ATC tutorial: Difference between revisions

In order to be able to effectively and reliably communicate, ATC and pilots agree on a set of keywords and jargon. This may vary between regions and the like. English is the agreed language for internaltional flights. <!-- <ref>{{cite web |url=http://www.icao.int/icao/en/trivia/peltrgFAQ.htm#23 |title=IDAO FAQ |accessdate=2009-03-03 |dateformat=lmdy}}</ref> -->

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So now you can choose your position, but beware: if you are the approach controller at an airport which doesn't have a ground / tower controller, planes will expect you to offer them all those facilities, but if you are a London Center controller, you are not expected to offer center facilities to airplanes in an adjacent sector, but could be expected to offer very basic facilities of GND / TWR / APP to airports in your sector...

Now, we'll have a look at each of the positions in details:

Ground is possibly the easiest position available to controllers. The basic responsibility is to get planes to and from the runway and terminal buildings as quickly as possible (to save fuel and time) and to avoid planes colliding with each other. For this, you might need a GROUND SECTOR FILE. This is optional as a very detailed map of a particular airport (can be downloaded from the Sector System on IVAO) which hold all the taxiways as geographic data (press F5 to view).

Depending on the airport, the taxiways may have letters, or descriptions (e.g.: Inner Taxiway) or each section of the airport may have a number (called blocks). At Heathrow, the last two are used, so a statement like 'taxi to block 76 via the outer taxi-way' would be valid.

Tower has responsibility for all planes coming into or out of the airport, and the planes wishing to enter or cross the active runways. For Tower you can use any sector file with the airport shown, and center on your airport and zoom in to give your short (10NM) range. The first responsibility is to choose which runways to use (there's always at least 2 - one runway being used either direction) according to the weather (more later). You will also be expected to give IFR clearances, but this is very simple.

The biggest responsibility the tower has is to ensure that planes can take-off and land as quickly as possible, without any two colliding. Your approach controller should make sure that all planes arriving are well spaced and already heading directly for the runway. When a plane you've given permission to take-off to has left the ground, they are given straight to APP (Approach). Normally, there will not be a ground controller, so you may have to also give basic ground instructions (just ask a plane to get to the runway - not giving them directions - but warn them of any other traffic).

Approach is the most complicated position. Approach controllers deal with all traffic arriving and leaving (unless there is a departures controller - unusual). The main aim, as always, is to keep the aircraft arriving and leaving separated. For departing traffic, the aim is to get them going in the right direction and give them to center as soon as possible; for arriving traffic, the aim is to get them onto the approach (the correct height and heading) so that they can follow an electronic system (the ILS) which gives them exact guidance onto the runway, and then you can hand them off to the tower, who will clear them to land and try and get planes taking off in between the landings.

The difficulty is, of course, dealing with the high volumes of traffic around an airport. In Lesson 3, SIDs and STARs are introduced which are standard ways of leaving from or arriving at an airport which ensure that planes maintain separation.

An unusual position in the virtual world, the departure controller controls all planes leaving an airport; normally _APP will handle these but sometimes traffic means that there is just too much for a single controller to do. It is the aim of the departures controller to get the departing aircraft away from the airport as soon as possible without interfering with approach's planes. Later, you will see that departures are kept below a certain altitude until they're a distance away so that any arrivals can fly over them without any mid-air collisions.

In this position you absolutely must co-ordinate very closely with the approach controller.

Center handles all airplanes in a specific area which are en route and not getting ready to land or having just departed. They navigate the plane from place to place as quickly as possible whilst ensuring that planes stay separated from each other. A plane may deal with many centers as it passes over many countries in a flight.  

Notice how I've mentioned separation in every description? SEPARATION is the first key to controlling. It does not matter how far out its way a plane has to go if you keep everybody on board alive. A pilot may well want to have landed five minutes earlier, but it's your job as the controller to keep them separated. Of course, having said that, the second key to controlling is expedite flow - that is keep traffic moving quickly and get it where it wants to go by the most direct route.

Let's look at a plane taxiing to the runway and taking off now. So, to do this, we'll consider two controllers:  

''ground control (_GND) and the tower (_TWR).''

The clearance can be given whilst on the ground, and is given by Clearance Delivery (_DEL) if one is online, else the GROUND (_GND), or TOWER (_TWR) controller. The pilot must read-back the whole clearance, to which you confirm by saying 'readback correct'. The Squawk code is a number used to identify the plane. It can be seen on the flight plan (will default to 1200) and means - in the real world - a controller can tell the dots apart as each one has a number. Just assign an available number in the 5000 or 6000 range (eg: 6001, 6002, 6003, etc.).

'''B-ELIO: B-ELIO requests start-up and push-back.'''

B-ELIO will then call you when he's ready to taxi. Note you don't have to type B-ELIO, just click on his icon on the screen and ProController automatically inserts it for you. You can often just respond with 'roger' or 'rgr' which means you've heard what the other person has said, or 'wilco' which means you have heard and will obey. When he calls to taxi:

'''B-ELIO: to runway 9 and h/s, alt 1009, B-ELIO (h/s is short for hold short)'''

If you were awaiting a plane to land, you could just leave the plane queuing, but if you are ready to have him on the runway tell him to get into position on the runway. Remember, it is your job to get aircraft onto and off the runways as quickly as possible, so that planes can land and take-off quickly:

'''B-ELIO: Runway 9, line up and wait, B-ELIO.'''

The plane may give a call back when he's ready like 'ready for departure' or 'on the numbers'. If not, just wait until his icon stops moving and give him his takeoff clearance:

'''B-ELIO: Cleared for takeoff.'''

