Aviation Standard Phraseology

Aviation communication is the backbone of safe flight operations, allowing pilots and air traffic controllers to exchange critical information in real time.

Aviation standard phraseology is a set of communication rules for simplified English language communication between an air traffic controller and the pilot in command of an aircraft.

Aviation phraseology in use is based on standards developed by the International Civil Aviation Organization (ICAO). Using phrases standardized by ICAO, pilots, and controllers communicate via radio to ensure clarity and uniformity in their conversations.

Purpose and Importance

The primary purpose of standard phraseology is to ensure quick, clear, and effective communication, reducing the opportunity for misunderstanding. Miscommunication or misunderstanding can lead to serious consequences in the aviation industry, including accidents and incidents. Standard phraseology minimizes these risks by providing a common language that is understood by all parties involved.

International Standards

International standards for phraseology are laid down by the International Civil Aviation Organization (ICAO) in several documents, including ICAO Annex 10 Volume II Chapter 5, ICAO Doc 4444 Chapter 12, and ICAO Doc 9432 – Manual of Radiotelephony. These documents provide comprehensive guidelines on how to communicate effectively in various situations encountered in aviation.

Commonly Used Phrases

Here are some of the most commonly used phrases in aviation communication, along with their meanings:

ACKNOWLEDGE: Let me know that you have received and understood this message.
AFFIRM: Yes.
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…
DISREGARD: Ignore.
HOW DO YOU READ: What is the readability of my transmission? (See Readability Scale below)
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.
OVER: My transmission has ended, and I expect a response from you. Note – Not normally used in VHF or satellite voice communications.
OUT: This exchange of transmissions is ended and no response is expected. Note – Not normally used in VHF or satellite voice 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 transmissions. Note – Under no circumstances is 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 a normal rate of speech, see Speech Transmitting Technique blew).
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 normally followed by a reason.
WILCO: Abbreviation for “will comply”. I understand your message and will comply with it.
WORDS TWICE:
- As a request: Communication is difficult. Please send every word, or group of words, twice.
- As information: Since communication is difficult, every word, or group of words, in this message will be sent twice.

Relay of ATC Communications

When a clearance, information, or request for information is relayed from a control facility to an aircraft, it is prefixed with the appropriate phrase “A-T-C clears,” “A-T-C advises,” or “A-T-C requests.” This ensures that the message is understood as coming directly from air traffic control, maintaining the integrity and authenticity of the communication.

Expeditious Compliance

In situations where prompt action is required, specific language is used to convey the urgency. The word “immediately” is used only when expeditious compliance is required to avoid an imminent situation. This signals to the recipient that immediate action is necessary.

On the other hand, the word “expedite” is used when prompt compliance is required to prevent the development of an imminent situation. This indicates that while the situation is not yet critical, swift action is needed to prevent it from becoming so.

In either case, if time permits, the reason for this action is included in the communication. This provides context and allows the recipient to understand the importance of the requested action.

Speech Transmitting Technique

Speech transmission technique should be such that each transmission involves the highest possible intelligibility. To achieve optimal legibility, both aircrew and ground personnel must follow precise guidelines:

Enunciation: Each word must be articulated clearly and distinctly, ensuring no ambiguity in transmission.
Speech Rate: 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.
Volume Control: Keep speaking volume consistent throughout communication to prevent fluctuations that could hinder understanding.
Microphone Technique: 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.
Interruption Management: Suspend speech temporarily if it becomes necessary to turn the head away from the microphone.

Readability Scale

1: Unreadable
2: Readable now and then
3: Readable but with difficulty
4: Readable
5: Perfectly readable

Additionally, I have seen aviators use the phrase “Loud and Clear” for satisfactory voice readability, often followed by the question “How do you read?“. The response can range from “Loud and Clear” (perfectly readable) to “Unreadable” (communication cannot be understood).

Phonetic Alphabet

To avoid confusion with similar-sounding letters/numbers, aviation uses the phonetic alphabet to pronounce letters and numbers clearly.

Letters: Alfa, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu.
Numbers: ZE-RO (0), WUN (1), TOO (2), TREE (3), FOW-er (4), FIFE (5), SIX (6), SEV-en (7), AIT (8), NIN-er (9).

Practical Tips for Effective Communication

Effective communication in aviation goes beyond memorizing phrases; it requires practice, attentiveness, and adherence to established protocols.

Here are some practical tips for improving communication skills in aviation:

Speak clearly and slowly, enunciating each word to ensure clarity.
Listen actively and attentively to instructions and messages from air traffic controllers.
Use standard phraseology consistently to convey information accurately and efficiently.
Confirm and clarify instructions as needed, especially when uncertainty arises.
Maintain a professional demeanor and tone in all communications, even during challenging situations.
Seek opportunities for training and practice to hone communication skills and stay current with industry standards.

Standard phraseology also allows for clear and concise communication, even in high-stress situations or when communicating in a non-native language. Ultimately, adherence to standard phraseology enhances situational awareness, minimizes the potential for errors, and contributes to the overall safety of aviation operations.