Non-Standard Phraseology

Feature Desk, Aviation Gurukul, GOLN

3 years ago

Non-standard phraseology refers to any words, phrases, or terminology used in aviation communication that do not adhere to the standardized procedures and language set by aviation authorities like the International Civil Aviation Organization (ICAO).

In the world of aviation, communication between air traffic controllers and pilots is of paramount importance. Standardized phraseology has been developed and is consistently practiced worldwide to ensure clear, unambiguous communication. However, there are times when non-standard phraseology is used, which can lead to miscommunication and potential safety risks.

Non-Standard Phraseology

Description

Of the many factors involved in the process of communication, phraseology is perhaps the most important because it enables us to communicate quickly and effectively despite differences in language and reduces the opportunity for misunderstanding.

Standard phraseology reduces the risk that a message will be misunderstood and aids the read-back/hear-back process so that any error is quickly detected.

Ambiguous or non-standard phraseology is a frequent causal or contributory factor in aircraft accidents and incidents.

International standards of phraseology are laid down in ICAO Annex 10 Volume II Chapter 5, ICAO Doc 4444 PANS-ATM Chapter 12, and in ICAO Doc 9432 – Manual of Radiotelephony.

Many national authorities also publish radiotelephony manuals that amplify ICAO provisions, and in some cases modify them to suit local conditions.

This article deals with non-standard phraseology, which is sometimes adopted unilaterally by national or local air traffic services in an attempt to alleviate problems; however, standard phraseology minimizes the potential for misunderstanding.

Effects

Where non-standard phraseology is introduced after careful consideration to address a particular problem, it can make a positive contribution to flight safety; however, this must be balanced with the possibility of confusion for pilots or ATCOs not familiar with the phraseology used.

Why is Standard Phraseology Important?

Clarity and Precision: In high-pressure situations, it is crucial to convey information clearly and without ambiguity. Standard phraseology is designed to be concise and universally understood.
Safety: Clear communication can prevent misunderstandings that might lead to accidents or near-miss incidents.
Efficiency: Using standardized terms can expedite communication processes, especially in busy airspace or airports.

Examples of Non-Standard Phraseology and their Potential Risks

Using plain language for critical instructions: Saying “Turn left” instead of “Turn left heading 220” might be understood as a general directive rather than a precise instruction.
Using non-standard terms: Using the word “taxiing fast” instead of “exceeding taxi speed” might not convey the severity or specific nature of the situation.
Being vague or omitting critical information: Saying “Watch out for that aircraft” without specifying the direction or nature of the potential conflict can lead to confusion.

Causes of Non-Standard Phraseology

Habit and Complacency: Over time, professionals might develop habits or become complacent, leading to the occasional use of non-standard terms.
Cultural and Language Differences: In regions where English is not the native language, local terms or translations might inadvertently be used.
Stress or Fatigue: In high-pressure situations or due to fatigue, there might be a deviation from standard procedures.

Mitigating the Use of Non-Standard Phraseology

Regular Training: Air traffic controllers and pilots should undergo regular training and refresher courses to ensure they are updated and aligned with standard procedures.
Monitoring and Feedback: Regular monitoring of communications and providing feedback can help in identifying and rectifying non-standard usage.
Promoting Awareness: Making professionals aware of the risks associated with non-standard phraseology can discourage its use.
Using Technology: Implementing technologies like automated voice recognition systems can help in monitoring and alerting deviations from standard phraseology.

Non-standard phraseology in Europe

European Union

Regulation 2016/1185 introduces some deviations from the standard ICAO phraseology at the EU level:

Flight levels that are whole hundreds (e.g. FL 100, FL 200, FL 300, etc.) are to be pronounced as “Flight level (number) hundred”.
The altimeter setting of 1000 hPa is to be pronounced as “One thousand”.
Transponder codes containing whole thousands are to be pronounced as “(number) thousand”.
For transfers of communication within one ATS unit, the call sign of the ATS unit may be omitted, when so authorized by the competent authority.

United Kingdom

The UK CAA has adopted certain non-standard phraseology designed to reduce the chance of mishearing or misunderstanding RTF communications.