The plane will commence his take-off roll, and - as soon as he is airborne - you want to get rid of him and get onto your next plane. You initiate the hand-off to approach, and handoff as soon as (s)he accepts. So now, onto approaches dealings...

''(In this section the approach controller is presumed to be handling departures, as there are very, very rarely departure controllers. If there were a departure controller, (s)he would deal with a departing plane, and the approach controller would deal with any planes arriving)''

Let's look at how the hand-off occurs this time:

'''B-ELIO (to you): Heathrow Approach, good-day, this is B-ELIO out of 1,700 for 6,000 on runway heading'''

'''Some examples of these:'''

When the plane is nearing its final destination, make sure it has descended to between 18,000 and 22,000 ft. This means that the approach controller can take the plane and descend it quickly -- it's no good trying to descend a plane 35,000 ft in 20 NM and still get it to land. Notice that the plane should remain above 18,000 ft (in your airspace) until you've handed off. Approach might decide not to take the plane and have you make it fly circles in the sky for 20 minutes until he has some room; otherwise arrivals and departures might crash while they're being handed over! So:

'''B-ELIO: down to 18,000 on 1221, will expect approach in five, B-ELIO.'''

I'm not sure how we ended up at Heathrow, but that's another story!

Our plane, B-ELIO, is now about 40NM east-south-east of Heathrow ready to start the approach to runway 9L - as tower has chosen runway 9R for departures, with the winds of 87@22 - the plane is at 18,000 ft and is heading at 270 (towards the left of our screen...).

The orange line shows the 'intercepting the localizer' as the plane will continue to fly this heading until the ILS tells it to turn right onto the center-line of the runway. As soon as the plane reports it's established on the localizer (it has direction signals), it can be cleared for the approach and told to descend with the glideslope which gives the plane height signals. The glideslope and localizer give precision approach information and are known - together - as the ILS (Instrument Landing System). Then get the plane to the tower, because - remember - you may well be dealing with planes taking off which you need to get out of your air-space, and other planes trying to get established on the ILS, as the tower wants a steady stream of well-separated planes on the ILS. You hopefully now know what you're supposed to be doing, but how do we do it. We'll look at each stage in turn.

'''B-ELIO: rgr, down to 8,000 to OCK.'''

Great... B-ELIO will now get to OCK and be at 8,000. Just before he gets to OCK, you need to issue the next instructions so that he can be ready for them:

'''B-ELIO: rgr, 2,500 on my heading for 9L, B-ELIO.'''

OK so far? Now let's head him towards the airport. This is the base leg:

'''B-ELIO: t/r (turn right) 360, B-ELIO'''

This is where judgment and cunning use of the feature for monitoring heading and distance come into play. It is also your duty to give the plane the frequency for the ILS (in the form xxx.xx) which can be found at www.ivao.aero/db/ss (or from database, sector system) using the search facility. The plane just hit the extended center-line at least 8NM away from the airport, so make sure you issue the turn to 45 at the correct time, otherwise B-ELIO will miss the ILS. Right place, so...

'''B-ELIO: right to 45 for LLZ to 9L, will report established'''

This is your cue to clear him for the approach and allow him to descend (otherwise he'll fly perfectly over the runway at 2,500ft). This is done with the following command:

'''B-ELIO: Over to the tower, thanks for your help.'''

Disaster! You've got a propeller aircraft doing an approach and you've started a 747 on the same approach behind it. There's nothing to hold it at, and there getting very close -- what do you do? You could take the plane away and start the approach again, but using an orbit -- a circle to the left or right and then on the original heading -- will increase your time, just give:

'''B-ELIO: wilco'''

Also, sometimes as approach you will want to slow a plane down to ensure that it isn't conflicting with a plane already on approach in front... if they are too close, the second plane will end up missing his approach because the plane in front will still be on the runway.

Anyway, back to our imaginary flight in which B-ELIO is flying the approach and is back with the tower...

Tower now has B-ELIO who is now cleared for the ILS approach, so can descend to the decision height. The decision minimum height is the height above the airport to which the plane can descend before being cleared to land. The plane cannot pass the decision height until he has visual contact (that is, he can see) the runway he wants to land on. If he cannot see the runway he will execute a missed approach and go around for another approach.

The pilot will report to the tower:

'''You: B-ELIO, Rgr. (you do not need to give radar contact, as the pilot no longer needs a radar service. He is using ILS)'''

You can then give the landing clearance, or - more likely - you can delay the clearance until he is 8NM from the airport and so are more certain that he will be able to land. The 8NM point of the approach is marked by a special device that causes a tone and light in the plane's cockpit. This device is known as the outer marker (O/M or OM). You can ask the pilot to tell you at this point for his clearance:

'''B-ELIO: at O/M'''

'''B-ELIO: 9L, cleared to land, B-ELIO.'''

After B-ELIO has landed, while he's still on the runway, you still control him. You want him off your runway as soon as possible, so you can land the next plane (otherwise, if he's still anywhere on the runway, you'd have to give a landing plane a missed approach), so:

'''B-ELIO: Thanks for your help, switching to ground.'''

And your job is done... let's look at a worse scenario. You landed a plane before B-ELIO and for some reason it hasn't been able to get off the runway yet. You must not let B-ELIO land whilst any other plane is on the runway, so you order B-ELIO to miss his approach:

B-ELIO: Missed approach, and will contact approach.'''

Approach will then climb the plane back to 6,000 ft (as it is almost a departure now) and complete the down-wind and base legs again (possibly on the other side of the airfield, depending on traffic). The plane can then be vectored back onto approach by the approach controller, and then given back to tower to try again. Of course a plane can initiate their own missed approach.

You: Rgr, c/m 6000 left to 60 (perhaps there's traffic straight ahead?) and contact approach on 192.72.'''