Introduction to phraseology[PDF]

What is phraseology?

Phraseology is the way to communicate between the pilot and air traffic controller (ATC unit) for the purpose of ensuring uniformity in RTF (radiotelephony) communication.

If standard phrases are adhered to when composing a message, any possible ambiguity will be reduced to a minimum.

Phraseology shows the text of a complete message. They are not intended to be exhaustive, and when circumstances differ, pilots and controllers will be expected to use plain language, which should be as clear and concise as possible.
As a pilot, you must repeat all air traffic controller clearances and instructions that you received. That’s called the read back procedure.
It’s a mandatory procedure except when a pilot is in state of emergency and he has no time to read back or when the pilot’s radio is broken.

Source of this phraseology is extracted from ICAO documentation 4444 16th edition dated 10/Nov/2016

Basic Rules

The phraseology shall be used in conjunction with call signs.
  • An ATC shall start all messages with the call sign of the addressed aircraft.
  • A pilot usually ends read-back messages with his call sign.
  • A pilot usually starts a message with the ATC call sign followed by his own call sign when he calls the ATC unit for the first time.
The Phraseology for the movement of vehicles, other than tow-tractors, on the manoeuvring area shall be the same as those used for the movement of aircraft, with the exception of taxi instructions, in which case the word “PROCEED” shall be substituted for the word “TAXI” when communicating with vehicles.

Some abbreviations may be spoken using their constituent letters rather than the spelling alphabet, for example, ILS, QNH, RVR.

The following words may be omitted from transmissions provided that no confusion or ambiguity will result:

  • “Surface” in relation to surface wind direction and speed
  • “Degrees” in relation to radar headings
  • “Visibility”, “Clouds” and “Height” in meteorological reports
  • “Hecto Pascal” when giving pressure settings
The use of courtesies should be avoided.
The word “IMMEDIATELY” should only be used when immediate action is required for safety reasons.
You shall avoid words like “this is”, “over”, and other similar terms from radio transmissions provided there is no likelihood of misunderstanding.

Conditional instructions

Conditional phrases, such as “behind landing aircraft” or “after departing aircraft”, shall not be used for movements affecting the active runway(s), except when the aircraft or vehicles concerned are seen by the appropriate controller and pilot.

The aircraft or vehicle causing the condition in the clearance issued shall be the first aircraft/vehicle to pass in front of the other aircraft concerned. In all cases a conditional clearance shall be given in the following order and consist of:

  • identification
  • the condition
  • the clearance and
  • brief reiteration of the condition

For example:

Icon ATC.png SAS947, behind DC9 on final runway 12, line up runway 12 and wait behind

Transmitting technique

The following transmitting techniques will assist in ensuring that transmitted speech is clear and satisfactorily received:

  1. before transmitting, listen out on the frequency to be used to ensure that there will be no interference with a transmission from another station
  2. use a normal conversational tone, and speak clearly and distinctly
  3. maintain the speaking volume at a constant level
  4. a slight pause before and after numbers will assist in making them easier to understand
  5. avoid using hesitation sounds such as "er"
  6. be familiar with the microphone operating techniques, particularly in relation to the maintenance of a constant distance from the microphone
  7. depress the transmit switch fully before speaking and do not release it until the message is completed

We give you a specific advice for using the IVAO voice server. After switching to a new channel using the voice server, be aware that you never hear the current speaking person. Always wait 3/5 seconds minimum, before transmitting your message.


The flight crew shall read back to the air traffic controller safety-related parts of ATC clearances and instructions which are transmitted by voice (and by text for IVAO).
Read-back requirements have been introduced in the interest of flight safety.
The following shall always be read back:
  • ATC route clearances
  • clearances and instructions to enter, land on, take off from, hold short of, cross and backtrack on any runway
  • runway-in-use, altimeter settings, SSR codes, level instructions, heading and speed instructions
  • transition level
ATC advice, suggestions and requests should not be read back.
Unless requested by an ATC unit, voice read back of a data link communication message is not required.

Strict adherence to read-back procedures ensures not only that the clearance has been received correctly, but also that the clearance was transmitted as intended.

The stringency of the read-back requirement is directly related to the possible seriousness of a misunderstanding in the transmission and receipt of ATC clearances and instructions.

Icon ATC.png DEHBA, taxi holding point runway 01
Icon VFR.png Taxi holding point runway 01, DEHBA
Icon ATC.png DEHBA, squawk 4525
Icon VFR.png Squawk4525, DEHBA

See also


  • ICAO Documentation 4444 - Air Traffic Management - 16th Edition 2016 - Chapter 12


  • VID 150259 - Creation


  • 00:41, 14 May 2021


  • This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.


  • The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.