Category Archives: Language

Limitations and Dangers of the use of the English Language in Aviation Communications

Limitations and Dangers of the use of the English Language in Aviation Communications

AVIA 300 Aviation Safety – Week Seven

John Kirk


This paper is an overview of the limitations and dangers of the use of the English language in aviation communications.  Although the internationally agreed language in the air has been English since 1951, there was little research into the safety implications of this policy. Later, after too many examples of accidents where language difficulties were factors, research took place. The major results of that research are examined. Examples of aircraft accidents where language difficulties were a factor are examined. Some examples of regional dialectic differences are highlighted. Finally conclusions and recommendations are listed.


The KLM/ Pan Am disaster at Tenerife airport (Los Rodeos) on March 27th 1977 was the worst accident in aviation history in terms of loss of life. A major contributory factor was the failure in communication using the English language. The KLM aircraft had taken off without take-off clearance, in the absolute conviction that this clearance had been obtained, which was the result of a misunderstanding between the tower and the KLM aircraft.

This misunderstanding had arisen from the mutual use of usual terminology, which gave rise to misinterpretation. In combination with a number of other coinciding circumstances, the premature take-off of the KLM aircraft resulted in a collision with the Pan Am aircraft, because the latter was still on the runway since it had missed the correct intersection.

International Agreement

One of the outcomes based on this and many other accidents and incidents was the introduction of Language Proficiency Requirements (LPR) by the International Civil Aviation Organization (ICAO) in 2004. ICAO grades English language performance on a scale from 6 (highest) to 1 (lowest):

Level 6:


Level 5:


Level 4:


Level 3:


Level 2:


Level 1:


Formal evaluation of language proficiency was required as of March 2008, but ICAO effectively extended the deadline to 5th March 2011. In the USA the Code of Federal Aviation Title 14 (CFR) Part 61 requires that pilots must be able to read, speak, write and understand the English language. This proficiency is recorded on a pilot’s license. The current FAA standards for English language proficiency are laid out in Advisory Circular AC 60-28, English Language Skill Standards reproduced at Appendix 2.

Testing Standards

Whilst the ICAO recommendations determines the standards to be achieved, there is little information available on the reliability and accuracy of testing methods. A survey of aviation English TESTS Alderson, (2010) states, inter alia, “We conclude that we can have little confidence in the meaningfulness, reliability, and validity of several of the aviation language tests currently available for licensure.” (P. 1) This raises considerable concern, as the lack of creditable standards for testing creates a shortfall in the intention in the ICAO document. See Appendix 1 for the standards to which testing should be directed.

Even native English speaking aviators and air traffic controllers must pass knowledge tests which include standard phraseology which must be included in their initial training. In the USA, check airmen are required to certify English proficiency per the Practical Test Standards (FAA). If there is any doubt, a candidate must be referred to an aviation safety inspector (ASI) at the local FAA Flight Standards District Office. In the United Kingdom, a signatory to the Joint Airworthiness Agreement, a similar requirement has been established with the major difference that there are two levels of testing, formal and informal. English Language Schools accredited to the English Council are nominated for formal examination for levels 5 and below, and UK CAA examiners and some others are accepted for level 6.

Specific Example of Dialectic and Foreign Speaking Difficulties

Mention has already been made of the Tenerif accident as perhaps one of the best examples of a non-native English speaker’s difficulty. The phrase “We are now at takeoff,” is the key to understanding the difficulties. In the pilot’s native Dutch, the present progressive tense of a verb is expressed by the word “at” in English plus the infinitive of the verb, “takeoff.” The obvious interpretations of that phrase are:

  1. “We are holding at the takeoff position,” (which is the meaning the Spanish speaking air traffic controller assumed,)
  2. “We are in the act of taking off,” i.e. actually moving.

It is the second meaning that the Dutch pilot assumed the controller understood. The ICAO recommendations address this specifically where level 4 proficiency assumes, “Basic grammatical structures and sentence patters are used creatively and are usually well controlled. Errors may occur, particularly in unusual or unexpected circumstances, but rarely interfere with meaning.” Clearly, a fuller understanding of English grammar, as opposed to word-for-word translation of another native language, is key to success as in this example.

Second Example, voice warning systems

On November 13, 1993, a McDonnell Douglas MD-82 jet crashed in Urumqi, China, while it was approaching to land, killing 12 and injuring 24. Heard on the Cockpit Voice Recorder (CVR) was the last words of the native Chinese speaking pilot who said, “What does ‘Pull-up, pull-up” mean?” It is almost impossible to believe that there should be such lack of knowledge of audio warnings, especially to anyone outside of aviation.

Sources of Errors

The sources of communication error:

  1. Phonology – language sound patterns, prosody, e.g. speech rate, stress, intonation, pauses.
  2. Syntax – language word patterns, sentence structure.
  3. Semantics – language ‘meaning patterns’.
  4. Pragmatics – language in context, situational influences on meaning.

