GEN 3.4 Communication Service

  1. Responsible Authority
    1. The authority responsible for the administration of communications services in the U.S. is the Federal Aviation Administration, Communications, Information and Network Programs Group, AJM-31.
      Postal Address:
      Federal Aviation Administration
      Communications, Information and Network Programs Group, AJM-31
      800 Independence Ave, SW
      Washington, D.C. 20591
      AFTN Address: KRWAYAYX
      Commercial Telegraphic Address:
      FAA WASH
  2. Area of Responsibility
    1. Communications services are available on a continuous basis without charge to the user. The Air Traffic Services Division is responsible for the establishment of the operational requirements of the U.S. communications system. Responsibility for the day to day operation of these services resides with the local air traffic facility. Enquiries or complaints regarding any communications services or facilities should be referred to the relevant air traffic facility or to the Federal Aviation Administration, Air Traffic Operations Services, as appropriate.
  3. Types of Services
    1. Radio Navigation Service
      1. Various types of air navigation aids are in use today, each serving a special purpose. These aids have varied owners and operators, namely: the Federal Aviation Administration, the military services, private organizations; and individual states and foreign governments. The Federal Aviation Administration has the statutory authority to establish, operate, and maintain air navigation facilities and to prescribe standards for the operation of any of these aids which are used by both civil and military aircraft for instrument flight in federally controlled airspace. These aids are tabulated in the Chart Supplement by State.
      2. Pilots should be aware of the possibility of momentary erroneous indications on cockpit displays when the primary signal generator for a ground-based navigational transmitter (for example, a glideslope, VOR, or nondirectional beacon) is inoperative. Pilots should disregard any navigation indication, regardless of its apparent validity, if the particular transmitter was identified by NOTAM or otherwise as unusable or inoperative.
      3. The following types of radio navigation aids are provided in the U.S.:
        1. VHF Direction-Finding (VHF-DF).
        2. LF Non-Directional Beacon (NDB).
        3. VHF Omni-Directional Radio Range (VOR).
        4. Distance Measuring Equipment (DME).
        5. Tactical Air Navigation (TACAN).
        6. Instrument Landing System (ILS).
        7. Final Approach Simplified Directional Facility (SDF).
        8. Precision Approach Radar (PAR) at certain military aerodromes.
        9. Global Positioning System (GPS).
      4. NAVAID Service Volumes
        1. The FAA publishes Standard Service Volumes (SSVs) for most NAVAIDs. The SSV is a three-dimensional volume within which the FAA ensures that a signal can be received with adequate signal strength and course quality, and is free from interference from other NAVAIDs on similar frequencies (e.g., co-channel or adjacent-channel interference). However, the SSV signal protection does not include potential blockage from terrain or obstructions. The SSV is principally intended for off-route navigation, such as proceeding direct to or from a VOR when not on a published instrument procedure or route. Navigation on published instrument procedures (e.g., approaches or departures) or routes (e.g., Victor routes) may use NAVAIDs outside of the SSV, when Extended Service Volume (ESV) is approved, since adequate signal strength, course quality, and freedom from interference are verified by the FAA prior to the publishing of the instrument procedure or route.


          A conical area directly above the NAVAID is generally not usable for navigation.

        2. A NAVAID will have service volume restrictions if it does not conform to signal strength and course quality standards throughout the published SSV. Service volume restrictions are first published in Notices to Air Missions (NOTAMs) and then with the alphabetical listing of the NAVAIDs in the Chart Supplement. Service volume restrictions do not generally apply to published instrument procedures or routes unless published in NOTAMs for the affected instrument procedure or route.
        3. VOR/DME/TACAN Standard Service Volumes (SSV).
          1. The three original SSVs are shown in FIG GEN 3.4-1 and are designated with three classes of NAVAIDs: Terminal (T), Low (L), and High (H). The usable distance of the NAVAID depends on the altitude Above the Transmitter Height (ATH) for each class. The lower edge of the usable distance when below 1,000 feet ATH is shown in FIG GEN 3.4-2 for Terminal NAVAIDs and in FIG GEN 3.4-3 for Low and High NAVAIDs.

            FIG GEN 3.4-1
            Original Standard Service Volumes

            A graphic depicting the three original SSVs;  Terminal, Low, and High.

            FIG GEN 3.4-2
            Lower Edge of the Terminal Service Volume (in altitude ATH)

            Graphic depicting the service volume lower edge terminal.

            FIG GEN 3.4-3
            Lower Edge of Low and High Service Volumes (in altitude ATH)

            A graphic depicting the Service Volume Lower Edge Standard High and Low.
          2. With the progression of navigation capabilities to Performance Based Navigation (PBN), additional capabilities for off-route navigation are necessary. For example, the VOR MON (See ENR 4.1, paragraph 2.6) requires the use of VORs at 5,000 feet AGL, which is beyond the original SSV ranges. Additionally, PBN procedures using DME require extended ranges. As a result, the FAA created four additional SSVs. Two of the new SSVs are associated with VORs: VOR Low (VL) and VOR High (VH), as shown in FIG GEN 3.4-4. The other two new SSVs are associated with DME: DME Low (DL) and DME High (DH), as shown in FIG GEN 3.4-5. The SSV at altitudes below 1,000 feet for the VL and VH are the same as FIG GEN 3.4-3. The SSVs at altitudes below 12,900 feet for the DL and DH SSVs correspond to a conservative estimate of the DME radio line of sight (RLOS) coverage at each altitude (not including possible terrain blockage).

            FIG GEN 3.4-4
            New VOR Service Volumes

            A graphic depicting Two of the new SSVs associated with VORs: VOR Low (VL) and VOR High (VH).

            FIG GEN 3.4-5
            New DME Service Volumes

            A graphic depicting Two of the new SSVs associated with DME: DME Low (DL) and DME High (DH).


            1. In the past, NAVAIDs at one location typically all had the same SSV. For example, a VORTAC typically had a High (H) SSV for the VOR, the TACAN azimuth, and the TACAN DME, or a Low (L) or Terminal (T) SSV for all three. A VOR/DME typically had a High (H), Low (L), or Terminal (T) for both the VOR and the DME. A common SSV may no longer be the case at all locations. A VOR/DME, for example, could have an SSV of VL for the VOR and DH for the DME, or other combinations.
            2. The TACAN azimuth will only be classified as T, L, or H.
          3. TBL GEN 3.4-1 is a tabular summary of the VOR, DME, and TACAN NAVAID SSVs, not including altitudes below 1,000 feet ATH for VOR and TACAN Azimuth, and not including ranges for altitudes below 12,900 feet for TACAN and DME.

