Study Guide:Delivery

Introduction

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.

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Radio Communication - Basics

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 all conducted in English. Link: Buchstabiertabelle

Basic Rules

In order to achieve the goals set above the following rules important:

1. 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.

2. 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.

3. 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 Delivery, Austrian 251, Radiocheck 
LOWW_DEL: Austrian 251, Wien Delivery, read you 5 by 5

In Subsequent calls the calling station part can be ommited.
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, headings, 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).

Examples:

LOWW_APP: AUA251, turn left heading 290, descend Altitude 5000 feet, QNH 1019.
AUA251: Turn left heading 290, descending altitude 5000 feet QNH 1019, AUA251 

LOWW_GND: OE-DLT, taxi to Holding Point Runway 29 via Exit 12, M and A1, QNH 1019, 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.

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METAR and TAF

References for detailed information: METAR, TAF 

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How is an Aerodrome organized

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.

1. Clearance delivery (DEL), responsible for checking flightplans and issuing IFR clearances to departing aircraft.
2. Ground (GND), responsible for all traffic on the apron and the taxiways.
3. 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:

1. APP Positions, managing the traffic within the airports vicinity (the so called TMA, Terminal Area). In Austria they are situated directly at the airports.
2. ACC (Area Control Center, on VATSIM the abbreviation CTR is used) positions, which are responsible for enroute traffic. They reside in Vienna.

If the air is too crowded, APP and CTR can be divided horizontally (lower and higher APP), vertically (north APP and south APP), or a director responsible for approach spacing - but we won't want to make it too complicated for now. Local procedures and agreements regulate it, how this is done.

• Since they all use their radar to control air traffic, they are also called Radar positions.

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Working Delivery Positions

Clearance Delivery is responsible for checking and correcting flightplans of departing aircraft and issue routing clearances to them.

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.

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).
2. 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.
3. 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.

For VFR flights, their 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.

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Workflow for DEL controllers

At VATSIM, he journey starts with an aircraft popping up at an airport. Initially, the tag (in Euroscope) will show "NOFP", meaning: No flight plan filed so far. Some time later, a destination and more will show up, and that means: The pilot has filed a flight plan. On this point, DEL controller work starts. At this point, Euroscope has done already some work for you. DEL's job is to check and complete it, and to give clearance to the pilot.

1. Setup

When you log in as DEL, you have to do two things (if waiting pilots jump on you, tell them to stand by until you have done it!):

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.

2. Check the flight Plan

Then you turn to the waiting pilots and work them down one by one. First, Check, if it is a VFR or IFR flight plan.

For IFR flight plans, ...

• Check, if "From"-Airport is correct and "To"-Airport makes sense. If not, then ask the pilot to refile the flight plan.
• Check, if departure runway corresponds to the active runway. If not, then check your runway settings in Euroscope.
• Check, if cruise altitude is correct: Cruise altitude is stated in flight levels (hundreds of feed): FL280 means 28000 feet (at QNH 1013, to be really correct). For flight levels below FL300, westbound flights have even flight levels, and eastbound flights have odd flight levels. If the cruise altitude, ask the pilot for the nearest correct altitudes 10 FL up or down.
• Check, if there is a valid SID from the active runway to the first waypoint in the flight plan. If not, then look for the cause. It could be an invalid flight plan (a flight plan must contain a waypoint which is the end of a SID - most SIDs have the waypoint in their names: SITNI5B is the SID leading from LOWW rwy 16 to SITNI). If the flight plan does not contain any valid waypoint, ask the pilot to refile a correct flight plan. If the flight plan is correct, then you might need to manually select the best SID.
• Euroscope has already selected the first matching SID in the alphabet. Check, if this SID is applicable to the aircraft and time (you might want to check with APP to clarify, which SIDs are correct), and select the best SID.

For VFR flight plans, the task is easier. usually, it contains the destination and a verbal description of the pilot's intention (could be "circuits" or "platzrunde", or "LOWL via Donau").

• Check, if this intention is possible and makes sense (you might check with TWR).

2. Set Squawk and initial clearance altitude

• Set a squawk now. The squawk number space 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 like Finally Austria, the squawk space runs out quickly, and Euroscope runs mad. The result is duplicate squawks. Technically, this is not a problem at VATSIM (as plane-data links are made by pilot ID, not by squawk code), but in reality this would be a nightmare. In this case, you have to set squawk codes by hand and start to fill other squawk number codes, like 2500+. Don't attempt to set a squawk with a number higher than 7 - squawks are octets and don't have 8 and 9 (4707 is good, 4708 does not work).
• Set the initial climb altitude. This differs from airport to airport. LOWW has 5000ft for all SIDs ("A50" in the list), LOWI has FL160 for all SIDs, and Salzburg has different altitudes for different SIDs (look into the SID description).

Wait for initial contact

ATC is a service job - you wait for the pilot to come to you, unless there is good reason not to do so. At some point, the aircraft will call you, ideally with the first (long) phrase. When congested, the short form is used:

LHA123: Wien Delivery, servus. Laipzich Air 123, gate C31, Fokker 70, requesting clearance to München, Info B on board.
LHA456: Wien Delivery, Laipzich Air 456 ready for clearance.

Issuing IFR Routing Clearances

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

Destination of flight
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) = given with taxi clearance
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.

Normal construction of a routing clearance:

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

Example:

Austrian 125, cleared to Frankfurt via LUGIM 1C departure, initial climb 5000ft,
Squawk 4601.

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, initial climb 5000ft,
Squawk 46XX

Example:

Austrian 125, cleared to Frankfurt, after departure Runway 29, turn left heading 240
expect vectors to LUGIM, initial climb 5000 ft, Squawk 4601.

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. Austrian 125, readback correct /(readback was correct)

Afterwards you either hand the pilot over to GND or wait for his startup request, depending on local procedures.

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

Slots

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.

Behavior in situations with increased traffic

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, readback correct, expect startup in 10 minutes.
Austrian 125, startup approved, expect departure in 10 minutes.