Radio Communications


  • Communications are a critical link in the ATC system
  • The most important thought in 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 but not at the price of understanding
    • Controllers must know what you want to do before they can properly carry out their control duties
    • Pilots, must know exactly what the controller wants you to do
    • Since concise phraseology may not always be adequate, use whatever words are necessary to get your message across
  • Talking on the radio however, can be intimidating to even experienced aviators
  • It is therefore important that pilots practice effective communication techniques
  • You must be familiar with ATC Radio Communications
    • Phraseology brings everyone to the same page and allows for an orderly flow of information for instances when you are in congested airspace and there is no time for extra verbiage
  • Calls to air traffic control facilities may be monitored and recorded for records/training
  • Visiting air traffic facilities is recommended, call ahead to ensure they can accommodate
  • Communications are dynamic and can be broken into two environments:
    • Controlled
    • Non-Controlled

Communication Techniques:

  • Listen:

    • If you have just changed frequencies, pause, listen, and make sure the frequency is clear
    • Don't broadcast until you know the frequency is clear or you will jam, or "step on" another call causing them to repeat their call
    • Keying a transmitter when someone is talking will be futile and you will probably jam their receivers causing them to repeat their call
    • Many times you can get the information you want through ATIS or by monitoring the frequency
  • Think:

    • Know what you're going to say before you say it
    • If it is lengthy; e.g., a flight plan or IFR position report, jot it down ahead of your call
  • Talk:

    • The microphone should be very close to your lips and after pressing the mike button
    • Be clear, concise, accurate and don't congest the frequency
    • A pause may be necessary for the first word to transmit
    • When you release the button, wait a few seconds before calling again as the controller or FSS specialist may be jotting down your number, looking for your flight plan, transmitting on a different frequency, or selecting the transmitter for your frequency

Air Traffic Clearance:

  • A clearance to land means that appropriate separation on the landing runway will be ensured. A landing clearance does not relieve the pilot from compliance with any previously issued altitude crossing restriction
  • Pilot:
    • Acknowledges receipt and understanding of an ATC clearance
    • Reads back any hold short of runway instructions issued by ATC
    • Requests clarification or amendment, as appropriate, any time a clearance is not fully understood or considered unacceptable from a safety standpoint
    • Promptly complies with an air traffic clearance upon receipt except as necessary to cope with an emergency. Advises ATC as soon as possible and obtains an amended clearance, if deviation is necessary
  • Controller:
    • Issues appropriate clearances for the operation to be conducted, or being conducted, in accordance with established criteria
    • Assigns altitudes in IFR clearances that are at or above the minimum IFR altitudes in controlled airspace
    • Ensures acknowledgment by the pilot for issued information, clearances, or instructions
    • Ensures that readbacks by the pilot of altitude, heading, or other items are correct. If incorrect, distorted, or incomplete, makes corrections as appropriate

Terminal Communications:

  • Pilots of departing aircraft should communicate with the control tower on the appropriate ground control/clearance delivery frequency prior to starting engines to receive engine start time, taxi and/or clearance information
    • Unless otherwise advised by the tower, remain on that frequency during taxiing and run-up, then change to local control frequency when ready to request takeoff clearance
  • Pilots are encouraged to monitor the local tower frequency as soon as practical consistent with other ATC requirements
  • The tower controller will consider that pilots of turbine-powered aircraft are ready for takeoff when they reach the runway or warm-up block unless advised otherwise
  • The majority of ground control frequencies are in the 121.6 to 121.9 MHz bandwidth
    • Ground control frequencies are provided to eliminate frequency congestion on the tower (local control) frequency and are limited to communications between the tower and aircraft on the ground and between the tower and utility vehicles on the airport, provide a clear VHF channel for arriving and departing aircraft
    • They are used for issuance of taxi information, clearances, and other necessary contacts between the tower and aircraft or other vehicles operated on the airport
    • A pilot who has just landed should not change from the tower frequency to ground control frequency until directed to do so by the controller
    • Normally, only one ground control frequency is assigned at an airport; however, at locations where the amount of traffic so warrants, a second ground control frequency and/or another frequency designated as a clearance delivery frequency, may be assigned
  • A controller may omit the ground or local control frequency if the controller believes the pilot knows which frequency is in use
    • If the ground control frequency is in the 121 MHz bandwidth the controller may omit the numbers preceding the decimal point; e.g., 121.7 "Contact ground point seven."
    • However, if any doubt exists as to what frequency is in use, the pilot should promptly request the controller to provide that information
  • Controllers will normally avoid issuing a radio frequency change to helicopters, known to be single-piloted, which are hovering, air taxiing, or flying near the ground
    • At times, it may be necessary for pilots to alert ATC regarding single pilot operations to minimize delay of essential ATC communications
    • Whenever possible, ATC instructions will be relayed through the frequency being monitored until a frequency change can be accomplished. You must promptly advise ATC if you are unable to comply with a frequency change
    • Also, you should advise ATC if you must land to accomplish the frequency change unless it is clear the landing will have no impact on the other air traffic; e.g., on a taxiway or in a helicopter operating area

