Voice procedure

Voice procedure includes various techniques used to clarify, simplify and standardise spoken communications over two-way radios, in use by the armed forces, in civil aviation, police and fire dispatching systems, citizens' band radio (CB), etc. Specially, for civil aviation, it used to be called aeronautical phraseology, and is also used for some railroad radio communications, such as on CSX Transportation.

Voice procedure communications are intended to maximize clarity of spoken communication and reduce misunderstanding. It consists of signalling protocol such as the use of abbreviated codes like the CB radio ten-code, Q codes in amateur radio and aviation, police codes, etc. and jargon.

Some elements of voice procedure are understood across many applications, but significant variations exist. The armed forces of the NATO countries have similar procedures in order to make cooperation easier and pseudo-military organisations often base their procedures on them, so some commonality exists there.

Words in voice procedure

See also: Procedure word

Some words with specialised meanings are used in radio communication throughout the English-speaking world, and in international radio communication, where English is the lingua franca. Note that the following list commingles incompatible terms used in different communication modes, each of which has its own terminology (e.g., no air-to-ground controller would ever use the term "10-4", a CB radio term).

Contrary to popular belief, Roger does not mean or imply both "received" and "I will comply." That distinction goes to the contraction wilco (from, "will comply"), which is used exclusively if the speaker intends to say "received and will comply". The phrase "Roger Wilco" is procedurally incorrect, as it is redundant with respect to the intent to say "received".[6]

Each area of usage will have its own subset of prowords, usually derived from the NATO set, but sometimes from earlier Q-code and morse operator practices.

Furthermore, the use of some special prowords is tightly controlled, with that word never used on the air in other contexts within that area of usage. Examples include "repeat" (for additional artillery fire in military communications), "take off" (granting permission for aircraft take off in airfield tower communications), "rescue" (rescue in progress in surf life saving), and "mayday" (safety-of-life emergency in maritime and aeronautics).

Example usage

Aeronautical mobile procedure

The Federal Aviation Administration uses the term phraseology to describe voice procedure or communications protocols used over telecommunications circuits. An example is air traffic control radio communications. Standardised wording is used and the person receiving the message may repeat critical parts of the message back to the sender. This is especially true of safety-critical messages.[8] Consider this example of an exchange between a controller and an aircraft:

Aircraft: Boston Tower, Warrior three five foxtrot (35F), holding short of two two right.
Tower: Warrior three five foxtrot, Boston Tower, runway two two right, cleared for immediate takeoff.
Aircraft: Roger, three five foxtrot, cleared for immediate takeoff, two two right.

On telecommunications circuits, disambiguation is a critical function of voice procedure. Due to any number of variables, including radio static, a busy or loud environment, or similarity in the phonetics of different words, a critical piece of information can be misheard or misunderstood; for instance, a pilot being ordered to eleven thousand as opposed to seven thousand. To reduce ambiguity, critical information may be broken down and read as separate letters and numbers. To avoid error or misunderstanding, pilots will often read back altitudes in the tens of thousands using both separate numbers and the single word (example: given a climb to 10,000 ft, the pilot replies "[Callsign] climbing to One zero, Ten Thousand"). However, this is usually only used to differentiate between 10,000 and 11,000 ft since these are the most common altitude deviations. The runway number read visually as eighteen, when read over a voice circuit as part of an instruction, becomes one eight. In some cases a spelling alphabet is used (also called a radio alphabet or a phonetic alphabet). Instead of the letters AB, the words Alpha Bravo are used. Main Street becomes Mike Alpha India November street, clearly separating it from Drain Street and Wayne Street. The numbers 5 and 9 are pronounced "fife" and "niner" respectively, since "five" and "nine" can sound the same over the radio. The use of 'niner' in place of 'nine' is due to German-speaking NATO allies for whom the spoken word 'nine' could be confused with the German word 'nein' or 'no'.

Over fire service radios, phraseology may include words that indicate the priority of a message, for example:[9]

Forty Four Truck to the Bronx, Urgent!


San Diego, Engine Forty, Emergency traffic!

