Revision as of 23:13, 11 February 2021

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General

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.

What is Ground's job?

Most aircraft have only very limited view. Therefore, Ground has to guide taxiing aircraft.

No aircraft knows, where to dock after landing. Therefore, Ground assigns gates to go to.

No aircraft knows exactly, from where to take off. In fact, only Tower knows, but Ground is responsible to queue departing aircraft in the appropriate order.

There are no fixed directions on where to taxi on an airport, and taxiways are too narrow to have traffic in both directions. Therefore, it is Ground's responsibility to maintain a traffic flow to avoid nose-to-nose situations which (in real life) need a pushback car to resolve.

How to set up Ground's job

First, contact your upstream controller and enquire the runway configuration: Where will departing aircraft take off and arriving aircraft land? You might need intermediate conversation, so you better "sit" in the same teamspeak room as your Tower.
Second: make a plan on how to circle traffic: Which taxiway will you want to use which way to queue departing aircraft where? Which taxiways will you use for arriving aircraft? The trick is to have a pattern in mind that minimizes conflicts: The less crossings you have, the less you will have to pay attention on crashes. There is more information for specific airports LOWW (Vienna) and LOWI (Innsbruck).

Phraseology

Basic principles

The basic principles for Radio Telephony apply:

You are responsible for all aircraft acting under your clearance or approval. If you have issued "pushback approved", then the space behind him is blocked in your mind - you must not clear anyone else to go into.
You are also responsible if a pilot takes a wrong turn, you have to act. This means: You have to monitor, if pilots comply.

Making contact

The pilot says hello by stating: Who, where, and the request:

AUA125: Wien Ground, servus. Austrian 125, Foxtrot 05 request startup and pushback.
GND: Austrian 125, Wien Ground. start and push approved.
AUA125: Start and push approved, Austrian 125.

Start-up clearance

Start-up clearance may be given if you expect the aircraft to depart in a timely manner. (coordinate with GND and TWR accordingly)

Austrian 125, start-up approved.

Push-back clearance

Push-back clearance can be given if no other aircraft is passing behind and the parking position requires push-back.

Austrian 125, push-back approved

2. It also means, that the space behind the aircraft is reserved in your mind. You won't clear anyone to taxi behind this aircraft.

If the aircraft does not initiate pushback within an adequate timeframe, you may cancel the pushback clearance:

AUA123 Pushback clearance cancelled, I call you (back).

Thereafter you may clear anyone else to pass behind, and you have to re-issue the clearance later on.

Start and Push clearance

Use these two phrases together

Austrian 125, start(-up) and push(-back) approved

Taxi Instructions

Bear in mind: Taxi instructions are clearances, that means: The pilot must and will do it regardless of other things - they don't have a great amount of choice. Don't clear anyone for taxiing around, without knowing that the path is safe for the aircraft.

The pilot will conduct startup and pushback. As soon as he is ready for taxi he will call you:

AUA125: AUA125, request taxi.

Depending on traffic you can give him the taxi instruction to his departure runway:

AUA125, taxi to holding point Rwy 16 via L and W.

So, how do you maintain traffic flow at a busy airport?

It is best to clear the aircraft to an intermediate stopping position: "Taxi via E hold before EX24".

AUA125, Taxi via the Blue Line and E, Hold before EX24.

You may also add a condition to this to keep things moving:

AUA125, Taxi H/P RWY 29 via Blue Line, E, EX24 and EX1, on E behind Company Airbus From the right.

This means: the A/C has to "hold before" (=to stop) in mid way for a condition which you specify.

This could be only to "hold short" --> until you tell them to "continue".
It could be "behind the A320 from left to right" --> the pilot will stop, wait for a passing A320 and continue.
It could be "follow company A320 taxiing on L" --> the pilot will look out for a A320 of his own airline and follow them.

The "Hold before" argument reduces your workload, as the pilot must now judge if they can meet the conditions given. As a controller, it is no good idea to tell pilots something they can't do (i.e. look behind) - pilots might oversee it and.

Bear in mind that it is the controllers' job to decide on wingspan clearance.

On VATSIM, you sometimes meet pilots who apparently don't have charts and/or lose orientation - especially when it is dark and the scenery is outdated. If a pilot starts sight-seeing, you can tell them to stop ("hold position") and to "expect progressive taxi", and that means: you taxi him step by step, and they are instructed to stop at every step.

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 the aircraft is conflict-free in your area of responsibility. This means, if no other aircraft can be in the way on his way to the runway. Example for LOWW: Suppose, RWY 29 - GND will line up all aircraft on taxiway M facing East. Hand them over to TWR as soon as practibale. Avoid unnecessary intermediate stops of taxiing aircraft.

AUA125 Contact Wien Tower on 119,400.

Air-taxiing is the Movement of a helicopter / VTOL above the surface of an aerodrome, normally in ground effect and at a ground speed of normally less than 20 KT (37 km/h). Please Note: The actual height may vary, and some helicopters may require air-taxiing above 25 FT (8 m) AGL to reduce ground effect turbulence or provide clearance for cargo sling loads.

OEBXR: request air taxi to Runway 29.
GND: OEBXR, contact TWR 119.400.
OEBXR: Servus Wien Tower, request air taxi to Runway 29 via Exit 13 and M.
TWR: OEBXR, air taxi to Runway 29 via Exit 13 and M. wind 280 deg 5 knots
OEBXR: air taxi to Runway 29 via M.

Ground Traffic Management

Bear in mind, that it is GND's job that they can taxi freely. If an aircraft has clearance, it can roll without looking anywhere else than straight ahead. You must see if the way is clear. But on a busy evening, you will have 5-10 aircraft taxiing at the same time. How you do this so that they don't bump into each other? It's called Ground Traffic Management.

To organize 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.