This phraseology is not by ICAO but is based on a careful study of the breakdown of pilot/controller communications. Some other European countries have also adopted similar non-standard phraseology.

The following paragraphs taken from the UK Manual of Radiotelephony summarise the main differences.

The word ‘to’ is to be omitted from messages relating to FLIGHT LEVELS.

All messages relating to an aircraft’s climb or descent to a HEIGHT or ALTITUDE employ the word ‘to’ followed immediately by the word HEIGHT or ALTITUDE. Furthermore, the initial message in any such RTF exchange will also include the appropriate QFE or QNH.

When transmitting messages containing flight levels each digit shall be transmitted separately. However, in an endeavor to reduce ‘level busts’ caused by the confusion between some levels (100/110, 200/220, etc.), levels which are whole hundreds e.g. FL 100, 200, 300 shall be spoken as “Flight level (number) HUNDRED”. The word hundred must not be used for headings.

Examples of the above are:
- “RUSHAIR G-BC climb flight level wun too zero.”
- “RUSHAIR G-BC descend to altitude tree thousand feet QNH 1014.”
- “RUSHAIR G-BC climb flight level wun hundred.”
- “RUSHAIR G-BC turn right heading wun wun zero.”

Non-standard North American phraseology

A particular example of non-standard phraseology which is in regular use in North America is the instruction “taxi into position and hold”, (which has the same meaning as the ICAO standard phrase “line up and wait”).

This can be confused with the old ICAO phraseology “taxi to holding position” (which means taxi to, and hold at, a point clear of the runway).

Use of this non-ICAO standard phraseology is fail-safe in North America, but in Europe can lead to an aircraft taxiing onto the runway when not cleared to do so. To overcome this problem ICAO has amended its phraseology to “taxi to holding POINT”.

Non-standard Phraseology in Abnormal/Emergency Situations

It is often necessary for pilots and controllers to revert to non-standard phraseology in abnormal and emergencies.

The extent to which this occurs, and leads to effective communication, will depend upon the quality of both speech delivery and language proficiency of those involved.

Neither Standard Nor Approved

Sometimes controllers and pilots use phraseology that is neither standard nor approved by a national civil aviation authority.

The reasons for this may be various, e.g. poor knowledge or training, a phrase that is rarely used, personal experience or preference, etc.

The main difference between approved and non-approved phraseology is that the latter has not undergone any safety impact assessment.

There are several major risks associated with such phraseology:

The other party may not hear the message correctly. When standard phraseology was developed, special attention was given to choosing words and phrases that sound distinctly different and therefore cannot be confused under any readability circumstances. When replacing standard phraseology with their people do not perform thorough research as to whether their custom phrase may sound similar to another one.
The other party may not understand the message. This may be due to e.g. using phrasal verbs or other words that are not commonly known. The different levels of knowledge of the English language contribute to this as well.
The message may be ambiguous, i.e. the transmitting person may mean one thing and the other one may understand something else, as was the case with the vehicle incursion in Perth in 2012 or an incident in Toronto in 2016.

Examples of unofficial “phraseology” (the list is not exclusive):

Ten/eleven thousand (instead of one zero thousand or one one thousand). This was considered by the investigation to be the cause of an incident in 2011
Read you five by five (or any other X by Y combination) instead of Reading you (number)
ARL10 is pronounced as Airline ten (instead of Airline one zero)
Light chops, smooth ride, what’s the ride, instead of phrases containing the word turbulence
Affirmative instead of affirming (note that affirmative may, under certain low-readability circumstances, be confused with negative due to having the same ending)
Double and triple (instead of pronouncing each digit separately)
Keep heading, speed, etc. (instead of continuing or maintaining)
Up and down instead of climbing and descending
Pronouncing 9 as nine instead of niner may lead to confusion with 5
Amending clearance starting with While we wait (which can be understood as line up and wait), was considered a contributor to a runway incursion event
Use take-off instead of departure in situations where no take-off clearance is issued or canceled. This has caused several occurrences, e.g. an accident in 1977 and an incident in 2008
A description of an ACAS maneuver instead of the standard TCAS RA. Such a description may be lengthy, unstructured, incorrect, or incomplete, and therefore the controller may request repetition or clarification