Words may be repeated to modify them from traditional use in order to describe a critical message:[10]

Evacuate! Evacuate! Evacuate!

A similar technique may be used in aviation for critical messages. For example, this transmission might be sent to an aircraft that has just landed and has not yet cleared the runway.

Echo-Foxtrot-Charlie, Tower. I have engine out traffic on short final. Exit runway at next taxiway. Expedite! Expedite!

Police Radios also use this technique to escalate a call that is quickly becoming an emergency.

Code 3! Code 3! Code 3!

Railroads have similar processes. When instructions are read to a locomotive engineer, they are preceded by the train or locomotive number, direction of travel and the engineer's name. This reduces the possibility that a set of instructions will be acted on by the wrong locomotive engineer:

Five Sixty Six West, Engineer Jones, okay to proceed two blocks west to Ravendale.

Phraseology on telecommunications circuits may employ special phrases like ten codes, Sigalert, Quick Alert! or road service towing abbreviations such as T6. This jargon may abbreviate critical data and alert listeners by identifying the priority of a message. It may also reduce errors caused by ambiguities involving rhyming, or similar-sounding, words.

Maritime mobile procedure

(Done on VHF Ch 16)

Boat "Albacore" talking to Boat "Bronwyn"

Albacore: Bronwyn, Bronwyn, Bronwyn* this is Albacore, over. (*3×1, repeating the receiver's callsign up to 3 times, and the sender's once, is proper procedure and should be used when first establishing contact, especially over a long distance. A 1×1, i.e. 'Bronwyn this is Albacore,' or 2×1, i.e. 'Bronwyn, Bronwyn, this is Albacore,' is less proper, but acceptable especially for a subsequent contact.)[11]

Bronwyn: Albacore, this is Bronwyn, over. (** At this point switch to a working channel as 16 is for distress and hailing only**)

Albacore: This is Albacore. Want a tow and are you OK for tea at Osbourne Bay? over.

Bronwyn: This is Bronwyn. Negative, got engine running, 1600 at clubhouse fine with us. over.

Albacore: This is Albacore, Roger, out.

"Copy that" is incorrect. COPY is used when a message has been intercepted by another station, i.e. a third station would respond:

Nonesuch: Bronwyn, this is Nonesuch. Copied your previous, will also see you there, out.

One should always use one's own callsign when transmitting.

British Army

Station C21A (charlie-two-one Alpha) talking to C33B (charlie-three-three Bravo):[12]

C21A: C33B, this is C21A, message, over.

C33B: C33B, send, over.

C21A: Have you got C1ØD Sunray at your location?, over.

C33B: Negative, I think he is with C3ØC, over.

C21A: Roger, out.

The advantage of this sequence is that the recipient always knows who sent the message.

The downside is that the listener only knows the intended recipient from the context of the conversation. Requires moderate signal quality for the radio operator to keep track of the conversations.

However a broadcast message and response is fairly efficient.

Sunray (Lead) Charlie Charlie (Collective Call - everyone), this is Sunray. Radio check, over.

C-E-5-9: Sunray, this is Charlie Echo five niner, loud and clear, five by five over.

Y-S-7-2 Sunray, this is Yankee Sierra Seven Two, reading three by four. over.

B-G-5-2: Sunray, this is Bravo Golf Five Two, Say again. over.

E-F-2-0: Sunray, this is Echo Foxtrot Two Zero, reading Five by Four over.

Sunray: Charlie Charlie this is Sunray, out.

The "Say again" response from B-G-5-2 tells Sunray that the radio signal is not good and possibly unreadable. Sunray can then re-initiate a Call onto B-G-5-2 and start another R/C or instruct them to relocate, change settings, etc.

So it could carry on with:

Sunray: Bravo Golf Five Two this is sunray, radio check over.

B-G-5-2: Sunray this is Bravo Golf Five Two, unclear, read you 2 by 3 over.

Sunray: Sunray copies, Relocate to Grid One Niner Zero Three Three Two for a better signal over.

B-G-5-2: Bravo Golf Five Two copies and is Oscar Mike, Bravo Golf Five Two Out.

