Aerospace Medicine Technical Reports

FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-08/21

Title and Subtitle: Pilot English Language Proficiency and the Prevalence of Communication Problems at Five U.S. Air Route Traffic Control Centers

Report Date: October 2008

Authors: Prinzo OV, Hendrix AM, Hendrix R

Abstract: Air traffic control (ATC) voice communication is built upon a readback-hearback loop: Controllers send messages to pilots who listen and then recite back their contents. Successful communication requires participants to conduct and understand ATC radiotelephony in the same language. Since inadequate language proficiency was involved in some aviation accidents (e.g., 1996 Charkhi Dadri; 1995 Cali; 1977 Tenerife), the International Civil Aviation Organization (ICAO) is requiring its contracting states to ensure that ATC personnel and flight crews are proficient communicators of the English language when operating in airspace where the English language is required.

Within the U.S., data are lacking concerning the prevalence of ATC communication problems attributable to the production and comprehension of English. This report presents communication problems involving readback errors, breakdowns in communication, and requests for repetition by commercial airline pilots.

An analysis was performed on 50 hrs of air-ground transmissions provided by five ARTCCs. Each controller transmission was paired with its readback. Each readback was scored for accuracy (Prinzo, Hendrix, & Hendrix, 2007). The ICAO Language Proficiency Rating Scale guided encoding English language proficiency. Aircraft call signs were used to classify transmissions by aircraft registry (U.S., Foreign) and language (English, Other), forming three groups: Foreign-English, Foreign-Other, and U.S.-English. Communications were analyzed from 832 aircraft (74% U.S., 26% Foreign) for 4,816 pilot transmissions (78% English, 22% Other).

Of these aircraft transactions, 23% contained one or more communication problems. MANOVA and ANOVA revealed that when English was the primary language or pilots flew U.S. aircraft, there were fewer communication problems, less time was spent on frequency, and fewer messages were transmitted than when pilots flew foreign aircraft or the primary language was not English.

A chi-square analysis of 276 communication problems revealed that English language proficiency was a factor for 75% communication problems among the Foreign-Other aircraft and 29% involving U.S.-English aircraft. The communication problems of the Foreign-English aircraft were excluded because of their joint classification with aircraft registry and language. Using the ICAO language proficiency scales as a guide revealed pronunciation (pilot accent) and fluency as contributing to communication problems among pilots of Foreign-Other registry aircraft.

Among the U.S.-English flights, although fluency was a factor, it signaled uneasiness with an ATC instruction. The location of pauses, “AHs” and “Ums,” might differentiate less proficient speakers (markers appear within a phrase or cause) from more proficient speakers (markers appear before and after a phrase or clause). ICAO required that its language proficiency standards be implemented in March 2008.

Being able to speak Aviation English may be necessary, but it may not be sufficient in limiting communication problems. Language proficiency requirements beyond the minimum specified by ICAO must be realized if communication problems are to decline.

Key Words: Communications, ATC Communication, Air Traffic Control

No. of Pages: 32


Last updated: Friday, June 1, 2012