 +
'''CAUTION: Regardless of separation minima to be used, the following rule ALWAYS applies:'''
 +
 
 +
Departing aircraft will not normally be permitted to commence take-off until
 +
*the preceding departing aircraft has crossed the end of the runway-in-use or
 +
*has started a turn or
 +
*until all preceding landing aircraft are clear of the runway-in-use.
 +
Note that this paragraph is not about the actual clearance. You may clear an aircraft - considering the minima below - for takeoff before the above conditions are fulfilled, taking into account the time it will take the aircraft, until the actual takeoff can be commenced.
 +
 
 +
==== Time Based Separation  ====
 +
To avoid hazards created by the turbulence formed at the wingtips of aircraft (wakes), separation based on time shall be applied between succeeding departing traffic. This is due to the fact, that wakes need a certain time to dissipate.
 +
 
 +
The actual time to apply depends on the wake turbulence category and thus on the weight of the aircraft:
 +
<div align="left">
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|
+
| Light Aircraft (L)
*Two aircraft are departing right after each other.
+
| &lt; 7 000 kg
*The first aircraft is a relatively slow Cessna 208 (~around 70 knots in climb), the second one a fast Boeing 767 (140-180 knots on the initial climb).
+
|-
*Both follow the same departure route.
+
| Medium Aircraft (M)  
 +
| 7 000 – 136 000 kg
 +
|-
 +
| Heavy Aircraft (H)  
 +
| &gt;136 000 kg
 
|}
 
|}
Obviously it would not take long until the B767 catches up with the Cessna, a potentially very dangerous situation! You can see, that it is very important to check the flightplan of the aircraft you are about to clear for takeoff. <br>
+
</div>
The minimum radar seperation in the area around an airport is 3 nm or 1000 feet. These are the limits radar stations have to obey. Tower Controllers should aim to achieve the following seperation for departing aircraft following departure routes which share a common part:
+
 
 +
===== 2 Minutes =====
 +
Provided that succeeding aircraft are using:
 +
*the same runway
 +
*crossing runways if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 300 m (1 000 ft) below
 +
*''parallel runways separated by less than 760m'' (no applicable in Austria)
 +
*''parallel runways separated by 760 m (2 500 ft) or more, if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 300 m (1 000 ft) below (not applicable in Austria)''
 +
a minimum separation of 2 minutes applies whenever a
 
<div align="left">
 
<div align="left">
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|Fast followed by slow||3 nm
+
| Light or Medium
 +
| follows
 +
| Heavy
 +
|-
 +
| Light
 +
| follows
 +
| Medium
 +
|}
 +
</div>
 +
 
 +
===== 3 Minutes =====
 +
Provided that succeeding aircraft are taking off from:
 +
*an intermediate part of the same runway (read: intersection)
 +
*''an intermediate part of a parallel runway separated by less than 760 m (2 500 ft) (not applicable in Austria)''
 +
a minimum separation of 3 minutes applies whenever a
 +
<div align="left">
 +
{| class="prettytable"
 
|-
 
|-
|Matching Types||5 nm
+
| Light or Medium
 +
| follows
 +
| Heavy
 
|-
 
|-
|Slow followed by fast||10 nm
+
| Light
|}</div>
+
| follows
In extreme examples like the one above it is often more advisable to coordinate with APP to find another solution. Often this involves clearing the aircraft to a non standard altitude or departure route:
+
| Medium
  TWR: DLH2441, after departure maintain runway heading, climb initially to 3000 ft
+
|}
  DLH2441: After departure maintaining runway heading, climbing to 3000 ft, DLH2441
+
</div>
  TWR: DLH2441, wind 320 degrees at 9 knots, runway 29, cleared for takeoff
+
Note: In LOWW the following intersections are, for the purposes of wake vortex, NOT considered to be intersection departures:
  DLH2441: Cleared for takeoff runway 29, DLH2441
+
<div align="left">
The other main task of ATC is to expedite the flow of traffic. Situation:
 
 
{| class="prettytable"
 
{| class="prettytable"
 +
| Runway
 +
| Intersections
 
|-
 
|-
|
+
| 11
*You have numerous aircraft departing from the same runway, following different departure routes. Some of them involve immediate right turns other SIDs immediate left turns.
+
| A11 and A12
*There are two holdingpoints available.
+
|-
 +
| 29
 +
| A1 and A2
 +
|-
 +
| 16
 +
| B1 and B2
 +
|-
 +
| 34
 +
| B11 and B12
 
|}
 
|}
It would benificial to use the gaps that arise between the aircraft using similar Departure Routes, so in close coordination with ground you should try to distribute aircraft over the holding points in a way to be able to fill those gaps.
+
</div>
 +
 
 +
To point out this hazard to a pilot the following phrase should be used:
 +
 
 +
DLH32C, wind 180 degrees, 3 knots, runway 16 cleared for takeoff, <u>caution wake turbulence.</u>
  
===Departure Seperation - Based on Wake Turbulence Category===
+
==== Radar Separation ====
There are two ways aircraft influence the air around them when passing through it:
+
For radar-equipped TWR stations, which in Austria are basically all controlled TWR stations, departure separation shall be as such, that departing aircraft are entering the approach airspace with radar separation. For LOWW_TWR these minima are for example:
 +
 
 +
<div align="left">
 
{| class="prettytable"
 
{| class="prettytable"
 +
|Traffic
 +
|Distance
 +
|Condition
 +
|-
 +
| Departing traffic on different SIDs
 +
| 3 nm
 +
| increasing
 
|-
 
|-
|
+
| Departing traffic on same SIDs
*Jetwash produced by the engines
+
| 5 nm
*Turbulence created at the wings and especially at the wingtips
+
| increasing
 
|}
 
|}
This turbulence can cause severe problems or even loss of control for following aircraft.
+
</div>
The wake turbulence categories are based on the Maximum Takeoff weight (MTOW) of the aircraft:
+
'''Same SID's:'''
 +
 
 +
'''RWY 11:'''
 +
 
 +
LANUX-BUWUT-LEDVA
 +
 
 +
OSPEN-RUPET
 +
 
 +
STEIN-ARSIN
 +
 
 +
KOXER-ADAMA
 +
 
 +
 
 +
 
 +
'''RWY 16:'''
 +
 
 +
LANUX-BUWUT-LEDVA
 +
 
 +
MEDIX-LUGEM
 +
 
 +
OSPEN-RUPET
 +
 
 +
STEIN-ARSIN
 +
 
 +
KOXER-ADAMA
 +
 
 +
 
 +
'''RWY 29:'''
 +
 
 +
LANUX-BUWUT-LEDVA
 +
 
 +
MEDIX-LUGEM
 +
 
 +
OSPEN-RUPET
 +
 
 +
STEIN-ARSIN-KOXER-ADAMA
 +
 
 +
 
 +
'''RWY 34:'''
 +
 
 +
LANUX-BUWUT
 +
 
 +
OSPEN-BUWUT
 +
 
 +
STEIN-ARSIN
 +
 
 +
KOXER-ADAMA
 +
 
 +
==== Deciding Which Separation to apply ====
 +
In order to provide an expeditious flow of traffic for departing traffic, it is imperative for the tower controller to always apply the lowest separation minimum. Since time-based separation is always the larger of the minima, it should always be strived to achieve radar separation. In principle, taking the minima above into consideration, radar separation may always be applied when succeeding departing traffic is in the same wake turbulence category or if a heavier aircraft is departing behind a lighter one.
 +
Otherwise, time based separation has to be applied.
 +
 
 +
==== Tips And Tricks ====
 +
*Try to avoid having multiple aircraft using the same SID depart the same runway right after each other. Throw in a departure with another SID in between to utilize the 3nm radar separation minimum instead of 5.
 +
*If possible, have heavier planes depart behind lighter ones, so you avoid having to use time-based separation. Of course, take this with a grain of salt, since you can't let the heavier aircraft wait forever.
 +
*To achieve radar separation as soon as possible, use initial visual turns if weather permits (VMC). Example:
 +
TWR: AUA117M, after departure visual right turn to SOVIL is approved, wind calm, runway 11 cleared for takeoff.
 +
In this case, the aircraft will make a very early right turn, allowing you to have the next aircraft takeoff within seconds, provided it is not lighter than the preceding.
 +
*The ground controller should send aircraft to your frequency early enough during taxi - provided that there are no conflicts on the ground - that you should be able to distribute the aircraft onto the different holding points to your needs. Use the holding points in order to prepare a proper departure sequence that allows you to use the lowest minima possible.
 +
Note: According to the austrian AIP, the pilot shall prepare and be ready to use the following intersections for departure:
 