Frequency Changes:

  • 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 there is no way of knowing whether you received the instruction or have had radio communications failure
    • At times, a controller/specialist may be working a sector with multiple frequency assignments. In order to eliminate unnecessary verbiage and to free the controller/specialist for higher priority transmissions, the controller/specialist may request the pilot "(Identification), change to my frequency 123.4." This phrase should alert the pilot that the controller/specialist is only changing frequencies, not controller/specialist, and that initial callup phraseology may be abbreviated
    • Example: United Two Twenty-Two on one two three point four" or "one two three point four, United Two Twenty-Two"
  • 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

Controlled Environments:

Non-Controlled Environments:

  • Air Operations Without Operating Control Tower:
    • No substitute for alertness, some aircraft may not have communication abilities
    • Radio communications in non-controlled environment are not required but highly encouraged
    • Remember pilot controlled lighting procedures
    • CTAF:
      • Common Traffic Advisory Frequency used by air and ground vehicles
      • Can be a multicom, unicom, FSS, or tower frequency
      • Obtained in the A/FD, IFR Supplement, charts, FSS
      • Pilots should monitor/communicate on CTAF when 10 miles inbound/outbound and when taxiing, takeoff, landing, etc
      • Request airport advisory prior to making announcements
      • This will include any important information such as winds, runways and procedures
    • Inbound:
      • PILOT: "[Station] radio, Centurion Six Niner Delta Delta is 10 miles south, two thousand, landing [Airport]. I have information [Information], request radar advisories"
    • Outbound:
      • PILOT: "[Station] radio, Centurion Six Niner Delta Delta, ready to taxi to runway 22, VFR, departing to the southwest. I have information [Information], request airport advisory"
    • 3 ways of communication:
      • FSS:
        • Local Airport Advisory (LAA):
          • Provided at airports that have a FSS physically located on the airport
        • Remote Airport Advisory (RAA):
          • Provided when nothing is located on the field
          • RAIS is provided in support of special events
        • Unicom Operator:
          • Unicom frequencies are non-government radio communications
          • Many FBOs will use this frequency
          • Frequency listing on AIM 4-1-11
          • Used for ATC purposes only for revisions, takeoff, arrival or flight plan cancellation time and clearances
        • Self-announce:
          • Pilots should regularly update other pilots in area of intentions
          • Use caution when conducting practice approach procedures
          • Begin a call with "[airport] traffic" and end with "[airport]"
    • Practice Approaches:
      • Announce departing the FAF, location on approach when switched frequencies, terminating or going missed approach
      • When landing at an airport without an operating control tower you will be advised to change to Airport Advisory Frequency (AAF) when direct communications with ATC are no longer required
      • An IAP may not be aligned with the runway therefore if traffic information has not been received the pilot must make an expeditious change to the AAF

Contact Procedures:

  • Initial Contact:

    • The terms initial contact or initial callup 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:
      1. Name of facility called
      2. Full aircraft callsign
      3. When operating on an airport surface, state your position
      4. Type of message
      5. Use the word "over," if required
    • Remote Communication Outlets:

