11. Radiotelephony procedures

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.

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.

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

5.2.1.7.3.4.1 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:

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.

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).