<div align="left">
 
<div align="left">
 
{| class="prettytable"
 
{| class="prettytable"
 +
| Runway
 +
| Intersections
 
|-
 
|-
| Light Aircraft (L)||< 7 000 kg
+
| 11
 +
| A10
 
|-
 
|-
|Medium Aircraft (M)||7 000 – 136 000 kg
+
| 16
 +
| B4
 
|-
 
|-
|Heavy Aircraft (H)||>136 000 kg
+
| 29
|}</div>
+
| A3 (west)
For departing aircraft, 2 minutes separation (3 minutes if the succeeding aircraft departs from an intersection) is applied when an aircraft in wake turbulence category LIGHT or MEDIUM departs behind an aircraft in wake turbulence category HEAVY, or when a LIGHT category aircraft departs behind a MEDIUM category aircraft.<br>
 
You may issue a take-off clearance to an aircraft that has waived wake turbulence separation, except, if it's a light or medium aircraft departing as follows:
 
{| class="prettytable"
 
 
|-
 
|-
|
+
| 34
*Behind a heavy a/c and takeoff is started from an interception or along the runway in the direction of take-off.
+
| B10
*Behind a heavy a/c that is taking off or making a low or missed approach in the opposite direction on the same runway.
 
*Behind a heavy a/c that is making a low or missed approach in the same direction of the runway.
 
 
|}
 
|}
To point out this hazard to a pilot the following phrase should be used:
+
</div>
  TWR:ESK32C, behind departing heavy B777 line up runway 16 behind and wait,
+
For those intersections it is normally not necessary to ask a pilot if he is able - it is his obligation to tell ground upon requesting taxi clearance or latest upon initial contact with the tower controller.
<u>caution wake turbulence.</u>
 
  ESK32C: behind departing B777 lining up rwy 29 and waiting, ESK32C.
 
  
===Use of the word takeoff===
+
=== Arriving Traffic  ===
The word take-off shall only be used in combination with the take-off clearance (cleared for take-off). For other phrases use the word departure (ready for departure – NOT ready for take-off!).
+
 
 +
Arriving Aircraft call you when they are established on an approach to a runway. Most of the time this is an ILS Approach but also other kinds are possible.  
 +
 
 +
  MAH224: Linz Tower, MAH224 established ILS Approach rwy 27.
 +
 
 +
Again you are not allowed to clear more than one aircraft onto the same runway at the same time.<br>
  
===Arriving Traffic===
 
Arriving Aircraft call you when they are established on an approach to a runway. Most of the time this is an ILS Approach but also other kinds are possible.
 
  MAH224:Linz Tower, MAH224 established ILS Approach rwy 27.
 
Again you are not allowed to clear more than one aircraft onto the same runway at the same time.<br>
 
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|In order to issue a landing clearance
+
| In order to issue a landing clearance  
#preceeding departing traffic must have overflown the opposite runway threshold or clearly turned onto either side of the runway.
+
#preceeding departing traffic must have overflown the opposite runway threshold or clearly turned onto either side of the runway.  
#preceeding landing traffic must have left the runway safety strip with all parts.
+
#preceeding landing traffic must have left the runway safety strip with all parts.  
 
#traffic crossing the runway must have left the runway safety strip with all parts.
 
#traffic crossing the runway must have left the runway safety strip with all parts.
 +
 
|}
 
|}
If these conditions are met use the following phrase to clear the aircraft:
+
 
  TWR:MAH224, Linz Tower, wind 300 degerees at 16 knots, runway 27, cleared to land.
+
If these conditions are met use the following phrase to clear the aircraft:  
  MAH224:cleared to land runway 27, MAH224.
+
 
During periods of high traffic it is likely that you have more than one aircraft approaching the same runway at the same time. Approach has to ensure the minimum radar seperation of 3 nm and additionally increased seperation due to wake turbulence.
+
MAH224, Linz Tower, wind 300 degrees 16 knots, runway 27, cleared to land.
   AUA26T:Linz Tower, AUA26T established ILS 27.
+
 
   TWR:AUA26T, Linz Tower, continue approach, wind 300 degrees at 16 knots.
+
During periods of high traffic, it is likely that you have more than one aircraft approaching the same runway at the same time. The approach has to ensure the minimum radar separation of 3 nm and additionally increased separation due to wake turbulence.  
  AUA26T:continuing approach, AUA26T.
+
 
 +
   AUA26T: Linz Tower, AUA26T established ILS 27.
 +
   TWR: AUA26T, Linz Tower, continue approach, wind 300 degrees 16 knots.
 +
 
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|Meanwhile MAH224 has left the runway.
+
| Meanwhile MAH224 has left the runway.
 
|}
 
|}
  TWR:AUA26T wind 310 degrees at 14 knots, runway 27 cleared to land.
+
 
  AUA26T:Runway 27, cleared to land, MAH224.
+
AUA26T wind 310 degrees 14 knots, runway 27 cleared to land.
Often it is useful to give pilots additional information, such as traffic information or wind:
+
 
 +
 
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|CSA276 is following NLY7751 (A320):
+
| AUA81 is approaching runway 16, OE-AGA is on left base runway 16 and there is a rescue helicopter operating in the area around Freudenau.
 
|}
 
|}
  CSA276: Wien Tower, CSA276 established ILS 34.
 
  TWR:CSA276, Wien Tower, preceeding traffic is a NLY Airbus A320 3,5 nm ahead of you, continue
 
  approach runway 34, wind 010 degrees at 4 knots.
 
  CSA276:We have the airbus in sight continuing approach, CSA276.
 
{| class="prettytable"
 
|-
 
|AUA81 is approaching runway 16, OE-AGA is on left base runway 16 and there is a rescue helicopter operating in the area around Freudenau.
 
|}
 
  AUA81:Wien Tower, AUA81 established ILS 16
 
  TWR:AUA81, Wien Tower, VFR traffic is on left base rwy 16, continue approach, wind 140
 
  degrees at 7 knots.
 
  AUA81:continuing approach, AUA81.
 
  TWR:AUA81, There is an helicopter operating west of the extended centerline, presently at
 
  your one o'clock position, 5 nm, 1400 ft.
 
  AUA81: Thank you, looking out, AUA81.
 
  AUA81: traffic in sight, AUA81.
 
To give you an idea how dense traffic can get in real life consider that during peak times and good weather the seperation is reduced to 2,5 nm. This equals to one landing every 75 seconds. However on VATSIM the minimum seperation is 3 nm which already requires good cooperation from all the pilots involved.
 
  
===Merging Departing and Arriving Traffic===
+
AUA81: Wien Tower, AUA81 established ILS 16
And now to the most fun part of being a Tower Controller. Sometimes you get into the situation that you use the same runway for departures and arrivals. Either your airport has only one runway or weather demand this configuration.
+
TWR: AUA81, Wien Tower, VFR traffic is on left base rwy 16, continue approach, wind 140
 +
degrees 7 knots.
 +
AUA81: continuing approach, AUA81.
 +
TWR: AUA81, There is a rescue helicopter operating west of the extended centerline, presently at
 +
your one o'clock position, 5 nm, 1400 ft.
 +
AUA81: Thank you, looking out, AUA81.
 +
AUA81: traffic in sight, AUA81.
 +
 
 +
Helicopters don't need a Runway for the approach, sometimes they are able to land at their parking position, lets have a look on the Phrases.
 +
 
 +
The rescue helicopter from the example above needs to land at your airport:
 +
OEBXR: Wien Tower, Freudenau 1500ft for landing.
 +
TWR: OEBXR, Fly direct G-A-C, stay north of extended centerline RWY 11, 020 deg 4 kts, land own discretion.
 +
 
 +
 
 +
To give you an idea of how dense traffic can get in real life consider that during peak times and good weather the separation is reduced to 2,5 nm. This corresponds to one landing every 75 seconds.
 +
 
 +
=== Merging Departing and Arriving Traffic ===
 +
 
 +
And now to the most fun part of being a Tower Controller. Sometimes you get into the situation that you use the same runway for departures and arrivals. Either your airport has only one runway or weather demand this configuration.  
 +
 
 +
<br> Still the above rule of only one aircraft at the same time applies, however, we also use conditional clearances which look very similar to those above in the departing traffic section.
 +
 
 +
AUA123, behind next landing C750 line up RWY 29 behind.
 +
 
 +
To depart an aircraft in front of an approaching aircraft at the time of the departure clearance given the arriving aircraft should not be closer than 4 nm to touchdown. To squeeze a departing aircraft between two arrivals you normally need a minimum of 6 nm between them. It is important for you to check carefully if you have the necessary gap, so have a close look at the distance between the arrivals and their speed. If the second one comes in faster than normal consider this in your calculation. Also, you should make sure, that the pilot will be ready for departure when you need him to depart. To check this use the following phrase:
  
 +
"Ready for immediate departure?"
  