            TBL GEN 3.4-1
            VOR/DME/TACAN Standard Service Volumes

            SSV Designator

            Altitude and Range Boundaries

            T (Terminal)

            From 1,000 feet ATH up to and including 12,000 feet ATH at radial distances out to 25 NM.

            L (Low Altitude)

            From 1,000 feet ATH up to and including 18,000 feet ATH at radial distances out to 40 NM.

            H (High Altitude)

            From 1,000 feet ATH up to and including 14,500 feet ATH at radial distances out to 40 NM. From 14,500 ATH up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet ATH up to and including 45,000 feet ATH at radial distances out to 130 NM.

            VL (VOR Low)

            From 1,000 feet ATH up to but not including 5,000 feet ATH at radial distances out to 40 NM. From 5,000 feet ATH up to but not including 18,000 feet ATH at radial distances out to 70 NM.

            VH (VOR High)

            From 1,000 feet ATH up to but not including 5,000 feet ATH at radial distances out to 40 NM. From 5,000 feet ATH up to but not including 14,500 feet ATH at radial distances out to 70 NM. From 14,500 ATH up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet ATH up to and including 45,000 feet ATH at radial distances out to 130 NM.

            DL (DME Low)

            For altitudes up to 12,900 feet ATH at a radial distance corresponding to the LOS to the NAVAID. From 12,900 feet ATH up to but not including 18,000 feet ATH at radial distances out to 130 NM

            DH (DME High)

            For altitudes up to 12,900 feet ATH at a radial distance corresponding to the LOS to the NAVAID. From 12,900 ATH up to and including 60,000 feet at radial distances out to 100 NM. From 12,900 feet ATH up to and including 45,000 feet ATH at radial distances out to 130 NM.

        4. Nondirectional Radio Beacon (NDB) SSVs. NDBs are classified according to their intended use. The ranges of NDB service volumes are shown in TBL GEN 3.4-2. The distance (radius) is the same at all altitudes for each class.

          TBL GEN 3.4-2
          NDB Service Volumes


          Distance (Radius) (NM)

          Compass Locator








          *Service ranges of individual facilities may be less than 50 nautical miles (NM). Restrictions to service volumes are first published as a Notice to Air Missions and then with the alphabetical listing of the NAVAID in the Chart Supplement.

      5. NAVAIDs with Voice
        1. Voice equipped en route radio navigational aids are under the operational control of either a Flight Service Station (FSS) or an approach control facility. Facilities with two-way voice communication available are indicated in the Chart Supplement and aeronautical charts.
        2. Unless otherwise noted on the chart, all radio navigation aids operate continuously except during shutdowns for maintenance. Hours of operation of facilities not operating continuously are annotated on charts and in the Chart Supplement.
    2. Mobile Service
      1. The aeronautical stations (Airport Traffic Control Towers, Air Route Traffic Control Centers, and Flight Service Stations) maintain a continuous watch on their assigned frequencies during the published hours of service unless otherwise notified. An aircraft should normally communicate with the air-ground control radio station which exercises control in the area in which it is flying. Aircraft should maintain continuous watch on the appropriate frequency of the control station and should not abandon watch, except in an emergency, without informing the control radio station.
      2. Flight Service Stations (FSSs) are allocated frequencies for different functions. For Airport Advisory Service, the pilot should contact the FSS on 123.6 MHz. Individually assigned FSS frequencies are listed in the Chart Supplement under the FSS entry. If you are in doubt as to what frequency to use to contact an FSS, transmit on 122.1 MHz and advise the FSS of the frequency on which you are receiving.
    3. Fixed Service
      1. Messages to be transmitted over the Aeronautical Fixed Service are accepted only if they satisfy the requirements of:
        1. ICAO Annex 10, Vol. II, Chapter 3, paragraph 3.3.
        2. Are prepared in the form specified in Annex 10.
        3. The text of an individual message does not exceed 200 groups.
      2. General aircraft operating messages, Class B traffic, including reservation messages pertaining to flights scheduled to depart within 72 hours, must not be acceptable for transmission over U.S. government operated telecommunications circuits except in those cases where it has been determined by the U.S. that adequate non-government facilities are not available.
    4. Broadcast Service
      1. The following meteorological broadcasts are available for the use of aircraft in flight:
        1. Sub-Area Meteorological Broadcast (Volmet).
        2. VHF RTF Meteorological Broadcasts.
      2. Full details of broadcast service are given in GEN 3.5, Meteorological Services.
      3. All broadcast services to aircraft are provided in the English language only.
  4. Aeronautical Fixed Services
    1. General
      1. All U.S. ATC facilities have the ability to communicate with all other ATS facilities via either telephone or other domestic telecommunications systems. Circuit diagrams depicting these connections are not available for this publication due to the number of ATS facilities available in the U.S.
    2. The Domestic Telecommunications Network
      1. The U.S. Domestic telecommunications network is an automated system operating through the National Airspace Data Interchange Network (NADIN) in Atlanta, GA, and Salt Lake City, UT. All Flight Service Stations (FSS) and Air Route Traffic Control Centers (ARTCC) connect through the NATCOM. All FSS and ARTCC facilities have both transmit and receive capabilities.
      2. Airport Air Traffic Control Towers (ATCT) and Approach Control (A/C) Facilities do not connect with this system. Messages originating from or destined to these facilities are relayed through the associated FSS. Associated FSSs for these facilities are listed in the Chart Supplement U.S.
      3. Airport administrative offices, airport managers or airport administrative officials do not normally connect with the domestic telecommunications network. Urgent messages destined to these facilities must be forwarded to the associated FSS for relay or the message must be sent through commercial telegraphic systems.
    3. The International Message Network (Aeronautical Fixed Telecommunications Network-AFTN)
      1. AFTN messages originating from outside the U.S. domestic telecommunications system must be prepared in accordance with ICAO procedures. All incoming messages are received by NADIN and relayed to the addressed facility through automated procedures. The automated system will interpret the international address group and automatically forward the message via the domestic system to the addressee. For example, a message addressed KIKKYFYX will be accepted by AFTN and relayed to IKK (Kankakee FSS). The Kankakee FSS will manually relay this message to the intended recipient when necessary. Intended recipients are to be addressed in the first line of the message text.
      2. All international flight plans entering the U.S. system must adhere to ICAO format. These flight plans are to be forwarded, via AFTN, to each affected, U.S. controlled, Flight Information Region (FIR) or Air Route Traffic Control Center (ARTCC) outside the continental U.S. (e.g., Miami FIR, San Juan, P.R. ARTCC) or the first FIR/ARTCC for flights entering the continental U.S. (e.g., New York FIR/ARTCC). If the flight plan content is acceptable, it is entered into the ARTCC system and is forwarded, automatically, via ARTCC computer, to all subsequently affected domestic ARTCCs. Flight plans which cannot be processed are rejected at the point of entry into the U.S. system and the originator is queried. Format adherence, once the flight plan is in the ARTCC system, is assured since each of the ARTCCs are automated facilities. Each subsequent ARTCC computer, however, will process incoming flight plans according to the requested routing. Flight plans can be rejected by any ARTCC due to errors in routing. Rejected flight plans, regardless of reason or point of rejection, are held in suspense until the needed clarification is received by the ARTCC facility.
    4. Radio Communications Phraseology and Techniques
      1. General
        1. 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 provides basic procedures for new pilots and also highlights safe operating concepts for all pilots.
        2. 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/she can properly carry out his/her control duties. And you, the pilot, must know exactly what he/she wants you to do. Since concise phraseology may not always be adequate, use whatever words are necessary to get your message across. 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.
        3. All pilots will find the Pilot/Controller Glossary 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. The Pilot/Controller Glossary is the same glossary used in the ATC controller's handbook. We recommend that it be studied and reviewed from time to time to sharpen your communication skills.
      2. Radio Technique
        1. Listen before you transmit. Many times 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 frequency, pause for your receiver to tune, listen, and make sure the frequency is clear.
        2. 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. (But do not lock your head in the cockpit.)
        3. The microphone should be very close to your lips and after pressing the mike button, a slight pause may be necessary to be sure the first word is transmitted. Speak in a normal conversational tone.
        4. 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, transmitting on a different frequency, or selecting his/her transmitter to your frequency.
        5. Be alert to the sounds or 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 in paragraph 12., Two-Way Radio Communications Failure.
        6. 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 facilities' available frequencies, particularly with regard to VOR sites where you can hear but not reach a ground station's receiver. Remember that higher altitude increases the range of VHF “line of sight” communications.
      3. Aircraft Call Signs
        1. 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/numbers, (e.g., Cessna 6132F, Cessna 1622F, Baron 123F, Cherokee 7732F, etc.).