      • Many FSSs have Remote Communication Outlets (RCOs) which can be found on charts inside communication boxes
        • These RCOs can transmit on the same frequency at more than one location
        • To enable the specialist to utilize the correct transmitter, advise the location and the frequency on which you expect a reply
        • Example: St. Louis FSS can transmit on frequency 122.3 at either Farmington, Missouri, or Decatur, Illinois, if you are in the vicinity of Decatur, your callup should be: "Saint Louis radio, Piper Six Niner Six Yankee, receiving Decatur One Two Two Point Three"
      • If radio reception is reasonably assured, inclusion of your request, your position or altitude, and the phrase "(ATIS) Information Charlie received" in the initial contact helps decrease radio frequency congestion
      • Use discretion; do not overload the controller with information unneeded or superfluous
      • If you do not get a response from the ground station, recheck your radios or use another transmitter, but keep the next contact short
      • Example: "Atlanta Center, Duke Four One Romeo, request V-F-R traffic advisories, Twenty Northwest Rome, seven thousand five hundred, over"
  • Initial Contact When Your Transmitting and Receiving Frequencies are Different:

    • If you are attempting to establish contact with a ground station and you are receiving on a different frequency than that transmitted, indicate the VOR name or the frequency on which you expect a reply. Most FSSs and control facilities can transmit on several VOR stations in the area. Use the appropriate FSS call sign as indicated on charts
    • Example: New York FSS transmits on the Kennedy, the Hampton, and the Calverton VORTACs. If you are in the Calverton area, your callup should be "New York radio, Cessna Three One Six Zero Foxtrot, receiving Calverton V-O-R, over"
    • If the chart indicates FSS frequencies above the VORTAC or in the FSS communications boxes, transmit or receive on those frequencies nearest your location
    • When unable to establish contact and you wish to call any ground station, use the phrase "ANY RADIO (tower) (station), GIVE CESSNA THREE ONE SIX ZERO FOXTROT A CALL ON (frequency) OR (V-O-R)." If an emergency exists or you need assistance, so state
  • Subsequent Contacts and Responses to Callup from a Ground Facility:

    • Use the same format as used for the initial contact except you should state your message or request with the callup 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 callups or clearances unless the controller or FSS specialist advises otherwise
    • There are some occasions when controllers must issue time critical instructions to other aircraft, and they may be in a position to observe your response, either visually or on radar
    • If the situation demands your response, take appropriate action or immediately advise the facility of any problem
    • Acknowledge with your aircraft identification, either at the beginning or at the end of your transmission, and 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


  • Use phonetic alphabet when appropriate
  • Acknowledge calls with "Wilco," Roger," Affirmative," or Negative" unless specific read back is required
  • Example: "New York Radio, Mooney Three One One Echo"
  • Example: "Columbia Ground, Cessna Three One Six Zero Foxtrot, south ramp, I-F-R Memphis"
  • Example: "Miami Center, Baron Five Six Three Hotel, request V-F-R traffic advisories"

Call signs:

  • Details can be found in the callsigns section

Obtaining a Clearance:

  • With tower:
    • Ground or specified clearance frequency
  • Without tower:
    • RCO
    • Telephone
    • Clearance delivery if available by geographic area
    • ARTCC when airborne provided you remain in VFR in class E


  • Maintain:
    • Last alt
  • Cruise:
    • Alt to minimum IFR
    • Once descent reported, cannot climb back up
  • Clearance Void Time:
    • Cannot exceed 30 min
  • Hold for Release:
    • Must wait for time or additional instructions
  • Required position reports:
    • "Marvelous VFR 500"
  • Min IFR Altitude
    • Mountains 2000, 4 NM
    • No mountains 1000, 4 NM
  • VFR on top IFR Clearance
    • VFR altitudes with magnetic courses
    • VFR over top - VFR on top of clouds
  • To Continue Approach: (91.175)
    • Stabilized approach
    • Visibility requirements for approach
  • Runway environment:
    • Defined in...

VFR/IFR Flights:

  • A pilot departing VFR, either intending to or needing to obtain an IFR clearance en route, must be aware of the position of the aircraft and the relative terrain/obstructions
  • When accepting a clearance below the MEA/MIA/MVA/OROCA, pilots are responsible for their own terrain/obstruction clearance until reaching the MEA/MIA/MVA/OROCA
    • OROCA is an off−route altitude which provides obstruction clearance with a 1,000 foot buffer in nonmountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the U.S. This altitude may not provide signal coverage from ground−based navigational aids, air traffic control radar, or communications coverage
  • If pilots are unable to maintain terrain/obstruction clearance, the controller should be advised and pilots should state their intentions
Is an an off-route altitude which provides obstruction clearance with a 1,000' buffer in non-mountainous terrain areas and a 2,000' buffer in designated mountainous areas within the U.S. This altitude may not provide signal coverage from ground-based navigational aids, air traffic control radar, or communications coverage