Frequency control

In public radio, voice procedure controls the behaviour and use of the frequency between each operator. Deregulated frequencies, such as Family Radio Service has no voice procedure, but due to the limited range of transmission it is unlikely a transmission will be heard outside of a single party. On signals open to the public with broader reception, such as citizens band, there is only enough protocol to allow operators to speak one at a time or allow emergency traffic to go through. Otherwise, there is no prioritisation or rules to the communication outside of following local and federal laws regarding communication. Other stations requiring licensure such as amateur radio bands or MARS users (which includes civilian amateur radio operators) have strict usage and transmission rules that operators are trained on (as part of their licensing process) that allows authorised users to communicate. Regulated Radio frequencies often have unlicensed users who are unaware of the protocol on a certain channel and are asked to sign off if they fail to identify a callsign as a licensed operator, or are reported by licensed operators to the licensing body for possible advisement or citation. Amateur radio frequencies also may have assigned functions that may allow or disallow certain traffic including voice, such as continuous wave (see Morse code) transmission or data-only transmission frequencies.

Structured use is seen in voice procedure for government, military and disaster command usage. In police and public safety use, voice procedure follows a protocol that governs who can speak on a frequency and when. Since modern police frequencies are on a restricted bandwidth it is unlikely that an unlicensed party will interrupt communication; all operators on a frequency are assumed to be authorised to utilise a channel unless proven otherwise. Licensed radios in law enforcement often utilise trunking, or multiple frequencies selected by a control tower at random, which prevents single-channel scanners from picking up a transmission. A frequency may be dispatch controlled (or controlled net), which is controlled by one control station and any parties wishing to use the frequency must direct all calls to the control station who routes calls as needed to necessary parties. A tactical frequency (or tactical net) has no control station, and is intended to be used on an ad-hoc basis for situations, such as multiple units attempting an arrest who surround a single property. Tactical frequencies may or may not be trunked and may be susceptible to single-channel scanner reception.

See also


  1. "Pilot-Controller Glossary". Federal Aviation Administration.
  2. "Radiotelephony Manual" (PDF). Civil Aeronautics Authority. p. 5.
  3. "Falcon Codes". Fighter Pilot University. Retrieved 22 January 2015.
  4. "Roger" was the U.S. military designation for the letter R (as in received) from 1927 to 1957.
  5. SDSTAFF Robin and Straight Dope Science Advisory Board (2007-02-27). "Why do pilots say "roger" on the radio?". The Straight Dope. Archived from the original on 2008-01-29.
  6. ACP 125(F), Communication Instructions Radiotelephone Procedure (PDF), Combined Communication Electronics Board (published 5 September 2001), September 2001, pp. 3–14 (page 46 of the pdf), retrieved 2012-02-20
  7. Eastern Railroad Discussion. "Defect Detector near Callahan, FL". Trainorders.com. Retrieved 20 January 2016.
  8. See: "Section 2: Radio Communications Phraseology and Techniques", Aeronautical Information Manual, US Department of Transportation, Federal Aviation Administration. Any year AIM will serve as an example. Another example is "Completing the Loop: Two-Way Communication", Special Report: Improving Firefighter Communications, USFA-TR-099/January 1999, (Emmitsburg, Maryland: U.S. Fire Administration, 1999) p. 27.
  9. See, "Problem Reporting", Special Report: Improving Firefighter Communications, USFA-TR-099/January 1999, (Emmitsburg, Maryland: U.S. Fire Administration, 1999) pp. 25-26. FDNY has implemented these ideas and they were observed on publicly released FDNY 9-11-01 logging recorder audio CDs. Portions of these CDs were broadcast on news programs.
  10. For an example of fire procedures, look at "Communications Procedures", XII-A-4.JH.970314, (Los Gatos, California, Santa Clara County Fire Department, Training Division, 03/14/1997).
  11. "VHF Radio Basics". sailonline.com. Retrieved Apr 13, 2015.
  12. Cannon, Mike (1994). Eavesdropping on the British Military. Dublin: Cara Press. pp. 85–85.

External links

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