          As an 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/her 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.

        2. 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. Pilots should use the phrase “Verify clearance for (your complete call sign)” if doubt exists concerning proper identity.
        3. Civil aircraft 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.


          “Bonanza Six Five Five Golf,” “Douglas One One Zero,” “Breezy Six One Three Romeo Experimental” (Omit “Experimental” after initial contact).

        4. Air taxi or other commercial operators not having FAA authorized call signs should prefix their normal identification with the phonetic word “Tango.”


          “Tango Aztec Two Four Six Four Alpha.”

        5. 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 “super” or “heavy” if appropriate.


          “United Twenty-five, Midwest Commuter Seven Eleven.”

        6. Military aircraft use a variety of systems including serial numbers, word call signs and combinations of letters/numbers.


          “Army Copter 48931” “Air Force 61782” “REACH 31792” “Pat 157” “AirEvac 17652” “Navy Golf Alpha Kilo 21” “Marine 4 Charlie 36”

        7. Air Ambulance Flights. Because of the priority afforded air ambulance flights in the ATC system, extreme discretion is necessary when using the term “MEDEVAC.” It is only intended for those missions of an urgent medical nature and to be utilized only for that portion of the flight requiring priority handling. It is important for ATC to be aware of a flight's MEDEVAC status, and it is the pilot's responsibility to ensure that this information is provided to ATC.
          1. To receive priority handling from ATC, the pilot must verbally identify the flight in radio transmissions by stating “MEDEVAC” followed by the FAA authorized call sign (ICAO 3LD, US Special, or local) or the aircraft civil “N” registration numbers/letters.


            If the aircraft identification of the flight indicates DAL51, the pilot states “MEDEVAC Delta Fifty One”.

            If the aircraft identification of the flight indicates MDSTR1, the pilot states “MEDEVAC Medstar One”.

            If the aircraft identification of the flight indicates N123G or LN123G, the pilot states “MEDEVAC One Two Three Golf”.

          2. If requested by the pilot, ATC will provide additional assistance (e.g., landline notifications) to expedite ground handling of patients, vital organs, or urgently needed medical materials. When possible make these requests to ATC via methods other than through ATC radio frequencies.
          3. MEDEVAC flights may include:
            1. Civilian air ambulance flights responding to medical emergencies (e.g., first call to an accident scene, carrying patients, organ donors, organs, or other urgently needed lifesaving medical material).
            2. Air carrier and air taxi flights responding to medical emergencies. The nature of these medical emergency flights usually concerns the transportation of urgently needed lifesaving medical materials or vital organs, but can include inflight medical emergencies. It is imperative that the company/pilot determine, by the nature/urgency of the specific medical cargo, if priority ATC assistance is required.
          4. When filing a flight plan, pilots may include “L” for “MEDEVAC” with the aircraft registration letters/digits and/or include “MEDEVAC” in Item 11 (Remarks) of the flight plan or Item 18 (Other Information) of an international flight plan. However, ATC will only use these flight plan entries for informational purposes or as a visual indicator. ATC will only provide priority handling when the pilot verbally identifies the “MEDEVAC” status of the flight as described above (in subparagraph


            Civilian air ambulance aircraft operating VFR and without a filed flight plan are eligible for priority handling in accordance with subparagraph c.1 above.


