Study Guide:Delivery

From VACC Austria DokuWiki
Jump to navigation Jump to search

<-- Back: Study Guide:OBS - Overview: Study Guide - Next--> Study Guide:Ground


This Study Guide has been designed to give you all the information needed to start controlling as a Clearance/Delivery controller on the VATSIM network. It assumes, that you have read and understood the Study Guide:OBS before and have logged in as observer.

Working Delivery Positions

Clearance Delivery is responsible for checking and correcting flightplans of departing aircraft and issue routing clearances to them. This task may sound boring, but is important for upstream controllers: Clearances take time (on the radio) and may block vital commands (like takeoff and landing clearances), and radar stations rely on the checked and cleared values (SIDs and clearance altitudes) for their controlling. If DEL makes mistakes, APP will have trouble.

There are 2 types of flight plans at VATSIM:

  • IFR: Any pilot who flies IFR must file a flight plan. It contains the exact routing from departure to arrival, cruise altitude and some more information which controllers need for their job.
  • VFR: VFR pilots can file flight plans, but they don't need to. They can simply ask for taxi clearance, take off and continue in uncontrolled airspace.

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.

At VATSIM, flight plans are filed with a VATSIM server.

For IFR flights, flight plans are used by air traffic control to initiate tracking and routing services.

Aircraft routing types used in IFR flight plans are: Airway, Navaid and Direct. A route may be composed of segments of different routing types.

  1. 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). Airways have letters and numbers like "Y868 or "UM125".
  2. Navaid: Navaid routing occurs between Navaids (short for Navigational Aids) which are not always connected by airways. Navaid flight plans are used for IFR aircraft which don't have a GPS receiver - they can't follow waypoints. 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.
  3. Direct: Direct routings are becoming more and more common as FRA (Free Route Airspace) is under ongoing development in Europe.

For VFR flights, the only purpose is to provide needed information should search and rescue operations be required. At VATSIM, a VFR flight plan is handy for controllers, as it shows vital information with the airplane tag on the radar, like the destination.

Lateral Syntax

Syntax for IFR flight plans is quite strict, and pilots are encouraged to look up flight plans via online tools and paste the code into the routing field. The format is usually <waypoint><via><waypoint><via>, where every waypoint is noted, where the itinerary changes from one route to another (waypoints on the same airway are omitted). This is necessary, as radar clients (Euroscope) read and interpret this data.

Example: A valid routing from LOWW to EDDM is the following:

  • SOVIL is the SID exit point.
  • SITNI DCT BAGSI DCT MATIG DCT AMADI are enroute waypoints.
  • Q113 is an airway.
  • The "DCT" in-between means that there is no airway between these points: they are "Direct".

Vertical Syntax

So far we have specified the lateral dimension. To further specify the vertical aspects a speed and level segment has to be attached to the RTE string:

Format -> NxxxxFyyy or NxxxxAyyy
i.e N0450F340
  • N0450 indicates the planned TAS (True Airspeed)
  • F340 indicates the planned FL (Flightlevel)

For flights which will remain in lower airspace i.e below the transition altitude the following is used:

  • A080 indicates Altitude 8000ft (QNH)

A "/" is used to attach such a speed and level group to a waypoint e.g:


The first group indicates the initial planned TAS and Level, the second group indicates a Level Change at DETSA to FL350.

VFR Syntax

  • Sector S is the preferred VFR exit route from Vienna TMA
  • The rest is a description of a popular route to Innsbruck through scenic mountains
  • Mike ist the appropriate entry into LOWI.

Workflow for DEL controllers


  1. Check with the upstream controller (TWR, APP, CTR) for active runways and set active airport and runways in your Euroscope "active runways" dialogue box.
  2. Check with the upstream controller the active ATIS letter. Set your ATIS dialog box to your airport and the active letter, but don't connect (ATIS is TWR's job). Set this way, Euroscope will show the valid ATIS letter in your METAR list and you don't need to ask every few minutes.
  3. If there is no Tower or upstream, then create an ATIS.