Considering numbers in voice communication conventional wisdom would say that as the digits are particularly standardized there should be little difficulty with regional language barriers. However, that assumption proves to be incorrect. Dr. Bürki-Cohen (Bürki-Cohen, 1995) researched the particulars of how complexity affects pilot recall. ATC normally are required to state digits individually, such as an altitude of 17,000 has to be stated as “one seven thousand.” ATC regulations allow controllers to add grouped digits after the individual digits were stated, i.e. “one seven thousand, seventeen thousand.” It was believed that this would aid retention and accuracy. However the research showed there was little difference with or without grouped digits added. Indeed, analysis showed an advantage of the restated format over the grouped format at higher complexity levels. It is axiomatic that increasingly complex verbal instructions carry a commensurate increase in the risk of misunderstanding.


If it is hoped to reduce the human factors accident rate more attention needs to be paid to language. The higher standard to which the international aviation community should aspire must constantly strive to ensure that the recommendations of ICAO in the area of English Language Proficiency should be achieved.


The following recommendations are suggested:

  1. Establish accredited schools for teaching English to all in aviation,
  2. Set clearer standards for testing and awarding all levels of proficiency,
  3. Research current “standard” phraseology, particularly differences between native English speaking nations, to harmonize those standards, reduce or eliminate ambiguity – particularly where cultural influences effect the use of language,
  4. Study pronunciation, and publish standard pronunciation for those words which exist in standard phraseology.


AC 60-28 CHG 1 Appendix 1


The following English language proficiency standards* must be met by the applicant and evaluated by the designated examiner or aviation safety inspector (ASI) when determining if the applicant meets the English language eligibility requirements of 14 CFR parts 61 and 63:

1.            PRONUNCIATION. Assumes that English is not the applicant’s first language and that the applicant has a dialect or accent that is intelligible to the aeronautical community. Pronunciation, stress, rhythm, and intonation are influenced by the applicant’s first language, but only sometimes interfere with ease of understanding.

2.            STRUCTURE. Relevant grammatical structures and sentence patterns are determined by language functions appropriate to the task. Basic grammatical structures and sentence patterns are used creatively and are usually well controlled by the applicant. Errors may occur, particularly in unusual or unexpected circumstances, but rarely interfere with meaning.

3.            VOCABULARY. The applicant’s vocabulary range and accuracy are usually sufficient to communicate effectively on common, concrete, and work-related topics. The applicant can often paraphrase successfully when lacking vocabulary in unusual or unexpected circumstances.

4.            FLUENCY. The applicant produces stretches of language at an appropriate tempo. There may be occasional loss of fluency on transition from rehearsed or formulaic speech to spontaneous interaction, but this does not prevent effective communication. The applicant can make limited use of discourse markers or connectors. Fillers are not distracting.

5.            COMPREHENSION. Comprehension by the applicant is mostly accurate on common, concrete, and work-related topics when the dialect, accent, or variety used is sufficiently intelligible. When the applicant is confronted with a linguistic or situational complication or an unexpected turn of events, comprehension may be slower or require clarification strategies.

6.            INTERACTIONS. Responses by the applicant are usually immediate, appropriate, and informative. The applicant initiates and maintains exchanges even when dealing with an unexpected turn of events. The applicant deals adequately with apparent misunderstandings by checking, confirming, or clarifying.

* Level 4 Rating Scale adopted from the ICAO Language Proficiency Rating Scale found in ICAO Document 9835 and the attachment in ICAO Annex 1.


Manual on the Implementation of the ICAO Language Proficiency Requirements – Doc 9835-AN/453

World Englishes, Vol. 23, No. 3, pp. 451–470, 2004. 0883–2919 Fatal miscommunication: English in aviation safety ATSUSHI TAJIMA

The challenge of regional accents for aviation English language proficiency standards: A study of difficulties in understanding in air traffic control–pilot communications. T. Tiewtrakul and S.R. Fletcher Ergonomics Vol. 53, No. 2, February 2010, 229–239

A survey of aviation English tests J. Charles Alderson, Language Testing 27(1) 51–72 2010 DOI: 10.1177/0265532209347196

An Analysis of Tower (Ground) Controller-Pilot Voice Communications. Final Report No. DOT-VNTSC-FAA-95-41

Bürki-Cohen, J. (1995). Say Again? How Complexity and Format of Air Traffic Control Instructions Affect Pilot Recall. In 40th Annual Air Traffic Control Association Proceedings, September 1995, 225-229.

Bürki-Cohen, J. (2003). Evidence for the Need of Realistic Radio Communications for Airline Pilot Simulator Training and Evaluation. In Proceedings of the International Conference Simulation of the Environment, Royal Aeronautical Society, 5-6 November, London, UK.

AC 60-28, English Language Skill Standards

Crew Resource Management            Date: 1/22/04            AC No: 120-51E TRAINING$FILE/AC120-51e.pdf