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Air Traffic Control Basics

Air Traffic Control (ATC) Basics

Listen and Learn - You might want to start here (easier than reading) and listen to ATC

Live ATC on-line - a very busy facility (like KSFO) will have separate feeds for clearance, ground, tower, approach and departure.  These are a bit easier to follow since everyone you hear is under the same controller type.  You can find airports that combine approach, tower, ground and departure like KSAT - can be confusing at times but you get to hear each phase of the flight - this helps in understanding the 'hand off' from one controller to another and the timing, technique and information that is given when transitioning from one phase to another.

Some brief, informative and entertaining examples of ATC:  Example-1    Example-2    Example-3 (MOCHA HAGoTDI = Make Our Customer's Happy and Have a Good Time Doing It - A slogan used by Massachusetts-based Cape Air [Callsign Cair - pronounced 'care'])

Sign up for VATSIM.  Look on ServInfo to see where there is active ATC.  Park at a gate or ramp parking (NOT on a runway or taxiway!), connect, tune your radio to the available controllers (try a spot where both center and tower are online - or more positions if they are there).  See the VATSIM website for more information and how to set up your radio or ask someone at IFR Jet Hops (we can help get FSInn set up for VATSIM also).  You should pull up the flight plan portion of FSInn and enter 'Observing Only' in the remarks.  Just listen, don't say anything (unless you are called - which should not happen).

And - the robot ATC in FSX can give you some idea of what happens but is only a rudimentary starting point.

Where do I find the right frequencies?

For sim flying one of the easiest ways to find ATC frequencies is with ServInfo.  You can get it at the VFR Prop Hops Useful Links page - scroll down to the 'Tools' section.  You can also get them at AirNav.com or SkyVector.com, but larger facilities may have multiple frequencies for the same controller position.  One of them should be right, so this might involve some trial and error.

Remember that the priority is always ...

  1. Aviate
  2. Navigate
  3. Communicate

Communication, although very important, takes a back seat to flying the plane and being in the right place.  Ask ATC to stand by if you need to.  ("Please stand by").  Having used the proper phrase to ask someone to wait (No, 'hold your horses', ' keep your shirt on' or 'don't get your panties in a bundle' is not acceptable phraseology) next we'll discuss ...

Terminology and Phraseology

You will hear many variations of accepted terms and phrases.  No one is going to (or at least should not) admonish you for not saying things exactly as prescribed as long as you stick to the basic principles but you should make an effort to stick to the recommended terms and phrasing.

Use the phonetic alphabet - review if needed - click here.  Note that there are some interesting pronunciations (right hand column)


Below 10,000 feet:  The number with the magnitude is spoken

800 - "eight hundred" (where eight is pronounced "ait" - pretty much as you would expect)

4,500 - "four thousand five hundred" (where five is pronounced "fife" - maybe not what you were expecting, so review the phonetic alphabet and the proper pronunciation - and you'll understand the not very funny [or accurate] joke "How do you turn a tree into a fife?  Turn it around").

9,000 - "nine (nin-er, the correct way to say it) thousand"

Between 10,000 to 17,999 feet (that's right, 18,000 not included)

12,500 - "one two thousand five hundred"

16,000 - "one six thousand"

11,500 - "one one, eleven thousand five hundred"

Ten and eleven thousand range numbers:  Note the pronunciation of 11,500 - and the use of the separate digits followed by the full number pronunciation.  This is the phrasing recommended by aviation safety experts - specifically they recommend this be done for any altitude involving 10 thousand or 11 thousand feet (10,000 - "one zero, ten thousand", 11,200 - " one one, eleven thousand two hundred").  Some pilots use this for all double digit altitudes up to 18,000 feet (15,500 - "one five, fifteen thousand five hundred") - not strictly correct but not totally unacceptable and it does reinforce the habit of the separate followed by full number pronunciation recommended for ten and eleven thousand foot levels.