            AIP, ENR 1.10, Flight Planning (Restriction, Limitation or Advisory Information)

          5. ATC will also provide priority handling requested. These aircraft may file “HOSP” or “AIR EVAC” in either Item 11 (Remarks) of the flight plan or Item 18 of an international flight plan. For aircraft identification in radio transmissions, civilian pilots will use normal call signs when filing "HOSP" and military pilots will use the "EVAC" call sign.
        8. Student Pilots Radio Identification. The FAA desires to help the student pilot in acquiring sufficient practical experience in the environment in which he/she will be required to operate. To receive additional assistance while operating in areas of concentrated air traffic, a student pilot need only identify himself/herself as a student pilot during his/her initial call to an FAA radio facility. For instance, “Dayton Tower, Fleetwing One Two Three Four, Student Pilot.” This special identification will alert FAA air traffic control personnel and enable them to provide the student pilot with such extra assistance and consideration as he/she may need. It is recommended that student pilots identify themselves as such, on initial contact with each clearance delivery prior to taxiing, ground control, tower, approach and departure control frequency, or FSS contact.
      4. Description of Interchange or Leased Aircraft
        1. Controllers issue traffic information based on familiarity with airline equipment and color/markings. When an air carrier dispatches a flight using another company's equipment and the pilot does not advise the terminal ATC facility, the possible confusion in aircraft identification can compromise safety.
        2. Pilots flying an “interchange” or “leased” aircraft not bearing the colors/markings of the company operating the aircraft should inform the terminal ATC facility on first contact the name of the operating company and trip number, followed by the company name as displayed on the aircraft, and aircraft type.


          AIR CAL 311, United (Interchange/Lease), Boeing 727.

      5. Ground Station Call Signs
        1. 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.

          TBL GEN 3.4-3
          Calling a Ground Station


          Call Sign

          Airport UNICOM

          “Shannon UNICOM”

          FAA Flight Service Station

          “Chicago Radio”

          Airport Traffic Control Tower

          “Augusta Tower”

          Clearance Delivery Position (IFR)

          “Dallas Clearance Delivery”

          Ground Control Position in Tower

          “Miami Ground”

          Radar or Nonradar Approach Control Position

          “Oklahoma City Approach”

          Radar Departure Control Position

          “St. Louis Departure”

          FAA Air Route Traffic Control Center

          “Washington Center”

    5. Radio Communications Phraseology
      1. Phonetic Alphabet
        1. 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. Air traffic control 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.

          TBL GEN 3.4-4


          Morse Code




          ● −




          − ● ● ●




          − ● − ●


          (CHAR-LEE) or


          − ● ●







          ● ● − ●




          − − ●




          ● ● ● ●




          ● ●




          ● − − −




          − ● −




          ● − ● ●




          − −




          − ●




          − − −




          ● − − ●




          − − ● −




          ● − ●




          ● ● ●







          ● ● −


          (YOU-NEE-FORM) or


          ● ● ● −




          ● − −




          − ● ● −




          − ● − −




          − − ● ●




          ● − − − −




          ● ● − − −




          ● ● ● − −




          ● ● ● ● −




          ● ● ● ● ●




          − ● ● ● ●




          − − ● ● ●




          − − − ● ●




          − − − − ●




          − − − − −



      2. Figures
        1. Figures indicating hundreds and thousands in round numbers, as for ceiling heights, and upper wind levels up to 9,900, must be spoken in accordance with the following:


          1. 500 . . . . . . . .five hundred
          2. 4,500 . . . . . . . .four thousand five hundred
        2. Numbers above 9,900 must be spoken by separating the digits preceding the word “thousand.”


          1. 10,000 . . . . . . . .one zero thousand
          2. 13,500 . . . . . . . .one three thousand five hundred
        3. Transmit airway or jet route numbers as follows:


          1. V12. . . . . . . .Victor Twelve
          2. J533. . . . . . . .J Five Thirty- Three
        4. All other numbers must be transmitted by pronouncing each digit.


          10 . . . . . . . .one zero

        5. When a radio frequency contains a decimal point, the decimal point is spoken as “Point.”


          122.1. . . . . . . .one two two point one


          ICAO procedures require the decimal point be spoken as “decimal.” The FAA will honor such usage by military aircraft and all other aircraft required to use ICAO procedures.

      3. Altitudes and Flight Levels
        1. Up to but not including 18,000 feet MSL, by stating the separate digits of the thousands, plus the hundreds.


          1. 12,000 . . . . . . . .one two thousand
          2. 12,500 . . . . . . . .one two thousand five hundred
        2. At and above 18,000' MSL (FL 180) by stating the words “flight level” followed by the separated digits of the flight level.


          1. 190 . . . . . . . .Flight Level One Niner Zero
          2. 275 . . . . . . . .Flight Level Two Seven Five
      4. Directions
        1. The three digits of a magnetic course, bearing, heading or wind direction, should always be magnetic. The word “true” must be added when it applies.


          1. (Magnetic course) 005 . . . . . . . .zero zero five
          2. (True course) 050 . . . . . . . .zero five zero true
          3. (Magnetic bearing) 360 . . . . . . . .three six zero
          4. (Magnetic heading) 100 . . . . . . . .heading one zero zero
          5. (Wind direction) 220 . . . . . . . .wind two two zero
      5. Speeds
        1. The separate digits of the speed are to be followed by the word “KNOTS” except that controllers may omit the word “KNOTS” when using speed adjustment procedures (e.g., “REDUCE/INCREASE SPEED TO TWO FIVE ZERO”).


          1. (Speed) 250 . . . . . . . . two five zero knots
          2. (Speed) 190 . . . . . . . . one niner zero knots
        2. The separate digits of the Mach number are to be preceded by the word “Mach.”


          1. (Mach number) 1.5 . . . . . . . .Mach one point five
          2. (Mach number) 0.64. . . . . . . .Mach point six four
          3. (Mach number) 0.7. . . . . . . .Mach point seven
      6. Time
        1. FAA uses Coordinated Universal Time (UTC) for all operations. The word “local” or the time zone equivalent must be used to denote local when local time is given during radio and telephone communications. The term “ZULU” may be used to denote UTC.


          0920 UTC. . . . . . . .zero niner two zero,
          zero one two zero pacific or local,

          or one twenty AM

        2. To convert from Standard Time to UTC:

          TBL GEN 3.4-5
          Standard Time to Coordinated Universal Time

          Eastern Standard Time

          Add 5 hours

          Central Standard Time

          Add 6 hours

          Mountain Standard Time

          Add 7 hours

          Pacific Standard Time

          Add 8 hours

          Alaska Standard Time

          Add 9 hours

          Hawaii Standard Time

          Add 10 hours


          For daylight time, subtract 1 hour.

