PILOT-CONTROLLER COMMUNICATION

Langley Control Tower

Prior to flying Pilot-in-command (under your Student Pilot Permit without an Instructor on board), you will have to obtain your Radio Operator’s Licence.  This entails writing an examination.  The study material for this examination, as well as study questions, appears in Langley Flying School’s Flight Training Handbook Examination Handbook.  This section reviews practical procedures with respect to radio procedures and will get you up and running.
Think of the radio as a telephone—it really is no different!  The only important thing to remember is that only one person can speak on a VHF frequency at one time.  This means that the frequency can get very busy—when it is busy, pilots must make effort to minimise their transmission time.  We also minimise communication to free the frequency for possible emergency communication—some fellow may be having engine trouble whereby quick communication would be critical, and for this reason we have code words or phrases that mean, essentially, “everyone else but the pilot having difficulty cease transmission.1  Just as important, however, controllers and pilots must ensure they do not misunderstand one another.  If you are confused about a clearance, traffic advisory, or instruction (or anything you think might be important), you must seek clarification—it is a matter of safety.  As you will see, for example, controllers are always advising you of vicinity traffic which could, of course, turn into a potential collision hazard; if you are advised of such traffic, you must make it absolutely clear whether or not you have visual contact with the aeroplane in question.2
There is lots of good advice in From the Ground Up concerning radio use, but here are some additional important considerations that are worthwhile reviewing:

Departure

When you tune in a frequency, do not transmit until you are sure you are not interrupting an exchange of information between the controller and another pilot already on frequency.  If an exchange between a pilot and a controller is taking place, simply wait until they are finished.  Your first transmission should just include your aircraft type (Cherokee), and your four-letter identification (in the examples below we use GABC—when using the phonetic alphabet, this identification is stated Golf, Alpha, Bravo, Charlie.

Permission to Taxi—Training Flight to Practise Area

Pilot:

 

“Langley Ground3 this is Cherokee GABC.”

Controller:

 

“GABC, Langley Ground.”

Pilot:

 

“ABC is by Hangar 4B4 with Information CHARLIE.5  Training flight to the North East.6

Controller:

 

“Runway zero one.  Winds zero two zero at five.  Altimeter three zero decimal one zero.  Taxi Alpha.  Squawk three four zero two.  ContactTower on one one nine decimal zero7 when ready.

Pilot:

 

“ABC.”

 

Permission to Taxi—Circuit Training

Pilot:

 

“Langley Ground, this is GABC.”

Controller:

 

“GABC, Langley Ground.”

Pilot:

 

“GABC is a Cherokee by Hangar 4B.  We have Information ALPHA and we will be doing circuits.”

Controller:

 

“ABC.  Runway one nine.   Winds two zero zero at five, gusting ten.  Altimeter two nine three two.  Taxi Bravo.  Squawk zero five seven three.  ContactTower one one nine decimal zero when ready.”

Pilot:

 

“ABC.”

The controller’s instructions include quite a bit of information and it is a good practice to have a pen and paper ready so that you can copy down the altimeter setting (30.10”Hg in the first example, and 29.32”Hg in the second example) and your transponder code (3402 in the first example, and 0573 in the second example).  At first it all seems rather rushed, but very quickly you will get used to the format with generally does not change.  Finish your radio exchange with the controller before you input your altimeter and transponder setting.
This is a good time to review transponder operations.  The transponder is that small four-digit radio located in the “radio stack” of Langley Flying School aircraft—usually located just below the VHF navigation/communication radio (see right).  As part of the pre-takeoff checklist procedures, the transponder is turned to “ALT” with the Code 1200 selected.8  When you make your initial contact with Control Tower equipped with radar display, ATC prefers to provide you a discrete or specific code when then enables them to attach or “tag” your aircraft identification to their radar display. 
It is a good idea to select the transponder to the “standby” setting before changing the displayed code—this is done to avoid the consequences of inadvertently selecting a seven in the first two digits of the display—Code 7700 is for emergencies, and 7600 is for a communications failure.9
After you have finished your pre-takeoff checks, taxi your aircraft to the hold position and switch your radio to the Tower Controller’s frequency.  Then check for any aircraft that might be on final approach for landing—if an aircraft appears on final approach, it is clear that you will not be given a clearance for takeoff and you might as well wait with your request until the aircraft has landed.  If the approach appears clear, make your request for a takeoff clearance:

Takeoff Clearance

Pilot:

 

“Langley Tower, ABC is ready for takeoff, request back-track.”