At or above 18,000 feet: "Flight level" followed by three separate digits

28,000 (FL280) - "Flight level two eight zero"

Airspeed:  Separate digits followed by the word "knots" or the word "mach" followed by the digits, using the word "point" for the decimal

250 knots - "two five zero knots"

85 knots - "eight five knots"

Mach 1.6 - "mach one point six"

Mach .64 - "mach point six four"

When changing speed the 'knots' or 'mach' can be omitted - "reducing speed to 190"; "reduce speed to 180 or less"

'Point' vs. 'Decimal' - FAA protocol is to use 'point' for a decimal point, as above.  International Civil Aviation Organization (ICAO) procedures use 'Decimal' - The FAA honors the use of 'decimal' for military and other aircraft operations required to use ICAO procedures.

Radio Communication

Tune to the desired frequency and ... LISTEN.  Then, LISTEN some more.  You don't want to 'step on anyone' (transmit when others are transmitting) or interrupt an exchange in progress.  Also, listening gives you good information - who else is in the area, what runway is being used, which 'one minute weather' is in effect or the 'Information' followed by a phonetic letter usually from ATIS.  (For automated weather service weather the correct term for AWOS, ASOS or AWSS weather is 'one minute weather').  Not only will you not interrupt things you will better understand the current situation and be better prepared.

Next - speak?  NO - Next THINK.  Think about what you are going to say and how it should be said (more on the how part, below).

Then, when you're ready, speak.  Remember that a complete exchange between ATC and a pilot includes information and read-back of that information so while you are listening, listen to be sure that not only has ATC finished transmitting but that the pilot has transmitted confirmation of that information.  When you speak, be brief.  Some pilots (and controllers) mistake fast for brief.  There is no need to speak fast (although you will hear plenty of examples of this).

Speak succinctly (back to the 'think' part before you speak) and when the total information is lengthy or complex make statements in 'packets'.  Do not unkey the mike - just take a breath at logical places.  This rule is a bit more applicable to the controller than the pilot in some circumstances - and there are plenty of examples where the controller races through a complex set of instructions, all running together and at the speed of a rabbit on his fourth cup from Starbucks.  If this happens, ask the controller to 'repeat more slowly'.

Initial Contact

When making initial contact the following information (at a minimum) should be given:

  • Who you are calling
  • Who you are - your plane type with N-number (drop the 'N' if you give your plane type but otherwise USE YOUR FULL call sign), your airline call sign and flight number, etc.
  • Where you are (several variations on this - best to see the examples that follow and those that you hear)
  • Type of message to follow (or if it is short, make your request or statement - again, some examples below will help)
  • With (In some cases - certain information.  This part is not always used)
  • The word 'Over' - but you will notice that this does not happen much, including in RW communications

Subsequent Contact

Due to the wide variety of communication content there will be many different variations on what happens after initial contact.  In general 

  • Acknowledge all call-ups, clearances or instructions unless advised by ATC not to do so.
  • Include information or remarks appropriate to the communication
  • End your communication with your call sign

Call Signs - Abbreviate or Not?

Always use your full call sign on initial contact.  Always.  A good rule to follow is that if you choose to use an abbreviated version of your call sign do so only after ATC does so.  Otherwise, continue to use your full call sign.

Example Communication -

Below is an example of the communication you might hear for a flight originating at KSAT and ending at KMEM.  You may not be familiar with some of the terms or at this point not exactly sure about how to file a flight plan.  These, and other aspects of IFR flying are explained in our IFR Flight Planning  page.  For now, just follow the communication sequence to get a feel for how this is done.  Also keep in mind that in sim flying (as occasionally happens in real world flying, usually only in a limited way such as Tower covering some Ground control activites) all positions may not (and usually are not) manned.  However, this example assumes that most are so you can see how hand-offs are done.

Initial contact, requesting and receiving clearance:


(Who you are calling) San Antonio Clearance Delivery, (Who you are) Jet Hops 5127 (Where you are) at Gate Alpha 2 (Type of message - in this case, we're going to say what we want) requesting IFR clearance to Memphis, flight plan on file, over.

Again, without the specific pieces identified and with a 'breath' to put the information into two chunks:


San Antonio Clearance Delivery*, Jet Hops 5127 at Gate Alpha 2 (pause)

requesting IFR clearance to Memphis, flight plan on file, over.