Still the above rule of only one aircraft at the same time applies, however we also use conditional clearances which look very similar to those above in the departing traffic section.
 
LOWW_TWR: AUA123, Traffic short final RWY 29, C750, report in sight
 
AUA123: Traffic in sight, AUA123
 
LOWW_TWR: AUA123, behind landing C750 line up RWY 29 behind and wait
 
AUA123: Behind landing C750 lining up RWY 29 behdind and waiting, AUA123
 
To avoid misunderstandings, this time we make sure that the Pilot has the the landing aircraft in sight.
 
You don't have to worry about wake turbulence seperation between landing and departing aircraft since they never cross through each others wake.
 
  
To depart an aircraft in front of an approaching aircraft at the time of the departure clearance given the arriving aircraft should not be closer than 4 nm to touchdown.
+
Example:  
To squeeze a departing aircraft between two arrivals you normally need a minimum of 6 nm between them. It is important for you to check carefully if you have the necessary gap, so have a close look at the distance between the arrivals and their speed. If the second one comes in faster than normal consider this in your calculation. Also you should make sure, that the pilot will be ready for departure when you need him to depart. To check this use the following phrase:
 
Callsign, are you ready for immediate departure?
 
Again it is a good idea to give the pilot an idea of the traffic situation around him.
 
  
Example:
 
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|You are the Tower Controller at Vienna airport. Runway 29 is active for departures and arrivals. One aircraft is on a 5 nm final, one at 12 nm out. Additionally you have two departures waiting at the holding point of ruwnay 29.
+
| You are the Tower Controller at Vienna airport. Runway 29 is active for departures and arrivals. One aircraft is on a 5 nm final, one at 12 nm out. Additionally, you have two departures waiting at the holding point of runway 29.
 
|}
 
|}
  TWR:CAL275, are you ready for immediate departure?
+
 
  CAL275:Affirmitive, ready for immediate departure, CAL275
+
  TWR: CAL275, ready for immediate departure?
  TWR:Traffic is now at a 4 nm final, wind 300 degrees at 7 knots, runway 29 cleared for
+
  CAL275: Affirm
immediate takeoff.
+
  TWR: Wind 250 deg 6 kts, Runway 29 cleared for immediate takeoff.
  CAL275:cleared for immediate takeoff runway 29, CAL275
+
  CAL275: cleared for immediate takeoff runway 29, CAL275
 +
 
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|After the CAL B747 has taken off.
+
| After the CAL B747 has taken off.
 
|}
 
|}
  TWR:AUA289, wind 300 degrees at 7 knots, runway 29, cleared to land.
+
 
  AUA289:Runway 29, cleared to land, AUA289.
+
  TWR: AUA289, wind 300 degrees 7 knots, runway 29, cleared to land.
TWR:AUA2LT, traffic is an AUA Airbus A320 on a 2 nm final rwy 29, do you have traffic in sight?
+
  AUA289: Runway 29, cleared to land, AUA289.
AUA2LT:Traffic in sight, AUA2LT.
+
  TWR: AUA2LT, behind landing Airbus line up runway 29 behind.
  TWR:AUA2LT, behind landing traffic line up runway 29 behind and wait.
+
  AUA2LT: Behind the landing Airbus, lining up runway 29 behind, AUA2LT.
  AUA2LT:Behind the landing Airbus, lining up runway 29 behind and waiting, AUA2LT.
+
 
 
{| class="prettytable"
 
{| class="prettytable"
 
|-
 
|-
|AUA289 has vacated the runway.
+
| AUA289 has vacated the runway.
 
|}
 
|}
TWR:AUA2LT, wind 300 degrees at 8 knots, runway 29 cleared for takeoff, landing traffic is
 
now on a 3,5 nm final.
 
AUA2LT:cleread for takeoff runway 29, AUA2LT.
 
  
==VFR Traffic - Differences==
+
TWR: AUA2LT, wind 300 degrees 8 knots, runway 29 cleared for takeoff.
The essential collision safety principle guiding the VFR pilot is "see and avoid." Pilots flying under VFR assume responsibility for their separation from all other aircraft and are generally not assigned routes or altitudes by air traffic control. Governing agencies establish specific requirements for VFR flight, consisting of minimum visibility, distance from clouds, and altitude to ensure that aircraft operating under VFR can be seen from a far enough distance to ensure safety.
+
AUA2LT: cleared for takeoff runway 29, AUA2LT.
  
To guide VFR TRaffic through your airspace you make use of VFR Routes, Sectors and reporting Points.
+
=== VFR Traffic  ===
'''Used phrases''':
+
 
  TWR:OE-AGA, enter control zone via VFR route Klosterneuburg – Freudenau, 1500ft or below,
+
==== Differences to handling of IFR Traffic  ====
  QNH 1020, Squawk 4604, report XXXX (i.e. Freudenau), expect runway 29.
+
 
 +
The essential collision safety principle guiding the VFR pilot is "see and avoid." Pilots flying under VFR assume responsibility for their separation from all other aircraft and are generally not assigned routes or altitudes by air traffic control. Governing agencies establish specific requirements for VFR flight, consisting of minimum visibility, distance from clouds, and altitude to ensure that aircraft operating under VFR can be seen from a sufficient distance to ensure safety.
 +
 
 +
To guide VFR Traffic through your airspace you make use of VFR Routes, Sectors, and reporting Points. '''Used phrases''':  
 +
 
 +
  TWR:OE-AGA, enter control zone via VFR route Klosterneuburg, 1500ft or below,
 +
  QNH 1020, Squawk 7000, report XXXX (i.e. Freudenau), expect runway 29.
 
  TWR:OE-AGA hold (orbit) overhead XXXX (i.e. Freudenau) in XXXX (i.e. 2500ft)
 
  TWR:OE-AGA hold (orbit) overhead XXXX (i.e. Freudenau) in XXXX (i.e. 2500ft)
  
VFR flights should be guided into downwind, base and final leg for landing.<br><br>
+
VFR flights can be cleared into any part of the pattern (departure, crosswind, downwind, base or final). Unless stated otherwise by the controller, a pilot shall join the pattern from the cleared position and finish it without requiring further clearance.<br><br>  
  TWR:OE-AGA, enter downwind for runway 29, report on downwind
+
 
  TWR:OE-AGA, enter base for runway 29, report on base
+
  TWR: OE-AGA, join downwind for runway 29
 +
TWR: OE-AGA, extend downwind for runway 29
 +
  TWR: OE-AGA, join base for runway 29, I will call you for final
 +
TWR: OE-AGA, join base for runway 29
 +
 
 +
VFR Flights Squawk and basic information (active runway, QNH etc.) from Delivery, the route clearance from <u>Tower</u>. After startup, they will contact Ground for taxi, thereafter the Tower will issue the clearance. A possible VFR clearance could be:<br>
  
VFR Flights get their Clearance from <u>Delivery</u> . After startup, they will contact Tower for taxi. A possible VFR Clearance could be:<br>
 
 
  TWR:OE-AGA, verlassen Sie die Kontrollzone über Sichtflugstrecke Klosterneuburg, 1500 Fuß
 
  TWR:OE-AGA, verlassen Sie die Kontrollzone über Sichtflugstrecke Klosterneuburg, 1500 Fuß
  oder darunter, QNH 1014, Squawk 4607, Rechtskurve nach dem Abheben so bald als möglich.
+
  oder darunter, QNH 1014, Squawk 7000, Rechtskurve genehmigt.
  TWR:OE-AGA, leave controlzone via VFR-route Klosterneuburg, 1500 feet or below,
+
  TWR:OE-AGA, leave Control Zone via VFR-route Klosterneuburg, 1500 feet or below,
  QNH 1014, Squawk 4607, right turn after departure as soon as possible.
+
  QNH 1014, Squawk 7000, right turn approved.
 +
 
 +
TWR: OE-AGA, steigen sie auf 3500 Fuß, melden Sie Donauturm.
 +
TWR: OE-AGA, climb 3500 feet, report Donauturm.
  