        3. 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.


          1. 0000 . . . . . . . . zero zero zero zero
          2. 0920 . . . . . . . . zero niner two zero
        4. Time may be stated in minutes only (two figures) in radio telephone communications when no misunderstanding is likely to occur.
        5. 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 or more, but less than eight seconds more, are stated as the preceding quarter minute; fractions of a quarter minute of eight seconds or more are stated as the succeeding quarter minute.


          1. 0929:05 . . . . . . . .time, zero niner two niner
          2. 0929:10 . . . . . . . .time, zero niner two niner and one-quarter
      7. Communications with Tower when Aircraft Transmitter/Receiver or Both are Inoperative
        1. Arriving Aircraft
          1. Receiver Inoperative. If you have reason to believe your receiver is inoperative, remain outside or above Class D airspace until the direction and flow of traffic has been determined; then, advise the tower of your type aircraft, position, altitude, intention to land, and request that you be controlled with light signals. When you are approximately 3 to 5 miles from the airport, advise the tower of your position and join the airport traffic pattern. From this point on, watch the tower for light signals. Thereafter, if a complete pattern is made, transmit your position when downwind and/or turning base leg.
          2. Transmitter Inoperative. Remain outside or above Class D airspace until the direction and flow of traffic has been determined, then join the airport traffic pattern. Monitor the primary local control frequency as depicted on sectional charts for landing or traffic information, and look for a light signal which may be addressed to your aircraft. During hours of daylight, acknowledge tower transmissions or light signals by rocking your wings. At night, acknowledge by blinking the landing or navigational lights.


            To acknowledge tower transmissions during daylight hours, hovering helicopters will turn in the direction of the controlling facility and flash the landing light. While in flight, helicopters should show their acknowledgment of receiving a transmission by making shallow banks in opposite directions. At night, helicopters will acknowledge receipt of transmissions by flashing either the landing or the search light.

          3. Transmitter and Receiver Inoperative. Remain outside or above Class D airspace until the direction and flow of traffic has been determined, then join the airport traffic pattern and maintain visual contact with tower to receive light signals.
        2. Departing Aircraft. If you experience radio failure prior to leaving the parking area, make every effort to have the equipment repaired. If you are unable to have the malfunction repaired, call the tower by telephone and request authorization to depart without two-way radio communications. If tower authorization is granted, you will be given departure information and requested to monitor the tower frequency or watch for light signals, as appropriate. During daylight hours, acknowledge tower transmissions or light signals by moving the ailerons or rudder. At night, acknowledge by blinking the landing or navigation lights. If radio malfunction occurs after departing the parking area, watch the tower for light signals or monitor tower frequency.
      8. Contact Procedures
        1. Initial Contact
          1. The terms “initial contact” or “initial call up” mean the first radio call you make to a given facility, or the first call to a different controller/FSS specialist within a facility. Use the following format:
            1. Name of facility being called.
            2. Your full aircraft identification as filed in the flight plan or as discussed under aircraft call signs.
            3. When operating on an airport surface, state your position.
            4. The type of message to follow or your request if it is short; and
            5. The word “Over,” if required.


              1. “New York Radio, Mooney Three One One Echo.”
              2. “Columbia Ground, Cessna Three One Six Zero Foxtrot, south ramp, I-F-R Memphis.”
              3. “Miami Center, Baron Five Six Three Hotel, request VFR traffic advisories.”
          2. Many FSSs are equipped with remote communications outlets and can transmit on the same frequency at more than one location. The frequencies available at specific locations are indicated on charts above FSS communications boxes. To enable the specialist to utilize the correct transmitter, advise the location and frequency on which you expect a reply.


            St. Louis FSS can transmit on frequency 122.3 at either Farmington, MO, or Decatur, IL. 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.”

          3. 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. When you do not get a response from the ground station, recheck your radios or use another transmitter and keep the next contact short.


            “Atlanta Center, Duke Four One Romeo, request VFR traffic advisories, Twenty Northwest Rome, Seven Thousand Five Hundred, over.”

      9. Initial Contact when your Transmitting and Receiving Frequencies are Different
        1. 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.


          New York FSS transmits on the Kennedy, Deer Park and Calverton VORTACs. If you are in the Calverton area, your callup should be “New York Radio, Cessna Three One Six Zero Foxtrot, receiving Riverhead VOR, over.”

        2. If the chart indicates FSS frequencies above the VORTAC or in FSS communications boxes, transmit or receive on those frequencies nearest your location.
        3. 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 (VOR).” If an emergency exists or you need assistance, so state.
      10. 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 callups or clearances unless the controller of FSS specialist advises otherwise. There are some occasions when the controller must issue time-critical instructions to other aircraft and he/she 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 such as VFR traffic advisories and you are leaving the area or changing frequencies, advise the ATC facility and terminate contact.
    6. Acknowledgement of Frequency Changes
      1. When advised by ATC to change frequencies, acknowledge the instruction. If you select the new frequency without an acknowledgement, the controller's workload is increased because he/she has no way of knowing whether you received the instruction or have had radio communications failure.
      2. 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 134.5.” This phrase should alert the pilot that he/she is only changing frequencies, not controller/specialist, and that initial call-up phraseology may be abbreviated.


        “United Two Twenty-two on One Three Four Point Five” or “One Three Four Point Five, United Two Twenty-two.”

      3. 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.
  5. Communications for VFR Flights
    1. FSSs and Supplemental Weather Service Locations (SWSLs) are allocated frequencies for different functions; for example, in Alaska, certain FSSs provide Local Airport Advisory on 123.6 MHz or other frequencies which can be found in the Chart Supplement U.S. 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 call-up.


      Dayton radio, November One Two Three Four Five on one two two point two, over Springfield V-O-R, over.