There are a few tools which you can use:

Taxiway configurations

Only one aircraft can taxi on a taxiway, so you have to order the traffic flow. On larger airports, you set the rules where outbound and where inbound aircraft roll. For LOWW, there is a nice document by Patrick Hrusa (thanks!). For LOWI, there is a nice LOWI_Primer by Claus and Hermann.

Step-by-step clearance

A very secure, but time-consuming way to control. Clear the aircraft only as far as it is definitely clear:

GND: AUA251, taxi via E hold before M.
GND: AUA251, taxi via M, hold before Exit 7.
GND: AUA251, taxi via L, hold clear of Exit 9.
GND: AUA251, continue to gate D21 via Exit 9.

Conditional clearance

This provides much more flow, but you have to think in advance. See, which aircraft approach to where and give one of them a conditional clearance to stop some point and give way. Make sure that the condition is clear: a specific intersection, a precise plane from a precise direction, like this:

GND: AUA251, taxi to gate D21 via E, M and Exit 9, On M give way to company A320 from the right.

"Conditional clearance" means: AUA251 is free to taxi until its final clearance limit (D21), but stops inbetween until the condition is met, in this case: another Austrian A320 taxiing (presumably on D) and turning in before him. Then, he is free to continue without instruction. "Hold short" means: You are cleared to your destination, but you should stop inbetween.

Intermediate instructions

Sometimes, things go differently as expected: Aircraft stop to sort out checklists, or they speed up. You might need to re-clear or stop the plane, like:

GND: AUA251, hold position.
GND: AUA251, continue.
GND: AUA251, hold before W, B190 crossing right to left.
GND: AUA251, gate change, taxi to gate F1 via M, EX7, at EX7 behind Swiss A320 crossing right - left.

Progressive Taxi

Some pilots don't know how to taxi, and some don't know where to taxi, and they can drive you mad. To them, you can issue progressive taxi instructions:

GND: Leipzig Air 600, turn next left hold next intersection.
GND: Leipzig Air 600, turn right, on third intersection left and hold.

Example

Consider the following situation:

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 B95.

GND:DLH6KM taxi to stand C40 via taxiway D and L.
DLH6KM:Taxiing to stand C40 via D and L, DLH6KM.
LZB421:Wien ground LZB421 stand B95, ready for taxi.
GND:LZB421, Taxi via L, hold before EX11.
LZB421:via L, hold before EX11.

The aircraft are now both approaching EX11.

GND:LZB421, When clear of the opposite 737, continue EX11 and M to H/P RWY 29.

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, at EX2 follow Austrian DASH 8 from the right to holding point runway 29.

Special Case Northern F stands

As this area is equipped with 3 parallel Taxilines, those being Taxiline 40 Center, Blue Line and Orange Line, it is vital to make use of these Lines in a sensible manner.

Taxiline 40 Center is issued to Heavy A/C up to a maximum Wingspan of 68.4 Meters
Blue and Orange Line may be issued to two A/C taxiing in parallel up to a maximum Wingspan of 36 Meters. This gives the Controller the ability to essentially double the flow rate in this area as also pushback may be conducted onto either of those lines. Make sure to state this in the Push Clearance accordingly

e.g

 "AUA9LT Start and Push approved - Blue Line"

Phraseology in this area is as follows:

 "Taxi to Position F08 via the Blue Line"

or

 "Taxi to Position G26 via Taxiline 40 Center"

Positions G16, G26 and G36 are used for Heavy A/C and are collocated with their respective F counterparts F16, F26 and F36. Nevertheless they provide greater wingtip clearance.

Swingovers

Another option to make use of this infrastructure is to clear "swingovers".

"AUA9LT Swingover Orange Line continue W to H/P RWY 16"

This procedure is particularly useful to clear e.g the Blue Line for incoming traffic.

Intersection departure

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 Departure Seperation).

Phraseology to ask an A/C for its ability to make use of an intersection is as follows:

 AUA4CM can you accept B4?

if answered positively ->

Roger, join B4 (report ready)

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

Intermediate Holding Positions (IHP)

In dynamic and high TFC situations it is advisable to make use of intermediate clearances to keep both your and the pilots flexibility to change route at a maximum. It is therefore suggested to make use of IHPs such as:

M2
L2
Blue 1
Orange 1

Nevertheless you should try to keep the A/C moving and avoid unnecessary stops at these positions if they are of no use to your flow management.

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.

Mind the wingtip: Size matters to GND controllers

As GND controller, you have to watch out for the size of an aircraft. You have two indications for the aircraft size in Euroscope: The Letter "L/M/H/S" in the flight strip, and the precise aircraft type in the departure list or tag - an abbreviation which you might need to google, but you will learn over time.

Light aircraft (L) need to go to stands, not to docks (you won't want to dock a Cessna, will you?). But "light" is not "light" - on some GAC aprons the aircraft has to be really light, especially when it comes to grass surface. Watch out to the aircraft type.

Medium aircraft have a different trouble: Some of them (like the Beech 99, the Dash or the Avro RJ are medium, but they need stands. Others, not much bigger, like the Fokker 70 or 100, can dock at the gate, whereas others (like the A319), only a little bigger, usually dock. In doubt: ask the pilot. The medium category goes up to the most-frequent cruisers A320 and B737.

Heavy aircraft are (almost) everything above: A330, B767 and B747, the MD11 and the new B787. They almost exclusively dock, but there is another risk: Not all docks are suitable for heavies - ground charts tell you more. Check this chart [1] to verify where you can park which A/C.

Superheavy aircraft e.g The A380 - which is parked at F35, D27 or H98.

as hint for parking, you could use follow flow Chart:

Additional Information

For further information relating to traffic flow management on ground in different configurations, please refer to: ATMM Guide

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

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