Radio communications are a critical link in the ATC system. The link can be a strong bond between pilot and controller or it can be broken with surprising speed and disastrous results. Discussion herein provide basic procedures for new pilots and also highlights safe operating concepts for all pilots.

The single, most important thought in pilot-controller communications is understanding. It is essential, therefore, that pilots acknowledge each radio communication with ATC by using the appropriate aircraft call sign. Brevity is important, and contacts should be kept as brief as possible, but the controller must know what you want to do before he can properly carry out his control duties. And you, the pilot, must know exactly what he wants you to do. Since concise phraseology may not always be adequate, use whatever words are necessary to get your message across.

All pilots will find the Standard ICAO Phraseology very helpful in learning what certain words or phrases mean. Good phraseology enhances safety and is the mark of a professional pilot. Jargon, chatter and "CB" slang have no place in ATC communications.

Listen before you transmit. Many time you can get the information you want through ATIS Or by monitoring the frequency. Except for a few situations where some frequency overlap occurs, If you hear someone else talking, the keying of your transmitter will be futile and you will probably jam their receivers causing them to repeat their call. If you have just changed frequencies, pause, listen and make sure the frequency is clear.

Think before keying your transmitter. Know what you want to say and if it is lengthy. e.g., a flight plan or IFR position report, jot it down. Speak in a normal conversational tone, no need to shout. When you release the button, wait a few seconds before calling again. The controller or FSS specialist may be jotting down your number, looking for your flight plan, or busy with traffic.

Be alert to the sounds or lack of sounds in Roger Wilco. Check your volume, recheck your frequency and make sure that your microphone is not stuck in the transmit position, and that it is NOT voice activated. Frequency blockage can, and has, occurred for extended periods of time due to unintentional transmitter operation. This type of interference is commonly referred to as a "stuck mike," and controllers may refer to it in this manner when attempting to assign an alternate frequency.

The term initial contact or initial call up means the first radio call you make to a given facility, Or the first call to a different controller or FSS specialist within a facility. Use the following format: Name of facility being called. Your full aircraft identification as filed in the flight plan or as discussed under Aircraft Call Signs below. Type of message to follow or your request if it is short and sweet.

EXAMPLE: "Denver Center, Frontier five seven six requesting IFR clearance to..."

If radio reception is reasonably assured, inclusion of your request, your position or altitude, the phrase "Have numbers" or "Information Charlie received" (for ATIS) in the initial contact helps decrease radio frequency congestion. Use discretion and do not overload the controller with information he/she does not need.

EXAMPLE: "Denver Approach Frontier four two two, with you flight level one eight zero, inbound to Denver International..."

Subsequent Contacts and Responses to Call up from a Ground Facility:
Use the same format as used for initial contact except you should state your message or request with the call up in one transmission. The ground station name and the word "Over" may be omitted if the message requires an obvious reply and there is no possibility for misunderstandings. You should acknowledge all call ups or clearances unless the controller advises otherwise. There are some occasions when the controller must issue time-critical instructions to other aircraft and he may be in a position to observe your response, either visually or on radar. If the situation demands your response, take appropriate action. Acknowledgment is made with one of the words "Wilco, Roger, Affirmative, Negative" or other appropriate remarks (e.g., "Piper two one four lima, ROGER"). If you have been receiving services (e.g., VFR traffic advisories and you are leaving the area or changing frequencies), advise the ATC facility and terminate contact.

Acknowledgment of Frequency Changes: When advised by ATC to change frequencies, acknowledge the instruction. If you select the new frequency without an acknowledgment, the controller's workload is increased because he has no way of knowing whether you received the instruction or have had radio communications failure.

Compliance with Frequency Changes: When instructed by ATC to change frequencies, select the new frequency as soon as possible unless instructed to make the change at a specific time, fix, or altitude. A delay in making the change could result in an untimely receipt of important information. If you are instructed to make the frequency change at a specific time, fix, or altitude, monitor the frequency you are on until reaching the specified time, fix, or altitudes unless instructed otherwise by ATC.

ATC Frequency Change Procedures:
The following phraseology will be used by controllers to effect a frequency change:
EXAMPLE: (Aircraft Identification) CONTACT (facility name or location name and terminal function) (frequency) AT (time, fix or altitude).

The following phraseology should be utilized by pilots for establishing contact with the designated facility;

When a position report will be made:
EXAMPLE: (Name) CENTER, (aircraft identification), (position/flight level).

