The AIM section on air traffic control gives standard radio calls for most situations, as well as the phonetic alphabet. In addition, this section of the AIM gives pilots the names of the different facilities and services they use when communicating, along with the Morse code for each letter of the alphabet.
National Airspace System
As a rule, the more complex the airspace, the more complex the communications requirements. All pilots in Class A airspace, for example, must be on an instrument flight plan and adhere to instrument flight rules (IFR) clearances. That means they must obtain clearances from ATC, respond to instructions, acknowledge handoffs; and in general, be in constant radio contact with ATC.
When you operate from Class B and C airspace, clearance delivery and approach control communications requirements can be added to the communications that pilots who fly at Class D airports must contend with. Nontowered airports in Class E and G airspace actually have no communication requirements, but the AIM recommends that pilots make position reports and ask for airport advisories.
Special-use airspace (Prohibited, Restricted, Alert, Warning, Military Operations Area, and Controlled Firing Areas) also exist throughout the nation. There are no special regulatory requirements to communicate with ATC within any special-use airspace. However, if you wish to fly through any special-use airspace, you should contact a flight service station (FSS) within 100 miles of that airspace, or the agency that controls the special use airspace, to check its status. No one can predict every directive or request an air traffic controller may make, but a very clear pattern exists with most types of ATC communication.
ATIS
Automatic terminal information service is a standard weather and airport information feature at almost all towered airports. A human or computer-generated voice gives pilots information about conditions at the airport of departure, the local weather, and NOTAMs (Notices to Airmen) concerning any information pertinent to aviation safety. Besides those airports that provide standard ATIS broadcasts, many other airports are now equipped with computer-generated Automatic Surface Observation System (ASOS) or Automatic Weather Observing System (AWOS) weather information broadcasts.
The frequency and type of service available is noted on VFR and IFR charts, the airport/facility directories (A/FD), and commercially available airport informational guides.
ATIS reports follow a standard format in this order: airport name; ATIS report identifier (a sequential letter from the phonetic alphabet); time in UTC (universal coordinated time, or Zulu); sky condition (ceiling); visibility; temperature and dew point (in degrees Celsius); wind direction and velocity; altimeter setting; active runway and instrument approach information; and NOTAMs.
For example, "Oakland International Airport Information Golf. 2300 Zulu weather. Few clouds at seven thousand, visibility twenty, temperature two-five, dewpoint one-one. Wind two-two-zero at fifteen. Altimeter two-niner-niner-two. Visual approach to Runway two-seven right in use. Taxiway bravo closed. Advise you have Golf."
Unlike other weather reports, ATIS gives surface winds in degrees magnetic (not true north) from the direction they are traveling, and the speed is in knots. Sky condition is given in reference to "Octas" - one-eighth sections of the sky, and temperature and dew point figures are in degrees Celsius. Ceiling height is given as its height above ground level, not mean sea level, so add the airport's elevation to calculate the ceiling's MSL altitude. The ATIS report may omit the ceiling and visibility report if the ceiling is higher than 5,000 feet and the visibility is greater than five miles.
When you fly to an airport with ATIS, you should listen to the current report before calling the tower. Tune in the ATIS frequency before requesting taxi clearance or, in flight, before reaching the terminal airspace (You'll find Class D, C, and B airspace boundaries on VFR sectional and terminal area charts.
Clearance Delivery
Most busy airports - usually Class B or C - have a Clearance Delivery frequency. Before you call ground control, you should contact the Clearance Delivery controller to request and receive a VFR or IFR departure route, altitude, and clearance. For VFR departures, the request is similar to that for taxi clearance. You tell the controller who you are (your aircraft's N-number, where you are on the airport, and where you want to go, i.e. "west departure" or your destination airport.
For example, after listening to ATIS, you should tune the clearance delivery frequency and listen to make sure another pilot is not communicating. Next, say: "Anytown clearance delivery, Trainer zero-zero-zero-zero-Yankee at the east ramp with [ATIS] information Golf, west departure."
The controller will give you a clearance that may include specific instructions on heading and altitude to fly, and a squawk code for your transponder.