TWR:OE-AGA, steigen sie auf 3500 Fuß, melden Sie Donauturm.
+
In the air ATC provides [[traffic information]].  
TWR:OE-AGA, climb 3500 feet, report Donauturm.
 
  
In the air ATC provides traffic information.
 
 
  TWR:OE-AGA, Traffic at your 12 o'clock position, 2100 feet, a PA28 on VFR inbound
 
  TWR:OE-AGA, Traffic at your 12 o'clock position, 2100 feet, a PA28 on VFR inbound
 
  route Klosterneuburg-Freudenau.
 
  route Klosterneuburg-Freudenau.
  
When the aircraft leaves the controlzone.
+
When the aircraft leaves the control zone.  
  TWR:OE-AGA, set Sqauwk 7000, leaving frequency is approved.
+
 
 +
  TWR: OE-AGA, Squawk 7000, you may leave.
 +
 
 +
==== Merging in VFR Traffic  ====
  
Wien Tower/Turm can also be contacted in German.
+
To manage VFR Traffic efficiently you have to use [[traffic information]] and visual separation.  
  
===Merging in VFR Traffic===
 
To manage VFR Traffic efficiently you have to use traffic information and visual seperation.
 
 
  TWR: OE-ANX, traffic at your 3 o´clock position, moving right to left, B767, distance 2.5
 
  TWR: OE-ANX, traffic at your 3 o´clock position, moving right to left, B767, distance 2.5
 
  miles, report mentioned traffic in sight
 
  miles, report mentioned traffic in sight
 
  OE-ANX: Traffic in sight, OE-ANX
 
  OE-ANX: Traffic in sight, OE-ANX
Because of other traffic it might be necessary for the aircraft to remain in the downwind leg until the traffic has passed:
+
 
  TWR:OE-AGA, fly extended right downwind, standby for base.
+
Because of other traffic, it might be necessary for the aircraft to remain in the downwind leg until the traffic has passed:  
 +
 
 +
  TWR: OE-AGA, Extend right downwind.
 
  OE-AGA: Extending right downwind, OE-AGA
 
  OE-AGA: Extending right downwind, OE-AGA
To instruct the aircraft to continue it's approach use the following procedure:
+
 
 +
To instruct the aircraft to continue it's approach use the following procedure:  
 +
 
 
  TWR: OE-ANX, traffic at your 3 o´clock position, moving right to left, B767, distance 2.5
 
  TWR: OE-ANX, traffic at your 3 o´clock position, moving right to left, B767, distance 2.5
 
  miles, report mentioned traffic in sight
 
  miles, report mentioned traffic in sight
 
  OE-ANX: Traffic in sight, OE-ANX
 
  OE-ANX: Traffic in sight, OE-ANX
  TWR:OE-AGA, behind B767 traffic, enter final RWY 29, caution wake turbulence
+
  TWR: OE-AGA, behind B767 traffic, join final RWY 29, caution wake turbulence
  OE-AGA: Behind B767, enter final RWY 29 behind, caution wake turbulence, OE-ANX
+
  OE-AGA: Behind B767, join final RWY 29 behind, caution wake turbulence, OE-ANX
When using an extended downwind you should always consider that the aircrafts speed might be considerably lower than the speed of other aircrafts involved. So if an aircraft has to fly a long way out it might take some time for it to come all the way back, generating a big gap in the arrival sequence. Instead you should aim to keep the plane within the vicinity of the airfield:
+
 
 +
When using an extended downwind you should always consider that the aircraft's speed might be considerably lower than the speed of other aircraft involved. So if an aircraft has to fly a long way out it might take some time for it to come all the way back, generating a big gap in the arrival sequence. Instead, you should aim to keep the plane within the vicinity of the airfield:  
 +
 
 
  TWR: OE-AGA, Make a right three-sixty.
 
  TWR: OE-AGA, Make a right three-sixty.
 
  OE-AGA: Making three-sixty to the right.
 
  OE-AGA: Making three-sixty to the right.
 
  TWR: OE-AGA, Orbit left
 
  TWR: OE-AGA, Orbit left
 
  OE-AGA: Orbiting left, OE-AGA
 
  OE-AGA: Orbiting left, OE-AGA
The second instructions means, that the pilot should make orbits until further advice.
 
===Information Positions===
 
  
==Special Situations (High Traffic, Slots, ...)==
+
The second instructions mean, that the pilot should make orbits until further advice.
===High traffic situations===
+
 
During high traffic situations communication with adjacent approach sectors is very important. Especially during single runway operations you might have to ask for increased inbound spacing to be able to fit in departing aircraft.
+
 
===Additional phrases during periods of high traffic===
+
It is also possible to ask VFR traffic for a speed reduction.
In order to expedite the flow of traffic use the following phrases:
+
 
  Austrian 125, wind is xxx/xx runway 29 cleared for takeoff, expedite
+
TWR: OEABW, Fly speed 90 kts
  Austrian 125, wind is xxx/xx runway 34 cleared to land, expedite vacating
+
OEABW: 90 kts, OEABW
 +
 
 +
 
 +
==== Special VFR  ====
 +
Could be used when weather Minimums are below VFR condition.
 +
 
 +
Weather minimums for (S)VFR are follow
 +
 
 +
- Base Cloud at min. 600ft
 +
 
 +
- visibility min 1500m
 +
 
 +
'''Used phrases''': 
 +
Verlassen Sie Kontrollzone als Sonder-Sichtflug über Donauroute.
 +
Verlassen Sie Kontrollzone als Sonder-Sichtflug. Nach dem Abheben geradeaus steigen auf 600 ft, dann Rechtskurve Steuerkurs 340. 
 +
Verlassen Sie Kontrollzone als Sonder-Sichtflug. Nach dem Abheben geradeaus bis zur Ende der Raffinerie. Folgen Sie der Donau. Ausflug Richtung Norden genehmigt.
 +
 
 +
Leave control zone special-VFR via November
 +
Leave control zone special-VFR. After departure climb on runway heading 600 ft then right turn heading 340
 +
Leave control zone special-VFR. After departure climb on runway heading until end of refinery. turn right heading 360, follow the Danube. Leaving control zone to the north approved.
 +
 
 +
==== Night VFR  ====
 +
 
 +
Night VFR is handled like any other VFR flight. Adherence to special procedures associated with flying VFR after ECET and clearance of terrain is the responsibility of the PIC.
 +
 
 +
==== Traffic Pattern ====
 +
 
 +
The traffic pattern is separated into departure, crosswind, downwind, base, and final.
 +
On request, the Tower controller can clear VFR traffic into the traffic pattern.
 +
 
 +
OEABC, after departure, join traffic pattern Runway 29.
 +
 
 +
or
 +
 
 +
OEABC, after departure, join downwind runway 29.
 +
 
 +
'''If the controller clears an aircraft into any part of the pattern, it implies the clearance for the whole pattern.'''
 +
To tell the pilot to maintain on the downwind use:
 +
 
 +
OEABC, extend downwind
 +
 
 +
or
 +
 
 +
OEABC, I call you for base
 +
 
 +
=== Helicopters ===
 +
 
 +
Helicopters are sometimes able to depart from their current position i.e helipad, GAC, TWY. Nevertheless they may also depart via runways:
 +
 