*In the real world you may well receive clearance by computer or from Clearance Delivery.  In sim flying this is often done by Center or, if Center is not on-line, by Tower or Approach (depending on who is currently working the airport you are at).

At this point, depending on how busy ATC is and how long it has been since you filed your flight plan ATC may tell ask you to stand by (may even tell you that you are number 'x' in line to receive clearance).  If told this, say roger but say no more.  Once ATC is ready it will go something like this:

(San Antonio Clearance Delivery)

Jet Hops 5127 you are cleared as filed using the ALAMO9 (Alamo nine) departure then to Memphis on the TAMMY4 (Tammy four) approach.

Expect runway one two right for departure (since we'll repeat 12 right and many other numbers several times, when you see numbers written assume the separate digits are spoken when they shoul be).

On departure maintain runway heading

Climb and maintain five thousand feet, expect planned altitude (may say what that is - "expect flight level 280 ...") 10 minutes after departure

Squawk 4221

Contact San Antonio Ground on one two one point two zero when ready to taxi

Now, you must read back your clearance (and acknowledge ANY OTHER COMMUNICATION anytime you receive it [some exceptions] unless otherwise instructed not to).  Note that one common instruction at this point is '"Read back squawk code only" in which case you would do just that.  In this case below is an example of an acceptable read-back (note that things are a bit abbreviated) - 


Cleared as filed

Expect 12 right

Runway heading, climb and maintain five thousand feet

Expect planned altitude in ten minutes (sometimes this part is omitted - if in doubt, read it back)

Squawk 4221

Contact Ground one two one point two zero when ready

Jet Hops 5127

(You're right - not exact, per-protocol phraseology but since ATC already knows the more detailed version it is acceptable to just hit the high points.  It is also acceptable to read back instructions exactly as given.  To provide more in the way of short-hand versions of acknowledgements that's what will be given in the remainder of this example).

Ready to Taxi

Unless otherwise instructed, you can start engines and push back before calling ATC to advise you are ready to taxi.  In general, ramp and gate areas, especially those managed by the airline personnel and include trucks, baggage carts, food and beverage vehicles in addition to the familiar guys with the flashlight safety batons are, in FAA parlance 'Non-Movement Areas" - a really bad name in my opinion since there is a lot of movement in these areas.  What the FAA means is that movement in these areas is not controlled by ATC.  They only control "Movement Areas".  So push back when ready and call ATC ...


San Antonio Ground

Jet Hops 5127 ready to taxi

(San Antonio Ground)

Jet Hops 5127 taxi for departure to runway 12 right via November - Golf - Kelo

Hold short runway 12 right (this part may or may not be included but if it is be sure to include the "hold short" in your readback)

Contact Tower one one niner point eight when in postion


November to Golf to Kelo

Hold short runway 12 right, contact Tower one one niner point eight at that time

Jet Hops 5127

"Departure vs. Take-off" - Two terms used frequently, each to be used in their specific situations even though they sound pretty much the same.  The general rule is - unless you are actually taking off then always use 'departure' - ATC will do the same.  They will NOT say "taxi for takeoff" they will say "taxi for departure" and so should you when requesting taxi for departure or when acknowledging instructions.  Use "take -off" in circumstances like "cleared for take-off" or "aborting take-off".

Taxi to 12 right and hold, and as instructed ...

Contact Tower


San Antonio Tower, Jet Hops 5127 ready for departure

(San Antonio Tower)

Jet Hops 5127 line up and wait, runway 12 right


Line up and wait 12 right

Jet Hops 5127

You then do just that, taxi onto the runway but only far enough to get yourself lined up - follow the yellow line to the centerline - then stop.

(San Antonio Tower)

Jet Hops 5127 cleared for take-off

Winds calm, altimeter three zero point one six


Cleared for take-off 12 right


I know - a couple of things you noticed.  Yes, it is OK (and almost always done) that the conditions (winds, altimeter, whatever is given) NOT be included in the readback.  And, even though ATC did NOT abbreviate the call sign you will also here this done - and generally is acceptable when there are short, contiguous exchanges back and forth between pilot and ATC.  Not strictly by the book,  but you will hear this.  BUT - it is always best to do things by the book so this really should have been the full call sign.  Just an example of something you will hear that is allowed to slip by but not strictly correct.