For example, "Trainer zero-zero-zero-zero-Yankee, maintain runway heading until reaching two-thousand feet, departure control frequency will be one-two-three-point-four-five [123.45 MHz], squawk one-two-three-four. Contact ground on point seven."
It helps to have a kneeboard pad on which to write this information. When the controller is done, you read back the clearance information. This ensures that the clearance was correct as delivered by the controller, and received by you.
Ground Control
The ground controller is responsible for the movement of aircraft on the surface at airports with control towers. For most ground control facilities, the frequency is 121.? MHz, e.g. 121.9. 121.7, etc. If the tower controller instructs pilots to "contact ground point four," he means 121.4 MHz. The omission of the full number indicates the frequency is 121 plus the decimal value the controller specifies.
Some airports do not use a 121.? ground control frequency so, as with all endeavors in aviation, you should make sure you have the information before you need it. On charts, the ground control frequency is not in the airport's data box, but you can find it on the back with the airport listings. It's also in the A/FD, as well as in commercial airport directories and in loran and GPS databases.
At some airports, the ground controller also handles clearance delivery, and the initial call is similar. You tell the controller who you are, where you are, and what you want to do. For example, "Anytown ground, Trainer zero-zero-zero-zero-Yankee at the east ramp, taxi for takeoff with [ATIS] information Golf, west departure."
The ground controller will respond with your taxi clearance, which you read back: "Trainer zero-zero-zero-zero-Yankee, taxi to Runway three-three."
Tower Control
A control tower is responsible for issuing takeoff and landing clearances, and coordinating traffic flow for all aircraft movements in the airport's Class B, C, or D airspace.
When you reach the run-up area at the departure runway, switch to the tower frequency and monitor it while you perform your pre-takeoff checklist. When you're ready for takeoff, use the same "who, where, and what" format for your initial call to the tower - "Anytown tower, Trainer zero-zero-zero-zero-Yankee , ready for takeoff Runway three-three." If you're at an intersection, give that information to the controller.
Because of conflicting traffic, the controller may not be ready to clear you for takeoff: "Trainer zero-zero-zero-zero-Yankee, hold short," or, if the traffic is landing on another runway you may hear "Trainer zero-zero-zero-zero-Yankee. Taxi into position and hold." It's vital that you read this clearance back to the controller before complying, to ensure it is correct.
The controller also may clear you for takeoff: "Trainer zero-zero-zero-zero-Yankee, cleared for takeoff." You respond with a read-back - "Trainer zero-zero-zero-zero-Yankee, cleared for takeoff." If the controller issues other instructions, such as "Maintain runway heading," include this in your read-back and follow the instructions.
Approach Control
Because they are responsible for directing traffic into and out of airport terminal areas, approach controllers assign transponder codes and provide radar traffic advisories for all pilots flying IFR, and for requesting VFR aircraft on a workload-permitting basis. When flying in Class B or C airspace, approach control provides these services to all aircraft.
Don't forget, however, that when you fly VFR, you have primary responsibility for collision avoidance, based on see-and-avoid procedures. ATC radar traffic advisories can help a pilot detect and avoid conflicting traffic, but it is not a substitute for see and avoid.
The proper approach control frequency is noted on VFR and IFR charts in the vicinity of the appropriate airports and airspace. The same approach control facility is generally divided into many sub-sections, or sectors, each with a discrete frequency. In other words, a pilot approaching from the east may use a different approach control frequency than a pilot approaching from the west. Approach and departure control are in the same ATC facility - usually a radar room at the base of the control tower for the Class B or C airport - but they may use different frequencies.
When you depart Class D airspace, you don't have to notify the tower controller that you are changing frequencies. After takeoff from a Class C or B airport, the tower controller usually tells you when to contact approach/departure control - "Trainer zero-zero-zero-zero-Yankee, contact approach one-two-three point four-five." You read back the frequency to make sure the controller gave it correctly and that you heard it correctly.
After tuning the frequency and listening to make sure the frequency is clear, you report in with "who" and "where." "Anytown departure [or approach, as the tower named it], Trainer zero-zero-zero-zero-Yankee climbing through six-hundred feet for two thousand five hundred."