 +
OEBXR: Wien Tower, OEBXR at G-A-C request to leave the Control Zone via Klosterneuburg.
 +
TWR: OEBXR, Wien Tower, after departure leave control zone via VFR Route Klosterneuburg, 1500 feet or below, SQ7000.
 +
OEBXR: After departure leave control zone via VFR Route Klosterneuburg, 1500 ft or below, SQ7000.
 +
TWR: Correct, ready for departure?
 +
OEBXR: Affirm
 +
TWR: 260 deg 4 kts, Takeoff own discretion.
 +
TWR: Airborn Time 52'
 +
 
 +
=== Coordination with other ATC Stations ===
 +
''Communication from one controller to another is as important as the communication from controller to pilot.'' This is especially true during high traffic situations where you might be tempted to concentrate solely on what is happening on your frequency. In these situations don't hesitate to take a call from a fellow controller even if it means that a pilot has to wait before you call him back. Secondly, if you know a controller is busy, try to keep your conversation with him concisely and avoid chatting in a TeamSpeak channel next to him.
 +
 
 +
Within VACC Austria we usually use TeamSpeak to coordinate with each other. The coordination with other ATC units is mostly done per private chat.
 +
Other means of communication are the Intercom functions of Euroscope which would be a very nice feature, however often they only work with certain controllers. The ATC Channel within Euroscope should not be used for individual coordination.
 +
 
 +
When you come online or go offline you should inform neighbouring ATC stations.
 +
 
 +
=== Special Situations (High Traffic, Slots, ...) ===
 +
 
 +
==== Reduced Runway Separation Minima  (LOWW) ====
 +
Each runway in Vienna has a 2400m-marker indicated on the runway - be aware that the second marker from the respective threshold is the 2400m-marker for that very threshold:
 +
For details refer to ICAO DOC4444 7.11
 +
 
 +
Application of RRSM:
 +
An aircraft may be cleared for takeoff, given that:
 +
* a preceding departing aircraft has passed the 2400m-marker.
 +
 
 +
An aircraft may be cleared to land, given that:
 +
* a preceding landing aircraft has passed the 2400m-marker, is in motion and is not required to make a backtrack.
 +
* a preceding departing aircraft has passed the 2400m-marker.
 +
 
 +
Reduced runway separation minima shall be subject to the following conditions:
 +
* wake turbulence separation minima shall be applied
 +
* visibility shall be at least 5 km and ceiling (BKN/OVC) shall not be lower than 1000ft.
 +
* tailwind component shall not exceed 5 kt
 +
* minimum separation continues to exist between two departing aircraft immediately after take-off of the second aircraft
 +
* [[traffic information]] shall be provided to the flight crew of the succeeding aircraft concerned
 +
* Reduced runway separation minima shall not apply between a departing aircraft and a preceding landing aircraft
 +
 
 +
==== High traffic situations ====
 +
 
 +
During high traffic situations, communication with adjacent approach sectors is very important. Especially during single runway operations you might have to ask for increased inbound spacing to be able to fit in departing aircraft.  
 +
 
 +
==== Additional phrases during periods of high traffic ====
 +
 
 +
In order to expedite the flow of traffic use the following phrases:  
 +
 
 +
  Austrian 125, wind xxx/xx runway 29 cleared for takeoff, expedite
 +
  Austrian 125, wind xxx/xx runway 34 cleared to land, expedite vacating
 
  OE-ABC, wind xxx/xx, runway 29 cleared for takeoff, after departure right turn
 
  OE-ABC, wind xxx/xx, runway 29 cleared for takeoff, after departure right turn
as soon as practicable
 
  
===Opposite runway operations===
+
==== Opposite runway operations ====
This is one of the more difficult situtions for a Tower controller. You have to consider the departure route of each aircraft to estimate the required spacing to arriving traffic. Again close coordination with approach is very important.
+
 
 +
This is one of the more difficult situations for a Tower controller. You have to consider the departure route of each aircraft to estimate the required spacing to arriving traffic. Again close coordination with approach is very important.
 +
 
 +
== Resources ==
 +
 
 +
*[http://downloads.vacc-austria.org/Documents/QRS_LOWI.pdf LOWI QRS]
 +
*[http://downloads.vacc-austria.org/Documents/QRS_LOWK.pdf LOWK QRS]
 +
*[http://downloads.vacc-austria.org/Documents/QRS_LOWL.pdf LOWL QRS]
 +
*[http://downloads.vacc-austria.org/Documents/QRS_LOWG.pdf LOWG QRS]
 +
*[http://downloads.vacc-austria.org/Documents/QRS_LOWW.pdf LOWW QRS]
 +
*[http://downloads.vacc-austria.org/Documents/QRS_LOWS.pdf LOWS QRS]
 +
 
 +
 
 +
*[http://vateud.net/index.php?option=com_content&view=article&id=77&Itemid=122 VATEUD Training Department]
 +
*[http://de.wikipedia.org/wiki/ICAO-Alphabet Wikipedia: Buchstabentafel]
 +
 
 +
If you really want to study hard, then read the relevant sections for DEL in the official [http://www.austrocontrol.at/jart/prj3/austro_control/data/dokumente/YQPMe_LO_Circ_2012_B_04_en.pdf radio telephony guide from Austrocontrol].
 +
 
 +
A really good index (and much more orderly is [http://contentzone.eurocontrol.int/phraseology/ here at Eurocontrol].
 +
 
 +
----
 +
 +
'' Prev: [[Study Guide:Ground]] - Overview: [[Study Guide]] - Next: [[Study Guide: Approach]]''
  
== Ressourcen ==
+
[[Category:Documents]][[Category:Study Guides]][[Category:Training]][[Category:Controller]]
* [http://vateud.net/index.php?option=com_content&view=article&id=77&Itemid=122 VATEUD Training Department]
 
* [http://de.wikipedia.org/wiki/ICAO-Alphabet Wikipedia: Buchstabentafel]
 
<br>
 
[[Category:Dokumentation]]
 

Latest revision as of 12:00, 19 April 2023

This study guide is still work in progress. Stay tuned for further chapters.

Prev: Study Guide:Ground - Overview: Study Guide - Next: Study Guide: Approach


Introduction

This Study Guide is designed to give you all the information you need to become an efficient Tower Controller within VACC Austria. We assume that you have already read the Study Guide:OBS, Study Guide:Delivery and Study Guide:Ground.

Tower's main responsibility is to make efficient use of all available RWY's.

The tower is therefore responsible:

- for all movements on the runways - for all movements within the control zone (see "Airspace Structure" below).

Euroscope visibility range for Tower should not exceed 50nm (regarding Vatsim CoC C12)

Aircraft Categories

A/C are categorized by their respective weight and approach IAS

Weight Categories

Aircraft are categorized into four weight categories:

Category MTOW
Light Aircraft (L) < 7 000 kg
Medium Aircraft (M) 7 000 – 136 000 kg
Heavy Aircraft (H) >136 000 kg
Super Aircraft (S) is only one: the A380

You can find a list of aircraft in this link [1]
Weight depicted is MTOW.

Approach Speed

Aircraft are categorized by their reference approach speed (Vref) at maximum landing weight:

Category Vref
A <= 90 knots
B 91 - 120 knots
C 121 - 140 knots
D 141 - 165 knots
E >= 165 knots

Theoretical Knowledge

Producing Lift

For an aircraft to fly the lift force produced by (mostly) the wings has to outweigh the gravitational force that affects the aircraft.

Basically, a wing produces lift by deflecting the air it moves through into one direction. According to Newton's third law of motion, the lift is produced in the opposite direction. This lift grows with the speed the aircraft has in relation to the air and with the angle, the wing draws with the direction of movement. This angle is called Angle of Attack (AoA).

The principle only works as long as a steady airflow around the wing exists. As soon as the airflow seperates from the wings surface the lift starts to decrease. The AoA at which this occurs is called critical Angle of Attack. It depends on the profile of the wing and it's dimensions but for subsonic aircraft, it typically lies between 8 and 21 degrees.

