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11. Radiotelephony procedures

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5.2.1.7.3 Radiotelephony procedures

5.2.1.7.3.1 An aircraft shall not change the type of its radiotelephony call sign during flight, except temporarily on the instruction of an air traffic control unit in the interests of safety.

5.2.1.7.3.1.1 Exept for reasons of safety no transmission shall be directed to an aircraft during take-off, during the last part of the final approach or during the landing roll.

5.2.1.7.3.2 Establishment of radiotelephony communications

5.2.1.7.3.2.1 Full radiotelephony call signs shall always be used when establishing communication. The calling procedure of an aircraft establishing communication shall be in accordance with Table 5-2.
Radiotelephony calling procedure

5.2.1.7.3.2.2 PANS.— Stations having a requirement to transmit information to all stations likely to intercept should preface such transmission by the general call ALL STATIONS, followed by the identification of the calling station.

    Note. No reply is expected to such general calls unless individual stations are subsequently called to acknowledge receipt.

5.2.1.7.3.2.3 The reply to the above calls shall be in accordance with Table 5-3.
Radiotelephony reply procedure

5.2.1.7.3.2.4 PANS.— When a station is called but is uncertain of the identification of the calling station, it should reply by transmitting the following:
STATION CALLING . . . (station called) SAY AGAIN YOUR CALL SIGN

    Note. The following example illustrates the application of this procedure:
    (CAIRO station replying)
    STATION CALLING CAIRO (pause) SAY AGAIN YOUR CALL SIGN

5.2.1.7.3.2.5 Communications shall commence with a call and a reply when it is desired to establish contact, except that, when it is certain that the station called will receive the call, the calling station may transmit the message, without waiting for a reply from the station called.

5.2.1.7.3.2.6 Interpilot air-to-air communication shall be established on the air-to-air channel 123.45 MHz by either a directed call to a specific aircraft station or a general call, taking into account conditions pertaining to use of this channel.

    Note. For conditions on use of air-to-air channels see Annex 10, Volume V, 4.1.3.2.1, also Volume II, 5.2.2.1.1.4.
      Annex 10, Volume V, 4.1.3.2.1 An air-to-air VHF communications channel on the frequency of 123.45 MHz shall be designated to enable aircraft engaged in 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.

        Note. Use of the air-to-air channel can cause interference to and from aircraft using the same frequency for air-ground communications.

      Annex 10, Volume II, 5.2.2.1.1.4 The user of the air-to-air VHF communications channel shall ensure that adequate watch is maintained on designated ATS frequencies, the frequency of the aeronautical emergency channel, and any other mandatory watch frequencies.

5.2.1.7.3.2.6.1 PANS.— As the aircraft may be guarding more than one frequency, the initial call should include the distinctive channel identification “INTERPILOT”.

    Note. The following examples illustrate the application of this calling procedure.
    CLIPPER 123 — SABENA 901 — INTERPILOT — DO YOU READ
    or
    ANY AIRCRAFT VICINITY OF 30 NORTH 160 EAST — JAPANAIR 401 — INTERPILOT — OVER
5.2.1.7.3.3 Subsequent radiotelephony communications

5.2.1.7.3.3.1 Abbreviated radiotelephony call signs, as prescribed in 5.2.1.7.2.2, shall be used only after satisfactory communication has been established and provided that no confusion is likely to arise. An aircraft station shall use its abbreviated call sign only after it has been addressed in this manner by the aeronautical station.

5.2.1.7.3.3.2 After contact has been established, continuous two-way communication shall be permitted without further identification or call until termination of the contact.

5.2.1.7.3.3.3 In order to avoid any possible confusion, when issuing ATC clearances and reading back such clearances, controllers and pilots shall always add the call sign of the aircraft to which the clearance applies.

5.2.1.7.3.4 Indication of transmitting frequency

5.2.1.7.3.4.1 PANS.— As the aeronautical station operator generally guards more than one frequency, the call should be followed by an indication of the frequency used, unless other suitable means of identifying the frequency are known to exist.