Choosing the active runways

The guiding principle in choosing the active runways is that aircraft prefer to depart and land into the wind.

An airport has one runway named 16/34. The wind is reported as 320 degrees at 14 knots. In 
this case runway 34 is chosen as the active runway.

Look at a more complicated example:

LOWW has two runways: 16/34 and 11/29.
Suppose, wind is 020°, and you see: runway 34 is only 40° off, while 110 is 90° off --> runway 34 is the better choice.

Beware: All major airports have preferential runway configurations which depend on approach configuration, noise abatement and terrain.

Generally, tailwind components of up to ten knots are accepted.

However due to noise abatement and terrain considerations most airports have some kind of preferential runway system. Bear in mind that it is the pilots decision whether he can accept a certain runway because only he knows the performance of his aircraft.

For details on the preferred runway configurations for a specific airport ask your mentor or look into the airport QRS (quick reference sheets). See in the Resources section at the very bottom for links to them.


ATIS stands for Automatic Terminal Information Service and is a usually automatically generated broadcast that contains essential information 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.

An ATIS broadcast consists of:

  • 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.

IFR flight plans

  • Check, if "From"-Airport is yours and "To"-Airport makes sense. It is unlikely that a C172 will fly to GATB (Timbuktu) without stopovers, as well as a B737 flies VFR to KJFK. If anything looks wrong, ask the pilot to confirm his details. Nevertheless, as soon as you modify the FPLN, the pilot won't be able to amend his own FPLN anymore. Reconnection is required.
  • Check, if departure runway corresponds to the active runway. If not, then check your runway settings in Euroscope (Pilots never file a particular runway - it's Euroscope setting it for you).
  • Check, if cruise altitude is correct: Cruise altitude is stated in flight levels (hundreds of feet): FL280 means 28000 feet (at QNH 1013, to be really correct). For flight levels below FL410, westbound flights have even flight levels, and eastbound flights have odd flight levels. Above FL410, flight levels increase by 20: west is FL430-470-510-550 etc, east is 450-490-530-570 etc. If the filed ALT requires a change - change it.
  • Check, if there is a valid SID from the active runway to the first waypoint in the flight plan.

Watch out:

  • At some airports (LOWI) there are more SIDs to the same waypoint, valid for different aircraft (usually, one is "standard" and the other are "special departures" depending on aircraft performance and equipment).
  • At most airports there are special SIDs for aircraft with no FMC (Non-RNAV departures.)
  • Some airports have noise abatement procedures.

Euroscope has already selected the first matching SID in the alphabet. Check, if this SID is applicable to the aircraft type, performance, equipment and time (you might want to check with APP to clarify, which SIDs are correct), and select the best SID.

SSR Assignment + Initial Climb

  • The squawk range is predefined for each airport and written in the sector file. For normal purposes, automatic squawk allocation in Euroscope works fine. In high traffic situations the squawk range might not be sufficient, and Euroscope indicates "DUPE" (for "duplicate squawk"). In this case, you have to set a new squawk.
  • Since 2016, real-life technology has changed. The so-called "transponder mode S" ("S" stands for "selective") allows aircraft to be linked with other means than the transponder code. Certain mode S aircraft receive squawk 1000.
  • Set the initial climb altitude. This differs from airport to airport. LOWW has 5000ft for all SIDs ("A50" in the list), In LOWI, you have to check with APP (it's between FL120 and 160), and Salzburg has different altitudes for different SIDs (look into the SID description).

Re-routing of traffic

If a filed routing is invalid or the decision to revise an A/C routing has been made by you it can be difficult to communicate this change in RTE to the pilot. In an ideal world you would reroute an A/C before it calls you, thus avoiding unnecessary discussions on frequency. It is therefore suggestable to make use of private messages for this special case.


By sending the message in this format you can reduce the likelihood of a possible discussion as it resembles an automatic message.