    2. Certain VOR voice channels are being utilized for recorded broadcasts; for example, ATIS. These services and appropriate frequencies are listed in the Chart Supplement U.S. 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.
  6. Over-water Flights Radio Procedure
    1. Pilots should remember that there is a need to continuously guard the VHF emergency frequency 121.5 MHz when on long over-water flights, except when communications on other VHF channels, equipment limitations, or cockpit duties prevent simultaneous guarding of two channels. Guarding of 121.5 MHz is particularly critical when operating in proximity to flight information region (FIR) boundaries; for example, operations on Route R220 between Anchorage and Tokyo, since it serves to facilitate communications with regard to aircraft which may experience in-flight emergencies, communications, or navigational difficulties. (Reference ICAO Annex 10, Vol II Paras. and
  7. Radio Communications and Navigation Facilities
    1. A complete listing of air traffic radio communications facilities and frequencies and radio navigation facilities and frequencies is contained in the Chart Supplement U.S. Similar information for the Pacific and Alaskan areas is contained in the Pacific and Alaskan Supplements (See GEN 3.2, Aeronautical Charts).
  8. U.S. Aeronautical Telecommunications Services
    1. The following services are available for aircraft engaged in international or overseas flight.
    2. The aeronautical voice communication stations listed are available to and utilized by the U.S. Federal Aviation Administration Air Traffic Control Centers for air traffic control purposes.
    3. The frequencies in use will depend upon the time of day or night and conditions which affect radio wave propagation. Voice communications handled on a single channel simplex basis (i.e., with the aircraft and the ground station using the same frequency for transmission and reception) unless otherwise noted in remarks.
    4. The stations will remain on continuous watch for aircraft within their communications areas and, when practicable, will transfer this watch to another station when the aircraft reaches the limit of the communications area.
    5. Stations listed below which are designated “FAA” are operated by the U.S. Federal Aviation Administration. Stations designated “Radio” are operated by Collins Aerospace, Incorporated, (formerly ARINC). Contact the Aviation Voice Services Support Section at (See TBL GEN 3.4-6.)
    6. All users of the North Atlantic HF MWARA services should consult International NOTAMS and ICAO Regional Supplementary Procedures, Document 7030, for current procedures concerning the operational use of the North Atlantic HF families. At present, procedures for the distribution of HF communications traffic in the North Atlantic are:
      1. All aircraft registered in the hemisphere west of 30W should use family alpha on the southern routes and family bravo on the central and northern routes. (Southern routes are those which enter the New York, San Juan and Santa Maria FIRs. The central and northern routes comprise all others).
      2. All aircraft registered in the hemisphere east of 30W should use family alpha on the southern routes and family charlie on the central and northern routes.
      3. All aircraft should use family alpha on the southern route and family delta on the central and northern routes while outside the organized track system (OTS).
      4. Aircraft registered in Australia will use families designated to aircraft registered east of 30W.
    7. Aircraft operating in the Anchorage Arctic CTA/FIR beyond line of sight range of remote control VHF air/ground facilities operated from the Anchorage ACC, must maintain communications with Cambridge Bay radio and a listening or SELCAL watch on HF frequencies of the North Atlantic D (NAT D) network (2971 kHz, 4675 kHz, 8891 kHz and 11279 kHz). Additionally, Cambridge Bay radio can provide Anchorage and Fairbanks surface observations and terminal forecasts to flight crews on request.

      TBL GEN 3.4-6

      Station and Operating Agency

      Radio Call

      Transmitting Frequencies



      Honolulu Radio

      122.6 122.2 #121.5 MHz

      #Emergency. Frequency 122.1 also available for receiving only.

      MIAMI (FAA)

      Miami Radio

      126.7 118.4 126.9 122.2 122.4 122.75 123.65 127.9 MHz

      Local and Short Range.



      #121.5 MHz


      NEW YORK (FAA)

      New York Radio (Volmet)

      3485* 6604 10051 13270* kHz

      *3485 Volmet broadcasts from 1 hour after sunset to 1 hour before sunrise.




      *13270 Volmet broadcasts from 1 hour before sunrise to 1 hour after sunset.




      Broadcasts at H+00-05; Aerodrome Forecasts, Detroit, Chicago, Cleveland. Hourly Reports, Detroit, Chicago, Cleveland, Niagara Falls, Milwaukee, Indianapolis.




      Broadcasts at H+05-10; SIGMET, (Oceanic-New York). Aerodrome Forecasts, Bangor, Pittsburgh, Charlotte. Hourly Reports, Bangor, Pittsburgh, Windsor Locks, St. Louis, Charlotte, Minneapolis.




      Broadcasts at H+10-15; Aerodrome Forecasts, New York, Newark, Boston. Hourly reports, New York, Newark, Boston, Baltimore, Philadelphia, Washington.




      Broadcasts at H+15-20; SIGMET (Oceanic-Miami/San Juan). Aerodrome Forecasts, Bermuda, Miami, Atlanta. Hourly Reports, Bermuda, Miami, Nassau, Freeport, Tampa, West Palm Beach, Atlanta.




      Broadcasts at H+30-35; Aerodrome Forecasts, Niagara Falls, Milwaukee, Indianapolis. Hourly Reports Detroit, Chicago, Cleveland, Niagara Falls, Milwaukee, Indianapolis.




      Broadcasts at H+35-40; SIGMET (Oceanic-New York). Aerodrome Forecasts, Windsor Locks, St. Louis. Hourly Reports, Bangor, Pittsburgh, Windsor Locks, St. Louis, Charlotte, Minneapolis.




      Broadcasts at H+40-45; Aerodrome Forecasts, Baltimore, Philadelphia, Washington. Hourly Reports, New York, Newark, Boston, Baltimore, Philadelphia, Washington.




      Broadcasts at H+45-50; SIGMET (Oceanic-Miami/San Juan). Aerodrome Forecasts, Nassau, Freeport. Hourly Reports, Bermuda, Miami, Nassau, Freeport, Tampa, West Palm Beach, Atlanta.


      New York

      3016 5598 8906 13306 17946 21964 kHz

      North Atlantic Family A Network.



      2962 6628 8825 11309 13354 17952 kHz

      North Atlantic Family E Network.



      2887 3455 5550 6577 8846 11396 kHz

      Caribbean Family A Network.



      5520 6586 8918 11330 13297 17907 kHz

      Caribbean Family B Network.



      3494 6640 8933 11342 13330 17925 kHz

      Long Distance Operations Control (LDOC) Service (phone-patch). Communications are limited to operational control matters only. Public correspondence (personal messages) to/from crew or passengers cannot be accepted.
      Note: New York RADIO can also provide HF communications over South America on these LDOC frequencies through their remote site located in Santa Cruz, Bolivia.