Controller:

 

“ABC, back-track approved.  Cleared takeoff Runway 19.”

Pilot:

 

“Cleared takeoff Runway 19, ABC.”

Notice that the “Golf” in GABC identifier is dropped—the controllers already have a record of your full identification following your first contact with the ground controller.  Also, the request for a “back-track” is always made for Runway 19 departures at Langley Airport—this enables use to taxi back (reverse) along this runway to use the extra 100’ that is available.  The back-track must be requested.  Departures for Runway 01 do not require back-track requests as the reverse manoeuvre is not required.  Note, finally, that the takeoff clearance is always repeated back (or “read back” to the controller—this is a Langley Flying School rule intended to reduce the probability of students inadvertently taking off without a clearance—this could be a dangerous mistake as it is common for the controller to hold an aeroplane in position on the runway while helicopter traffic is cleared to cross over the runway.  Here is an example of this “line-up and wait” clearance:

Takeoff Clearance Delay—Line-up and Wait

Pilot:

 

“LangleyTower, ABC is ready for takeoff.”

Controller:

 

“ABC, line-up and wait Runway 01.  Helicopter traffic to cross the runway.”

Pilot:

 

“Line-up and wait Runway 01, ABC.”

Controller:

 

“ABC, cleared takeoff Runway 01.”

Pilot:

 

“Cleared takeoff Runway 01, ABC.”

Arrival

On your first transmission inbound to the airport, simply say your aircraft type and aircraft registration.  Once the controller acknowledges you, provide the controller with your position (remember to include your altitude) and be sure to provide an accurate description of your location and your intentions.  Do not go into great detail (e.g. “I’m two and a half miles east of Ft. Langley near the ferry docks, indicating 22.7 DME on the 074° Radial on the Vancouver VOR”).10  If the controller wants clarification, you will be asked.  Here is an example:

Pilot:

 

“Langley Tower, this is Piper Cherokee GABC.”11

Controller:

 

“Cherokee GABC, Langley Tower, go ahead.”

Pilot:

 

“ABC is two miles East Ft.Langley 2,000’.  Information CHARLIE12.  Inbound for landing.”

Controller:

 

“Winds are one nine zero at five, altimeter two eight point nine four.  Cleared Straight in Runway one nine.  Report crossing the freeway.”

Pilot:

 

“ABC.”

Clearance Limit

When initially contacting the tower during an arrival, the tower will provide you with a “clearance limit,” which is simply the point relative to the airport to which you have been cleared.  For example:

Pilot:

 

“LangleyTower, this is Piper Cherokee GABC . . .  over Aldergrove at one thousand five hundred feet’.  Information CHARLIE.  Inbound for landing.”

Controller:

 

“ABC cleared Right Base, Runway one nine.”

In this instance, the pilot has been cleared to join right base and this is his clearance limit.  When the pilot arrives at the right base position (and it is assumed that he will begin a normal approach descent), the position of the aircraft must be reported to the controller:

 

Pilot:

 

“ABC Right Base, one nine.”

Controller:

 

“ABC, Cleared to Land Runway one nine.”

Pilot:

 

“Cleared to Land Runway one nine, ABC.”

Notice that when the pilot reports reaching the initial clearance limit—in this case the right base position—the controller provides a new clearance limit—i.e., clearance to land on the specified runway.  The controller, however, may not be able to provide you immediately with a landing clearance, in which case you will likely be advised additional information:

Pilot:

 

“ABC Right Base, one nine.”

Controller:

 

“ABC, number 2 behind a Cessna on short final.”

Pilot:

 

“ABC has the traffic (in sight).”

In this example a landing clearance will be provided once the Cessna has cleared the runway.