Do not forget to also amend the ATC FPL in Euroscope.

RTE Clearance

DEL gives routing clearances to all departing aircraft with the following information:

  • aircraft identification
  • clearance limit (normally destination aerodrome / or last IFR waypoint)
  • assigned SID
  • initial climb
  • allocated SSR code (squawk)
  • QNH if false or no ATIS letter reported.
  • any other necessary instructions e.g. instructions relating to change of frequency or CTOT (= Calculated take-off time) Slot time.

Normal construction of a routing clearance:

Callsign, cleared to XXXX via XXXXX XX departure, initial climb 5000ft, Squawk 46XX, QNH XXXX


Austrian 125, cleared Frankfurt, LUGEM 1C departure, 5000ft, SQ1000, Q1022.

Traffic unable SID

Some Aircraft are not able to follow SIDs for various reasons, most of the time due to missing equipment.

Vienna is equipped with a NON-RNAV SID -> the SNU departures. Any IFR equipped aircraft is sufficiently equipped to fly this SID, even if it has no FMS. This is your safest bet if a pilot has an old AIRAC or is simply unable for anything else.

If you issue such a clearance you will need to connect the SID, in our case SNU2C, to the filed RTE. First filed waypoint would be SITNI - this is issued as follows:

AUA43EM, cleared Zürich SNU2C departure, SITNI next, 5000ft, SQ 1000, Q1032

Additionally you can 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.

AUA125, cleared XXXX, RWY XX, when airborn turn XXXX, climb 5000ft, SQ46XX, QNH XXXX


Austrian 125, cleared Frankfurt, RWY29, when airborn turn left heading 200 , climb 5000 ft, SQ1000, Q1032.

If the pilot responds with a correct readback you should answer with the following phrase:

Austrian 125, readback correct, report ready.


Upon receiving the ready call - you may handover to Ground

Austrian 125, Ground 121,775 - Servus

This is done to keep the A/C on your Frequency until it is fully ready to move. By doing this DEL has the chance to communicate any RTE or Slot changes should they arise, thus reducing workload for the GND Controller.

VFR Flights

The Tower is responsible for VFR traffic. However, pilots have to contact DEL for clearance. You have to enquire with Tower about the details of the departure.

- runway to expect (VFR is not bound to the active rwy)

- route to expect

OE-DLT: C172 at General aviation center, request to leave control zone via sector S.
DEL: OE-DLT Expect RWY 16, leave Control Zone via Sector S, 1500ft or below, Squawk 7000, Q1032.
OE-DLT: leave via Sector Sierra, 1500ft or below, Squawk 7000, Q1032.
DEL: Readback correct, contact Ground 121.600Mhz.
OE-DLT: C172 Abstellplatz der Allgemeinen Luftfahrt, erbitte Freigabe zum verlassen der Kontrollzone über Sektor S.
DEL: OE-DLT Aktive Piste 16, verlassen Sie die Kontrollzone über Sektor Sierra, 1500ft oder darunter, Squawk 7000, Q 1032.
OE-DLT: Verlassen die Kontrollzone über Sektor Sierra, 1500ft oder darunter, Squawk 7000, Q1032.
DEL: Korrekt, rufen Sie Wien Rollkontrolle 121.600Mhz.

Mode-S SQ7000

As Mode-S transponder are mandatory in Austria, using the VFR squawk 7000 exclusively is sufficient.

Should the need for a different Squawk arise - use 0001-0020.

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

IFR Flights Terminating at Waypoints or Uncontrolled Aerodromes

An IFR Flight does not necessarily have to terminate at the destination Aerodrome.

IFR Flights to Bad Voeslau (LOAV) or Wiener Neustadt (LOAN) for example terminate at a specified Fix:

  • MOVOS for LOAV arrivals
  • GESGI for LOAN arrivals

To clear the following flight with destination LOAV:


the following phraseology is to be used:

OEFVR cleared to MOVOS, SNU2C departure, 5000ft, SQ4601, Q1014

As MOVOS is the clearance limit you may not clear an A/C any further. The flight is then expected to hold at MOVOS if not instructed to continue.