Think of a level flying aircraft that reduces its speed. In order to compensate for the reducing lift, the pilot has to raise the nose. However, at some point, the Angle of Attack will cross the critical angle of attack and the pilot will find himself in a stall. So the speed of an aircraft is limited on the lower side by the so-called stall speed but the aircraft is also limit by aerodynamics in the higher range of speed (buffeting). Because the stall speed depends on the profile most aircraft are equipped with devices that alter the profile during flight such as flaps or slats (Approach). In General, when an aircraft flies it will produce thrust but at the same time it produces drag. So if you fly just horizontal (cruise) you have at the same time Lift=weight and thrust=drag. Drag produce automatic noise and that is the big problem. to prevent this we have different procedures in the approach and a lot of research in aviation to reduce the sound of the aircraft but the main part are the engines.

On approach, pilots have to fly in a certain speed range in order to conduct a safe landing. The lower boundary is called landing reference speed and is often a fixed multiple of the stall speed. As a result of this, the approach speed also depends on the weight and aircraft configuration (Flap/Slat setting). For safety, the Approach Vapp is higher than Vref and the difference depends mostly on the weather conditions.

Generally, you can say that bigger aircraft also have a bigger approach speed however at some point this rule does not work anymore because the Vref depends largely on the aircraft's weight in relation to its maximum takeoff weight (MTOW). The speed ranges from 50 knots in a C150 up to 170 knots with a fully loaded 747. However for example it is possible that a light 747 is slower than a fully loaded 737.

Transition Altitude/Transition Level

Aircraft Altimeters use the air pressure around them to determine their actual altitude. In order to get correct readings, you have to use the actual local pressure in your area. As a memory hook, you can use this: The altimeter needle moves in the same direction you turn the rotary knob to adjust the pressure. If you turn it counterclockwise, the needle also turns counterclockwise and therefore indicates a lower altitude.

As ground pressure changes every hundred miles, aircraft would need to update their settings every few minutes. If ALL aircraft would need to do this, it would be terribly unpractical and dangerous. Guess what happens if one forgets? So the altitude is "sliced":

  • In lower areas (where the terrain is in close proximity), aircraft have to update local settings. Most aircraft are there only for takeoff and landing, so no big deal.
  • In higher areas, aircraft all tune a standard-setting (QNH 1013 or 29.92 HG) - this setting may be "wrong", but as all aircraft have the same "wrong" setting, it does not matter.

And where is the altitude where that changes?

  • For climbing aircraft, it is the Transition Altitude, where they change from local to standard pressure.
  • For descending aircraft, it is the Transition Level, where they change from standard to local pressure.

Between the two, there is a safety layer (called "Transition Layer") which compensates for the difference between local and standard pressure, which is 1000ft minimum, so the stack is:

Upper airspace: measured in Flight Levels (FL220 = Altitude 22.000ft at standard settings)
Transition Level: the lowest Flight Level
Transition layer (to keep distance)
Transition Altitude (TA): the highest altitude cleared at local pressure settings
Lower airspace, where the altitude is given (you write "A5000ft").

As the difference between TA and TL varies with pressure (the lower local pressure, the thinner), the size of the Transition Layer varies (the lower local pressure, the thicker). Use the following table to calculate your TRL:

QNH      < 0977: TA + 3000 ft.
QNH 0978 - 1013: TA + 2000 ft.
QNH 1014 - 1050: TA + 1000 ft.
QNH 1051 >     : TA = TL


Before you start controlling

Tower decides which runways are in use and maintains the ATIS. The tower is also responsible for ground and delivery if they are not online or if they are not defined for that particular airport (LOWS has DEL, but no GND; LOWI, LOWG and LOWK have only TWR).

Airspace Structure around Major Airports

Major airports in Austria are surrounded by a control zone (CTR) which is class D airspace. This means that A/C need clearance for entry. So either they are cleared for an approach or they are cleared into the control zone. Details will be discussed in the VFR part later on.

Tower Workflow

Setting the right priorities

The moment you are responsible for more than one aircraft you will have to set priorities in your handling. As a general guideline:

  1. aircraft in the air have top priority - you take care of them first. Reason: They can't stop.
  2. aircraft moving on the ground have next priority. They could bump into each other.
  3. aircraft standing on ground have the least priority.

Runway Separation

The runways are one of the most dynamic spots on an airport. Aircraft are travelling at high speed with little room to manoeuvre and most of the time no ability to stop at a reasonable distance. In general only one aircraft may be cleared to use a runway at the same time., nevertheless there are exceptions to this rule which will be described in the upcoming chapters.

Departing Traffic

So now we are at the point where the pilot reaches the Holding Point of his departure runway and reports ready for departure. What are the things you should check before issuing the takeoff clearance?

  • Have a look at the Flightplan. Take note of the type of aircraft and the Departure Route.
  • Check the traffic approaching the runway.

To give a takeoff clearance the following phrase should be used:

AUA2CM, wind 320 degrees, 7 knots, Runway 29, cleared for takeoff.

When the A/C is well established in climb check if squawking Mode C and the right Code. Afterwards, he is handed off to the next Controller, in this case, a radar position:

AUA2CM, contact Wien Radar frequency 134.675.


The next aircraft reports ready for departure. Again check the points above, but this time we cannot give the takeoff clearance straight away because the preceding aircraft is still occupying the runway. Now you get to know the first exception to the Runway separation rule above. To speed things up you can instruct the next aircraft to line up behind the first one while this one is still in the takeoff roll occupying the runway:

 AZA639, behind departing Austrian Airbus A319, line-up rwy 29 behind.

Note: you must add another "behind" at the end of the clearance!!

This type of clearance is called conditional clearance.
The earliest possible point where you can issue the next takeoff clearance is, when the Proceedings aircraft has overflown the opposite runway end or has clearly turned onto either side of it.


Take care! Phraseology around the runway is vital

In 1977, at the Tenerife Airport, two 747 Jumbo Jets collided on the runway and burst up in flames, killing more than 500 people. There was a simple cause: misunderstandings in the takeoff phraseology: Tower said "standby for takeoff", the pilot understood "cleared for takeoff". So, there are two iron rules which you should never break as a Tower controller:

  • Use the word "takeoff" only when you clear for takeoff: Say "<aircraft> cleared for takeoff" and nothing else. If you have to say anything else (like that the aircraft can leave in 2 minutes), then use the word "departure".
  • Use the word "landing" only when you clear for landing: Say "<aircraft> cleared to land" and nothing else. If you have to say anything else (like where to leave the runway after touchdown), use the word "arrival".

Departure Separation

There are several factors to take into consideration when deciding what the minimum separation between succeeding aircraft is. It is the tower controller's responsibility to decide which kind of separation to apply. The following types of separation shall be considered:

CAUTION: Regardless of separation minima to be used, the following rule ALWAYS applies:

Departing aircraft will not normally be permitted to commence take-off until

  • the preceding departing aircraft has crossed the end of the runway-in-use or
  • has started a turn or
  • until all preceding landing aircraft are clear of the runway-in-use.

Note that this paragraph is not about the actual clearance. You may clear an aircraft - considering the minima below - for takeoff before the above conditions are fulfilled, taking into account the time it will take the aircraft, until the actual takeoff can be commenced.

Time Based Separation

To avoid hazards created by the turbulence formed at the wingtips of aircraft (wakes), separation based on time shall be applied between succeeding departing traffic. This is due to the fact, that wakes need a certain time to dissipate.

The actual time to apply depends on the wake turbulence category and thus on the weight of the aircraft:

Light Aircraft (L) < 7 000 kg
Medium Aircraft (M) 7 000 – 136 000 kg
Heavy Aircraft (H) >136 000 kg
2 Minutes

Provided that succeeding aircraft are using:

  • the same runway
  • crossing runways if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 300 m (1 000 ft) below
  • parallel runways separated by less than 760m (no applicable in Austria)
  • parallel runways separated by 760 m (2 500 ft) or more, if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 300 m (1 000 ft) below (not applicable in Austria)

a minimum separation of 2 minutes applies whenever a

Light or Medium follows Heavy
Light follows Medium
3 Minutes

Provided that succeeding aircraft are taking off from:

  • an intermediate part of the same runway (read: intersection)
  • an intermediate part of a parallel runway separated by less than 760 m (2 500 ft) (not applicable in Austria)

a minimum separation of 3 minutes applies whenever a

Light or Medium follows Heavy
Light follows Medium

Note: In LOWW the following intersections are, for the purposes of wake vortex, NOT considered to be intersection departures:

Runway Intersections
11 A11 and A12
29 A1 and A2
16 B1 and B2
34 B11 and B12

To point out this hazard to a pilot the following phrase should be used:

DLH32C, wind 180 degrees, 3 knots, runway 16 cleared for takeoff, caution wake turbulence.