General Information

When you transmit, be prepared to take down information provided by the controller.  Controllers usually give you a clearance that specifies a destination and how you are to get there.  For example:

Controller:

 

“ABC.  Left Base 25.  Maintain one thousand five hundred feet until advised.”

Unless you are extremely familiar with procedures, this information should be written down—for example, LB 25 – 1500. 13  With all the concentration required for landings and departures, it is too easy to forget a basic instruction.  Always have a paper and pencil at the ready.  An IFR pilot is required to write down clearances for reasons of safety and it is a good habit for all pilots to develop.
Anticipate what the controller will say.  If you are getting a taxi clearance, you know he will provide routing information.  If you are inbound, you know he will tell you the runway in use, circuit clearance, and an assigned altitude.
Make use of conventional expressions: ROGER, WILCO, AFFIRM,14 NEGATIVE.
Be polite.  At the same time, however, recognize “busy” and economize your transmissions accordingly.  Overall, understand that you cannot operate in Class C Airspace (e.g., the Vancouver Terminal Control Area or Langley Airport) without a clearance from the controller; simultaneously, however, the controllers are there to facilitate your movement.  The result is that pilots must make “requests” and operate according to the requirements of the controllers, but they expect controllers to be co-operative and facilitating.  For reasons of safety (but it better be a good one), pilots can always over-rule a controller.  If a controller issues you a clearance that you will compromise safety, simply deline the clearance and advise the controller. If the controller issues you an instruction, you can only not comply for reasons of safety and you must immediately advise the controller.  Remember, controllers have their own safety mandate, and that is safely organizing the movement of numerous aircraft simultaneously.  It is good advice that if you ever feel uncomfortable with a clearance—i.e., it deviates from your normal procedures or requirements to the point that you are uncomfortable with it—do not hesitate to request another clearance.
Reading back, or repeating clearances is sometimes appropriate, and in the case of receiving a clearance to move on to or takeoff from a runway—whether a clearance to taxi to position, or a clearance to takeoff—it is mandatory.15  Additionally, if there is any potential confusion or doubts concerning the clearance you just received, then this is also good reason for a readback.  As mentioned earlier, during taxi or landing, we must read back a “hold short” clearance.  Here are a few more examples:

Controller:

 

“ABC Runway zero one.  Taxi Papa, Alpha.  Hold short Runway zero seven.”

                Pilot:

 

“Papa, Alpha16 to hold short zero seven.  ABC.”

 

Controller:

 

“ABC taxi to position and wait Runway one nine.  Back-track approved.”

Pilot:

 

“To position one nine.  ABC.”

                               

Controller:

 

“ABC cleared takeoff runway three four.  No delay please.  Left turn to five thousand, five hundred feet.”

Pilot:

 

“ABC cleared takeoff three four.  ABC.”

 

Controller:

 

“ABC, we check inbound for landing.  Right base Runway two five.”

Pilot:

 

“Right Base two five, ABC.”

                               

Controller:

 

“ABC, I’d like you to climb to five thousand five hundred feet.”

Pilot:

 

“ABC up to five thousand five hundred."

               

Controller:

 

“ABC you are cleared to land runway two five.”

Pilot:

 

“Cleared to land two five.  ABC.”

               

Controller:

 

“ABC you are cleared to land three four, holding short two eight.”

Pilot:

 

“Cleared to land three four, holding short two eight, ABC.”

Notice here that we say the clearance first, and then add in the identifier at the end.  Nevertheless, it should be emphasized that, in all other occasions, it is normal to simply acknowledge an instruction or communication by saying your aircraft identification:

Controller:

 

“ABC I’d like you to turn left three zero degrees when safely able.”

Pilot:

 

“Alpha Bravo Charlie.”

Remember that, when in a control zone, you must always advise a controller when you have reached a level altitude.  It is a requirement.17

Pilot:

 

“ABC is level at five thousand five hundred feet.”

Controller:

 

“ABC, roger.”

Traffic Advisories

Also, you must acknowledge traffic (other aircraft) cautions or advisories by informing the controller immediately whether or not you have visual contract with the target.  Similarly, as the controller updates you on traffic, you must update him as to whether visual contact exists.  For example:

Controller:

 

“ABC.  Traffic to look for is a Cessna 172 westbound at five thousand five hundred feet, 4 miles at your 10 o’clock position.”