      129.90 MHz

      Extended range VHF. Coverage area includes Canadian Maritime Provinces, and oceanic routes to the Caribbean, from Boston, New York and Washington areas to approximately 250 nautical miles from the east coast.



      130.7 MHz

      Extended range VHF. Full period service is provided within most of the Gulf of Mexico. Also on routes between Miami and San Juan to a distance of approximately 250 nautical miles from the Florida coast and within approximately 250 nautical miles of San Juan.
      Note: New York RADIO also provides VHF communications over the Northern two-thirds of Mexico on 130.7 MHz for 14 CFR Section 121.99 compliance.




      Aircraft operating within the New York Oceanic FIR.


      San Francisco

      3413 3452 5574 5667 6673 8843 10057 11330 13354 kHz

      Central East Pacific One Network.



      2869 5547 11282 13288 21964 kHz

      Central East Pacific Two Network.



      2998 4666 6532 8903 11384 13300 17904 21985 kHz

      Central West Pacific Network.



      3467 5643 8867 13261 17904 kHz

      South Pacific Network.



      2932 5628 6655 8915 8951 10048 11330 13273 13339 17946 21925 kHz

      North Pacific Network



      3494 6640 8903 11342 13348 17925 21964 kHz

      Long Distance Operations Control (LDOC) Service (phone-patch). Communications are limited to operational control matters only. Public correspondence (personal messages) to/from crew or passengers cannot be accepted.
      Note: San Francisco RADIO can also provide HF communications along the polar routes on these LDOC frequencies through their remote site located at Barrow, Alaska.



      131.95 MHz

      Extended range VHF. Coverage area includes area surrounding the Hawaiian Islands and Guam. Coverage extends out approximately 250 NM from Hawaii and from the West coast.



      129.40 MHz

      For en route communications for aircraft operating on Seattle/Anchorage/Routes.




      Aircraft operating within the Oakland and Anchorage Oceanic FIRs.



      122.5 122.2 #121.5 MHz


      SAN JUAN P.R. (FAA)

      San Juan

      #121.5 122.2 126.7 123.65 #243.0 255.4 114.0 113.5 108.2 108.6 109.0 110.6 MHz

      Unscheduled broadcasts H+00, H+15, H+30 and H+45 as appropriate, for Weather and Military Activity Advisories, on 110.6, 109.0, 108.6, 108.2, 113.5, and 114.0 MHz. #Emergency. For frequencies 114.0, 113.5, 108.2 and 109.0 MHz use 122.1 MHz for transmissions to San Juan Radio. For frequency 108.6 use 123.6 MHz.

  9. Selective Calling System (SELCAL) Facilities Available
    1. The SELCAL is a communication system which permits the selective calling of individual aircraft over radio-telephone channels from the ground station to properly equipped aircraft, so as to eliminate the need for the flight crew to constantly monitor the frequency in use.

      TBL GEN 3.4-7





      New York




      San Francisco




  10. Special North Atlantic, Caribbean, and Pacific Area Communications
    1. VHF air-to-air frequencies enable aircraft engaged on flights over remote and oceanic areas out of range of VHF ground stations to exchange necessary operational information and to facilitate the resolution of operational problems.
    2. Frequencies have been designated as follows:

      TBL GEN 3.4-8



      North Atlantic

      123.45 MHz


      123.45 MHz


      123.45 MHz

  11. Distress and Urgency Communications
    1. A pilot who encounters a distress or urgency condition can obtain assistance simply by contacting the air traffic facility or other agency in whose area of responsibility the aircraft is operating, stating the nature of the difficulty, pilot's intentions, and assistance desired. Distress and urgency communications procedures are prescribed by the International Civil Aviation Organization (ICAO), however, and have decided advantages over the informal procedure described above.
    2. Distress and urgency communications procedures discussed in the following paragraphs relate to the use of air ground voice communications.
    3. The initial communication, and if considered necessary, any subsequent transmissions by an aircraft in distress should begin with the signal MAYDAY, preferably repeated three times. The signal PAN-PAN should be used in the same manner for an urgency condition.
    4. Distress communications have absolute priority over all other communications, and the word MAYDAY commands radio silence on the frequency in use. Urgency communications have priority over all other communications except distress, and the word PAN-PAN warns other stations not to interfere with urgency transmissions.
    5. Normally, the station addressed will be the air traffic facility or other agency providing air traffic services, on the frequency in use at the time. If the pilot is not communicating and receiving services, the station to be called will normally be the air traffic facility or other agency in whose area of responsibility the aircraft is operating, on the appropriate assigned frequency. If the station addressed does not respond, or if time or the situation dictates, the distress or urgency message may be broadcast, or a collect call may be used, addressing “Any Station (Tower) (Radio) (Radar).”
    6. The station addressed should immediately acknowledge a distress or urgency message, provide assistance, coordinate and direct the activities of assisting facilities, and alert the appropriate Search and Rescue coordinator if warranted. Responsibility will be transferred to another station only if better handling will result.
    7. All other stations, aircraft and ground, will continue to listen until it is evident that assistance is being provided. If any station becomes aware that the station being called either has not received a distress or urgency message, or cannot communicate with the aircraft in difficulty, it will attempt to contact the aircraft and provide assistance.
    8. Although the frequency in use or other frequencies assigned by ATC are preferable, the following emergency frequencies can be used for distress or urgency communications, if necessary or desirable:
      1. 121.5 MHz and 243.0 MHz. Both have a range generally limited to line of sight. 121.5 MHz is guarded by direction finding stations and some military and civil aircraft. 243.0 MHz is guarded by military aircraft. Both 121.5 MHz and 243.0 MHz are guarded by military towers, most civil towers, flight service stations, and radar facilities. Normally ARTCC emergency frequency capability does not extend to radar coverage limits. If an ARTCC does not respond when called on 121.5 MHz or 243.0 MHz, call the nearest tower or flight service station.
      2. 2182 kHz. The range is generally less than 300 miles for the average aircraft installation. It can be used to request assistance from stations in the maritime service. 2182 kHz is guarded by major radio stations serving Coast Guard Rescue Coordination Centers and Coast Guard units along the sea coasts of the U.S. and shores of the Great Lakes. The call “Coast Guard” will alert all Coast Guard Radio Stations within range. 2182 kHz is also guarded by most commercial coast stations and some ships and boats.
  12. Two-Way Radio Communications Failure
    1. It is virtually impossible to provide regulations and procedures applicable to all possible situations associated with two-way radio communications failure. During two-way radio communications failure when confronted by a situation not covered in the regulation, pilots are expected to exercise good judgment in whatever action they elect to take. Should the situation so dictate, they should not be reluctant to use the emergency action contained in 14 CFR Section 91.3(b).
    2. Whether two-way communications failure constitutes an emergency depends on the circumstances, and in any event is a determination made by the pilot. 14 CFR Section 91.3 authorizes a pilot to deviate from any rule to the extent required to meet an emergency.
    3. In the event of two-way radio communications failure, ATC service will be provided on the basis that the pilot is operating in accordance with 14 CFR Section 91.185. A pilot experiencing two-way communications failure should (unless emergency authority is exercised) comply with 14 CFR Section 91.185 as indicated below.
    4. Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR must comply with the following conditions:
      1. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot must continue the flight under VFR and land as soon as practicable.