You have now taken off ... holding the runway heading and will not exceed 5,000 feet.  Wait for Tower to call ...

(San Antonio Tower)

Jet Hops 5127 turn left heading 360, climb and maintain 12 thousand


Turn left heading 360, climb to 12 twelve thousand

Jet Hops 5127

(Sometimes there might be a sense there is a more causal ATC environment, or some pilots just like to be a bit more 'folksy', so you might hear something like 'Left to 360, up to 12 thousand'.  Like talking to your parents [or your kids] you'll get a feel for when you can be easy-going or adhere strictly to the rules.  Just be sure to communicate the key information.)

So - you've turned and are climbing to twelve thousand feet - but not up there yet, and you hear ...

(San Antonio Tower)

Jet Hops 5127 contact San Antonio Departure on 125.7


Contact Departure 125.7

Jet Hops 5127

Good day. (The traditional 'goodbye' in controlled flight communication)

Again, you will hear more casual versions of this - maybe something like "Over to departure one two five point seven, g'day" (This at least got the key information in - the frequency to switch to.)  Not strictly by the book but not unusual to hear the acknowledgement done this way.

A hint regarding frequency changes - put the next anticipated frequency in the Comm 1 standby spot.  Then all you need to do is hit the "switch frequency" button and you'll be on the right channel - BUT - when you read back the frequency to ATC look at your radio to be sure the frequency in the standby slot is the right one.  Once you change, when you have a chance (remember - Aviate, Navigate, Communicate) input the next anticipated frequency.

You should be able to make the frequency switch and contact the controller you have been handed off to quickly, generally within 15 seconds or so.  The quicker the better especially when the hand-offs are on the departure or approach leg.  You should switch frequency quickly - because before you say anything you will need to LISTEN to be sure no other communication is occurring.  As soon as you are sure the frequency is clear contact Departure ...

Departure Phase:


San Antonio Departure

Jet Hops 5127 [with you], climbing 7 thousand eight hundred for one two, twelve thousand.

(San Antonio Departure)

Jet Hops 5127 climb and maintain flight level 270

Proceed direct GOBBY


Climb to flight level 270, proceed direct GOBBY

Jet Hops 5127

Note that ATC may have turned you, kept you at 12,000 feet for a time, put you at some other intermediate altitude or done other variations on the above. In this case they have cleared you to your planned altitude and to proceed direct to the GOBBY intersection.  You should expect one thing at least - hand-off to Houston Center.  So, if you have not already put Center's frequency into the Comm 1 standby slot (or didn't pre-program Comm 2, another useful way of handling multiple frequency changes in a short time period) then do so now.

Regarding altitude change reporting:  Note the phrase used above ... climbing 7 thousand eight hundred for ..., specifically the use of the term 'climbing' (vs. 'ascending' or 'going up to', etc.) - this is the proper terminology.  Likewise, if you are descending that the proper word is 'descending' or if you are level then you say 'level' (or if you prefer, 'level at', which is also acceptable).  You will hear other ways of reporting altitude changes but this is the 'official' way to do it.

"With you" - We stuck that in brackets here because that's where you usually hear this used - the brackets were to indicate that aviation communication experts say this is not proper and should not be used.  This is adding words that don't give any meaning.  One controller said that "if the pilot were really with me he would be sitting next to me in a comfy lether rolling chair drinking bad coffee out of a styrofoam cup"

(San Antonio Departure)

Jet Hops 5127 contact Houston Center on 132.8


Contact Houston Center 132.8

Jet Hops 5127


Tune to Houston Center, listen to be sure no one else is transmitting, then make initial contact with Center (remember the components of an Initial Contact although in approach and departure situations the controller you have been handed off to usually has some knowledge of what has occurred prior to handoff and what your clearance and other intentions are).