At times controllers will ask pilots to verify that they are at a particular altitude. The phraseology used will he: "VERIFY AT (altitude)." In climbing or descending situations, controllers may ask pilots to "VERIFY ASSIGNED ALTITUDE AS (altitude)." Pilots should confirm that they are at the altitude stated by the controller or that the assigned altitude is correct as stated. If this is not the case, they should inform the controller of the actual altitude being maintained or the different assigned altitude. CAUTION: Pilots should not take action to change their actual altitude or different assigned altitude to the altitude stated in the controllers verification request unless the controller specifically authorizes a change.

ATIS (Airport Terminal Information Service)
ATIS broadcasts a repetitive tape containing information such as runways in use, altimeter setting, weather conditions, wind direction and velocity, communication frequencies and other information pertinent to operating in the vicinity of or on the airport. Prior to departure, you should listen to ATIS before to calling Clearance Delivery or Ground Control. On arrival, listen to ATIS before calling Approach Control.

Whenever the weather or other conditions change during the day, the recording is updated. Each time a new recording is made, it is assigned an identifier name, starting with ALPHA. Subsequent updates are identified as BRAVO, CHARLIE, etc. When making initial contact with approach Control or Tower on arrival, and Clearance Delivery or Ground Control on departure you should state that you have the ATIS information. Use it’s identifier name; i.e. CHARLIE.

Clearance Delivery
At larger airports which have a high volume of operations, Clearance Delivery provides initial departure information to the pilot. This frees Ground Control to concentrate directing traffic on the ramps and taxiways. Clearance Delivery coordinates information with Departure Control by assigning a transponder code prior to becoming airborne. This saves time both for the Ground Controller and the Departure Controller. It allows the pilot to set-up the transponder and departure frequencies prior to departure, as well as giving the pilot advance information on departure procedures. Not always available though, on VATSIM, but if it is, look for something like DEN_DEL or DEN_V_DEL.
EXAMPLE: “Denver Clearance Delivery, Frontier four three four, request IFR clearance to Seattle, with information bravo."

Clearance delivery will respond like this:

"Frontier four three four, you are cleared to Seattle via the rockies three departure red table transition, then as filed, climb maintain one zero thousand, expect flight level three one zero, one zero minutes after departure. Expect runway three four. Altimeter two niner point niner two, squawk one three five two. Departure Control frequency is one two six point seven five." Something along these lines, every controller is different, and if its center giving you clearance, expect the following at the end of the clearance delivery "expect runway three four, departure with me, squawk one three five two." Read back everything exactly. And when the controller is satisfied that you have the correct routing "frontier four three four read back correct, advise ready to taxi, clear push back and engine start." Acknowledge this "roger, we will call, frontier four three four.

Ground Control
Ground Control is responsible for the flow of aircraft taxiing on the ramps and taxiways. On your call up, identify your aircraft type and number, your location on the airport, with request to taxi. If no Clearance Delivery is at the airport, include the ATIS Identifier

EXAMPLE: "Denver ground, Frontier six three five at concourse alpha, request taxi to the active (or you can say the runway you were assigned to in your clearance delivery)."

The controller’s response will be similar to: "Frontier three five four taxi to three four via golf. Advise holding short."

You respond: Roger, taxi to three four via golf, hold short." (Note: the term ROGER means that you understand the instruction, and know how to comply)

You should read back the controllers instructions, in particular any HOLD SHORT instructions. You are under the supervision of Ground Control during your taxi and run-up. When you are ready to depart, you then switch to the tower frequency.

Tower Control
The tower controls operations on the runways and in the airspace around the airport. After you have completed all pre-flight actions, call the tower on their frequency with the following information.

-Address the Tower: "Denver tower"
-Who you are: "Frontier three five four"
-Your intention: "holding short, runway three four."

The tower may respond: "Roger, taxi into position and hold." OR "Roger, cleared for takeoff, squawk normal (take it off SQUAWK STANDBY)

You acknowledge the instruction, and read back the holding instruction: "Roger, taxi to position and hold Frontier three five four." OR "Roger, cleared for takeoff, runway three four, Frontier three five four." You should monitor the tower frequency until told by the tower to contact Departure Control or until tower ends the communication.

Tower will shortly hand you off to the Departure Control: "Frontier three five four, contact Denver departure on one three two point seven five. See ya."

You respond: "Roger, over to departure, one three two point seven five, Frontier three five four."

