ICAO Aviation Phraseology

Standard ICAO radiotelephony words and phrases

Acknowledge

Let me know that you have received and understood this message.

Affirm

Yes

Approved

Permission for proposed action granted

Break

Indicates separation between messages

Break Break

Indicates separation between messages transmitted to different aircraft in a busy environment

Cancel

Annul the previously transmitted clearance

Changing to

I intend to call. . . (unit) on. . . (frequency).

Check

Examine a system or procedure. (Not to be used in any other context. No answer is normally expected.)

Cleared

Authorised to proceed under the conditions specified.

Climb

Climb and maintain

Confirm

I request verification of: (clearance, instruction, action, information).

Contact

Establish communications with... (your details have been passed).

Correct

True or accurate

Correction

An error has been made in this transmission (or message indicated). The correct version is...

Descend

Descend and maintain

Disregard

Ignore

Fanstop

I am initiating a practice engine failure after take off. (Used only by pilots of single engine aircraft.) The response should be, “REPORT CLIMBING AWAY”

Freecall

Call. . . (unit) (your details have not been passed – mainly used by military ATC).

Hold short

Stop before reaching the specified location. (Only used in limited circumstances where no defined point exists (e.g. where there is no suitably located holding point), or to reinforce a clearance limit)

How do you read?

What is the readability of my transmission?

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)

Negative

No; or Permission not granted; or That is not correct; or Not capable.

Negative I say again

May be used if repeated incorrect readbacks are given by the pilot and additional emphasis is required.

Pass your message

Proceed with your message

Read back

Repeat all, or the specified part, of tis message back to me exactly as received

Recleared

To be used only in relation to routings and NOT for instructions to climb or descend.

Report

Pass me the following information

Roger

I have received all your last transmission. (Under no circumstances to be used in reply to a question requiring 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

Standby

Wait and I will call you. (No onward clearance to be assumed. 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. Unable is normally followed by a reason.

Wilco

I understand your message and will comply with it (abbreviation for will comply)

Words Twice

As a request: Communication is difficult. Please send every word twice.

As Information: Since communication is difficult, every word in this message will be sent twice.