RADIO TELEPHONY PROCEDURES
GENERAL OPERATING PROCEDURES 2.1 Introduction
Radiotelephony (RTF) is the medium by which pilots and ground personnel communicate with each other. For the safe and expeditious aircraft operations, the information and instructions transmitted are of vital importance. However, the use of non-standard procedures and phraseology can cause misunderstanding. Use of non-standard procedures and phraseology have been the cause of many incidents and accidents. Thus it is very important to use correct and precise standardised phraseology.
2.2 Transmitting Technique
2.2.1 The following transmitting techniques are highly recommended to assist in ensuring that
transmitted speech is clearly and satisfactorily received.
(a) Before transmitting, receiver volume is to be set at the optimum level. Listen-out on the frequency to be used to ensure that there will be no interference with a transmission from another station.
(b) One must be familiar with microphone operating techniques. Do not turn your head away from the microphone while talking or vary the distance between the microphone and your mouth. Speech may be severely distorted by:
(i) Keeping the microphone too close while speaking; (ii) Lips touching the microphone; or
(iii) Holding the microphone or boom with the fingers (of a combined headset/microphone system). (c) Speech should be clear and distinct, using a normal conversation tone.
(d) An even rate of speech not exceeding 100 words per minute should be used. When it is expected that the message will be written down by the recipients, speech should be at a slightly slower rate. (e) Speaking volume must be maintained at a constant level.
(f) Before and after numbers, a slight pause will assist in making them easier to understand. (g) Using hesitation sounds such as ‘er’ must be avoided.
(h) Exchange of courtesies and entering into non-operational conversations is to be avoided.
(i) Depress the press-to-talk switch fully before speaking and do not release it until the message is complete. This will ensure that the entire message is transmitted. However, do not depress transmit switch until ready to speak, this will block the channel.
(j) Mother tongue of the person receiving the message may not be English. Therefore, speak clearly and as far as possible, use standard radiotelephony (RTF) words and phrases.
(k) Wait for a period of at least 10 seconds before making a second call. This will avoid unnecessary transmissions while the receiving station is getting ready to reply to the initial call.
2.2.2 Language to be Used
The air-ground radiotelephony communications shall be conducted in the language normally used by the station on the ground or in the English language. The language normally used by the station on the ground may not be the language of the State in which it is located. A common language may be agreed upon regionally as a requirement for stations on the ground in that region. On request from any aircraft station, English language must be made available, at all stations on the ground that are serving designated airports and routes used by international air services.
2.3 Transmission of Letters
2.3.1 In RTF, letters are usually spoken in the form of phonetics. If it is required to expedite
communications, the use of phonetic spelling should be avoided if there is no risk of this affecting correct reception and intelligibility of the message.
2.3.2 Each letter in the aircraft call sign, except the telephony designator and the type of aircraft,
should be spoken separately using the phonetic spelling.
2.3.3 The words to be used when using the phonetic spelling are given below. Underlined
syllables are to be emphasised.
Table 2.1 Phonetic word of English alphabets
Letter Word Appropriate pronunciation
A Alpha AL FAH
B Bravo BRAH VO H C Charlie CHAR LEE or SHAR LEE D Delta DELL TAH
E Echo ECK OH
F Foxtrot FOKS TROT
G Golf GOLF
H Hotel HOH TELL I India IN DEE AH J Juliett JEW LEE ETT
K Kilo KEY LOH
L Lima LEE MAH
M Mike MIKE
N November NO VEM BER O Oscar OSS CAH
P Papa PAH PAH
Q Quebec KEH BECK R Romeo ROW ME OH S Sierra SEE AIR RAH
T Tango TANG GO
U Uniform YOU NEE FORM or OO NEE FORM V Victor VIK TAH
W Whiskey WISS KEY X X-ray ECKS RAY Y Yankee YANG KEE
Z Zulu ZOO LOO
2.4 Transmission of Numbers
2.4.1 When the English language is used for communication, numbers should be transmitted using
the following pronunciation. The syllables in capital letters are to be stressed; for example, the two syllables in ZE-RO are given equal emphasis, whereas the first syllable of FOW-er is given primary emphasis.
Table 2.2 English numbers and their pronunciation
Numeral or numeral
element Latin alphabet representation
0 ZE-RO 1 WUN 2 TOO 3 TREE 4 FOW-er 5 FIFE 6 SIX 7 SEV-en 8 AIT 9 NIN-er Decimal DAY-SEE-MAL Hundred HUN-dred Thousand TOU-SAND
2.4.2 All numbers, other than as specified in 2.4.3, will be transmitted, pronouncing each digit
separately.