Departure Control
Departure Control is a Radar Service at Class B and C airports. The Departure Controller will assign altitudes and headings as required to provide traffic separation. If the controller’s instructions place you into a position to violate VFR rules (such as clearance from clouds) , you should inform the controller to get an amended clearance.

Your initial call to departure control will be something like this: "Denver departure, Frontier three five four, climbing through eight thousand for ten."

Departure may respond: "Frontier three five four, radar contact. Turn left to two three zero and climb to two three thousand."

After you are clear of the airport traffic area, the controller may terminate radar: "Frontier three five four, leaving my airspace, radar service terminated. Resume your own navigation." OR if there is a center "Frontier three five four, contact Denver center on one three three point niner, good day.

You respond: "Roger. Own nav, have a good day, Frontier three five four." OR "Roger, over to center, good day, Frontier three five four."

Approach Control
Approach Control is a radar service similar to Departure Control. Contact with Approach Control is mandatory prior to entry into Class B and C airspace. On initial call-up, identify type and number of aircraft, position, altitude and destination. The controller will respond with a “SQUAWK” code for the transponder.

Example: The initial call-up can be: "Denver approach, Frontier three five four, with you, ten thousand five hundred, inbound Denver on the dandd three arrival."

Response: "Frontier three five four, Denver approach, good evening, squawk two three one five and Ident."

You set the squawk code 2315 into the transponder, press the ident button in Squawk Box, and respond: "Roger, squawk two three one five, ident, Frontier three five four."

After the controller identifies you on the radar screen, the controller will confirm: " Frontier three five four, radar contact, two miles south of Dandd intersection. Continue as filed for Denver." OR they will give you a lower altitude they want you at, and possibly a vector for your landing runway.

You respond: "Roger, continue as filed Frontier three five four." OR read back anything they tell you.

You acknowledge the instruction. The radar controller will continue to track your “blip” on the radar screen, give traffic advisories as necessary, and again, they may vector you into the downwind leg in the pattern. The controller will then hand you off to the tower controller for landing instructions.

If you are flying through Class C airspace without landing, tell the controller the planned route of flight and altitude you wish to maintain. Radar Flight Following will be granted outside the class B or C airspace on a “workload permitting” basis upon pilot request. The radar surveillance usually can be provided up to 20 or 30 miles from the radar site.

There have been a number of modes of transponder operation during it’s history. The mode now required for operation in Class B and C airspace is Mode C. This mode couples an encoder in the altimeter which reports the altitude in hundreds of feet. The Transponder also has 4 digital dials, each with numbers 0 through 7. Therefore, number combinations from 0000 to 7777 can be dialed in. This is called the “SQUAWK code. The numbers 7500, 7600, 7700 and 7777 are reserved for special use

-7700 - emergency
-7600 - lost radio communications
-7500 - code for hijacking
-7777 - used by military

The transponder operates by receiving an interrogation signal from the radar station. It in turn returns certain coded information back to the radar when the transponder is set for normal operation. The SQUAWK code and the altitude in hundreds of feet are returned to the radar. The controllers radar scope shows a “blip” on the radar screen along with the SQUAWK code and altitude.

A Mode C altitude reporting transponder is required:

When flying at or above 10,000 feet
· When flying within Class B Mode C veil (30 Nm around a Class B airport). (Note: there are exceptions for operations into smaller airports which lie within the 30 Nm veil).
· When flying in or above Class C airspace
· When crossing the US Air Defense Identification Zone (ADIZ).

A button, called the IDENT BUTTON, when depressed in Squawk Box, sends a special identifying signal to the radar. The IDENT should only be sent when requested by the controller.

Controllers may use the following terminology when referring to transponder operation

· SQUAWK (number) - set the 4 digit code into the transponder. Example: Squawk 4316.
· IDENT - depress the IDENT Button within Squawk Box
· Squawk (number) and IDENT - set code into the transponder dials, then IDENT.
· SQUAWK STANDBY - Access the pull down menu, check SQUAWK STANDBY
· SQUAWK MAYDAY - select code 7700
· SQUAWK VFR - select code 1200 when operating without ATC contact. 1200 is known as the VFR squawk code.

Precautions In the Use of Call Signs:
Improper use of call signs can result in pilots executing a clearance intended for another aircraft. Call signs should never be abbreviated on an initial contact or at any time when other aircraft call signs have similar numbers/sounds or identical letters/number (e.g., Cessna 6132F, Cessna 1622F, Baron 123F, Cherokee 7732F, etc.).

