How is the ATC language structured?

Question

Is the content of spoken communications used by air traffic control and pilots defined as part of a rigorous language definition? Such as a morphological or lexical foundational system, or is phraseology the extent of formalization?

And with the advent of text/computer based communications and automation on the horizon so to speak, what is the state of formalizing a language of communication? (If not already answered in the first part of my question.)

References to white papers and other research is fine if the answer requires you to almost write one.

Answer 1

I don't know about a formal structure, but ground to air and air to ground communications usually follow the 3-W or the 4-W rule.

For air to ground communication - use the 4-W rule:

• Who the controller is (identification of the controlling agency)
• Who you are (Aircraft Identification)
• Where you are (what is you position and altitude)
• What do you want (state your intentions or request)

Example:

Grand Junction Approach, Cessna one seven two Sierra Papa, five miles southwest of the ABC VORTAC at five thousand, five hundred, inbound for Grand Junction to land with ATIS Kilo.

Here the pilot identifies himself as a Cessna with the identification N172SP, that he is five miles southwest of the ABC VORTAC at 5,500 ft MSL, and that he intends to land at Grand Junction airport and has the latest ATIS weather report for Grand Junction.

ARTCC and other air traffic controllers will generally use the 3-Ws to communicate with you

• Who you are (the aircraft they are giving their instructions to)
• Who they are (the name of the controlling agency)
• What they want you to do (instructions for the aircraft in question to follow)

Example:

Cessna one seven two Sierra Papa, Grand Junction Approach, turn right to 030. Descent and maintain three thousand two hundred. Expect vectors for runway three zero left. Squawk six four one one and ident.

Here the controller (Grand Junction approach) has advised Cessna 172SP to turn to a heading of 030 and to descend to 3,200 ft MSL. He should also expect further heading instructions for insertion into traffic for runway 30L at Grand Junction airport. The controller also tells the pilot to set his transponder to the code 6411 and ident, so the controller can verify his position.

As a courtesy, and often requested or implied by controllers to verify the pilot in question heard the instructions and will comply, the pilot will read back the instruction in full to the controller, followed by his/her callsign.

Example:

Right to 030, descend and maintain three thousand two hundred, expect vectors for runway three zero left, squawk six four one one and ident, Cessna one seven two Sierra Papa.

The NATO phonetic alphabet will be used for individual letters to avoid confusion by both parties as many letters can sound similar on a garbled radio transmission. Other oddities include the use of the word 'niner' in place of the number 9; This is to distinguish from the number 5, which is pronouced "fife".

English is also the accepted international language for use in flying and radio communications, but is only required for flights under instrument flight rules (IFR).

Answer 2

No, aviation phraseology is not part of a rigorous language definition. When learning to speak on the radio, we do not learn specific sentence structures and grammar. Instead, phraseology is defined as a set of standard phrases, which we have to learn by heart and use appropriately. Although these phrases are based on the English language, they do not necessarily follow normal grammar rules, because they have been designed to be as short and unambiguous as possible.

With regards to the advance of electronic communication between ATC and cockpits, standard CPDLC (controller pilot datalink communications) messages have been established. These are based on the spoken phraseology, and are often an exact copy. You can get an idea from the image below of how CPDLC messages are structured. The first column displays the intended message, the second column indicates how it is actually transmitted.

(excerpt from PANS-ATM Appendix 5)

Answer 3

Yes. For ATC, clearance order is formalized in FAA Order 7110.65 in Chapter 4-2-1 "Clearances". It outlines specifically how clearances are to be issued, and the order in which the individual elements are to be issued. Clearance Items

In addition to this, phraseology examples in the 7110.65 are to be regarded as standard phraseology, and are to be used when such an example is given, eg, for "do this speed or SLOWER, November tree six fife Tango, do not exceed two five zero knots is correct, while the often-used November tree six fife Tango, Maintain two five zero knots or less is incorrect.

This is to give the verbiage a definitive difference from November tree six fife Tango, maintain two eight zero knots or greater, which is correct for "do this speed or FASTER"

There are also specific formats for issuing traffic advisories, weather information, airport conditions, pretty much anything a controller would have to issue as information or a directive.

Plain English is approved for use in situations where prescribed phraseology does not exist, or to aid in eliminating misunderstandings.

When obtaining information from a previously unknown aircraft, the four Ws format who are you, where are you, what do you want, and sometimes why do you want it.

With all that said, pilots abide by their (or their company's) rules, which usually entail "bookending" our transmissions, by reading the information back, and ending the reply with the call sign. As far as I know, that's not a required format, but it closes the communication loop nicely.

Answer 4

Supplementing other answers: there is no formal language for ATC communications, although it has been discussed, and several tasks in contracts have attempted to make recommendations. The language for ATC has its origins in railroad communications.