Table 2.3 Pronunciation of numbers in different usages
Aircraft call signs JET 062
Sahara 221
Transmitted as Jet Air zero six two Sahara two two one
Flight levels FL100 FL180
Transmitted as
Flight Level one zero zero Flight Level one eight zero Headings
150 degrees 080 degrees
Transmitted as
Heading one five zero Heading zero eight zero Wind direction and speed
200 degrees 25 knots 160 degrees 18 knots gusting 30 knots
Transmitted as
Wind two zero zero degrees two five knots Wind one six zero degrees one eight knots gusting three zero knots
Transponder codes 2 400
4 203
Transmitted as
Squawk two four zero zero Squawk four two zero three Runway
27 30
Transmitted as Runway two seven Runway three zero Altimeter setting
1 010 1 000
Transmitted as
QNH one zero one zero QNH one zero zero zero
2.4.3 All numbers used in the transmission of altitude, height, cloud height, visibility and runway
visual range (RVR) information which contain whole hundreds and whole thousands must be transmitted by pronouncing each digit in the number of hundreds or thousands followed by the word HUNDRED or TOUSAND as appropriate. Combinations of thousands and whole hundreds shall be transmitted by pronouncing each digit in the number of thousands followed by the word TOUSAND and the number of hundreds followed by the word HUNDRED; examples of this convention are as follows:
Table 2.4 Exceptions for pronunciation of numbers
Altitude 800 3400 12000 Transmitted as Eight hundred
Three thousand four hundred One two thousand
Cloud height 2200
4300
Transmitted as
Two thousand two hundred Four thousand three hundred
Visibility 1000 700
Transmitted as
Visibility one thousand Visibility seven hundred Runway visual range
600 1700
Transmitted as RVR six hundred
RVR one thousand seven hundred
2.4.4 When indicating the frequency of the transmitting channel in VHF RT communications, all
six digits of the frequency should be used. Exceptions to this rule are given in 2.4.5. If both fifth and sixth digits are zeros, only the first four digits should be used. Examples are given below:
Table 2.5 Transmission of frequency indications
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 1:- There are two types of VHF communication systems with respect to the channel spacing. Channel spacing can either be 8.33 KHz or 25 KHz. On some aircraft installations (especially older systems) with a channel separation capability of 25 KHz or more, it is possible to select only the first five digits of the frequency on the control unit of VHF communication system. In the newer systems with 8.33 KHz channel spacing, it is possible to select all the six digits of the frequency. In some airspace, only five digits of the frequency are used and in some other airspace, all the six digits of the frequency are used. Therefore, caution must be exercised in indicating the frequency, while flying in airspace which uses only five digits of the frequency but the aircraft equipment is capable of selecting all the six digits (8.33 KHz spacing). Similarly, caution must be exercised in indicating the frequency while flying in airspace which uses all the six digits of the frequency, but the aircraft equipment is capable of selecting only the first five digits of the frequency.
Note 2:- The frequency allotment for worldwide utilisation is given in ICAO Annex 10, Volume V, Table 4-1.
2.4.5 In airspace where all VHF voice communications channels are separated by 25 kHz or more
and the use of six digits as in 2.4.4 is not substantiated by the operational requirement determined by the appropriated 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 3:- The following examples illustrate the application of the procedure in 2.4.5 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.
Table 2.6 Transmission of frequency indications
Radio management panel setting for communication equipment with Channel Transmitted as (5 digits)25 kHz
8.33/ 25 kHz (6 digits) 118.000 ONE ONE EIGHT DECIMAL ZERO 118.00 118.000 118.025 ONE ONE EIGHT DECIMAL ZERO TWO 118.02 118.025 118.050 ONE ONE EIGHT DECIMAL ZERO FIVE 118.05 118.050 118.075 ONE ONE EIGHT DECIMAL ZERO SEVEN 118.07 118.075 118.100 ONE ONE EIGHT DECIMAL ONE 118.10 118.100
2.5 Transmission of Time
2.5.1 When transmitting time, only the minutes of the hour are required to be transmitted. Each
digit should be pronounced separately. However, if there is any possibility of confusion, the hour too should be included. Time checks are given to the nearest half minute and preceded by the word 'TIME'. Coordinated Universal Time (UTC) is to be used at all times, unless specified. 2400 hours designates midnight, the end of the day, and 0000 hours the beginning of the day. Following examples illustrate the idea.
Table 2.7 Transmission of time
Time Transmitted as Pronounced as
0823 Two Three or Zero Eight Two Three TOO TREE (or ZERO AIT TOO TREE) 1300 One Three Zero Zero WUN TREE ZERO ZERO
2057 Five Seven or Two Zero Five Seven FIFE SEVEN (or TOO ZERO FIFE SEVEN)
2.5.2 Pilots may require checking the time with the ATS unit. Time checks are given to the
nearest half minute.