Radar Separation

For radar-equipped TWR stations, which in Austria are basically all controlled TWR stations, departure separation shall be as such, that departing aircraft are entering the approach airspace with radar separation. For LOWW_TWR these minima are for example:

Traffic Distance Condition
Departing traffic on different SIDs 3 nm increasing
Departing traffic on same SIDs 5 nm increasing

Same SID's:

RWY 11:

LANUX-BUWUT-LEDVA

OSPEN-RUPET

STEIN-ARSIN

KOXER-ADAMA


RWY 16:

LANUX-BUWUT-LEDVA

MEDIX-LUGEM

OSPEN-RUPET

STEIN-ARSIN

KOXER-ADAMA


RWY 29:

LANUX-BUWUT-LEDVA

MEDIX-LUGEM

OSPEN-RUPET

STEIN-ARSIN-KOXER-ADAMA


RWY 34:

LANUX-BUWUT

OSPEN-BUWUT

STEIN-ARSIN

KOXER-ADAMA

Deciding Which Separation to apply

In order to provide an expeditious flow of traffic for departing traffic, it is imperative for the tower controller to always apply the lowest separation minimum. Since time-based separation is always the larger of the minima, it should always be strived to achieve radar separation. In principle, taking the minima above into consideration, radar separation may always be applied when succeeding departing traffic is in the same wake turbulence category or if a heavier aircraft is departing behind a lighter one. Otherwise, time based separation has to be applied.

Tips And Tricks

  • Try to avoid having multiple aircraft using the same SID depart the same runway right after each other. Throw in a departure with another SID in between to utilize the 3nm radar separation minimum instead of 5.
  • If possible, have heavier planes depart behind lighter ones, so you avoid having to use time-based separation. Of course, take this with a grain of salt, since you can't let the heavier aircraft wait forever.
  • To achieve radar separation as soon as possible, use initial visual turns if weather permits (VMC). Example:
TWR: AUA117M, after departure visual right turn to SOVIL is approved, wind calm, runway 11 cleared for takeoff.

In this case, the aircraft will make a very early right turn, allowing you to have the next aircraft takeoff within seconds, provided it is not lighter than the preceding.

  • The ground controller should send aircraft to your frequency early enough during taxi - provided that there are no conflicts on the ground - that you should be able to distribute the aircraft onto the different holding points to your needs. Use the holding points in order to prepare a proper departure sequence that allows you to use the lowest minima possible.

Note: According to the austrian AIP, the pilot shall prepare and be ready to use the following intersections for departure:

Runway Intersections
11 A10
16 B4
29 A3 (west)
34 B10

For those intersections it is normally not necessary to ask a pilot if he is able - it is his obligation to tell ground upon requesting taxi clearance or latest upon initial contact with the tower controller.

Arriving Traffic

Arriving Aircraft call you when they are established on an approach to a runway. Most of the time this is an ILS Approach but also other kinds are possible.

 MAH224: Linz Tower, MAH224 established ILS Approach rwy 27.

Again you are not allowed to clear more than one aircraft onto the same runway at the same time.

In order to issue a landing clearance
  1. preceeding departing traffic must have overflown the opposite runway threshold or clearly turned onto either side of the runway.
  2. preceeding landing traffic must have left the runway safety strip with all parts.
  3. traffic crossing the runway must have left the runway safety strip with all parts.

If these conditions are met use the following phrase to clear the aircraft:

MAH224, Linz Tower, wind 300 degrees 16 knots, runway 27, cleared to land.

During periods of high traffic, it is likely that you have more than one aircraft approaching the same runway at the same time. The approach has to ensure the minimum radar separation of 3 nm and additionally increased separation due to wake turbulence.

 AUA26T: Linz Tower, AUA26T established ILS 27.
 TWR: AUA26T, Linz Tower, continue approach, wind 300 degrees 16 knots.
Meanwhile MAH224 has left the runway.
AUA26T wind 310 degrees 14 knots, runway 27 cleared to land.


AUA81 is approaching runway 16, OE-AGA is on left base runway 16 and there is a rescue helicopter operating in the area around Freudenau.
AUA81: Wien Tower, AUA81 established ILS 16
TWR: AUA81, Wien Tower, VFR traffic is on left base rwy 16, continue approach, wind 140
degrees 7 knots.
AUA81: continuing approach, AUA81.
TWR: AUA81, There is a rescue helicopter operating west of the extended centerline, presently at
your one o'clock position, 5 nm, 1400 ft.
AUA81: Thank you, looking out, AUA81.
AUA81: traffic in sight, AUA81.

Helicopters don't need a Runway for the approach, sometimes they are able to land at their parking position, lets have a look on the Phrases.

The rescue helicopter from the example above needs to land at your airport:
OEBXR: Wien Tower, Freudenau 1500ft for landing.
TWR: OEBXR, Fly direct G-A-C, stay north of extended centerline RWY 11, 020 deg 4 kts, land own discretion.


To give you an idea of how dense traffic can get in real life consider that during peak times and good weather the separation is reduced to 2,5 nm. This corresponds to one landing every 75 seconds.

Merging Departing and Arriving Traffic

And now to the most fun part of being a Tower Controller. Sometimes you get into the situation that you use the same runway for departures and arrivals. Either your airport has only one runway or weather demand this configuration.


Still the above rule of only one aircraft at the same time applies, however, we also use conditional clearances which look very similar to those above in the departing traffic section.

AUA123, behind next landing C750 line up RWY 29 behind.

To depart an aircraft in front of an approaching aircraft at the time of the departure clearance given the arriving aircraft should not be closer than 4 nm to touchdown. To squeeze a departing aircraft between two arrivals you normally need a minimum of 6 nm between them. It is important for you to check carefully if you have the necessary gap, so have a close look at the distance between the arrivals and their speed. If the second one comes in faster than normal consider this in your calculation. Also, you should make sure, that the pilot will be ready for departure when you need him to depart. To check this use the following phrase:

"Ready for immediate departure?"


Example:

You are the Tower Controller at Vienna airport. Runway 29 is active for departures and arrivals. One aircraft is on a 5 nm final, one at 12 nm out. Additionally, you have two departures waiting at the holding point of runway 29.
TWR: CAL275, ready for immediate departure?
CAL275: Affirm 
TWR: Wind 250 deg 6 kts, Runway 29 cleared for immediate takeoff.
CAL275: cleared for immediate takeoff runway 29, CAL275
After the CAL B747 has taken off.
TWR: AUA289, wind 300 degrees 7 knots, runway 29, cleared to land.
AUA289: Runway 29, cleared to land, AUA289.
TWR: AUA2LT, behind landing Airbus line up runway 29 behind.
AUA2LT: Behind the landing Airbus, lining up runway 29 behind, AUA2LT.
AUA289 has vacated the runway.
TWR: AUA2LT, wind 300 degrees 8 knots, runway 29 cleared for takeoff.
AUA2LT: cleared for takeoff runway 29, AUA2LT.

VFR Traffic

Differences to handling of IFR Traffic

The essential collision safety principle guiding the VFR pilot is "see and avoid." Pilots flying under VFR assume responsibility for their separation from all other aircraft and are generally not assigned routes or altitudes by air traffic control. Governing agencies establish specific requirements for VFR flight, consisting of minimum visibility, distance from clouds, and altitude to ensure that aircraft operating under VFR can be seen from a sufficient distance to ensure safety.

To guide VFR Traffic through your airspace you make use of VFR Routes, Sectors, and reporting Points. Used phrases:

TWR:OE-AGA, enter control zone via VFR route Klosterneuburg, 1500ft or below,
QNH 1020, Squawk 7000, report XXXX (i.e. Freudenau), expect runway 29.
TWR:OE-AGA hold (orbit) overhead XXXX (i.e. Freudenau) in XXXX (i.e. 2500ft)

VFR flights can be cleared into any part of the pattern (departure, crosswind, downwind, base or final). Unless stated otherwise by the controller, a pilot shall join the pattern from the cleared position and finish it without requiring further clearance.