The approach/departure controller will respond with your aircraft's N-number and "radar contact." From that point on the controller will make traffic advisories and issue heading or altitude changes as necessary to ensure aircraft separation.
When a VFR aircraft exits the approach/departure control airspace and has not requested continuing traffic advisories, the controller will instruct the pilot to "Squawk VFR [1200 code on the transponder], frequency change approved, resume own navigation."
If the pilot has requested radar advisories, the controller will try to arrange a hand-off with the next controller, and instruct the pilot to change to that frequency.
Air Route Traffic Control Center
Often referred to as just "Center," air route traffic control centers are responsible for controlling aircraft en route from one airport to another. As with other ATC radar facilities, IFR traffic takes priority, but center controllers offer traffic advisory services to VFR aircraft on a workload-permitting basis.
Center frequencies are printed on IFR charts, but not on VFR charts. VFR pilots can find the center frequency in an airport's A/FD listing, or by asking the tower controller or flight service station for the frequency. You can also get the frequency from an airport's instrument approach charts. Approach charts are a good source of frequency information for VFR pilots because they clearly list all the airport's frequencies - ATIS, Approach Control, Tower, Ground, and for the outbound flight, Clearance Delivery.
You can request VFR traffic advisories - flight following - with your initial call to ground control by ending the call with "request radar traffic information." If approach and/or center can accommodate your request, the ground controller will give you the appropriate frequency and, possibly, the transponder squawk code. When the tower approves your frequency change, you tune the ATC frequency, listen for activity, and report in, as you would when departing from a Class B or C airport.
In other cases, ground control will give you the appropriate ATC frequency, and you'll have to request flight following from the controller. For this you use another variation of "who, where, and what" - "Anytown Center, Trainer zero-zero-zero-zero-Yankee, southbound from Anytown Airport at two-thousand feet, destination Next Town, request VFR traffic advisories."
If the controller can accommodate your request, he will give you a squawk code, which you dial in on your transponder. He also may ask you to "ident" - push the Ident button on the transponder, which makes your transponder signal brighter on his radar scope. When the controller finds you on his scope, he will report "radar contact."
When the controller sees a possible traffic conflict, he will advise you by saying something like, "Trainer zero-zero-zero-zero-Yankee, traffic ten o'clock, northbound, three-thousand-five-hundred feet."
If you don't spot the traffic immediately, you respond by saying, "Trainer zero-zero-zero-zero-Yankee, no contact." When you do spot the traffic, you report, "Trainer zero-zero-zero-zero-Yankee, traffic in sight." The controller may not advise you of all nearby traffic if it does not pose a collision threat, but he will notify you about potential conflicts. Again, flight following doesn't absolve pilots from their see-and-avoid responsibilities.
Reverse Communication
In-flight communication procedures are basically in the reverse order from the start of the flight. When approaching an airport, you start by listening to ATIS/AWOS/ASOS, move to approach control if applicable, then when instructed, the airport control tower controller, and, after landing, the ground controller. Naturally, you must contact the appropriate controller before entering "his" airspace.
Remember, you cannot enter Class B airspace without a specific clearance - "Trainer zero-zero-zero-zero-Yankee , cleared into Anytown Class Bravo." You must establish two-way communication with ATC before entering Class C airspace, and the controller establishes that communication by stating your aircraft's N-number in response to your initial call-up.
Regardless which facility you talk to, the key to effective ATC communications is telling the controller who you are, where you are, and what you want to do. With practice and patience all pilots can learn to communicate safely and efficiently in the air traffic system. The AIM is a basic source of ATC communication information. Always remember to listen and ask for an explanation or a repeat if you need help or do not understand a directive or call.
Also, make sure you know the light gun signals used by tower controllers in the event of a communications breakdown with an arriving or departing aircraft. All the proper communication technique in the world won't help if you have to contend with a radio/electrical failure. Aviation is filled with acronyms and radio phraseology, but in the end, all ATC controllers speak plain English and will respond in that language if called on to do so.