Pilot:

 

“ABC, with the traffic.” or “ABC, negative contact.  Looking.”

 

Controller:

 

“ABC, that traffic is now at your 9 o’clock, 2 miles.”

Pilot:

 

“ABC.  Still negative contact.”

Pilots must be very careful how they respond to traffic information passed by a controller.  Although the pilot is never relieved of the responsibility to maintain safe separation from other aircraft, the controller also has responsibility for separation within his or her controlled airspace.  The controller essentially ends all responsibility for separation once traffic information is acknowledged by the pilot.  Note the ambiguity in the following examples:

Controller:

 

“ABC there is traffic at your 2 o’clock position, west-bound at one thousand five hundred.”

Pilot:

 

“ABC, Roger.”

 

Controller:

 

“ABC you are number two, following traffic on left base.”

Pilot:

 

“ABC.”

So often pilots respond to traffic advisories without relaying back to the controller whether or not they have the target aircraft in sight—simple acknowledgement of this sort technically relieves the controller of further responsibility.  If, on the other hand, you advise the controller “Negative Contact”—meaning that you do not see the target—the controller is “kept in the play” and must provide additional separation information; additionally, the pilot of the target aircraft becomes aware of the continued risk caused by the lack of visual contact.
As well, use careful language when responding to traffic advisories.  You are at risk if you respond with the statements “Contact” or “No contact”—a burp in the VHF transmission could “cover” the word “No” and now you are dealing with a misunderstanding that could be really dangerous!  Instead, use the expression “with the traffic” to indicate traffic sighted, or “negative contact” to indicate traffic not sighted.
It is not all that uncommon to lose sight of traffic after you have already acknowledged that you had it in sight.  Simply ask the controller for an update; unless he hears otherwise, he will assume you are maintaining visual contact and separation.18

Repetitive Circuits

When flying repetitive circuits, the pilot should advise the tower of his position each time he passes mid-field in the downwind leg.  When advising the tower of his position, he should also provide his landing intentions.  For example:

Pilot:

 

“ABC Downwind Left, Runway one nine, touch-and-go.”

Controller:

 

“ABC Cleared touch-and-go, Runway one nine.”

 

Pilot:

 

“ABC Downwind Left, Runway one nine, full stop.”

Controller:

 

“ABC Number 3 behind a Cherokee on short final, and a Cessna on left base.”

In the latter instance, again a landing clearance would be expected when you reach your final approach.

Airports with Two Tower Controllers

At some airports there may be two tower frequencies, an “outer” frequency, and an “inner frequency”—e.g., Victoria Airport and Abbotsford Airport.  Inbound for landing, you first contact the outer frequency controller, and he will subsequently advise you when to switch to the inner controller.  It is always a good idea to have your radios adjusted so that you switch frequencies with the flick of a switch.  The communication will go something like this:

Outer Tower Controller:

 

“ABC, Cleared Left Base Runway zero seven.  Contact tower now on one eight decimal two.”

     Pilot:

 

“ABC, Roger.”

After you switch, check in with the controller.

Pilot:

 

“Tower, ABC with you on a Left Base zero seven."

InnerTower Controller:

 

“ABC Roger, Number 2 behind a Cessna on short final.”

Pilot:

 

“ABC.”

If you are asked to change frequency and have not been provided a circuit clearance, then report your current altitude:19

Pilot:

 

“Tower, ABC with you, level two thousand.”

InnerTower Controller:

 

“ABC Roger, Cleared Left Base, zero seven.”

Pilot:

 

“Left Base zero seven, ABC.”

You don’t have to sound like an Air Canada pilot just yet, but the Examiner will expect you handle radio transmissions and receptions effectively during your flight test.  At first it will sound absolutely confusing, but very quickly you will be able to decipher patterns and then radio work will make sense to you.

Further Readings:

Transportation Safety Board's Risk of collisions on runways

 

References

1 These phrases are “mayday” repeated three times, meaning the pilot is facing “grave and imminent danger and requires immediate assistance,” and “PAN” repeated three times as well, meaning the pilot or controller has an “urgent message concerning the safety of an aircraft or of some person on board or within sight.”