High Traffic Situations

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:

Austrian 125, expect startup in 15 minutes.

Add 2 mins for each waiting aircraft.

Delivery Split

If the traffic at your departure airport is increasing even more, delivery may need additional ressources to manage all calls. In this case a second person (Delivery Coordinator) is required. Splitting the workload between the current Delivery Operator, who is solely responsible for voice transmissions (to prevent unnecessary step-ons due to two controller talking) and the Coordinator is the key here:

  • Coordinator:
    • Maintains coordination with other stations
    • Checks capacity at holding points and taxiways
    • Handles the webbased slottool to assign slots to aircrafts
    • Handles text pilots and route adjustments (via private chat)
  • Operator:
    • Checks the routes and reports wrong routings to Coordinator
    • Is in charge of frequency transmissions and provides IFR clearances via voice
    • Handoffs pilots to the correct GND frequency


  • AUA123 logs in and files to EDDM

--> Operator checks routing and spots an error

--> Coordinator is in charge to send the pilot a message

  • AUA123 logs in again

--> Operator checks routing, which is correct now

  • AUA123 transmits on frequency "Wien Delivery, AUA123, info X, requesting clearance to Munich"

--> Coordinator assigns a slot in the webbased tool (earliest CTOT now +15min, to take Push and Taxi into account)

--> Operator clears the aircraft for IFR

  • AUA123 reads back correctly and the Operator communicates the slot time: “AUA123, readback correct, TSAT 12:34z, call me at time 12:34z"
  • at 12:34z AUA123 calls again and is ready for push and start

--> Operator checks the stand (DEP List or radar screen) and handover the pilot to the corresponding GND frequency (121.6 or .775)


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 (Calculated Time Of Takeoff) 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.

Responsible for Slot coordination in RL is the CFMU called "Central Flow Management Unit" in Brussels.

Slottool and Plugin Usage

The webbased slottool (as of 26.11.2021) allows for drag and drop assignment of aircraft to certain slots:


While there are identical flags for clearance and taxi as in Euroscope, there is no connection between both systems. Therefore a plugin SLOTHEL has been developed, to get at least the information of slot-times from the tool into an active controller session (see below, second column from right)


You have to adapt the DEPList settings (F button on the top left corner of the list) and select the SLOT-column.

CAUTION: Use the Plugin only in one ES instance, as every instance is triggering a call to the VACC server and too many requests may result in a blocked connection. -> To prevent this, unload the Plugin via ES “Other Set” -> “Plugins”

The data in the SLOT-column are presented in the following formats:


-CTOT- = Aircraft has received a taxi clearance/flag and will proceed to the holding point. It will most likely depart within time

TSAT/CTOT grey = Slot start up time is more than 5 minutes in the future

TSAT/CTOT green = Slot is open, aircraft may be transferred to GND for push and start

TSAT/CTOT yellow = Slot is still open, but aircraft is already 5 minutes late.

OVERDUE = Slot is closed 10 minutes after start up time, new slot necessary

Example of handling:

Slotgrey.png Pilot: "AUA123, ready for push and start" -- Controller: "AUA123, your slot is not open yet. Call me again at 11:48z"

Slotgreen.png Pilot: “AUA123, ready for push and start” -- Controller: “AUA123 contact ground on…”

Slotyellow.png Pilot: “AUA123, ready for push and start” -- Controller: “AUA123 contact ground on…” OR if the aircraft has not called in yet, and workload permits, the controller can actively call the pilot.

Slotred.png Pilot: “AUA123, ready for push and start” -- Controller: “AUA123, you missed your slot. New TSAT xx:xx, call me again at xx:xx”, after you or your Coordinator has assigned a new slot.

More Information

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.

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