En-Route Phase (Center)


Houston Center

Jet Hops 5127 with you, climbing one six thousand five hundred for flight level 270

Proceeding direct GOBBY

(Houston Center)

Jet Hops 5127 radar contact

Proceed on course


Proceed on course, Jet Hops 5127

'What about the altimeter?' - Depending on where you are at and where you are going (both vertically and horizontally) and whether you are going up or down, Center may not give you the current altimeter setting.  In your case, at this point, you are climbing to FL270 and once you pass 18,000 feet you should reset your altimeter to 29.92 in Hg because all flights at or above 18,000 feet are based on pressure altitude - the altitude based on standard atmospheric pressure.  So, once you pass 18,000 feet reset your altimeter to 29.92!

At this point you will level off at your planned altitude.  Center will likely have nothing more to say to you until they hand you off to the next Center (or Approach, if you stay within that Center's region) but you should still be alert for any communication.  And - tune your standby or Comm 2 frequency to the next expected frequency.

For this trip you would be passed from Houston Center to Fort Worth Center and then to Memphis Center.  The first handoff will be to Fort Worth Center - 

(Houston Center)

Jet Hops 5127 contact Fort Worth Center on 133.30

Smooth flight (on of the typical controller-used 'goodbye' phrases)


Over to Fort Worth Center 133.30

Thanks for you help (another 'goodbye' phrase you will hear)


'Huh? - Looks like some typos' - No, this is still not strictly correct but often heard (and accepted) - dropping the first digit (the 'one') is done.  And, like earlier, we've dropped the 'Jet Hops' also.  And, 'Over to' (instead of 'Contact') is another one of those more casual phrases that get inserted.  Beware when you do this - just because others do it does not mean it is correct.

Back to another 'Initial Contact' - for this part of the example we'll use an exchange that might be the briefest you encounter:


Fort Worth Center

Jet Hops 5127, flight level 270

(Fort Worth Center)

Jet Hops 5127, roger

That's it - nothing more to say and no need to acknowledge Center's acknowledgement.

Your flight plan includes a Standard Terminal Arrival Route (STAR) called 'TAMMY4'.  STARs are explained in our IFR Flight Planning page but for this example of ATC communication the important thing is that your transition point is the El Dorado (ELD) VOR that is located within the Fort Worth Airspace.  So - If ATC does not contact you first you should contact Fort Worth Center to advise you are going to execute the STAR:

Fort Worth Center
Jet Hops 5127 entering the TAMMY4 approach at El Dorodo

(Fort Worth Center)
Jet Hops 5127 descend via the TAMMY4 arrival
Contact Memphis Center 128.47

Descend via TAMMY4
Contact Memphis Center 128.47
Jet Hops 5127
Good day

Again, what a STAR is, how you knew that the transition point occurred in the Fort Worth Center airspace and why you were (and should have expected to be) handed off right after contacting Fort Worth Center (or at least shortly thereafter) is explained in our IFR Flying - How To page.  AND - as you descend per the published approach, remember to reset you altimeter once you are below 18,000 feet (note that Memphis center tells you the Memphis altimeter, because they know you will be descending).


Memphis Center

Jet Hops 5127, flight level 270

Descending via the Tammy four arrival for Memphis

(Memphis Center)

Jet Hops 5127, radar contact

Proceed to Memphis, descend via Tammy four

Memphis altimeter 29.97


Proceed to Memphis, descend via Tammy four

Jet Hops 5127

The next thing you should expect is to be handed off to Memphis Approach, so - TUNE THAT RADIO STANDBY FREQUENCY NOW while things are still fairly calm and you are not trying to hit published altitudes.  The same thing would apply if you were going direct to KMEM (not using a STAR) since at some point Center is going to have you descend, maybe turn or do other maneuvers so while not much is happening get the Memphis Approach frequency in the radio.

Expect handoff just outside the KMEM controlled airspace (distance depends on your speed and the amount of traffic).  Expect something that will allow you to contact the facility when you are around 40 miles away - a bit more or less depending on the aircraft you are flying (speed, weight, etc.).  So, if you're flying a Boeing 737 then probably about 50 miles out (gives you a minute or so to contact and provides for contact about 40 miles out) or if you're in a Cessna 172 probably more like 30 to 35 miles out - even 30 or 45 seconds or so later you're still between 30 to 35 miles away and not moving all that fast.  Nonetheless - anticipate handoff and have your radio standby frequency tuned to the correct frequency.