2 This important issue is further discussed below.

3 “Langley Ground” refers to the Air Traffic Controller who is working the ground frequency (121.9 MHz at Langley Airport) and who is in charge of aircraft ground movements at the airport.

4 Hangar 4B is the Langley Flying School Hangar—as a professional courtesy, company and school names are avoided.

5 “Information Charlie” refers here to the Automatic Terminal Information Service (ATIS) identification.  The ATIS is a recorded message that is continuously broadcast over the ATIS frequency—in the case of Langley Airport, the frequency is 124.5 MHz.  The message includes the current winds, altimeter setting, cloud heights, active runway, and any other information ATC wishes to provide to pilots planning on taking off or landing at the airport.  Before they contact the controller, pilots listen to the ATIS; when they advise the controller that they have heard the ATIS, this information does not have to be repeated by the controller.  The content of the ATIS normally changes throughout the day as winds, etc., change, and the phonetic identifier—in this example, “Charlie”—allows everyone to keep track of what information is current.

6 The direction of flight after departure.

7 The frequency for the Air Traffic Controller in charge of aircraft movements on the runway is the Tower Controller, and at Langley Airport, the frequency for this person is 119.0 MHz.

8 The Code 1200 is a generic setting used by all VFR aircraft at or below 12,500’ ASL.

9 ATC radar displays, and the associated software, are designed to set off an aural alarm whenever a “7” has been selected by the pilot (purposefully or accidentally) as the first digit of a transponder code.  When this occurs, the controllers have to hit a reset button, and of course it can apparently become an irritation to them.  There is lots of information in From the Ground Up regarding transponder operations and procedures (check the index at the back of this book).

10 Keep in mind, however, that there is nothing worse than inaccurate position reported—it is unnecessarily hazardous.  If you are two miles south of 232nd interchange, report your position as such—don’t advise the controller “Over 232nd.”

11 We have simply written “GABC” in the above, but of course this should be voiced as “Golf Alpha Bravo Charlie” to make use of the phonetic alphabet.  Notice too that the first letter—in this case “G” is dropped after the first exchange.  Also note that the acknowledgement of a transmission by the pilot simply requires the repeating of the aircraft’s identifier.

12 Information “CHARLIE,” representing the letter “C” in phonetics, refers to the fact that we have listened to the ATIS (Automatic Terminal Information Service) recording named Charlie and have received the current data regarding airport operations.  Importantly, a good pilot always writes down the ATIS so as not to forget crucial information.  After the ATIS is copied, the altimeter setting should be immediately updated—don’t defer this as you might forget.

13 For this and other reasons, a pilot should always have a notebook on hand—something that is small and will not get in the way in the somewhat cramped cockpit environment.

14 Meaning “affirmative.”

15 Note that it is not required by the Canadian Aviation Regulations for a VFR aircraft to readback a clearance unless asked to do so by a controller (readbacks are mandatory for IFR aircraft).  All students of Langley Flying School, however, are required to read back “takeoff” clearances, and “taxi to position” clearance—because of the dangers of collision owing to misunderstanding or miscommunication.

16 Letters—in this case “Papa” for P and “Alpha” for A—are used to identify taxiways (as opposed to numbers used to identify runways).

17 Don’t get confused with reporting clear of the control zone—this is not a requirement (unless the controller specifically tells you to do so) and is considered unnecessary use of the frequency.

18 This is perhaps one of the most dangerous scenarios—all the players think you have a target in sight when in fact you don’t.  Don’t hesitate to say you have lost your target.  As well, it is not uncommon for a pilot to lose contact with a target that has been assigned by a controller and reported in sight by the pilot.  In such a case the pilot must immediately advise the controller that visual contact has been lost—“Tower, Alpha Bravo Charlie has lost the target.”  “ Alpha Bravo Charlie, Tower, aircraft (target) no longer a factor, turn base at your discretion.”

19 The outer and inner controllers are sitting next to each other in the tower cab (control tower) and are continuously exchanging information—really quite interesting how they work.