5.2.1.7.3.4.2 PANS.— When no confusion is likely to arise, only the first two digits of the High Frequency (in kHz) need be used to identify the transmitting channel.

    Note. The following example illustrates the application of this procedure:
    (PAA 325 calling Kingston on 8 871 kHz)
    KINGSTON CLIPPER THREE TWO FIVE — ON EIGHT EIGHT

5.2.1.7.3.4.3 PANS.— Wherever VHF communications channels are separated by 25 kHz, only the first 5 digits should be used to identify the transmitting carrier frequency in radiotelephony communications. Not more than two significant digits after the decimal point are used. In the case of these being two zeros, a single zero is considered significant.

    Note 1. The following examples illustrate the application of this procedure:
    Channel – Transmitted as
    118.000 ONE ONE EIGHT DECIMAL ZERO
    118.005 ONE ONE EIGHT DECIMAL ZERO ZERO FIVE
    118.010 ONE ONE EIGHT DECIMAL ZERO ONE ZERO
    118.025 ONE ONE EIGHT DECIMAL ZERO TWO FIVE
    118.050 ONE ONE EIGHT DECIMAL ZERO FIVE ZERO
    118.100 ONE ONE EIGHT DECIMAL ONE

    Note 2. Caution must be exercised with respect to the indication of transmitting channels in VHF radiotelephony communications when all six digits of the numerical designa- tor are used in airspace where communication channels are separated by 25 kHz, because on aircraft installations with a channel separation capability of 25 kHz or more, it is only possible to select the first five digits of the numerical designa- tor on the radio management panel.

    Note 3. The numerical designator corresponds to the channel identification in Annex 10, Volume V, Table 4-1 (bis) see below.

5.2.1.7.3.4.4 PANS.— In airspace where all VHF voice communications channels are separated by 25 kHz or more and the use of six digits as in 5.2.1.7.3.4.3 is not substantiated by the operational requirement determined by the appropriate authorities, the first five digits of the numerical designator should be used, except in the case of both the fifth and sixth digits being zeros, in which case only the first four digits should be used.

    Note 1. The following examples illustrate the application of the procedure in 5.2.1.7.3.4.4 and the associated settings of the aircraft radio management panel for communication equipment with channel separation capabilities of 25 kHz and 8.33/25 kHz:
Channel Transmitted as Radio management panel setting for communication equipment with 25 kHz (5 digits) Radio management panel setting for communication equipment with 8.33/25 kHz (6 digits)
118.000 ONE ONE EIGHT DECIMAL ZERO 118.00 118.00
118.025 ONE ONE EIGHT DECIMAL ZERO TWO 18.02 18.025
118.050 ONE ONE EIGHT DECIMAL ZERO FIVE 18.05 118.050
118.075 ONE ONE EIGHT DECIMAL ZERO SEVEN 118.07 118.075
118.100 ONE ONE EIGHT DECIMAL ONE 118.10 118.100
    Note 2. Caution must be exercised with respect to the indication of transmitting channels in VHF radiotelephony communications when five digits of the numerical designator
    are used in airspace where aircraft are also operated with channel separation capabilities of 8.33/25 kHz. On aircraft installations with a channel separation capability of 8.33 kHz and more, it is possible to select six digits on the radio management panel. It should therefore be ensured that the fifth and sixth digits are set to 25 kHz channels (see Note 1).
    Note 3. The numerical designator corresponds to the channel identification in Annex 10, Volume V , Table 4-1 (bis) see below.

Channelling frequency pairing

    Chapter 6. VHF Air-Ground Digital Link (VDL)
    6.1 Definitions And System Capabilities

    The VHF digital link (VDL) is a constituent mobile subnetwork of the aeronautical telecommunication network (ATN), operating in the aeronautical mobile VHF frequency band. In addition, the VDL may provide non-ATN functions, such as, for instance, digitized voice. The very high frequency (VHF) digital link (VDL) Standards and Recommended Practices (SARPs) defined and referenced below apply to aeronautical VHF digital communications systems operating within the aeronautical telecommunication network (ATN).

Source: ICAO Annex 10.2, 10-5

 
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