EXAMPLE: Assume that a controller issues an approach clearance to an aircraft at the bottom of a holding stack and an aircraft with a similar call sign (at the top of the stack) acknowledges the clearance with the last two or three numbers of his call sign. If the aircraft at the bottom of the stack did not hear the Clearance and intervene, flight safety would be affected, and there would be no reason for either the controller or pilot to suspect that anything is wrong. This kind of "human factors" error can strike swiftly and is extremely difficult to rectify.

Pilots; therefore, must be certain that aircraft identification is complete and clearly identified before taking action on an ATC clearance. ATC specialists will not abbreviate call signs of air carrier or other civil aircraft having authorized call signs. ATC specialists may initiate abbreviated call signs of other aircraft by using the prefix and the last three digits/letters of the aircraft identification after communications are established. The pilot may use the abbreviated call sign in subsequent contacts with the ATC specialist. When aware of similar/identical call signs, ATC specialists will take action to minimize errors by emphasizing certain numbers/letters, by repeating the entire call sign, repeating the prefix, or by asking pilots to use a different call sign temporarily. General aviation (non airline) pilots should state the aircraft type, model or manufacturer's name followed by the digits/letters of the registration number. When the aircraft manufacturer's name or model is stated, the prefix "N" is dropped (e.g. Aztec Two Four Six Four Alpha).

EXAMPLE: Cessna one papa charlie.

Air Taxi or other commercial operators not having FAA authorized call signs should prefix their normal identification with the phonetic word 'Tango".

EXAMPLE: Tango Aztec one bravo hotel.

Air carriers and commuter air carriers having FAA authorized call signs should identify themselves by stating the complete call sign, using group form for the numbers and the word "heavy" if appropriate.

EXAMPLE: Frontier four zero eight heavy.

Military aircraft use a variety of systems including serial numbers, word call signs and combinations of letters/numbers. Examples include Army Copter 48931, Air Force 61782, Reach 31792, Pat 157, Air Evac 17652, Navy Golf Alfa Kilo 21, Marine 4 Charlie 36, etc.

Air Ambulance Flights:
Civilian air ambulance flights responding to medical emergencies (carrying patients, organ donors, organs, or other urgently needed lifesaving medical material) will be expedited by ATC when necessary. When expeditious handling is required, add the word "LIFEGUARD" in the remarks of the flight plan. In radio communication, use the call sign "LIFEGUARD" followed by the aircraft type and registration letters/numbers. When requested by the pilot, necessary notification to expedite ground handling of patients, etc., is provided by ATC. Extreme discretion is necessary in using the term "LIFEGUARD." It is intended only for those missions of an urgent medical nature and for use only for that portion of the flight requiring expedited handling. Similar provisions have been made for the use of "AIR EVAC" and "MED EVAC" by military air ambulance flights, except that these military flights will receive priority handling only when specifically requested.

EXAMPLE: Lifeguard Cessna two six four six.

Student Pilots Radio Identification:
VATSIM desires to help the student pilot in acquiring sufficient practical experience in the environment in which he will be required to operate. To receive additional assistance while operating in areas of concentrated air traffic, a student pilot need only identify himself as a student pilot during his initial call to a VATSIM radio facility

EXAMPLE: Denver Tower this is Frontier one five six, student.

This special identification will alert ATC personnel and enable them to provide the student pilot with such extra assistance and consideration as be may need. This procedure is not mandatory.

Ground Station Call Signs
Pilots, when calling a ground station, should begin with the name of the facility being called followed by the type of the facility being called, as indicated in the following examples.

• Airport Unicom: "Denver Unicom"
• FAA FSS (En Route flight Advisory Service (Weather): "Denver Flight Watch"
• Airport Traffic Control Tower: "Denver Tower"
• Clearance Delivery Position (IFR): "Denver Clearance Delivery"
• Ground Control Position in Tower: "Denver Ground"
• Radar or Non-Radar Approach Control Position: "Denver Approach"
• Radar Departure Control Position: "Denver Departure"
• FAA Air Route Traffic Control Center: "Denver Center"

What is the ICAO Phonetic Alphabet? Well, its basically a way for pilots and controllers to interact by using phrases for letters, rather than saying just the letter by itself. It clears up a lot of mis-understandings with letters that sound the same. Such as T and C. Below, is the standard phraseology for all pilots and controllers to exercise. Trust me, in time this will become second nature to you. As an example, if an airplane has a registration (or "N" number) of N175RW, the correct way to say the letters is..."NOVEMBER one seven five ROMEO WHISKEY." Pretty easy.