        This procedure also applies when two‐way radio failure occurs while operating in Class A airspace. The primary objective of this provision in 14 CFR Section 91.185 is to preclude extended IFR operation by these aircraft within the ATC system. Pilots should recognize that operation under these conditions may unnecessarily as well as adversely affect other users of the airspace, since ATC may be required to reroute or delay other users in order to protect the failure aircraft. However, it is not intended that the requirement to “land as soon as practicable” be construed to mean “as soon as possible.” Pilots retain the prerogative of exercising their best judgment and are not required to land at an unauthorized airport, at an airport unsuitable for the type of aircraft flown, or to land only minutes short of their intended destination.

      2. If the failure occurs in IFR conditions, or if VFR conditions cannot be complied with, each pilot must continue the flight according to the following requirements.
    5. Route requirements:
      1. By the route assigned in the last ATC clearance received.
      2. If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance.
      3. In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance.
      4. In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
    6. Altitude requirements. At the HIGHEST of the following altitudes or flight levels FOR THE ROUTE SEGMENT BEING FLOWN:
      1. The altitude or flight level assigned in the last ATC clearance received.
      2. The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in 14 CFR Section 91.121(c)) for IFR operations.
      3. The altitude or flight level ATC has advised may be expected in a further clearance.


        The intent of the rule is that a pilot who has experienced two-way radio failure should select the appropriate altitude for the particular route segment being flown and make the necessary altitude adjustments for subsequent route segments. If the pilot received an “expect further clearance” containing a higher altitude to expect at a specified time or fix, he/she should maintain the highest of the following altitudes until that time/fix: (1) his/her last assigned altitude, or (2) the minimum altitude/flight level for IFR operations.
        Upon reaching the time/fix specified, the pilot should commence his/her climb to the altitude he/she was advised to expect. If the radio failure occurs after the time/fix specified, the altitude to be expected is not applicable and the pilot should maintain an altitude consistent with 1 or 2 above.
        If the pilot receives an “expect further clearance” containing a lower altitude, the pilot should maintain the highest of 1 or 2 above until that time/fix specified in paragraph 12.7, Leave Clearance Limit.


        1. A pilot experiencing two-way radio failure at an assigned altitude of 7,000 feet is cleared along a direct route which will require a climb to a minimum IFR altitude of 9,000 feet, should climb to reach 9,000 feet at the time or place where it becomes necessary (see 14 CFR Section 91.177(b)). Later while proceeding along an airway with an MEA of 5,000 feet, the pilot would descend to 7,000 feet (the last assigned altitude), because that altitude is higher than the MEA.
        2. A pilot experiencing two-way radio failure while being progressively descended to lower altitudes to begin an approach is assigned 2,700 feet until crossing the VOR and then cleared for the approach. The MOCA along the airway is 2,700 feet and MEA is 4,000 feet. The aircraft is within 22 NM of the VOR. The pilot should remain at 2,700 feet until crossing the VOR because that altitude is the minimum IFR altitude for the route segment being flown.
        3. The MEA between a and b - 5,000 feet. The MEA between b and c -5,000 feet. The MEA between c and d -11,000 feet. The MEA between d and e - 7,000 feet. A pilot had been cleared via a, b, c, d, to e. While flying between a and b the assigned altitude was 6,000 feet and the pilot was told to expect a clearance to 8,000 feet at b. Prior to receiving the higher altitude assignment, the pilot experienced two-way failure. The pilot would maintain 6,000 to b, then climb to 8,000 feet (the altitude the pilot was advised to expect.) The pilot would maintain 8,000 feet, then climb to 11,000 at c, or prior to c if necessary to comply with an MCA at c. (14 CFR Section 91.177(b).) Upon reaching d, the pilot would descend to 8,000 feet (even though the MEA was 7,000 feet), as 8,000 was the highest of the altitude situations stated in the rule 14 CFR Section 91.185.
    7. Leave Clearance Limit
      1. When the clearance limit is a fix from which an approach begins, commence descent or descent and approach as close as possible to the expect further clearance time if one has been received, or if one has not been received, as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
      2. If the clearance limit is not a fix from which an approach begins, leave the clearance limit at the expect further clearance time if one has been received, or if none has been received, upon arrival over the clearance limit, and proceed to a fix from which an approach begins and commence descent or descent and approach as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
  13. Transponder Operation During Two-Way Communications Failure
    1. If an aircraft with a coded radar beacon transponder experiences a loss of two-way radio capability, the pilot should adjust the transponder to reply on Mode 3/A, Code 7600.
    2. The pilot should understand that the aircraft may not be in an area of radar coverage.
  14. Reestablishing Radio Contact
    1. In addition to monitoring the NAVAID voice feature, the pilot should attempt to reestablish communications by attempting contact:
      1. On the previously assigned frequency.
      2. With an FSS, New York Radio, or San Francisco Radio.
    2. If communications are established with an FSS, New York Radio or San Francisco Radio, the pilot should advise the aircraft's position, altitude, and last assigned frequency; then request further clearance from the controlling facility. The preceding does not preclude the use of 121.5 MHz. There is no priority on which action should be attempted first. If the capability exists, do all at the same time.


      New York Radio and San Francisco Radio are operated by Collins Aerospace, Incorporated (formerly ARINC) under contract with the FAA for communications services. These Radio facilities have the capability of relaying information to/from ATC facilities throughout the country.