Formation Communications:

  • Whomever is in the lead will have the comms
  • Comm 1 is Pri, "primary"
  • Comm 2 is Aux, "auxiliary"


  • Figures:

    • Figures indicating hundred and thousand in round numbers, as for ceiling heights, and upper wind levels up to 9,900 shall be spoken normally
      • 500: Five Hundred
      • 4,500: Four Thousand Five Hundred
    • Numbers above 9,900 shall be spoken by separating the digits preceding the word "thousand:"
      • 10,000: One Zero Thousand
      • 13,500: One Three Thousand Five Hundred
  • Jet/Victor Routes/Airways:

    • Victor airways are called by their name while jet routes are abbreviated
      • V12: Victor Twelve
      • J533 J: Five Thrity-Three
  • Numbers:

    • All other numbers must be transmitted by prounouncing each digit:
      • 10: One Zero
  • Frequencies:

    • Same as numbers but for the . use "point"
      • Typical in the United States
      • 122.1: One Two Two Point One
    • If operating under ICAO procedures then use "decimal" instead of "point"
      • The FAA will honor such usage by military aircraft and aircraft required under ICAO procedures
  • Altitudes and Flight Levels:

    • Up to but not including 18,000' MSL, state the separate digits of the thousands plus the hundreds if appropriate
      • 12,000: One Two Thousand
      • 12,500: One Two Thousand Five Hundred
    • At and above 18,000' MSL (FL180) state the words "flight level" followed by the separate digits of the flight level:
      • 190: Flight Level One Niner Zero
      • 275: Flight Level Two Seven Five
  • Directions:

    • The three digits of bearing, course, heading, or wind direction should always be magnetic
      • The word "true" must be added when it applies
    • Again, said the same as numbers above, but the word degrees is not typically used
      • (Magnetic course) 005: Zero Zero Five
      • (True course) 050: Zero Five Zero True
      • (Magnetic bearing) 360: Three six zero
      • (Magnetic heading) 100: Heading One Zero Zero
      • (Wind Direction) 220: Wind Two Two Zero
  • Speeds:

    • The separate digits of the speed followed by the word "knots"
      • Controllers may omit the word knots when using speed adjustment procedures, "[Reduce/Increase] speed to two five zero"
        • 250: Two Five Zero
        • 190: One Niner Zero
      • The separate digits of the Mach Number preceded by "Mach"
        • Mach 1.5: Mach One Point Five
        • Mach 0.64: Mach Point Six Four
        • Mach 0.7: Mach Point Seven
  • Time:

    • The FAA uses Coordinated Universal Time (UTC) for all operations and therefore time is generally UTC time unless prefaced with the word "local"
    • The term "Zulu" may be used to denote UTC
      • 0920 UTC: Zero Niner Two Zero Zulu
    • To convert from Standard Time to Coordinated Universal Time:
      • Eastern Standard: Add 5 hours
      • Central Standard: Add 6 hours
      • *Mountain Standard: Add 7 hours
      • Pacific Standard: Add 8 hours
      • Alaska Standard: Add 9 hours
      • Hawaii Standard: Add 10 hours

      • For daylight savings time (summer), subject to +1 hour
      • * Arizona does not observe daylight savings time
    • A reference may be made to local daylight or standard time utilizing the 24-hour clock system
    • The hour is indicated by the first two figures and the minutes by the last two figures:
      • 0000: Zero Zero Zero Zero
      • 0920: Zero Niner Two Zero
    • Time may be stated in minutes only in radiotelephone communications when no misunderstanding is likely to occur
    • Current time in use at a station is stated in the nearest quarter minute in order that pilots may use this information for time checks
      • Fractions of a quarter minute less than 8 seconds are stated as the preceding quarter minute; fractions of a quarter minute of 8 seconds or more are stated as the succeeding quarter minute
        • 0929:05: Time, Zero Niner Two Niner
        • 0929:10: Time, Zero Niner Two Niner and One-Quarter
Phonetic Alphabet/Morse Code
Figure 1: Phonetic Alphabet/Morse Code

Phonetic Alphabet:

  • The International Civil Aviation Organization (ICAO) phonetic alphabet is used by FAA personnel when communications conditions are such that the information cannot be readily received without their use [Figure 1]
  • ATC facilities may also request pilots to use phonetic letter equivalents when aircraft with similar sounding identifications are receiving communications on the same frequency
  • Pilots should use the phonetic alphabet when identifying their aircraft during initial contact with air traffic control facilities
    • Additionally, use the phonetic equivalents for single letters and to spell out groups of letters or difficult words during adverse communications conditions


  • The following listing depicts UNICOM and MULTICOM frequency uses as designated by the Federal Communications Commission (FCC):

Unicom/Multicom Frequency Usage
Figure 2: Unicom/Multicom Frequency Usage
1. In some areas of the country, frequency interference may be encountered from nearby airports using the same UNICOM frequency. Where there is a problem, UNICOM operators are encouraged to develop a “least interference” frequency assignment plan for airports concerned using the frequencies designated for airports without operating control towers. UNICOM licensees are encouraged to apply for UNICOM 25 kHz spaced channel frequencies. Due to the extremely limited number of frequencies with 50 kHz channel spacing, 25 kHz channel spacing should be implemented. UNICOM licensees may then request FCC to assign frequencies in accordance with the plan, which FCC will review and consider for approval

2. Wind direction and runway information may not be available on UNICOM frequency 122.950

  • The following listing depicts other frequency uses as designated by the Federal Communications Commission (FCC):

Other Frequency Usage Designated by FCC
Figure 3: Other Frequency Usage Designated by FCC

Use of UNICOM for ATC Purposes:

  • UNICOM service may be used for ATC purposes, only under the following circumstances:
    • Revision to proposed departure time
    • Takeoff, arrival, or flight plan cancellation time
    • ATC clearance, provided arrangements are made between the ATC facility and the UNICOM licensee to handle such messages

ASA Communications Trainer
Figure 4: ASA Communications Trainer


  • Be alert to the sounds or the lack of sounds in your receiver
  • Check your volume, recheck your frequency, and make sure that your microphone is not stuck in the transmit position
    • 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
  • If the assigned frequency is completely blocked by this type of interference, use the procedures described for en route IFR radio frequency outage to establish or reestablish communications with ATC
  • Be sure that you are within the performance range of your radio equipment and the ground station equipment
    • Remote radio sites do not always transmit and receive on all of a facility's available frequencies, particularly with regard to VOR sites where you can hear but not reach a ground station's receiver
    • Remember that higher altitudes increase the range of VHF "line of sight" communications
The Pilot's Radio Communications Handbook
Figure 5: The Pilot's Radio Communications Handbook
Squawk VFR - Your Guide to VFR Communications
Figure 6: Squawk VFR - Your Guide to VFR Communications

Communications for VFR Flights:

  • FSSs and Supplemental Weather Service Locations (SWSLs) are allocated frequencies for different functions; for example, 122.0 MHz is assigned as the En Route Flight Advisory Service frequency at selected FSSs. In addition, certain FSSs provide Local Airport Advisory on 123.6 MHz or other frequencies which can be found in the A/FD. If you are in doubt as to what frequency to use, 122.2 MHz is assigned to the majority of FSSs as a common en route simplex frequency
    • In order to expedite communications, state the frequency being used and the aircraft location during initial callup:
      • Example: "Dayton radio, November One Two Three Four Five on one two two point two, over Springfield V-O-R, over"
  • Certain VOR voice channels are being utilized for recorded broadcasts; i.e., ATIS, HIWAS, etc. These services and appropriate frequencies are listed in the A/FD. On VFR flights, pilots are urged to monitor these frequencies. When in contact with a control facility, notify the controller if you plan to leave the frequency to monitor these broadcasts
  • If you are struggling with VFR communications, consider these communication guides


  • Communication can be broken with surprising speed and disastrous results
  • Pilots are to maintain vigilance in monitoring air traffic control radio communications frequencies for potential traffic conflicts with their aircraft especially when operating on an active runway and/or when conducting a final approach to landing
  • The Pilot/Controller Glossary is an outstanding resource for learning what certain words or phrases mean
    • Good phraseology enhances safety and is the mark of a professional pilot whereas jargon, chatter, and slang have no place in ATC communications
  • It is recommended to review the pilot/controller glossary from time to time to sharpen communication skills
  • If you're having a difficult time with radio communications or just wish to improve, check out Aviation Communication Training guides
  • Consider different types of Headsets to suit your needs
  • Hear it for yourself at Live