TWR: OE-AGA, join downwind for runway 29
TWR: OE-AGA, extend downwind for runway 29 
TWR: OE-AGA, join base for runway 29, I will call you for final
TWR: OE-AGA, join base for runway 29

VFR Flights Squawk and basic information (active runway, QNH etc.) from Delivery, the route clearance from Tower. After startup, they will contact Ground for taxi, thereafter the Tower will issue the clearance. A possible VFR clearance could be:

TWR:OE-AGA, verlassen Sie die Kontrollzone über Sichtflugstrecke Klosterneuburg, 1500 Fuß
oder darunter, QNH 1014, Squawk 7000, Rechtskurve genehmigt.
TWR:OE-AGA, leave Control Zone via VFR-route Klosterneuburg, 1500 feet or below,
QNH 1014, Squawk 7000, right turn approved.
TWR: OE-AGA, steigen sie auf 3500 Fuß, melden Sie Donauturm.
TWR: OE-AGA, climb 3500 feet, report Donauturm.

In the air ATC provides traffic information.

TWR:OE-AGA, Traffic at your 12 o'clock position, 2100 feet, a PA28 on VFR inbound
route Klosterneuburg-Freudenau.

When the aircraft leaves the control zone.

TWR: OE-AGA, Squawk 7000, you may leave.

Merging in VFR Traffic

To manage VFR Traffic efficiently you have to use traffic information and visual separation.

TWR: OE-ANX, traffic at your 3 o´clock position, moving right to left, B767, distance 2.5
miles, report mentioned traffic in sight
OE-ANX: Traffic in sight, OE-ANX

Because of other traffic, it might be necessary for the aircraft to remain in the downwind leg until the traffic has passed:

TWR: OE-AGA, Extend right downwind.
OE-AGA: Extending right downwind, OE-AGA

To instruct the aircraft to continue it's approach use the following procedure:

TWR: OE-ANX, traffic at your 3 o´clock position, moving right to left, B767, distance 2.5
miles, report mentioned traffic in sight
OE-ANX: Traffic in sight, OE-ANX
TWR: OE-AGA, behind B767 traffic, join final RWY 29, caution wake turbulence
OE-AGA: Behind B767, join final RWY 29 behind, caution wake turbulence, OE-ANX

When using an extended downwind you should always consider that the aircraft's speed might be considerably lower than the speed of other aircraft involved. So if an aircraft has to fly a long way out it might take some time for it to come all the way back, generating a big gap in the arrival sequence. Instead, you should aim to keep the plane within the vicinity of the airfield:

TWR: OE-AGA, Make a right three-sixty.
OE-AGA: Making three-sixty to the right.
TWR: OE-AGA, Orbit left
OE-AGA: Orbiting left, OE-AGA

The second instructions mean, that the pilot should make orbits until further advice.


It is also possible to ask VFR traffic for a speed reduction.

TWR: OEABW, Fly speed 90 kts
OEABW: 90 kts, OEABW


Special VFR

Could be used when weather Minimums are below VFR condition.

Weather minimums for (S)VFR are follow

- Base Cloud at min. 600ft

- visibility min 1500m

Used phrases:

Verlassen Sie Kontrollzone als Sonder-Sichtflug über Donauroute. 
Verlassen Sie Kontrollzone als Sonder-Sichtflug. Nach dem Abheben geradeaus steigen auf 600 ft, dann Rechtskurve Steuerkurs 340.  
Verlassen Sie Kontrollzone als Sonder-Sichtflug. Nach dem Abheben geradeaus bis zur Ende der Raffinerie. Folgen Sie der Donau. Ausflug Richtung Norden genehmigt. 
Leave control zone special-VFR via November
Leave control zone special-VFR. After departure climb on runway heading 600 ft then right turn heading 340
Leave control zone special-VFR. After departure climb on runway heading until end of refinery. turn right heading 360, follow the Danube. Leaving control zone to the north approved.

Night VFR

Night VFR is handled like any other VFR flight. Adherence to special procedures associated with flying VFR after ECET and clearance of terrain is the responsibility of the PIC.

Traffic Pattern

The traffic pattern is separated into departure, crosswind, downwind, base, and final. On request, the Tower controller can clear VFR traffic into the traffic pattern.

OEABC, after departure, join traffic pattern Runway 29.

or

OEABC, after departure, join downwind runway 29.

If the controller clears an aircraft into any part of the pattern, it implies the clearance for the whole pattern. To tell the pilot to maintain on the downwind use:

OEABC, extend downwind

or

OEABC, I call you for base

Helicopters

Helicopters are sometimes able to depart from their current position i.e helipad, GAC, TWY. Nevertheless they may also depart via runways:

OEBXR: Wien Tower, OEBXR at G-A-C request to leave the Control Zone via Klosterneuburg.
TWR: OEBXR, Wien Tower, after departure leave control zone via VFR Route Klosterneuburg, 1500 feet or below, SQ7000.
OEBXR: After departure leave control zone via VFR Route Klosterneuburg, 1500 ft or below, SQ7000.
TWR: Correct, ready for departure?
OEBXR: Affirm
TWR: 260 deg 4 kts, Takeoff own discretion.
TWR: Airborn Time 52'

Coordination with other ATC Stations

Communication from one controller to another is as important as the communication from controller to pilot. This is especially true during high traffic situations where you might be tempted to concentrate solely on what is happening on your frequency. In these situations don't hesitate to take a call from a fellow controller even if it means that a pilot has to wait before you call him back. Secondly, if you know a controller is busy, try to keep your conversation with him concisely and avoid chatting in a TeamSpeak channel next to him.

Within VACC Austria we usually use TeamSpeak to coordinate with each other. The coordination with other ATC units is mostly done per private chat. Other means of communication are the Intercom functions of Euroscope which would be a very nice feature, however often they only work with certain controllers. The ATC Channel within Euroscope should not be used for individual coordination.

When you come online or go offline you should inform neighbouring ATC stations.

Special Situations (High Traffic, Slots, ...)

Reduced Runway Separation Minima (LOWW)

Each runway in Vienna has a 2400m-marker indicated on the runway - be aware that the second marker from the respective threshold is the 2400m-marker for that very threshold: For details refer to ICAO DOC4444 7.11

Application of RRSM: An aircraft may be cleared for takeoff, given that:

  • a preceding departing aircraft has passed the 2400m-marker.

An aircraft may be cleared to land, given that:

  • a preceding landing aircraft has passed the 2400m-marker, is in motion and is not required to make a backtrack.
  • a preceding departing aircraft has passed the 2400m-marker.

Reduced runway separation minima shall be subject to the following conditions:

  • wake turbulence separation minima shall be applied
  • visibility shall be at least 5 km and ceiling (BKN/OVC) shall not be lower than 1000ft.
  • tailwind component shall not exceed 5 kt
  • minimum separation continues to exist between two departing aircraft immediately after take-off of the second aircraft
  • traffic information shall be provided to the flight crew of the succeeding aircraft concerned
  • Reduced runway separation minima shall not apply between a departing aircraft and a preceding landing aircraft

High traffic situations

During high traffic situations, communication with adjacent approach sectors is very important. Especially during single runway operations you might have to ask for increased inbound spacing to be able to fit in departing aircraft.

Additional phrases during periods of high traffic

In order to expedite the flow of traffic use the following phrases:

Austrian 125, wind xxx/xx runway 29 cleared for takeoff, expedite
Austrian 125, wind xxx/xx runway 34 cleared to land, expedite vacating
OE-ABC, wind xxx/xx, runway 29 cleared for takeoff, after departure right turn

Opposite runway operations

This is one of the more difficult situations for a Tower controller. You have to consider the departure route of each aircraft to estimate the required spacing to arriving traffic. Again close coordination with approach is very important.

Resources


If you really want to study hard, then read the relevant sections for DEL in the official radio telephony guide from Austrocontrol.

A really good index (and much more orderly is here at Eurocontrol.


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