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08. Transmitting technique

Wikis > Communications > 08. Transmitting technique Transmitting technique PANS. Each written message should be read prior to commencement of transmission in order to eliminate unnecessary delays in communications. Transmissions shall be conducted concisely in a normal conversational tone.


    See the language proficiency requirements in the Appendix to Annex 1. PANS. Speech transmitting technique should be such that the highest possible intelligibility is incorporated in each transmission. Fulfilment of this aim requires that air crew and ground personnel should:

    • a) enunciate each word clearly and distinctly;


    • b) maintain an even rate of speech not exceeding 100 words per minute. When a message is transmitted to an aircraft and its contents need to be recorded the speaking rate should be at a slower rate to allow for the writing process. A slight pause preceding and following numerals makes them easier to understand;


    • c) maintain the speaking volume at a constant level;


    • d) be familiar with the microphone operating techniques particularly in relation to the maintenance of a constant distance from the microphone if a modulator with a constant level is not used;


    e) suspend speech temporarily if it becomes necessary to turn the head away from the microphone. Recommendation. Speech transmitting technique should be adapted to the prevailing communications conditions. PANS. Messages accepted for transmission should be transmitted in plain language or ICAO phraseologies without altering the sense of the message in any way. Approved ICAO abbreviations contained in the text of the message to be transmitted to aircraft should normally be converted into the unabbreviated words or phrases which these abbreviations represent in the language used, except for those which, owing to frequent and common practice, are generally understood by aeronautical personnel.


    The abbreviations which constitute the exceptions mentioned in are specifically identified in the abbreviation encode sections of the PANS-ABC (Doc 8400). PANS. To expedite communication, the use of phonetic spelling should be dispensed with, if there is no risk of this affecting correct reception and intelligibility of the message. PANS. The transmission of long messages should be interrupted momentarily from time to time to permit the transmitting operator to confirm that the frequency in use is clear and, if necessary, to permit the receiving operator to request repetition of parts not received. The following words and phrases shall be used in radiotelephony communications as appropriate and shall have the meaning ascribed hereunder:

NEGATIVE“No” or “Permission not granted” or “That is not correct” or “Not capable”.

ACKNOWLEDGE“Let me know that you have received and understood this message.”
APPROVED“Permission for proposed action granted.”
BREAK“I hereby indicate the separation between portions of the message.”
(To be used where there is no clear distinction between the text and other portions of the message.)
BREAK BREAK“I hereby indicate the separation between messages transmitted to different aircraft in a very busy environment.”
CANCEL“Annul the previously transmitted clearance.”
CHECK“Examine a system or procedure.”
(Not to be used in any other context. No answer is normally expected.)
CLEARED“Authorized to proceed under the conditions specified.”
CONFIRM“I request verification of: (clearance, instruction, action, information).”
CONTACT“Establish communications with…”.
CORRECT“True” or “Accurate”.
CORRECTION“An error has been made in this transmission (or message indicated). The correct version is…”
GO AHEAD“Proceed with your message.”
Note. Not used whenever the possibility exists of misconstruing “GO AHEAD” as an authorization for an aircraft to proceed. The phrase “GO AHEAD” may be omitted and, in its place, a response made by using the calling aeronautical station’s call sign followed by the answering aeronautical station’s call sign.
HOW DO YOU READ“What is the readability of my transmission?” (see
I SAY AGAIN“I repeat for clarity or emphasis.”
MAINTAIN“Continue in accordance with the condition(s) specified” or in its literal sense, e.g. “Maintain VFR”.
MONITOR“Listen out on (frequency).”
OVER“My transmission is ended, and I expect a response from you.”
Note. Not normally used in VHF communications.
OUT“This exchange of transmissions is ended and no response is expected.”
Note. Not normally used in VHF communications.
READ BACK“Repeat all, or the specified part, of this message back to me exactly as received.”
RECLEARED“A change has been made to your last clearance and this new clearance supersedes your previous clearance or part thereof.”
REPORT“Pass me the following information…”
REQUEST“I should like to know…” or “I wish to obtain…”
ROGER“I have received all of your last transmission.”
Note. Under no circumstances to be used in reply to a question requiring “READ BACK” or a direct answer in the affirmative (AFFIRM) or negative (NEGATIVE).
SAY AGAIN“Repeat all, or the following part, of your last transmission.”
SPEAK SLOWER“Reduce your rate of speech.”
Note. For normal rate of speech, see b).
STANDBY“Wait and I will call you.”
Note. The caller would normally re-establish contact if the delay is lengthy. STANDBY is not an approval or denial.
UNABLE“I cannot comply with your request, instruction, or clearance.”
Note. UNABLE is followed by a reason.
WILCO(Abbreviation for “will comply”.)
“I understand your message and will comply with it.”
WORDS TWICEa) As a request: “Communication is difficult. Please send every word, or group of words, twice.”
b) As information: “Since communication is difficult, every word, or group of words, in this message will be sent twice.”

Source: ICAO Annex 10.2

The presented material is for training purpose only!