So, as you expected ...

(Memphis Center)

Jet Hops 5127

Contact Memphis Approach on 119.1

Approach Phase


Contact Memphis Approach 119.1

Jet Hops 5127

Good day.


Memphis Approach

Jet Hops 5127 descending via the Tammy four approach west of TAMMY

Level at 12 twelve thousand feet  (DID YOU REMEMBER TO RESET YOUR ALTIMETER??)

Huh?  How did I get to 12,000 feet - that's the published altitude for the approach at TAMMY (actually, you can be anywhere between 10,000 and 16,000 feet) - all explained in the  IFR Flight Planning  page.

(Memphis Approach)

Jet Hops 5127 radar contact

Proceed inbound, descend via Tammy four

Expect runway 18 left


Descend via Tammy four

Expect 18 left

Jet Hops 5127

If you were not on a defined STAR it is likely that Center would have transitioned you to a lower altitude and possibly turned you to optimize your approach.  So, when you are handed off to Approach you will be at some lower altitude than your en-route altitude and at some position that is not necessarily on the direct route between your last planned fix and your destination.  In this case, once you are transitioned to Approach you should not only give your altitude but also give your position (just like you did above "west of TAMMY").  BUT - since you were not on a STAR with well identified reporting points once Center hands you off and again, like everything else, you should be anticipating this so you should be following a chart as Center maneuvers you so when handed off to Approach you will have a pretty good idea of where you are, and where you've been.

At some point of the STAR, or as a continuation of previous vectors and altitude changes on your direct approach you will begin the 'vectored' portion of the approach.  For FAA-controlled facilities (vs. ICAO rules, used outside the US) STARs and SIDs (Standard Instrument Departures, AKA 'Departure Procedures') include a vectored portion - direct intervention by ATC in the portion of the approach or departure near the facility.

"Descend via" and "Climb via":  As of August 2012 the FAA has changed the phraseology SIDs to use "Climb via [SID name] so it is consistent with the "Descend via [STAR name]" phraseology.  See the examples in the FAA publication on "Climb Via" and "Descend Via" Procedures and Phraseology.

Remainder of Approach, Transition to Tower then to Ground:

At this point you have had many examples of communications between ATC and pilots.  At some point you will be handed off from Approach to Tower, but most if not all of the vectoring has usually been completed.  The remainder of arrival will not be detailed out but the following procedures should be followed:

  1. When you get instructions to change to a certain heading or altitude, radio back to confirm EVERY instruction just as it was given.

2.  You may be advised of traffic in the area - the correct response is either 'Negative Contact' if you do not see the traffic (you will likely be instructed to advise when the traffic is in sight so you can pre-empt this by saying "Negative contact but we will advise when the traffic is in sight" - or something to that effect) or "Contact, traffic in sight" if you do see the traffic.  (If you do not have visual contact but have TCAS or are using the FSCopilot radar as a form of traffic monitoring you can advise ATC accordingly - "Negative visual contact but we have the traffic on TCAS")

3.  You may hear that you are cleared to the ILS approach, runway XX - this is an area of (recognized) confusion but so far the rules have not changed.  This phraseology is still in use, in spite of the fact that this has caused confusion with being 'cleared to land'.  So - be aware and be careful.  You are not cleared to land until you are told "Cleared to land".

Once you are on the ground you will recieve further instruction regarding exiting the runway and taxiing.  You may be handed off to Ground but this position may not be manned.  As described above this happens in some real-world situations but it is not uncommon in sim flying to have one controller covering multiple positions. So, be aware that in this and any other situation where you might expect to be handed off, you will be told "stay with me this frequency".  Do just that, you will receive further instructions in the same manner as if you were handed off to a different controller.

A couple of publications that might give you more information:

From the AOPA:  Communicating with ATC

From the FAA: Instrument Flying Handbook - see chapter two on communications.  (Very large .pdf file - you may want to download and save it)

If you have questions ask another Jet Hops or Prop Hops pilot!